LIBRARY OF THE UNIVERSITY OF CALIFORNIA. Class THE BUILDING AND OENAMENTAL STONES OF GREAT BRITAIN AND FOREIGN COUNTRIES. a A TEEATISE ON THE , BUILDING AND ORNAMENTAL STONES OF GREAT BRITAIN AND FOREIGN COUNTRIES, ARRANGED ACCORDING TO THEIR GEOLOGICAL DISTRIBUTION AND MINERAL CHARACTER, WITH ILLUSTRATIONS OF THEIR APPLICATION IN ANCIENT AND MODERN STRUCTURES. BY EDWARD HULL, M.A., F.R.S. I Director of the Geological Survey of Ireland ; Profeftor of Geology in the Royal College of Science, Dublin ; Matter in Engineering (Hon. Caut.), Dublin Univertity ; Honorary Member of the Edinburgh, Glasgow, Dudley, and Midland Geological Societiet ; Fellow of the Geological Society of London. MACMILLAN AND CO. 1872 / [All rights reserved] PREFACE. THE Council of the Royal College of Science, Dublin, having assented to a course of lectures to be delivered during the evenings of 1870-71, on Building and Ornamental Stones, I commenced the necessary preparation. Circumstances, however, occurred to prevent the delivery of the course; but while arranging the materials, the subject seemed to grow in interest, and ultimately developed into the form in which it is presented to the reader. During the progress of my investigations I made the discovery that there is no work in our lan- guage especially devoted to the subject itself; a discovery which is the ground on which I now come before the public. Building and Ornamental Stones are, it is true, to a certain extent described in many of the works on masonry, architecture, and engineering, but not in a complete manner, nor with much attempt at scientific arrangement. The 224207 IV PREFACE. nearest approach to such a work as seems to me to be required is the excellent book of Mr. G. Wilkinson, M.E.I. A., &c., on the 'Ancient Architec- ture and Practical Geology of Ireland;' and if its author had extended its scope so as to embrace the British Islands, and the more important build- ing materials of other countries, my task would have been unnecessary. In some of the works on Architecture such as Gwilt's elaborate volume and in many scattered Journals of Societies, notices and descriptions of Building and Ornamental Stones are abundantly distributed. We have, also, an admirable French work, ' Technologie du Batiment/ in two volumes, by M. T. Chateau, full of correct details regarding the nature and uses of such materials, especially as they are found in France; but while this latter work is in a language differing from our own, and fails to give sufficient details regarding British stones for British readers, the former works are, for various reasons, not easily available. A great difficulty which at the outset presents itself in arranging materials on a scientific, as well as a practical, basis, is to be found in the absence of a generally received mode of classification of rocks, PREFACE. V and a system of nomenclature founded both on origin and composition. Thanks to the labours of microscopists, and partly in consequence of our in- creasing knowledge regarding the phsenomena at- tending the origin of rock-masses, we are gradually attaining truer views than once prevailed regarding the basis of classification. The use of the micro- scope has now come to be regarded as absolutely essential to the determination of the composition of igneous and metamorphic rocks, and in such ques- tions exceeds in value even chemical analysis. As an example of the necessity of microscopic examina- tion, I may mention a case which recently came under my own observation. Amongst certain Silurian strata in Clare Island, off the western coast of Ireland, is a dyke of trap-rock, of a dark and dense appearance, strongly resembling basalt. On submitting a slice to microscopic examination, how- ever, it turned out to be a silicated felstone, which owed its basalt-like appearance to innumerable black crystalline grains of magnetite invisible to the naked eye. The arrangement which has been adopted in this essay follows to a great degree that of the English edition of B. von Cotta's valuable work, ' Eocks VI PREFACE. Classified and Arranged,' which, with Bristow's 'Glossary of Mineralogy,' is an indispensable hand- book to every practical geologist. One of the crying evils of the present day is the erection of ephemeral buildings either for dwell- ing-houses or other purposes On the other hand, the superior advantages in the long run of substan- tial structures scarcely admits of an exception. A city which, like Chicago, has been raised up with mushroom-speed, is laid low by fire in a few hours ; while solid buildings of stone are capable of resist- ing the effects both of fire and time, depending in a greater or less degree on their solidity. This observation extends to all classes of build- ings alike. The cottage of the labourer, or his tenement in a single story or 'flat,' ought to be constructed with a view to decency as well as health ; while houses of a higher class, unless con- structed with substantial walls, well-fitting doors and windows, sound roofs, and proper drainage, are liable to become constant sources of discomfort and outlay. As regards public buildings, the credit of the whole community is at stake if they are not in keeping with the importance, or commercial pros- perity, of the city they are intended to adorn. PREFACE. v If such be the principles which should guide us in the erection of edifices for secular or domestic use, how much more are we bound to take care that those consecrated to the worship of Jehovah should not be unworthy of a destiny so sacred and noble. During the last century, and part of the present, the full appreciation of our responsibility in this respect seems to have been dormant. Now, however, a more proper feeling has been resusci- tated; and the House of God, instead of being the last, is generally the first, object of care and veneration. Such were, apparently, the views of those who, in an age generally unenlightened, devoted all their skill and means to the erection of churches which are objects of admiration in our own day. The motives which impelled men to erect the noble minsters, cathedrals, and parish churches of the twelfth and three succeeding centuries, may not always have been of the purest kind, or free from superstition ; nevertheless, the founders and archi- tects had clear ideas of this duty that we should offer unto God of the best of our substance, and that man should not dwell in ' habitations of cedar ' while the House of God was mean in form, or VL11 PREFACE. crumbling into decay. That such a spirit has been happily revived amongst ourselves is attested, both by the restoration of the venerable churches of former days, and the erection of modern ones in a style not unworthy of their sacred purpose ; and amongst the foremost of those who have taken a prominent part in this good work are two citizens of this metropolis, whose names will ever be had in remembrance ; members of a Church despoiled and cast off by the State, but men of whom any State or any Church might well be proud 1 . EDWARD HULL. / DUBLIN, July i, 1872. 1 Sir Benjamin Lee Guiness, who restored St. Patrick's Cathedral at a cost of 150,000?. ; and Mr. Henry Roe, who is now engaged in the restoration of Christ Church Cathedral, Dublin. CONTENTS. PAKT I. CHAPTER I. PAGE Introductory observations ...... 1 Arrangement of the subject ...... 4 General classification of crystalline rocks .... 5 General classification of geological formations ... 6 CHAPTER II. Classification of British Strata 17 PAKT II. GRANITIC ROCKS. CHAPTER I. Granite and Granitoid Rocks. Nature and composition . . . . . .20 Foliated Granite 23 Graphic Granite . . ... . . . . .23 Geological age _. , J . . . . -. . .24 Mode of occurrence . . . . . V . .24 Mode of formation, irruptive and metamorphic , . .25 Chemical composition . .. ... . . .27 Varieties of Granite, and examples . . . . .29 Specialities. . _ -\ ' ; ' . ' '* . . . . .30 CHAPTER II. Granites of Scotland. Peterhead 32 Aberdeen and Kirkcudbrightshire . . . . .33 Strontian, Argyleshire, Isle of Arran, Isle of Mull, &c. . .34 X CONTENTS. CHAPTER III. Granites of England and Wales. PAGE Dartmoor, Devonshire, with illustrations of use . . -35 Cornwall, with illustrations of use . . . . -35 The Channel Islands 37 Mount Sorel, Leicestershire . . . . . .37 Lundy Island . . . . . . . . .38 Shap, Cumberland . . . . ' ., . . .38 CHAPTER IV. Granites of Ireland. Donegal . . . .39 Galway .......... 41 Wicklow, Wexford, and Dublin, with illustrations of use . 42 Mourne .......... 44 Newry and Slieve Croob, with illustrations of use . . . - . 44 Carlingford . . . ' . , t . 45 Belleek, use in china manufactory . . . . . 46 Arranmore and Tory Islands . . .. , . . : .46 CHAPTER V. Continental Granites. France, with illustrations of use . r . . . . .47 Italy, with illustrations . . . .'. . . .47 Other Granitic districts, The Alps, Pyrenees, and Germany . 49 Granite of Scandinavia, with illustrations of use . . .51 Egyptian Granite, with illustrations . -. , * . 51 CHAPTER VI. Granites of America. North America . . . . . . ' , ' . 57 Canada, &c. . . . . .... .57 India 58 CHAPTER VII. Syenite. Composition ; how distinguished from Granite and Diorite . 59 Varieties . . .=? .' / ' . ..'' . . . . 60 Syenites of England . i,- . . ". . .60 Syenites of Wales, Ireland, and Scotland . . . . 61 The Continent . . . . . . .61 Canada 61 Nova Scotia 62 CONTENTS. x PART III. PORPHYRITIC ROCKS. CHAPTER I. Porphyries. PAGE Origin and meaning of name . . . . . .63 Varieties of Porphyry ... . . 63 Chemical analysis . . . . . . . .64 G-eological ages ... 65 CHAPTER II. British Porphyries. Scotland . . .67 England and Wales, with illustrations of its use . .67 Ireland . .71 CHAPTER III. Porphyries of the Continent. Sweden, with illustrations of use . . . . v .72 Germany . ......... 72 France and Belgium . . . . . . . .73 Greece, with illustrations of use , . . . . .73 Corsican Porphyry . . . . . . . .74 CHAPTER IV. Egyptian Porphyry. Egyptian Porphyry, with illustrations of use . . .75 Concluding observations . . . . . . .77 PART IV. GREENSTONE ROCKS. CHAPTER I. Diorite, Diabase, Minette, &c. } generally called Greenstones. Origin, and general geological distribution . . .79 Greenstone Group . . . . . . . .80 Diorite; composition, mode of occurrence . . . .80 Analyses of specimens . . . . . . . .82 Gabbro .82 Diabase . . . /' . ... .82 Minette, or Mica-trap . * . , . ' . . .83 Xll CONTENTS. CHAPTER II. Augitic Rocks. PAGE Basalt, Dolerite, and Melaphyre . . . . . .85 Vertical dykes 87 Intrusive sheets . . . . . . . .87 Tabular sheets, Antrim . . *,-.' . . . .88 Chemical analyses .. . . . . . . . .89 Basalt, &c., of foreign countries ... . . . .89 Art Illustrations of the use of Basalt, &c 90 Melaphyre of Ternuay 91 Special uses of Basaltic rocks . ... . . .91 CHAPTER III. Lavas. Trachytic Lavas, origin and distribution . : . -. . 93 Application of Lava to building purposes . ^ . . . 95 Its uses in ancient times in Italy . . . . .95 PAET Y. SEEPENTINOUS ROCKS. CHAPTER I. Varieties, composition and origin . . . . .97 Chemical composition . . . . . . .98 Serpentines of England and Wales, with applications in the arts . 100 Anglesea ''...- .102 Ireland, with applications . . . . . ." . 102 Scotland ' .- , . 104 CHAPTER II. Serpentine of the Continent. Saxony 105 Moravia . . . . . . ... .105 The Vosges Mountains . . . , . . . .* .105 The Alps . . . ; : 'Vi . . . . ' .105 France . . . ; f. , . 106 Italy, chief varieties, with illustrations of use .. J .106 Greece . - . ,-* . . , ... .: . .108 Egypt . ;. . ; , 109 Spain, with illustrations of use 109 Ural Mountains 109 India. . 110 CONTENTS. xiii CHAPTER III. Serpentines of the American Continent. PAGE Canada, Eozonal Serpentine . . . . .111 Newfoundland . . . . . . . . .112 United States 112 PAKT VI. CHAPTER I. Marble. Definition of the term, and general character . . .114 Marbles of Great Britain . . . . . .115 Devonian marbles, with illustrations of use . . . .116 Purbeck and Sussex marbles . . . . . .117 Derbyshire, with illustrations . . . . . .119 Anglesea 120 Isle of Man, with illustrations 120 Ireland, with illustrations . . . . . . .120 Scotland . . 123 CHAPTER II. Continental Marbles. Italian marbles, with illustrations of use . . . .126 Carrara quarries, and statuary marble . . . .128 Island of Elba 130 Bardiglio, and other coloured marbles . . . .131 Verona, with illustrations of use . . . .132 Marble of Monte Candido, its use in Milan Cathedral . . 133 List of marble quarries in the Apuan Alps . . .134 Greece, Parian and Pentellic marbles, their applications in ancient sculpture . . . . . .136 Sicily .141 Corsica, Florence, and Belgium . . . . . .141 Spain, with illustrations . *-.-..; .. . .. * 142 Portugal ..;..' -'"'%. . . . . .143 Gibraltar . 143 Phrygian marble, with illustrations . . . . .143 CHAPTER, III. Marbles of the American Continent. Canada . . . . . . . . . .145 Nova Scotia, &c. . . . . . . . .145 United States 146 XIV CONTENTS. CHAPTER IV. Marbles of other Countries. PAGE Egypt and Brecciated marble . . . .148 Oriental Alabaster, &c. . . . . . . .149 Palestine . ... . . ' 150 Persepolis . . . . . . . . . .151 India . , . . , . . . . 152 CHAPTER V. Art Illustrations in Marble historically treated . . . 153 PAET VII. CHAPTER I. Alabaster. Composition and mode of occurrence . . ' . . .159 Anhydrite . . . . ... . . .-., 160 British Localities . . "',. , '" . 161 Ireland . . . . . . . . . .' . . 163 France . , . -. . ... . . . ' '. 163 Spain . . . . . ... . . 164 Germany, Switzerland, and Austria . . .... 164 Italy, with art illustrations . . . . . .165 CHAPTER II. British Possessions of North America . . . . . 167 United States . 167 Specialities . . . . . - . . . 168 PAET VIII. THE RARER ORNAMENTAL STONES. CHAPTER I. Fluor-spar, composition i : ' ,'- V T : _.. ^ . . . .169 British sources, with art uses . . . . .169 Continental, with art uses . .... .170 American . . . . . . . .171 Specialities, origin and mode of occurrence . . . .171 CONTENTS. XV CHAPTER II. Quartz Group. PAGE (a) Rock-crystal, smoke quartz, rose quartz. . . .175 (6) Amethyst . . . . . . . .175 (c) Chalcedony . . . . . . . .175 (d) Agate . .... 176 (e) Jasper Bloodstone . . . . . . .176 (/)0pal . . 177 (g) Aventurine . '.. 179 CHAPTER III. Art Illustrations. Historical sketch, Italian sculpturing . . . . .180 Examples . . . . .- . . . .182 Russian sculpturing in siliceous stones . . . .185 PAET IX. CHAPTER I. Malachite. Composition and character . . . . . .187 Continental and foreign sources . . . . . .188 Art illustrations ...... 190 PAET X. CALCAREOUS GROUP OF BUILDING STONES. CHAPTER I. Limestones. Mode of occurrence of limestones, geologically considered . 191 Limestone-builders of each geological period . . . 193 CHAPTER II. British Limestones. Carboniferous period . 195 XVI CONTENTS. CHAPTER III. Magnesian Limestones. PAGE Permian . . ... . . . . .198 General observations . i . . . . . .201 Illustrations of use ". ' ' . . * . . . . 202 CHAPTER IV. Oolitic or Jurassic. Nature of the limestones . . . . . .204 Structure and specialities . . . , . . .205 Geological position of best building stones . . . .206 Inferior Oolite, range and illustrations of use . . .206 Great or Bath Oolite, range and illustrations . . . 207 Coralline Oolite, use in Oxford . . . . . .211 Portland Oolite, illustrations of use (London, &c.) . .212 CHAPTER V. Cretaceous Limestone, or Chalk. Its geological distribution . . . -. . . 217 Chalk as a building material, with illustrations . . .218 CHAPTER VI. Limestones of Ireland and Scotland. Geological position and characters . . ... 219 Architectural illustrations . . . . , .220 Petrological details . .221 Chalk formation . . . .222 Limestones of Scotland . . . - . . . . 222 CHAPTER VII. Continental Limestones. France and Belgian . . . . . . * 224 (a) Silurian and Devonian . . . .224 (b) Carboniferous '',.;'.. . . . . . 225 (c) Triassic ' . . . ' .' . . ., . 225 (d) Jurassic ...... . 225 Caen-stone, &c., with Illustrations of use . . 226 (e) Cretaceous limestones . . . . . .231 (/) Tertiary limestones, with architectural illustrations 232 CONTENTS. XV11 PAGE Prussia, Carboniferous limestone . . . . .234 Wiirtemberg, various formations . . . . .234 Spain .......... 235 Italian limestones 235 Africa, Asia Minor, &c., Nummulite limestones . . .236 PAET XL SANDSTONE GROUP OF BUILDING STONES. CHAPTER I. Siliceous Freestones. Geological formations . . . . . . .238 Composition and texture . . . . . . .238 Chemical analysis . . . . . . . .240 Colour 241 Forms of stratification . . . . . . .242 CHAPTER II. Sandstones of England and Wales. (a) Old Red sandstone, or Devonian . . . .244 (b) Carboniferous sandstones and Grits , . . .245 Flagstones of Lower Coal-measures . . . .246 (c) Coal-measure sandstones 247 (d) Permian sandstones . . . . . . .251 (e) Triassic, or New Red sandstones . . . .252 Lower Keuper sandstone principal quarries . .253 Sandstones newer than the Trias . . . .258 (f) Yorkshire Jurassic sandstones ..... 258 (g) Kentish Rag, with architectural illustrations . .259 CHAPTER m. Sandstones of Scotland. (a) Old Red sandstone . ... * . . 261 (b) Carboniferous sandstones . . . . . 263 Principal quarries, with illustrations of use .. . . 264 CHAPTER IV. Sandstones of Ireland. (a) Old Red sandstone 266 (b) Carboniferous sandstones and Flags . . . .267 (c) New Red sandstone Bunter 269 (d) Lower Keuper sandstone of Scrabo Hill . . . 269 b XV111 CONTENTS. CHAPTER V. Continental Sandstones. PAGE France ..*... . . . . . .271 Luxembourg . ... . . . . . . 272 Germany . . . . . . . . . 272 Switzerland . V . '.'-' 273 Italy . . . . .274 CHAPTER VI. Building Sandstones of India . . . . . .275 CHAPTEE VII. Sandstones of North America. Canada . . . . . , . . 277 United States 278 PAET XII. TUFACEOUS AND VOLCANIC BUILDING STONES. CHAPTER I. Travertine. Italy ... .279 Architectural illustrations . . . -. . .. . 280 CHAPTER II. Volcanic Tuff, or Peperino. Nature and composition . . . . , . . . 283 Laterite of India . 283 PAET XIII. SLATES. CHAPTER I. Clay Slate. Cleavage, its nature, and origin . . . , . .285 Geological formations of slate rocks 287 Uses of slate ......... 289 Density, strength, and analysis of slate . . . .289 CONTENTS. XIX CHAPTER II. Slates of Great Britain. PAGE (a) Cambrian slates 292 (6) Lower Silurian slates . 292 List of slate quarries in Wales 293 (c) Devonian slates of Cornwall, &c 295 (d) Lake districts 296 () Scotland 296 (/) Ireland /.. . .297 CHAPTER III. Slate Rocks of the Continent. France .... 299 Belgium 299 Germany 300 Austria, &c 300 Italy .... .300 Sweden and Norway ..... .301 CHAPTER IV. Slate Rocks of the American Continent. Slate rocks of Canada . . . . . . . 302 Slate rocks of United States . 303 PAKT XIV. CONCLUDING OBSERVATIONS. CHAPTER I. On the physical and chemical characters of Building Stones . 304 CHAPTER II. On the selection of Building Stones, with special regard to climate and the nature of the atmosphere . . . 311 APPENDIX. Weights per cubic foot of British Building Stones . 317 LIST OF ILLUSTRATIONS. PAGE FORUM ROMANUM, SHEWING THE EXTENT OF THE RECENT EXCAVATIONS Frontispiece PIAZZA OF ST. MARK, VENICE 55 MAGNIFIED SECTION OF TRACHYTE FROM PUT CAPUCHIN 94 APPROACH TO CARRARA QUARRIES 125 INSCRIPTION. TO SIR CHAELES LYELL, BART., D.C.L., F.K.S. MY DEAR SIR CHARLES, To you, who, amongst the first, encouraged me to undertake the preparation of this little Work, I now heartily inscribe it ; as a small acknowledg- ment of the benefits I have derived from the perusal of your scientific writings, especially your ' Principles of Geology/ and of the uniform friend- ship with which you have honoured me during many years of my life as a migratory Geologist. Ever faithfully yours, E. H. August, 1872. PART I. CHAPTEE I. INTKODUCTOKY OBSEEVATIONS. THE materials used in building and architectural decoration are divisible into two classes, the artificial and the natural ; and, as the latter is incomparably superior to the former, artificial materials are only admissible when those offered by nature are beyond the reach of the architect, or the means at his disposal. The general use of artificial materials has stamped with an aspect of comparative meanness the street architecture of many large cities and towns, such as London itself, together with Dublin, Birming- ham, and Manchester; while, on the other hand, the employment of stone in the construction of the dwelling-houses, as well as the public buildings, has imparted to the cities of Edinburgh, Aberdeen, Glasgow, Brussels, Paris, and Rome a character of solidity and beauty which forces itself on the at- tention of the most careless observers. B OBSERVATIONS. All persons of taste must, with Mr. Kuskin, de- plore the manner in which modern English towns are run up on * the brick-and-plaster system/ pre- senting interminable lines of streets, in which every house is an exact counterpart of its neighbour, except perhaps in size, and in which one street resembles another as much as two of the bricks with which they are built. The town of Crewe in Cheshire, built within the last half century, and now containing a large number of inhabitants, is the most perfect specimen of a modern brick town built upon the strictest principles of utility without taste; and yet, that it is possible to make use even of red brick with an eye to beauty, is sufficiently clear from the examples we have in the cities of Chester and Shrewsbury, and the quaint and picturesque old farms and manor-houses which bedeck the shires of Chester and Salop them- selves. In contemplating these monotonous lines of brick walling, the only relief which is afforded to the mind is by the reflection that, owing to the flimsy manner in which they have been built, and the badness of the material itself, they cannot last for a lengthened period ; and that they may possibly be replaced by other structures, in which some slight regard for appearance may be exhibited. I here wish to anticipate the reply, that small INTRODUCTORY OBSERVATIONS. 3 and mean houses are necessary as dwellings for the working classes. Such a defence of the system here condemned is inadmissible in presence of the examples of Glasgow and Edinburgh. By the em- ployment of the system of flats where each family has its own door in a building common to several houses of lofty and substantial proportion may be rendered available for persons and families receiv- ing weekly wages. In this way the fine public buildings which are to be found amongst all our large towns would not necessarily present such a frightful contrast to the meaner architecture of the streets ; but a fitting harmony of effect would per- vade the whole of the buildings, both public and private, of cities and towns. The metropolis of the British Empire itself is a conspicuous example of a city in which structures of the grandest pro- portions, and of elaborate workmanship, stand in striking contrast to streets of houses without archi- tectural beauty. It is with those materials which nature has so lavishly supplied that we have here to do ; and in the following pages the attempt has been made to deal with them in a manner which, while in ac- cordance with our scientific knowledge, does not overlook their practical application ; the illustrations of the application of most of these materials to sculpture and architecture may, it is hoped, in- B 2 4: INTRODUCTORY OBSERVATIONS. terest the general reader, while they may serve as a guide to the architect and sculptor. Arrangement of the Subject. In arranging the matter treated in this work, I have not followed any very definite order, but rather that which the subject seemed to indicate. Commencing with granite, the noblest of all rocks, I have been naturally led onwards to the allied rocks, such as syenite, porphyry, and from these to other plutonic or vol- canic rocks. After these, the metamorphic serpen- tines and marbles form a transition series through the simpler and rarer ornamental stones into those adapted for building, and of aqueous formation. Other modes of arrangement suggested themselves, such as that of adopting the mineral basis of dif- ferent rocks ; but this plan though probably more theoretically accurate would not have proved so easy of reference, or so suitable in an architectural point of view. On the other hand, a purely archi- tectural plan of arrangement appeared to be equally objectionable ; as it would have necessitated the arrangement under the general heading , of * free- stones' of such rocks as sandstones and oolitic lime- stones, which both in mineral composition and mode of formation are essentially distinct ; while, again, under the head of ' marbles,' crystalline lime- stones, serpentines, and even granites (often called ' hard marbles 7 ) would have been grouped together. INTRODUCTORY OBSERVATIONS. O It cannot, indeed, but be considered as matter for regret, that so incorrect a system of nomen- clature should still obtain in regard to building and ornamental stones ; and as our knowledge of the relations and distinctions between the rocks themselves advances, it should be our endeavour to introduce, and render current, a more exact system of naming as applied to such materials. Classification of Rocks. The classification of the crystalline rocks including granitic, plutonic, and volcanic is confessedly a question of extreme diffi- culty; and of the systems least open to objection, are that of Dr. Zirkel, who makes the varieties of felspar the basis of division, and that of MM. Durocher and Bunsen, who make the proportions of silica the basis. Without venturing on the ques- tion of the comparative merits of these two systems, that of the two eminent physicists just mentioned has the merit of being the more gene- rally available; as it is much easier to come to a conclusion in the case of the generality of these rocks whether they are rich or deficient in silica than to judge of the nature of their felspathic bases. Durocher, indeed, from an analysis of a large number and variety of forms, has arrived at the conclusion that the basic rocks (those poor in silica) have been derived from a deeper magma, or envelope, within the interior of the earth, than that 6 INTRODUCTORY OBSERVATIONS. of the acidic (or highly silicated) rocks, and that silica holds the same essential place amongst these rocks that carbon does amongst products of vege- tation. Whatever may be the intrinsic merits of this theory, it is unquestionable that the arrange- ment of the plutonic and volcanic rocks into basic and acidic is one extremely valuable as a basis for classification ; and the following arrangement and definitions of the rocks is one which the author believes will be found approximately accurate, and useful for purposes of reference in this work. He has received valuable suggestions from Messrs. A. and J. Geikie, Mr. G. H. Kinahan, and Dr. Emerson Reynolds, to which he has given due regard. General Classification and Definition of Granitic, Plutonic, and Volcanic Rocks, of most frequent occurrence. IGNEOUS AND METAMOEPHIC. GRANITIC GROUP. (Acidic highly silicated.) GRANITE. A ternary compound of quartz, felspar, and mica ; crystalline and granular. (a) Often a quaternary compound, from the oc- currence of two felspars (orthoclase and oligoclase, or orthoclase and albite) or two micas. INTRODUCTORY OBSERVATIONS. " (b) Less frequently a quinary compound. (c) PorpTiyritic granite ; when containing large distinct crystals of felspar. (d) Foliated granite ; when presenting a foliated structure, and thus verging into gneiss. (e) Eurite ; when the mica disappears or becomes very scarce, and the rock is finely crystalline- granular. Granite may be either intrusive or metamorphic, or both ; and sometimes passes into quartz-porphyry, and even felstone. SYENITE. A ternary compound of quartz, felspar, and hornblende. Syenite may be either metamorphic (Ayrshire), or irruptive. (a) When the free silica disappears, the rock passes into diorite ; this variation is not unfrequent. (b) Syenitic granite, when, in addition to quartz, felspar, and mica, hornblende appears, as in part of the Sleeve Croob range, Co. Down. IGNEOUS. Acidic, generally plutonic, but sometimes volcanic, products of past geological periods. QUARTZ-PORPHYRY. A rock of a felsitic base with crystalline grains or blebs of quartz. (a) By the disappearance of free quartz, this rock merges into a felstone. 8 INTRODUCTORY OBSERVATIONS. (6) By the appearance of mica it merges into a granite. FELSTONE. A rock of a felsitic base, more or less crystalline, or apparently compact, with a smooth conchoida], or fissile, texture ; in colour yellow, grey, green, or reddish, generally weathering white ; con- taining silica 71-81 per cent. (a) Felstone porphyry ; felstone when containing distinct crystals of felspar. (Basic deficient in Silica.) PORPHYRITE. (Quartzless porphyry.} Felsitic base of Labradorite or oligoclase, usually of a dark colour, sometimes amygdaloidal, with individual crystals of felspar. Proportion of silica, 59-61 per cent. (a) By the appearance of augite, porphyrite shades into melaphyre. MELAPHYRE. Dark-coloured, greenish, brownish, or black ; formed of felspar, augite, and magnetite intimately associated, and often only to be distin- guished under the microscope. (Melaphyre is the representative amongst the Car- boniferous and Permian rocks, of basalt and dolerite amongst the Tertiary ones.) DIABASE. A rock formed of felspar, augite, and chlorite. Magnetite is generally, or perhaps always, present : in its fresh state diabase is dark green. INTRODUCTORY OBSERVATIONS. 9 DIORITE (Greenstone). A crystalline granular rock composed of felspar and hornblende. Magnetite in small opaque crystals is generally present. (The diorites are generally found as intrusive masses amongst the older Palaeozoic formations.) MINETTE (Mica-trap). A felsitic base with much mica ; distinct crystals of orthoclase, and sometimes of hornblende, are present in some specimens. (Minette generally occurs in dykes amongst the older Palaeozoic rocks.) TEETIAEY AND MODERN VOLCANIC BOCKS. I. CRYSTALLINE. (Basic.) BASALT. A micro-crystal] ine compound of Labra- dorite, augite, and titano-ferrite or magnetite, gene- rally black or dark green. Olivine is frequently present. Basalt occurs in dykes or sheets. DOLERITE. A largely crystalline rock of the same composition as basalt. An intermediate stage is sometimes called ' anamesite.' LEUCITE ROCK. A crystalline-granular compound of leucite and augite, with magnetite, porphyritic or compact. (Mr. S. Allport has discovered this mineral in the Wolf Rock, off the coast of Cornwall.) HYPERSTHENE ROCK. Crystalline granular com- pound of Labradorite and hypersthene with titano- 10 INTRODUCTORY OBSERVATIONS. ferrite. Much of the doleritic lava of the north of Ireland is of this composition. Hypersthene is a variety of pyroxene rich in oxides of iron, and man- ganese. Generally hypersthene rock is associated with strata older than the Tertiary period. (Acidic.) TRACHYTE. Generally a light greyish rock com- posed of sanidine and other felspars, with accessory minerals such as mica (biotite), hornblende or augite. (a) Trachyte porphyry. Felspathic base with crystals of sanidine, and grains of quartz. (Co. Antrim and Down, Ireland.) EHYOLITE. A compact, enamel-like, or vitreous matrix, enclosing grains or crystals of sanidine and quartz. PHONOLITE (or Clinkstone). A compact base, in its fresh state dark greenish grey, showing here and there single cleavage surfaces of vitreous felspar. PITCHSTONE. A homogeneous vitreous mass, with conchoidal fracture, translucent at the edges, of various colours, of red, yellow, brown, green, to black. (a) Pitchstone porphyry. A base of the above when enclosing crystals of glassy felspar, quartz, or mica. II. FRAGMENTAL. (Of various Geological Ages.) FELSPATHIC ASH, or TUFF. A mass, generally INTRODUCTORY OBSEEVATIONS. 11 rudely stratified, composed of small fragments or dust of volcanic materials, along with which fragments of other rocks may also occur. These materials are generally more or less consolidated, and when bound together by carbonate of lime form a calcareous ash of tolerable hardness. AGGLOMERATE. A mass, rudely stratified or amor- phous, composed of large and small fragments of felspathic materials, which have been shot out of a volcanic vent during eruption. Sometimes large bombs are imbedded in ash and agglomerate, as is the case amongst the Lower Carboniferous rocks of Ayrshire. GRENSTONE ASH, or TUFF (Diabase-tuff}. Under this head are included the tuffs which are composed mainly of comminuted materials of some variety of trap -rock, probably diabase or melaphyre. They occur in Co. Limerick and Wexford. (Jukes.) METAMOEPHIC EOCKS. GNEISS. A crystalline granular aggregate of quartz, felspar, and mica ; texture foliated. (Gneiss often passes into foliated granite on the one hand, and into mica-schist, &c., on the other.) (a) Porphyritic- gneiss ; when containing large distinct crystals of felspar. (b) Sy enitic- gneiss ; when hornblende is present as an essential. 12 INTRODUCTORY OBSERVATIONS. (c) Pr otogine- gneiss ; when chlorite or talc is present as an essential. GRANTJLITE. An aggregate of felspar and quartz, fine grained, foliated or laminated ; usually with some mica. MICA-SCHIST. A foliated aggregate of mica and quartz, generally in alternate laminae. (a) Quartz-schist; when the proportion of mica is very small, and the quartz presents a foliated structure. (b) Chlorite-schist, Talc-schist, Epidote-schist ; when these minerals respectively prevail. (We may also have compounds, such as chloritic mica-schist, &c.) HORNBLENDE-ROCK. A compact or crystalline granular rock, formed chiefly of hornblende, with felspar and accidental minerals ; structure more or less amorphous. (a) Hornblende-schist; the above when foliated. QUARTZITE (Quartz-rock). A granular or compact mass of quartz, firmly bound together, splintery frac- ture. (Veins of white quartz are generally present in this and other metamorphic rocks.) SERPENTINE. Hydrated silicate of magnesia ; massive, or foliated, or fibrous ; soft ; colour varying from pale leek-green to dark olive-green, or reddish- brown, &c. ; often associated with diallage rock. DIALLAGE-ROCK. A variety of gabbro, composed of Labradorite or Saussurite and diallage ; usually INTRODUCTORY OBSERVATIONS. 13 with other minerals. (Dial lage -rock is not always a metamorphic rock, though generally associated with rocks of this class.) CRYSTALLINE LIMESTONE, and MARBLE. Limestone which has taken the crystalline structure owing to metamorphic action. It is often schistose and mica- ceous. (Connemara, Donegal, Apuan Alps in Italy.) SEDIMENTARY ROCKS. (Mechanically formed.) CONGLOMERATE, or PUDDINGSTONE. A rock con- sisting of consolidated pebbles, more or less rounded, and imbedded in a basis of varying material ; either calcareous, siliceous, or ferruginous. Quartzose sand often forms the binding material. BRECCIA. When the component fragments, instead of being rounded, are angular. Some of the most beautiful marbles are breccias bound together by a calcareous paste. Breccias are generally more littoral in their mode of formation than conglomerates, and in some cases are referable to the agency of floating ice. SANDSTONE, or GRITSTONE. Under this head is included siliceous freestone. Sandstones consist of small particles of silex and other materials bound together by various cementing substances, such as oxide of iron, silica, or calcareous matter. When flakes of mica occur generally in the planes of bed- 14 INTRODUCTORY OBSERVATIONS. ding the stone is called a 'micaceous sandstone/ Amongst this class of rocks, the phenomena of oblique lamination and ripple marks are of frequent occur- rence; and when the stone is of a light colour and suited for buildings of a higher class, it is termed a 'freestone/ The hard and coarser varieties, with a rough surface, are called grits ; as, for example, the millstone grit of Yorkshire. FLAGSTONE. Sandstones which split into thin and even layers along the planes of bedding, are called ' flagstones/ Generally this tendency to split is due to laminae of mica deposited over the surfaces of successive strata. CALCAEEOUS BOOKS. (Organically formed ; less frequently chemically formed.) LIMESTONE. A rock, in its pure state composed of carbonate of lime, but generally containing foreign ingredients, such as silica, alumina, carbonate of mag- nesia, carbonate of oxide of iron, and carbonaceous matter. Limestones are of all colours ; and all the great marine limestone formations may be referred, directly or indirectly, to the agency of marine animals. Tufaceous limestones, travertine, and ' Egyptian alabaster' have been formed by precipitation from waters charged with carbonate of lime. INTRODUCTORY OBSERVATIONS. 15 Crystalline limestone. Some kinds of unaltered limestones, full of organic remains, are highly crystal- line in structure, as sometimes is the case with the Carboniferous limestone of Derbyshire. In other cases, the crystalline structure is due to metamorphic action, as in that of the Carrara marble (see ante, p. 13). Compact limestone. This rock is generally earthy, devoid of crystalline structure, and of dull blue, grey, black, or mottled colours. The limestones of the Lias are generally of this character. Chalk. A white, fine-grained, generally soft lime- stone, often enclosing nodules or bands of flint, and on microscopic examination found to consist of shells of marine animals, such as Foraminifera, &c. Oolite, and oolitic freestone. A. limestone com- posed of innumerable little spheroidal concretions, firmly cemented by carbonate of lime or calc-spar. When the concretions are as large as a pea, it is called a * pisolite/ such as occurs at the base of the Inferior Oolite near Cheltenham. The oolitic lime- stones of the Jurassic system are generally fossil- iferous, and of a light yellowish colour, producing an agreeable building material, and durable when not exposed to a smoky atmosphere. Oolite also occurs in the Carboniferous system, as on the shores of Killala Bay, in Co. Mayo. Nummulite limestone. A great formation of white, yellow, or reddish-mottled limestone, formed princi- 16 INTRODUCTORY OBSERVATIONS. pally by the agency of a genus of foraminifera called Nummulites. This rock has been used as a marble in Italy, though seldom occurring with a crystalline structure. Hydraulic limestone. Limestone which has the property of setting under water after calcination. This is considered to be due to certain proportions of silica and alumina, and perhaps of carbonate of mag- nesia. These limestones are generally earthy, compact, and of a blue colour. They are derived from the Lias of England, the lower Carboniferous series of Scotland, and of Ballycastle, Co. Antrim, &c. Dolomite, or Magnesian limestone. A limestone containing a large proportion of carbonate of magne- sia ; crystalline or granular ; generally of a yellowish colour, and weathering into a brownish powder with a sandy appearance ; sometimes fossiliferous, and con- taining various proportions of foreign matter. The dolomite of the north-east of England is one of the chief building stones of the country. Gypsum, or Alabaster. White, yellow, red, or mottled, crystalline, or granular sulphate of lime ; occurring in beds, or lenticular masses amongst the sedimentary rocks ; often in connection with rock- salt. INTRODUCTORY OBSERVATIONS. 17 CHAPTEE II. CLASSIFICATION OF BRITISH STRATA. For the sake of those who may not be familiar with the order of succession of the geological forma- tions into which the strata have been distributed, the following outline is here presented. For fuller details, which would here be out of place, the reader may consult Lyell's Student's Manual of Geology ; Jukes' Manual of Geology, edited by Professor Geikie ; or other books on the subject. Those formations to which special reference is made in this work are printed in italics. TABLE OF BRITISH SEDIMENTARY STRATA. POST TERTIARY. f Recent strata. Pleistocene. . \ *?+ LPre-Glacial strata. CAINOZOIC, OB TERTIARY. Pliocene . . . . . Crag of East of England. Miocene ..... Lignite and basalt of Antrim and Mull. t Hempstead Beds, f Upper . < Bembridge Beds. L Osborne Beds. T, T . i ,, ( Headen Beds. Eocene . . . -! Middle . { Bagshot j^ f Beds of London and Paris Basins, Lower . < also Nummulite Limestone of \ South of Europe, &c. 18 INTRODUCTORY OBSERVATIONS. MESOZOIC, OE SECONDARY. Cretaceous Chalk, &c. Upper Greensand. Gault. Lower Greensand (UpperNeocomian). Weald Clay. Hastings Sand, &c. Ashburnham Beds, &c. Jurassic New Bed Sand- stone, or Trias . Tipper Lower Upper Middle Lower Liassic Penarth Beds. K Red Marl. ' ) Lower Keuper Sandstone. iDolomitic Conglomerate (Somerset) Bunter . New Red Sandstone. fPurbeck Beds (Limestone). I Portland Stone. ] Portland Sand. L Kimmeridge Clay. ( Coralline Oolite. \ Oxford Clay. ( Great Oolite. I Fuller's Earth. ( Inferior Oolite. C Tipper Lias. < Middle Lias, or Marlstone. Lower Lias. PALAEOZOIC, OB PRIMARY. Permian Carboniferous . < Upper Middle Lower Upper Lower .St. Bees 1 Sandstone, &c. Magnesian Limestone, &c. {Lower Permian Sandstone, or Marls and Breccias, &c. ( Coal-measures. \ Millstone Grit. IToredaU Beds. Carboniferous Limestone. Lower Limestone Shale (England). Calciferous Sandstone (Scotland). Lower Carboniferous Slate, Coomhola Grits, &c. (Ireland.) INTRODUCTORY OBSERVATIONS. 19 Devonian Silurian Upper Devonian (Devonshire) . Middle Devonian (Devonshire) . Lower Devonian (Devonshire) . Upper Old Red Sand- stone (Scotland). Middle Old Red Sand- stone (Scotland). Lower Old Red Sand- stone (Scotland), Upper Lower f Tilestones (passage Beds). 1 Ludlow Beds. \ Wenlock Beds. V. Upper Llandovery Beds. " Lower Llandovery Beds. Caradoc or Bala Beds. Llandeilo Flags. Tremadoc Slates. Primordial Zone or Lingula Bed* C Harlech Grits . "| Grits, Quartzites, \ Red Sandstone Cambrian I Purple Slates . > and Schists V &Conglomerate ( Longmynd Rocks J (Ireland) . . j (Scotland). Laurentian . /Fundamental Gneiss (N. W. Highlands). I Grits and Quartzites (St. David's Head). ] Laurentian Gneiss, Schists, and Serpentines I (Canada). C 2 PART II. GKANITIC EOCKS, OHAPTEE I. GEANITE. Granit (Germ.} Granite (Fr.) Granito (Ital) Sp. gr. 2.6-2.9. THE origin of the name 'granite' is involved in obscurity. It is stated by Scipio Breislack to have been used by Caesalpinus as far back as the year 1596, and was found by Emmerling in a work by Pitton de Tournefort, written in ibpS; 1 and while it was subsequently employed to designate rocks of a coarsely granular character, it is probable that Werner and Hutton gave more precision to its use. On the other hand, Chateau traces the name to the Italian 'granito/ from the grains being of different colours. 2 But whatever its derivation, the name is now understood amongst petrologists to designate a rock of a crystalline-granular texture of igneous or metamorphic origin and composed of, at least, three constituents, quartz, felspar, and mica. 1 Zirkel, Petrographie, i. 475. 2 Technologic du Batiment. GRANITE. 21 Granite is an acidic (or highly silicated) rock, the proportion of silica varying from 65-81.7 per cent. 1 The different minerals of which it is formed may generally be distinguished by the eye, and are so arranged, that the felspar and flakes of mica are imbedded in the free silica (or quartz) ; owing to this condition of the minerals, it has been inferred by Senft that the silica which was the most difficult to fuse was the last to solidify, and retained a certain degree of viscosity after the other minerals had assumed the crystalline form. 2 Where the silica has been in excess, it appears to have been injected into the veins which are often found traversing granitic rocks ; on the other hand, Dr. S terry Hunt considers that such veins, even when containing large crystals of orthoclase, may have been deposited from aqueous solution. 3 From microscopic examination by Mr. Sorby, 4 and more recently by Dr. F. Zirkel, it has been ascer- tained that the quartz of granite contains minute cells partially filled with water, and these observers have inferred the presence of steam under great 1 In rare cases, however, the proportion is lower ; the Rev. Dr. Haughton finds one of the Galway granites to contain only 55.20 percent, of silica. Quart. Journ. Geol. Soc. rvii. 2 See Lyell, Elem. Geol. p. 538 (1871). 3 'On Granite Veins,' American Journal of Science, 1870. * 'On the Microscop. Structure of Crystals, &c.,' Journ. Geol. Soc. Lond. vol. xiv. p. 453. 22 GRANITE. pressure, and a high temperature during the process of formation. 1 Varieties of Composition. From the primary composition of granite already described, there are frequently considerable variations. Many varieties have two kinds of felspar, such as that of Egypt, which contains orthoclase and oligoclase ; or that of Mourne, which contains orthoclase and albite ; others again have two varieties of mica. Accidental minerals are sometimes present, generally in druses, such as tourmaline or schorl, beryl, chlorite or talc, while hornblende often appears and sometimes replaces the mica, in which case the rock becomes a syenite. When large and distinct crystals of orthoclase felspar are individually developed, the rock assumes a por- phyritic structure, which adds much to its value and beauty for ornamental purposes. In this case, the orthose crystals often occur as twins, reflecting the light differently from their facets, and thus are capable of easy determination by the eye. These crystals frequently have a rich pink or flesh-colour, as 1 Mr. Sorby has even gone further than this, and has shown from calculations founded on the extent to which the cavities are now filled with fluid, that certain conclusions may be arrived at regard- ing the relative depths at which granite has been formed in different localities. Thus he finds that the granites of the Highlands of Scotland indicate a pressure of 26,000 feet of superincumbent rocks more than those of Cornwall ; the elvans (or granitic dykes) of the Highlands, one of 28,700 feet more than those of Cornwall ; but these pressures depend on the temperatures of consolidation. GRANITE. 23 in the case of the porphyritic granites of Galway, Shap Fell, and Syene in Egypt. But perhaps the most generally admired of the varieties of granite are those which, like the Peter- head stone, are of a rich pink colour, arising from the predominance of rose-coloured felspar. There are indeed few rocks in this country which are superior to such in richness of colour, and suitability for ornamental purposes, especially when they are capa- ble of being extracted in blocks of large size, and of receiving a high polish. Foliated Granite, or Gneiss. The minerals of which granite is composed are sometimes arranged in parallel layers or leaves, in which case the rock is said to be ' foliated/ and passes into gneiss. This structure is often observable over large tracts of country, as in Donegal and Galway, and is usually characteristic of those masses which have been formed by a process of metamorphism. The structure also is sometimes only apparent when the rock is viewed in its natural position, and often is persistent as regards general direction over large tracts of country. Graphic Granite. This variety seems to occur almost exclusively in veins, particularly those which traverse gneiss. 1 It contains but little mica ; and the peculiarity of the structure to which it owes its name is due to the arraogement of the quartz and 1 McCulloch'e Geol. Classification of Bocks, p. 235 (1821). 24 GRANITE. felspar of which it is composed in long parallel prisms, which are sometimes triangular, in other cases hexa- gonal and flattened. The prismatic structure is seen, therefore, in only one direction, and the letter-like arrangement in another, or transversely to the axes of the prisms. Geological Age. Although it was once supposed that granite is the oldest of rocks, it is now known, from observations extending over large tracts of the earth's surface, that granites have been formed at several geological periods from the Silurian down to, at least, the close of the Cretaceous period. Thus it is known that the granite of Cornwall and Devon is more recent than the Carboniferous period ; that the granite of the Alps of Savoy is more recent than the Jurassic period ; and that the granite of the Eastern Pyrenees is more recent than the White Chalk. On the other hand, there are granitic rocks of great antiquity, such as some of those found in Scandinavia, the Highlands of Scotland, Donegal, and Galway, all of which are older than the Devonian ; some, than the Upper Silurian periods. Mode of Occurrence. From the massive and homo- geneous character of granite, it is eminently capable of yielding large blocks suitable for structures which are intended to withstand the assaults of time, the vio- lence of the waves of the sea, or the crushing effects of enormous pressure. It is, therefore, used for the GRANITE. 25 construction of breakwaters and harbours, light- houses, docks, fortifications, foundations, and voussoirs of bridges. On the other hand, it is unsuited for fine sculpturing on account of its crystalline-granular structure and coarseness ; so that when we require a material suited for the ornamental portions of an ecclesiastical or public edifice, we are obliged to have recourse to the less granular and softer materials which are to be found amongst the formations of limestone, sandstone, or dolomite. Mode of Formation. The igneous origin of granite was first demonstrated by the philosopher Hutton from actual observation, 1 and maintained by him against his rival Werner and his school during the celebrated controversy of ' the Neptunists ' and ' the Vulcanists.' But while nearly all physical geologists are agreed that granite has resulted from a state of igneous fusion in presence of vapour of water, and under a high degree of pressure, it has been demon- strated by Professor Haughton, that there are two great classes under which probably all granites may be arranged, namely, metamorphic and eruptive. 2 1 Playfair's Illustrations of the Huttonian Theory. Hutton, convinced in his own mind, from the crystalline structure of granite, that it had been formed by cooling from a state of igneous fusion, went in search of an illustration of his views amongst the mountains of Scotland ; and in Glen Tilt, to his great delight, discovered veins of granite traversing schistose rocks. 2 Journ. Geol. Soc. Lond. vols. xii. and xviii. 26 GRANITE. The same observer also shows that there are certain specialities of structure and composition attached to each of these classes. Thus, under the metamorphic series, he groups the granites of Scandinavia, of the Scottish Highlands (in part), of Donegal, Galway, and Newry ; and under the eruptive series he places the granites of Wicklow, the Mourne mountains, and Dartmoor. Unquestionably this is a classification which will hold good in a general way ; and several special districts, such as Gal way and Down in Ireland, afford examples of each of these classes of granite in close proximity. At the same time, it is somewhat difficult to define very clearly what we mean by 'metamor- phic ' as distinguished from ' eruptive ' origin ; for, as we may assume that sedimentary rocks, such as grits and slates or shales, when fused by heat under great pressure of superincumbent strata will some- times result in the production of granite, it is clear that all granites may be originally in some sense metamorphic rocks. The distinction, however, refers not to the original state and origin of a granitic mass, but to its position in relation to the stratified rocks by which it is bounded or enclosed. If, as in the case of the foliated granite of Galway, it is found to occur merely as a portion of the general mass of sedimentary rocks in which the metamorphic action has been carried out GRANITE. 27 to a greater or less extent, it may be regarded as metamorphic ; if, on the other hand, after it has been elaborated by fusion or metamorphic action at a certain depth in the interior of the earth's crust, it has been irrupted amongst strata occupying a higher zone, and not connected with those out of which it has been formed, it may then be regarded as irrup- tive. In the former case we have a process of assimilation of stratified materials into the mass of crystalline rock ; in the latter, of assimilation followed by intrusion amongst higher strata, the result of internal forces. Chemical Composition. Many analyses of granite have been made, of which I here quote thirteen examples, 1 from which it will be observed that the predominating constituent is silica, and the next in importance alumina. The relative proportions of potash and soda are also features of importance, because in the soda granites the orthoclase is replaced or accompanied by albite, as in the case of the granite of the Mourne mountains in Downshire. 1 Chiefly taken from Dr. F. Zirkel's Lehrbuch der Petrographie, vol. i. 1866. Zirkel states that the granite of the Devil's Wall (Teufelsmauer) near Krems contains as much as 81.77 per cent, of silica ; and that of Goragh Wood, near Newry, only 62.08 ; this latter analysis having been determined by the Rev. Dr. Haugh- ton, F.RS. 28 GRANITE. CHEMICAL ANALYSES OF GRANITES. I. II. III. IV. V. VI. VII. Silica 73-13 .. 72.11 .. 69.31 .. 70.72 .. 73-00 .. 73.20 .. 72.24 Alumina .... 12.49 .. 15.60 .. 16.40 .. 14.16 .. 13-64 1548 .. 14.92 Oxides of Iron 2.58 - i-53 .. 4.30 .. 3.22 .. 2.44 .. 1.72 .. 1.86 Oxides of Man- jo.57 .. 0.26 .. 0.03 __ .. 0.32 ganese .... 5 Lime 2. 4 .. 1.26 .. 3-o6 .. 1.03 .. 1.84 .. 0.96 . . j.68 Magnesia .... 0.27 .. 0.34 .. 0.83 .. 0.66 .. O.I I .. .. 0.36 Potash 4.13 .. 5.00 .. 2.87 5-37 4.21 .. 4.80 .. 5.10 Soda 2.61 .. 2.27 .. 3.29 .. 2.54 .. 3.53 3-18 3-51 Water 0.53 .. 0.83 . . 0.84 .. .. .. .. T. osq 98.71 99.20 100.93 98.80 99-97 99-34 99-99 VIII. IX. X. XI. XII. XIII. Silica . 74.82 .. 70.09 .. 66.81 .. 75.00 .. 71.41 .. 70.25 A-limiiTin 16 14 I AA IO OS 1 3 24. _ . .- .. 16.00 Oxides of Iron . 1.52 '.' 6.'i 3 .. 5.02 .. 2.52 .. 2.58 Oxides of Manganese . .. trace .. ] 3 -5 Lime . 1.68 i. 20 ;; 3.26 " 0.69 . . 2.49 .. 1.16 Magnesia -47 . . trace .. o. 3 i .. .. i. ii Potash , 3-55 .. 4.19 .. 2. 7 8 .. 4-33 2.77 9.00 Soda 6 12 a 2"? 2 8 .. 3 OV 3 OK Water O- */ ** V O ' .. 1.30 .. 0.80 .. 1.25 .. 0.65 104-30 101.38 101.38 99.65 99 .II 100.00 I. Large-grained granite, of white orthoclase, greyish white quartz, a little oligoclase, and black mica, from Streitberg in Silesia. Streng, Poggend. Ann. 1852, 122. II. Fine-grained granite of Heidelberg, with much quartz, without oligoclase and with magnesia-mica (Biotite). Streng, supra cit. 130. III. Granite from Meerauge im Fischseethal (Carpathians); coarse- grained, with much oligoclase and orthoclase, little quartz, much green biotite, a little white mica. Streng, supra cit. 125. IV. Fine-grained, from Monte Mulatto in the Tyrol ; consists of quartz, orthoclase, and tourmaline instead of mica. Kjerulf, 1855- V. Large-grained granite, with much quartz, from Fox Rock near Dublin. Haughton, Quart. Journ. Geol. Soc. Lond. vol. xii. 1856. GRANITE. 29 VI. Medium-grained granite, from Blackstairs Mountain, Co. Wexford. Haughton, supra cit. Contains no oligoclase. VII. Medium-grained granite, from Doocharry Bridge, Co. Donegal ; consisting of flesh-coloured orthoclase, grey oligoclase, quartz, and a little black mica. Haughton, ibid. vol. xviii. p. 402 (1863). VIII. Granite from Baveno, Italy ; containing flesh-coloured orthoclase, white oligoclase, quartz, and dark green mica. Bunsen, Mittheilung an Roth, Gesteinsanalysen, 1862. IX. Granitite from Warmbrunn in Silesia ; red orthoclase, yel- lowish oligoclase, quartz, and a little biotite. Ibid. X. Granite from Meineckenberg in the Harz ; prevalent bright greenish oligoclase, a little orthoclase, much mica and little quartz. Fuchs, N. Jahrb. fiir Mineralogie, &c., 1862. XI. Granite from the Mourne Mountains ; containing quartz, orthoclase, albite, and green mica. Haughton, Quart. Journ. Geol. Soc. vol. xii. 192. XII. Protogine granite, from the northern flank of Mont Blanc. Schonfeld and Roscoe, quoted by Zirkel, Petrographie, vol. i. 492. XIII. Egyptian granite (or ' syenite '), from a fragment of an antique in the collection of the Louvre, Paris, by Professor Delesse. Journ. Geol. Soc. Lond. vol. vii. 7. Varieties of Granite and Examples. The varieties caused by variations in the number and proportions of the constituents, their colours, and the presence of accidental minerals, are almost endless; but I shall select a few of the most remarkable and more useful examples for description. In some cases, as in the Western Alps, talc replaces the mica, in which case the rock receives the name of protogine ' granite ; * 1 Some doubt has been thrown, on the authority of Dr. Haughton, on the accuracy of this generally received view. See Jukes' Manual of Geology, 3rd edit. 124 (1872). 30 GRANITE. in others, schorl or tourmaline appears and produces ' schorlaceous ' granite as at Killiney Hill near Dub- lin, and several localities in Cornwall ; in others, hornblende replaces or accompanies the mica, and we have ' syenite ' and ' syenitic ' granite ; and lastly, when the orthoclase crystals assume an angular arrangement with reference to the quartz, or the quartz with reference to the felspar, so that they present the appearance of oriental characters, we have the variety known as 6 graphic granite/ ex- amples of which occur in the Schloitzbachthal, near Tharand in Saxony, 1 and at Clifden in Connemara, Ireland. 2 Specialities of Granite. The specific gravity of ordinary granite being 2.66, a cubic foot weighs 166.2 Ibs., and a cubic yard as nearly as possible two tons ; just about twice the weight of a cubic yard of coal. Granite, according to Professor Ansted, generally contains about 0.8 per cent, of water, and is still capable of absorbing about one-fourth more, or 0.2 per cent. In other words, a cubic yard of two tons contains in its ordinary state about 3.5 gallons of water, and some specimens can absorb nearly a gallon more, on being placed in pure water for a short period. It is important, in selecting specimens of this rock 1 Rocks Classified, by B. von Cotta (Lawrence's Trans.), p. 206. 2 Observed by the Officers of the Geological Survey. GRANITE. 31 for structural purposes, to observe the quantity of water they are capable of absorbing, as the influence of frost on stone is in proportion to the quantity of water it takes up, and the result determines to some extent its durability. The power of granite to resist crushing forces varies much with the character of the rock. The valuable series of experiments made by Mr. Wilkin- son on the granites of Ireland, show considerable variations even amongst selected specimens. Cubes of one-inch sides having been tested by means of a lever, specially prepared by Mr. Mallet, C.E., it was found that the weight in Ibs. required to crush the specimens varied from 2310 up to 13,400, the maximum being obtained from a specimen from Newry, County Down ; the minimum from Bally- knockan. The granites from Killiney and Kings- town afforded good results. 1 1 Prac. Geol. and Arch, of Ireland, by GK Wilkinson, M.B.I.A. (18450 OHAPTEE II. GEANITES OF SCOTLAND. Peterhead, Aberdeenshire. The red granite of Peterhead, quarried at Stirling Hill, is justly prized for the beauty of its colour, its closeness of texture, and the large blocks which it yields from the quarry. It is extensively employed for columns, tesselated pavements, and ornamental work both within and outside of buildings ; and fine examples may be ob- served in the pillars of Carlton Club House, the Fishmongers' Hall, in London ; the columns for the interior of St. George's Hall, Liverpool ; and those of the Provincial Bank of Ireland, in Dublin. The large pedestal and tazza formed out of this granite in the hall of the Museum of Practical Geology, London, is also a most successful example, both of skilful workmanship and excellence of material. 1 The granite of Peterhead is composed of red orthoclase, albite, black mica, and quartz, and is considered by Dr. Haughton to be of eruptive origin. 2 It weighs 165 Ibs. 14 ozs. per cubic foot. 1 This large tazza (or vase) was made by Messrs. Macdonald and Leslie, Aberdeen. 2 Proc. Koy. Soc. vol. xviii. (1870). A specimen of this granite, showing the two felspars, orthoclase and albite, is in the Museum of Trinity College, Dublin. GRANITES OF SCOTLAND. 33 A finely crystalline light red granite is obtained at Cornegie, also in the county of Aberdeen. Aberdeen. This rock has been very extensively employed for building and ornamental purposes over the United Kingdom, as well as in America and the Continent ; as it can be extracted in large blocks, and takes a fine polish. It has a prevailing greyish tint, and, according to Haughton, 1 is of metamorphic origin, and probably much more ancient than the red granite of Peterhead. It is a compound of quartz, orthoclase, oligoclase, and black and white mica ; re- sembling in composition, though not in colour, the granites of Donegal and Norway. Out of this stone the city of Aberdeen, perhaps the cleanest and freshest- looking city in the British Islands, is built ; and might be referred to by Mr. Euskin to illustrate his views of the purifying influences of granitic rocks on the inhabitants of countries where they prevail. 2 The principal quarries are at Dancing-Cairn, Eubislaw, and Tyrebagger. Kirkcudbrightshire. This granite is largely quar- ried at Craignair and Creetown, and has been used in the construction of the Liverpool Docks ; the Birken- head, Newport, and Swansea Docks ; the Liverpool Borough Bank, Branch Bank of England, and other buildings, both of that town and of Man- 1 Proc. Roy. Soc. vol. xviii. (1870). 2 Modern Painters, iv. pt. v. ch. 8. D 34 GRANITES OF SCOTLAND. Chester. 1 It is of a greyish colour, and generally porphyritic. Strontian, Argyleshire. Medium- grained grey granite, consisting of quartz, oligoclase white felspar, and black mica in abundance. 2 Island ofArran. The central group of mountains of this remarkable island, rising at Goat Fell to an elevation of 2875 feet, is composed principally of granite of two varieties, the coarse-grained and the fine-grained, formed probably at successive periods. In composition, however, they are similar, being formed of white orthoclase, a triclinic felspar pro- bably oligoclase, quartz, and a little black mica ; the quartz is very abundant. 3 Isle of Mull, (&c. This island produces fine pink and red granites, which are now largely worked by the Scottish Granite Company. From the Ross of Mull it was proposed to obtain a monolith, to be erected in honour of the late Prince Consort, in Hyde Park. 4 The rock consists of pink orthoclase, a little mica, and much silica. Granite is also obtained from Portsoy, in Banffshire ; Dalmore, Sutherland ; Oban, in Argyleshire ; High Rock, Breadalbane, Perthshire ; and Tiree, in the Hebrides. 1 Mr. R. Hunt, Mineral Statistics, part ii. 1858, p. 273. * Brit. Assoc. Rep. 1863, p. 62. 3 This determination of the composition of the Arran granite has been kindly communicated to me by Mr. S. Allport, F.G.S. 4 Descrip.sGruide to the Museum of Prac. Geol. p. 18 (1867). OHAPTEE III, GEANITES OF ENGLAND. THE occurrence of granite in England is limited to a very few localities, viz. : Shap Fell, in Cumber- land ; Anglesea, Devon and Cornwall, Lundy Island, the Channel Islands, and the Isle of Man. Of these the following are selected for description : Granite of Dartmoor. Granite forms at Dartmoor an elevated tract of moorland, rising into fantastic masses, or Tors, resulting from the process of weather- ing along the original joints of the rock. It has a prevailing greyish colour, and is frequently porphy- ritic ; in which form it has been used in the construc- tion of London Bridge. Quarries were formerly opened at High Tor, on the east of Dartmoor, and at Kingston Down ; but those at the former locality are now abandoned, and others at Cheesewring, near Liskeard, have been opened, from which a stone of a beautiful quality is raised, and exported in large quantities from Looe. 1 There are also quarries at Fremator, near Tavistock, and at Blackenstone, Dartmoor. Granites of Cornwall. The granites of Cornwall 1 Descrip. Guide M. P.GK, p. 19. D 2 36 GRANITES OF ENGLAND. are extremely variable in quality, structure, and composition, being sometimes so soft as to produce kaolin, or porcelain clay ; sometimes hard and dura- ble ; again, they are frequently schorlaceous and porphyritic, as at Land's End. 1 In composition, there are also varieties containing two felspars, pink and white ; or two micas, grey and black. 2 The principal quarries are those near Liskeard (already referred to), those of Lamorna, west of Penzance ; Penryn, near Falmouth; and Mill Hill, in Maldron. The stone from those quarries is of excellent quality. The granites of Devon and Cornwall have been shown by Sir H. De la Beche to be of an age inter- mediate between the Lower Carboniferous and Tri- assic periods. 3 The following are some of the principal works which have been constructed in part, or altogether, of Cornish granite : The Portland breakwater, from Pen- ryn and Lamorna quarries ; the Keynham Docks ; the Commercial Docks, London ; the Birkenhead Docks ; the National Works at Chatham and Portsmouth, from the same localities ; the Wellington monument at Strathfieldsaye, the shaft of the column being of one solid block thirty feet in height, from Constantine. 1 See a good representation of this porphyritic granite in LyelPs Student's Manual of Geology, p. 540. 2 A fine collection of varieties of granite from the neighbourhood of Penzance is to be seen in the Mus. of Trinity College, Dublin. 8 Geological Observer, p. 563. GRANITES OP ENGLAND. 37 The Cheesewring granite has been used in the London Docks, Westminster Bridge, the Thames Embankment, Eochester Bridge, the Docks at Copen- hagen, the Great Basses lighthouse near the Island of Ceylon, and the tomb of the Duke of Wellington in the crypt of St. Paul's. Waterloo Bridge is built of Cornish granite ; and London Bridge of a porphyritic granite from Devonshire. 1 The Channel Islands. Large quantities of granite have been raised and exported from the quarries of Mount Mado and La Perruque in Jersey, as well as from Guernsey and the little island of Herm. Mount Sorel 9 Leicestershire. The syenitic-granite of Mount Sorel is highly esteemed in London and elsewhere, on account of its warm rose-tint which renders it suitable for ornamental purposes and as a contrast to the light grey or brown colours of the ordinary building stones. It is, however, extremely 1 Kaolin, or Porcelain Clay. This substance as used in England is chiefly derived from the decomposed granites of Cornwall and Devon, as well as at Fetlar, one of the Shetland Islands (Bristow's Glossary of Mineralogy, 1861). Large quantities of this material are sent to Worcester and the Staffordshire Potteries, where, along with flints from the Chalk, and chert from the Carboniferous lime- stone of Derbyshire, it is ground under water into a fine mud } perfectly white, which is manipulated into various porcelain wares which vie with those of Dresden and Sevres in beauty of design and excellence of execution. The decomposition of the felspar in the granite is probably due to the percolation of water holding carbonic acid in solution. 38 GBANITES OF ENGLAND. hard, and consequently expensive ; but is capable of being extracted from the quarry of any required dimensions, and may be moulded to any desired form. It is also well suited for paving. Lundy Island, Entrance to Bristol Channel. This granite has been worked to some extent, but not largely. It is a quaternary compound of quartz, white felspar, and black and silvery white mica, the latter comparatively rare. It is traversed by elvan dykes. 1 SJiap, Cumberland. The granite of Shap is a very handsome porphyritic stone, forming a portion of Wasdale Crag, near Penrith. It is somewhat variable in texture ; but the general appearance is that of a rich reddish-brown crystalline granular base, composed of reddish orthoclase, yellowish oligo- clase, quartz, and black mica, in which large flesh- coloured orthoclase crystals are abundantly distributed, sometimes as twins. 2 The stone takes a fine polish, and is now systematically worked by a company, who have set up machinery for cutting and polishing by the side of the Lancaster and Carlisle Railway, near Shap Station. Immense numbers of boulders of Shap granite are dispersed over the country east of the Fell. 1 Sir H. F. De la Beche, ' Eep. Devon and Cornwall,' p. 186. 2 Dr. Nicholson and Prof. Harkness, Geol. of the Lake District. OHAPTEK IV. GRANITES OF IEELAND. GRANITE is developed in four districts of Ire- land : i. Donegal, on the north-west; 2. Galway and Mayo, on the west; 3. Wicklow and Wexford, on the south-east; and 4. Down and Armagh, on the north- east. i. Donegal. The granite of this region is as- sociated with the great tract of metamorphic rocks which range from Donegal Bay on the south-west to Glengad and Inishowen Head on the north-east, and reappear amongst the Highlands of Scotland. The principal mass of the granite coincides very nearly with the axis of the Gweebarra and Glenveagh valleys ; but from the head of Gweebarra the granite spreads out westward, and forms the whole of the coast-line from Bloody Foreland to the mouth of Gweebarra River. From the admirable Report 1 presented to the Bri- tish Association by Mr. R. H. Scott, Sir R. Griffith, 1 ' On the Constitution of the Granites of Donegal,' Brit. Assoc. Rep. 1863, p. 51, et seq. ; also Haughton, ' On the Granites of Done- gal/ Journ. Greol. Soc. Lond. vol. xviii. 402. 40 GRANITES OF IRELAND. and the Eev. Dr. Haughton, it appears that the main mass of the granite is of a reddish colour, and may be regarded as a quaternary, and sometimes a quinary, aggregate of red orthoclase, oligoclase, quartz, black mica, and sometimes white mica ; and that hornblende, sphene, schorl, beryl, and garnets are occasionally to be recognised. This granite pre- sents a bedded aspect, while at the same time it has been observed to branch off into dykes traversing the surrounding metamorphic strata of schist and crystalline limestone. There is also another ' white granite ' with sphene and black mica occurring at Kindrum in Fanad, and in Arranmore Island. It is coarsely crystalline. In this island also there is a largely crystalline red granite which takes a fine polish, and is capable of being extracted in large blocks ; one of these measur- ing 90x20 feet, having been found on the shore at the south-east corner of the island. The granite rocks of Donegal are unquestionably capable of yield- ing a very handsome ornamental stone. The analysis of the granite from Doochary Bridge by Dr. Haughton has already been given (p. 29). 1 It has a rose-tint, is moderately fine-grained, and consists of large-sized pink orthoclase, a little green- 1 In the Museum of Trinity College, Dublin, are fine specimens of beryl in Donegal granite ; also specimens of granite from Gar- vary Wood, Doocharry Bridge, and Dunglow. Haughton, Brit. Assoc. Rep. 1863, p. 58. GRANITES OF IRELAND. 41 ish oligoclase in crystals of smaller size, quartz, and black mica. 1 The granite of Garvary Wood is also a handsome stone, and 'consists of large pink orthoclase crystals, oligoclase, quartz, and black mica. 2. Galway. The granitic district of Gal way extends over a large and wild tract from the town of that name to Roundstone Bay. It contains at least two principal varieties, which, according to the observa- tion of the officers of the Geological Survey, may be arranged under the heads of metamorphic and intrusive. 2 These granites are associated with meta- morphic strata, probably of lower Silurian or (still more ancient) date, together with quartz-porphyries, felstones, dioritic, and diabasic rocks, of intrusive origin. The former of these is a very handsome porphyritic rock, in which large crystals, of red orthoclase are imbedded in a base composed of quartz, orthoclase, greenish oligoclase, and mica. This forms the characteristic Galway granite. It has been quarried at Furbogh, eight miles from Galway, and takes a fine polish. The latter, or ' Oughterard gra- nite/ is composed of quartz, orthoclase, white and black mica, with iron pyrites as an accessory. 1 'On the Granites of Donegal,' Brit. Assoc. Rep. 1863, p. 61. 2 Mr. G. H. Kinahan, Explanatory Memoir to accompany Sheets 104 and 113 of the Geol. Survey Maps: The intrusive granite occurs in mass near Oughterard, and is very quartziferous ; the metamorphic is porphyritic aucl foliated, (p. 15.) 42 GRANITES OF IRELAND. Little has been done in the way of utilizing these rocks, though there can be no doubt that the por- phyritic granite is capable of yielding a stone of great beauty, and is well adapted for architectural purposes. A polished pillar of a porphyritic variety of granite may be seen in the Museum of the Royal College of Science, Dublin. Another mass of intrusive granite occurs at Aille- more, to the south of Louisburg, consisting of ortho- clase, oligoclase, quartz, and mica. It has not as yet been turned to any useful purpose. 3. Wicklow and Wexford. This granite forms a tract of mountainous country, extending in a S.S.W. direction from Blackrock near Dublin to Pollmounty near New Boss, and rising in Lugnaquilla to an ele- vation of 3039 feet, where it is capped by schist. It is composed generally of quartz, orthoclase, and silvery grey mica, but occasionally contains black mica, tourmaline, killinite, fluor spar, and albite ; 1 the prevalent colour of the rock is light grey ; it has a mean specific gravity of 2.634, its general chemical composition may be judged of by analysis V. (page 28) of specimens from Fox Rock by Professor Haughton. 2 The granite of this district is capable of yielding 1 First observed by Mr. Westropp in the granite of Dalkey. Journ. Geol. Soc. Dub. vol. ii. new ser. 213. 2 Quart. Journ. Geol. Soc. vol. xii. p. 177, and vol. xiv. p. 300. Also Address to Dublin Geol. Soc. 1862. I GRANITES OF IRELAND. 43 stone of large dimensions and superior quality. From Killiney Hill enormous quantities have been extracted for the construction of the fine harbour and pier of Kingstown, the Thames Embankment, and O'ConnelTs Monument in Glasnevin, besides nu- merous structures in and around the Irish metropolis. Care in selection is, however, absolutely necessary, as there is considerable variation in the texture and durability of the stone. Dr. Haughton informs me that the old buildings of Trinity College were con- structed with granite of inferior quality from Three Eock Mountain, while there is a beautiful fine- grained bluish granite which works kindly, from Blessington, and which has been employed with good effect in the new campanile which adorns the central quadrangle of the University. The granite of Glen- cullen and Kilgobbin, Co. Dublin, and Ballyknockan, Co. Wicklow, being less siliceous and more uniform in texture than that of Killiney, has been more gene- rally employed in buildings in the city of Dublin, such as the Law Courts, the Wellington Monument in the Phoenix Park, erected by public subscription in 1829, and Nelson's Pillar in Sackville Street, 1 A cubic foot of Dalkey granite weighs 169 Ibs. 9 ozs. 1 A most valuable series of experiments on the crushing weight and other qualities of the Irish granites has been published by Mr. G. Wilkinson, M.R.I. A., in his work on Practical Geology and Ancient Architecture of Ireland, 1845. 44 GRANITES OF IRELAND. The Killiney granite in one or two places is dis- tinctly foliated. 1 4.' The granites of the north-east of Ireland lie in three distinct tracts of considerable extent, form- ing the mountain ranges of Mourne, which attains in Slieve Donard an elevation of 2975 feet ; of Carlingford, and of Slieve Croob. The granite of Mourne has been already partially described. 2 It forms a group of exceedingly pic- turesque hills, generally of conical outline, with occa- sional scarped cliffs and deep ravines. It is truly irruptive, and seems to Lave been intruded amongst the stratified rocks in a state bordering on solidity ; and with a temperature only sufficient to indurate, but not to metamorphose, the Silurian rocks by which it is surrounded, and, in some places, surmounted. The granite of Mourne has hitherto been used only to a very limited extent for building; and, owing to the numerous cavities it contains, and its distinct- ively crystalline structure, it is probably not as well adapted to architectural purposes as the granite from the Newry district adjoining. Newry and Slieve Croob. This granite is alto- gether different in texture and composition from that 1 A representation of the foliated granite is given by Mr. Du Noyer in the Explanation of Sheets 102 and 1 12 of the Geological Survey, P-33- 2 First described by Dr. J. E. Bergtr in the Trans. Geol. Soc. Loud., first ser. vol. iii. GRANITES OF IRELAND. 45 of Mourne. 1 It is a potash granite, consisting of quartz, orthocla.se, and black mica. The analysis of this granite from Goragh Wood Station shows an unusually low percentage of silica. 2 The rock is finely granular, uniform in texture, is capable of being delicately wrought, and produces a stone well adapted for building and decorative purposes. From a quarry near Castlewellan, large blocks were extracted and sent to London for the base and pedestal of the Albert memorial in Hyde Park, the stone having, I understand, been selected from amongst several others by the Queen herself. Carlingford. The granite of Carlingford mountain is separated from that of Mourne by Carlingford Bay, and from that of Newry by a narrow band of Silurian rock. It is partly a syenite, or is associated with that rock, as also with diorites ; and as regards its geo- logical age, both Griffith 3 and Haughton 4 concur in regarding it as newer than the Carboniferous, as it is seen to penetrate the Carboniferous limestone in dykes at Grange Irish. North of Dundalk, it has decomposed into sand, and is penetrated by numerous dolerite dykes. 5 1 The granite of Slieve Croob and Newry is metamorphic, and is much older than that of Mourne and Carlingford. 2 Haughton, supra cit. See also Zirkel, Petrog. vol. i. p. 486. 3 Journ. Geol. Soc. Dublin, vol. ii. 113. 4 Quart. Journ. Geol. Soc. vol. xii. 193. 6 A specimen of the syenite from Carlingford Mountain is placed in the Museum of Trinity College, Dublin. 46 GRANITES OF IRELAND. Belleek. The justly admired porcelain ware of Bel- leek, Co. Fermanagh, is obtained from an orthoclase granite in the vicinity of the factory which is situated at the spot where the waters of Lough Erne precipitate themselves along a series of cascades into the river of the same name. In general, porcelain is made from granitic rocks in a decomposed state, known as kaolin; but in this case the red orthose felspar retains its crystalline form in its original perfection, and on being calcined loses colour and becomes white. The metallic iron which separates itself from the rock during the process of calcination is afterwards extracted by simply immersing magnets into the powdered china clay when mixed with water ; the particles of iron then adhere to the magnets, and are lifted out. It is probably this rock which is de- scribed by Mr. E. H. Scott, Sir E. Griffith, and the Eev. Dr. Haughton, as occurring in veins pene- trating gneiss and schist. 1 Arranmore Island. Porphyritic granite, consisting of quartz, reddish felspar, and black mica. In this granite the felspar predominates. Tory Island. Coarse granite, almost entirely com- posed of quartz and felspar, a little mica, green or white. 2 1 Brit. Assoc. Rep. 1863, 'On the Granites of Donegal,' p. 54. 2 Brit. Assoc. Rep. 1863. CHAPTER V. CONTINENTAL GKANITES. France. Granite is largely distributed over the central parts of France, as well as Normandy and Brittany. It forms the plateau from which rise the giant volcanic cones of Auvergne, l and in Normandy is largely employed as a building stone both for churches and secular structures, which, receiving their characteristic features from the rock itself, are for the most part massive,* severe, and devoid of elaborate ornamentation. 2 A handsome porphyritic variety comes from Laber, in Brittany, consisting of grey and white felspar, quartz, and black mica, with large crystals of light pink orthoclase. A tazza formed of this stone is in the collection of the Royal College of Science, Dublin. A red granite which takes a good polish is obtained from Avallon, near Auxerre, Department of Yonne. 3 Italy. The most important granite quarries in Italy are those of Fariolo, near Baveno, situated on the western bank of Lago Maggiore ; of this rock the com- 1 Scrope's Volcanoes of Central France, second edit. p. 37. 2 Chateau, Technologic du Batiment/ i. 147. 3 Ibid. p. 237. 48 CONTINENTAL GRANITES. position has already been given (p. 28.) It has a warm pinkish tinge, is fine grained, takes a good polish, and can be quarried in huge blocks, up to forty metres in length. It has been largely employed in the buildings of the cities of Milan, Florence, and Turin ; and columns for the restored Basilica S. Paolo fuori le Mura at Eome of 10.40 metres in length have recently been extracted. In the interior of Milan Cathedral, on either side of the main porch, are two huge monolith columns of polished Baveno granite ;* and of the same material are the columns which support the dome of the church of S. Carlo, Borromeo, which is built after the style of the Pan- theon at Eome. 2 The granites of the islands of Sardinia and Elba have been occasionally employed in some parts of Italy, especially along the western shores. The massive columns, eight in number, which support the dome of the Baptistry of Pisa (built A.D. 1278) are of granite from Elba. It is of a grey or slightly pink colour, consisting of white felspar, quartz, and black mica. 1 These columns show traces of bands of foliation, which I have elsewhere observed in the granite of Baveno, and leads me to infer that it is a metamorphic rock. There is also a greyish granite from the same neighbourhood, consisting of quartz, white felspar, and mica ; this may be irruptive. Fine crystals of orthoclase can be obtained from Baveno. 2 For interesting details regarding the formation of minerals in this granite, see M. Fournet, Ge'ologie Lyonnaise. CONTINENTAL GRANITES. 49 Other Continental Countries. It would be beyond the scope of this work to attempt to give an ac- count in any detail of the distribution and charac- teristics of granite as it occurs over Europe. 1 I shall therefore only refer to a few localities of special interest. Granite forms a portion of the higher altitudes of the Pyrenees, the Western Alps, and the Carpathians. In Mont Blanc, of which it forms the higher elevations, it is composed of orthoclase, oligoclase, quartz, and talc, 2 and has received the designation of protogine granite, or granitoid gneiss, and was considered by the late Mr. D. Sharpe to have assumed a ' fan-shaped ' structure. The granite of Monte Rosa is also of a similar composition. Granite also occurs at Brixen in the Tyrol; it forms the higher elevations of the Eiesengebirge, as well as portions of the Harz, the Thiiringer Wald, the Odenwald, the Schwarzwald, and the region north of the Neckar. It also occurs in Den- mark and Sweden, there being large quarries north of Stockholm, and it enters largely into the great mountain chain of Scandinavia, and the dreary wastes of Finland. 3 1 The reader will find a large number of examples in Zirkel's Petrographie, vol. i. 476. 2 L. von Buch, Mineral. Taschenbuch, 1824, 393. See analysis, ante, p. 28. 3 A specimen of Finland granite, in the Museum of Trinity 50 CONTINENTAL GRANITES. According to Murchison, these granites are of very ancient date, geologically considered, and are gen- erally of a rose colour, and penetrate the crystalline schists in such countless divergent veins, that geolo- gists have generally given the mass the name of ' granitic gneiss.' On the other hand, the granites of the Uralian range of mountains are of more recent date. 1 The use of granite for architectural purposes is splendidly illustrated in the city of St. Petersburg, to which it is brought from Finland. Here, not only the Imperial palaces and public buildings are constructed with this material, but even ordinary dwellings are partially or entirely built of it ; so that St. Petersburg may be considered a city of granite. The left bank of the Neva, from the Foundry to the Gulf of Cronstadt, and both banks of the Fontanka and of the Catherine canals, are lined with high walls constructed of blocks of granite, as are the bridges over the Neva. 2 The pillars, stairs, and balconies, &c., in the palace of Cronstadt, are almost all of the finest kinds of granite, sometimes beautifully polished ; and one College, Dublin, shows the following constituents : red orthoclase, a little greenish oligoclase (1), much black mica, and a little quartz. The specimen comes from Yiborg. 1 Kussia and the Ural Mountains, i. 10. 2 Nicholson's Die. of Architecture, i. 474. CONTINENTAL GRANITES. 51 of the largest blocks of granite in the world, con- taining about 50 cubic yards of material, as I am informed by Professor O'Reilly, forms the pedestal for the statue of Peter the Great. Of this block Sir E. Murchison states that it has been reduced two-thirds of its original size, and that it was found imbedded in a bog between St. Petersburg and Cesterbeck. 1 Gothland. This country produces a large-grained granite, consisting of chrome-red felspar, often por- phyritically developed, quartz, and black mica. Finland produces a nearly similar rock, but the felspar is of the more usual flesh colour. Speci- mens of these granites are placed in the Museum of Trinity College, Dublin. Egypt. The granite of Syene ('syenite rose d'Egypte ') occupies large tracts in Upper Egypt between the first cataract and the town of As- souan, the ancient Syene, including several islands both above and below the cataract. It was ex- tensively quarried by the Egyptians as far back, at least, as the reign of Zestus, King of Thebes, 1300 years before the Christian era, and been fashioned into columns, obelisks, sarcophagi, and colossal statues which have lasted with but little injury down to the present day, and adorn the 1 Russia and the Ural Mountains, i. 507 (note). B 2 52 CONTINENTAL GRANITES. cities and public galleries of modern Europe. These quarries may still be traced at intervals ; and the marks of the pick and chisel are still fresh. From the specimens which have come under my own observation, both in the Louvre, in Paris, and Italian cities, the granite of Egypt, when once recognised, can scarcely be mistaken. It consists of large crystals of red orthoclase, sometimes in twins, and porphyritically developed, a little yellowish oligoclase, quartz, and dark mica, with occasionally a little hornblende. 1 Sometimes the orthoclase crystals are of very large size, and the whole rock extremely coarse-grained. The general colour of the rock is reddish, and it takes a fine polish. Its durability has been put to the proof by the sharp- ness of the sculpturing on the obelisks, which have in some cases lasted 3000 years. It was formerly supposed to be syenite a rock in which hornblende replaces the mica but De Roziere has shown this view to have been founded on error, and that the stone is a true granite ; as any one may convince himself who will carefully examine the fresh frac- tures in the monument of the Sphinx in the Louvre. Hornblende is only an accessory, as is also garnet and pyrites. The proportion of silica is 70.25 per cent. 1 This description agrees with that of M. Delesse, who says it is formed of quartz, orthose, oligoclase, mica, and frequently also of hornblende. Journ. Geol. Soc. Lond. vol. vii. 9. CONTINENTAL GRANITES. 53 As regards Geological position, from the clear de- scription of the relations of the granite to the sur- rounding rocks given by Lieut. Newbold, 1 and more recently by Mr. J. C. Hawkshaw, 2 it appears that this rock forms a ridge, throwing off meta- morphic schists on the south, and passing under a newer formation of brown sandstone, which, ac- cording to M. Eussegger, is again found with the same characters in Upper Egypt, in Nubia, and in Sinai. 3 The granite is traversed by dykes of diorite, and the metamorphic rocks in contact with it are composed of gneiss, generally the lowest, talc and hornblende schists, clay-slate and quartz- ite ; with these are also found dykes of diorite, porphyry, and masses of serpentine. The analysis of a large piece of the granite obtained from the Egyptian Museum in the Louvre has already been given (p. 28). Whether we consider its antiquity, or the noble monolithic works of art of which it has formed the material, we must allow the granite of Egypt to be the most remarkable of all building or orna- mental stones. We cannot but admire the skill and labour which have been expended in quarry- ing these huge blocks, in covering them with 1 Journ. Geol. Soc. Lond. vol. iv. 328. 2 Hid. vol. xxii. 115. * Reisen in Europa, Asien und Afrika. 54 CONTINENTAL GRANITES. sculptured hieroglyphics despite the hardness of the material, and often in reducing the surface to a beautiful polish. These monuments of ancient civilization are now scattered over Europe, embel- lishing the cities and galleries of France, Germany, and especially Italy. Kings, emperors, and popes despoiled the ruined cities of Egypt in order to adorn the more modern cities of Borne and Paris. One of the noblest of these monoliths is the obelisk of Luxor, brought from Egypt in the reign of Louis Philippe, and placed on a granite pedestal in the Place de la Concorde in Paris, under the direction of the engineer Lebas. According to G-wilt, its height is 79.1 English feet, with a base eight feet square. Another of these obelisks was brought to Eome by Caligula, and under Sixtus V. was placed in its present position in the centre of the Piazza di S. Pietro by the engineer Dom. Fontana, in the year 1586. Other obelisks occupy positions in the Piazza del Popolo, the Piazza di Monte Cittorio, the Piazza di Monte Cavallo, and the gar- dens of the Pincio. The Museums of Florence, Eome, and Naples also contain statues, urns, basins, and sarcophagi formed out of Egyptian granite. One of the most remarkable of the Egyptian granitic monoliths is the column, one of two, which stands in the Piazza of St. Mark in Venice, and on which is perched the marble group of St. Theo- Monoliths of red and grey Egyptian Granite, erected on pedestals of white marble, Piazza of St. Mark, Venice. [.To face p. 55. CONTINENTAL GRANITES. 55 dore and the crocodile. The other column, sup- porting the Lion of St. Mark, is of grey granite, and both are stated to have been brought to Venice from Tyre by the Doge Michielli, in the year 1127. Similar columns of grey and red Egyptian granite are still to be found amongst the ruins of Tyre not, indeed, the ancient city of Hiram but of the more modern imperial city, which rose to great magnificence during the Roman Empire. 1 As the former of these columns is unquestionably of Egyp- tian origin, so also, I believe, is the latter ; for in some cases Egyptian works of art are to be found wrought in a fine-grained greyish granite, as in the case of the statue of the Sphinx in the Vatican collection. There appears, therefore, good ground for believing, that besides the red porphyritic granite, there exists in Egypt a greyish granite of ordinary composition, which, however, was less fre- quently used for architectural purposes and works of art than the characteristic granite of Syene ; of this grey granite are some of the columns at the entrance to the portico of Saint Peter's at Rome ; and probably, also, those which support the portico of the Pantheon, sixteen in number, and resting on pedestals of marble. Obelisks and sarcophagi of red granite are found in all parts of Egypt, of which Pompey's Pillar, and 1 See Tristram's Land of Israel, p. 53 (1866). 56 CONTINENTAL GRANITES. Cleopatra's Needle at Alexandria are examples. The stone was used for the inside polished lining of the Great Pyramid of Cheops, 1 and the monolith sanc- tuary of Sais ; and as the seats of government suc- cessively approached the Mediterranean, we find that the materials necessary to the construction of sacred and palatial buildings were transported farther down the valley of the Nile from their sources in the neighbourhood of the cataracts. 1 Piazzi Smyth, Quart. Journ. Science, vol. xxx. 191 ; Nicholson's Die. Arch. vol. i. 474. A small urn of Egyptian granite, finely crystalline white felspar, and black mica, is in the Royal College of Science, Dublin. CHAPTER VI, GEANITES OF AMEEICA. North America. Granite is largely developed in some portions of the Rocky Mountains, and north- eastern portions of the American continent. Massa- chusetts, Ehode Island, New Hampshire, and Main are the principal sources of this rock in the United States. The so-called Chelmsford granite comes from Westford and Tyngsborough, beyond Lowell, and an excellent variety is obtained at Pelham, a short distance north in New Hampshire. Masses sixty feet in length are obtained at several of the quarries, and are worked into columns for build- ings for the cities of New York and Boston. The new Exchange, considered to be the finest public building in New York, is built of granite, probably from New Hampshire. Good granite is also quar- ried in Waterford, Greenwich, and elsewhere in Connecticut. 1 Low&r Canada. Granite is extensively used for buildings, and is quarried at Stanstead, Barnston, and Nicolett. 1 Dana, Man. of Mineralogy, 352 (1870). 58 GRANITES OF AMERICA. The granite of Stanstead is of a greyish hue, uni- form texture, and can be extracted from the quarry in large blocks. A beautiful variety also occurs at Barford. 1 It is also extensively developed in various parts of Nova Scotia and New Brunswick. 2 India. Granite occurs amongst the higher altitudes of the Nepal Himalayas. 3 It is also widely distri- buted over portions of India, accompanying gneissose and other metamorphic rocks, as at Trichinopoly, Nerbudda, and the sub-Himalayan district between the Granges and the Ravee. It is often used (in company with gneiss) as the stone for the basement story of Hindoo temples. In the Shillong district, it has a composition, according to Mr. Medlicot, much resembling that of many places hi Europe, the favourite quaternary assemblage of pink ortho- clase, often in large crystals, pale greenish felspar (probably oligoclase), hyaline quartz, and dark green mica. 4 1 Logan, Geology of Canada. 2 Dawson, Acadian Geology, Geol. Map. 3 Hooker, Himalayan Journal, vol. i. ch. 1 1 . 4 * Geology of the Shillong Plateau,' Mem. Geol. Survey, India. CHAPTEE VII. / SYENITE. ACCORDING to the views of most British, and some Continental geologists, as Brongniart, 1 syenite is a crystalline granular aggregate of quartz, felspar, and hornblende, differing from granite only in the substi- tution of the last-named mineral for mica. 2 On the other hand, most Continental petrographers consider the quartz as unessential, in which case it is simply a binary compound of orthoclase felspar, and horn- blende, 3 the rock of the Plauenschen Grund, near Dresden, being eminently characteristic. According to this view, the distinction between syenite and diorite lies in the difference of the fel- spars, which in the latter may be oligoclase, labra- dorite, or albite, but not orthoclase. This may be a good distinction in theory, but in practice it is generally impossible, by the ordinary process of ex- 1 Classif. des Roches, p. 69 (1827). 2 Jukes' Manual of Geology, 3rd edit. 124; Ramsay, Descrip. Catalogue M. P. G. p. 241 ; Sir H. De la Beche, Geological Ob- server, p. 585 ; R. Hunt, Descrip. Guide Mus. Prac. Geol. 3rd edit, p. 2 1 ; J. Phillips, Mem. Geol. Survey, vol. ii. 3 Zirkel, Petrog. i. 578; B. von Cotta, Eng. Trans, p. 178. 60 SYENITE. amination, 1 to determine the nature of the felspar, whereas the presence or absence of free silica in a rock composed of hornblende and felspar may gene- rally be determined by the aid of a lens. For this reason I prefer to hold by the British definition ; as it is more available for observers in the field. Varieties. Granite, by the appearance of horn- blende crystals, gradually replacing those of mica," passes in rare instances through the stages of sye- nitic-granite into syenite ; instances of which are to be found amongst the Carlingford, and Slieve Croob mountains in the north-east of Ireland, and amongst the Vosges mountains on the east of France. 2 Sye- nite cannot be considered as an eruptive rock of frequent occurrence. England. Jersey and Guernsey, sometimes as sye- nitic-granite, or passing into porphyry. 3 The Malvern Hills, Worcestershire, where it consists of reddish felspar, quartz, hornblende, and sometimes epidote ; the rock is beautiful and varied. 4 Mount Sorel, Leicestershire, as syenitic granite, rose-tinted, hard, and durable, and largely quarried for architectural purposes of an ornamental character. It is formed 1 That is, by means of a pocket lens, or the eye. The deter- mination of the felspar may generally be obtained by microscopic examination of translucent slices. 2 Delesse, Ann. des Mines, vol. xix. 150 (1851). 3 McCulloch's Geog. Die. 4 Phillips, Mem. Geol. Survey, vol. ii. part i. 40, 41. SYENITE. 61 of reddish felspar, green hornblende, a little quartz and mica. There are, however, variations from this the typical constitution. 1 Wales. Mynyd Cefn, Amwlch, near Pwllheli, N.W. of Ffestiniog, Pen-ar-fynydd, three miles east of Abardaron. Ireland. At Loughrusmore a large-grained syenite (or diorite) is found consisting of a crystalline gra- nular aggregate of hornblende and felspar. Analyses of four varieties of syenite from Co. Donegal, by the Rev. Dr. Haughton, gives the proportion of silica as ranging from 49.2 to 58.05 per cent. In Carlingford mountain there occurs a handsome variety of ' anorthite syenite/ composed of anor- thite felspar and hornblende. Scotland. Strontian, Argyleshire ; syenitic gra- nite and syenite. Ben Grlamich, Island of Skye. The Continent. A very handsome syenite is found in the Dresdner Falsterstein, the constituents of which are reddish felspar, hornblende, and a little quartz. A specimen is placed in the Museum of Trinity College, Dublin. Canada. Syenite, of handsome appearance and good quality for architectural purposes, occurs at Grenville. It consists of deep red orthoclase felspar, greenish-black hornblende, and grains of quartz in small quantity. A similar rock is also found at 1 Specimen in Museum of Trinity College, Dublin. 62 SYENITE. Chatham, and Wentworth, and at Barrow Island in the St. Lawrence. 1 Nova Scotia. Syenite, in company with porphyry, suitable for building and ornamental purposes, is extensively developed amongst the Cobequid Moun- tains, and on the east side of Bras d'Or; but owing to the inland position of the former locality, and the absence of local demand, it is not at present turned to much use. 2 1 Logan, Geology of Canada. 2 Dawson, Acadian Geology, p. 593. PART III. PORPHYRITIC ROCKS. OHAPTEE I. PORPHYEIES. Specific gravity, 2.49-2.60. Porphyr (Germ.) Porphyre (fr.) Proportions of silica in quartz-porphyry . . . 70-81 per cent. in porphyrites (basic) ..59-61 THE term ' porphyry ' was originally applied to certain kinds of igneous rocks of reddish or purple tints, such as the red porphyry of Egypt, 1 but this primary signification has now given place to one in which structure, and not colour, is the guiding characteristic. A porphyry, as the term is now generally received, is a rock of plutonic origin, with a compact, or micro- crystalline, felspathic base, in which individual crys- tals of quartz, or felspar, sometimes with other minerals, are developed. Thus we have the following varieties : (a) Quartziferous porphyry ; 2 a finely crystalline 1 Mr. R. Hunt, Descrip. Guide M. P. G. 3rd edit. p. 20. 2 This is the felsite porphyry of Zirkel. Ibid. i. 530. 64 PORPHYRIES. granular felspathic rock, with individual crystals of silica and felspar. (b) Feist one-porphyry ; a compact or micro-crys- talline highly silicated felspathic rock, with indi- vidual crystals of felspar. (c) Porphyrite; 1 a quartzless porphyry or basic felstone, with individual crystals of felspar. Chemical Analysis. The following are several analyses of porphyries, including both the quartz- iferous and quartzless varieties : Analyses of quartziferous porphyries (acidic). I. II. III. IV. V. VI. Silica *7A A A . 81 ex . 67. CA . 72 33 ., 7o no .. 72 2O Alumina 1 T 1 T"T * 13.51 ' l.W . , 11.49 ' V /*OT 14.97 .. /*'OO " 8.97 .. < W '0 W 13-50 / ' 12.50 Oxides of Iron. . . . 2.25 .. 2.28 .. 5.14 7.46 .. 5-50 3-70 Lime I.I 9 .. 0.40 .. 2.8 4 .. I. 9 8 .. 0.25 .. 0.90 Magnesia O.OI .. 0.40 .. 1-30 .. trace . . 0.40 .. Potash 5-31 2.07 .. 4 .58 .. 1.46 .. 5-5 - 3.88 Soda 1.40 .. 2.56 " 2.28 .. 5.83 3.55 5.30 Water 1.34 .. 0-93 - 1 .08 .. 1.86 .. 0.77 .. 0.60 99.45 101.18 99.73 99.89 99.97 99.08 I. Quartz-porphyry (or felsite-porphyry) from the Harz Moun- tains. II. Quartz-porphyry (or felsite-porphyry) of Falkenstein, near the Donnersberg in the Palatinate. 2 III. Quartz-porphyry from the flanks of the Bodenthal, below Lucashof, with quartz, orthoclase, and oligoclase. Sp. gr. 2.66. 3 1 A name proposed by Naumann (Geognosie, i. 600) ; with him Von Cotta (Gfesteinslehre,ip. 105, 1862); Zirkel's name is ' quartzless orthoclase porphyry' (quarzfreier orthoklas Porphyr), ibid. i. 596. 2 Bischof, Lehrb. der phys. Geol. 1862. 8 Streng, N. Jahrb. fur Miner, p. 267, 1860. PORPHYRIES. 65 IV. Elvanite (quartz-porphyry), Co. Wexford, Ireland. J. A. Phillips, Phil. Mag., June 1870. V. Reddish porphyry from Kreuznach. 1 VI. Rose-coloured quartziferous porphyry ( * orthophyre ') from Grenville, Canada. Sp. gr. 2.o. 2 Analyses of Porphy rites (basic). Silica I. n. 6382 in. cc an 18 78 Iron oxide 5aT O 4.6 2 6* 3 14 o /to I 1A. Soda 3-54 4.04) 868 Potash 4-03 2 4O 4-56 | " i 17 Carbonic acid . . 1.K2 1.54 98.42 98.36 100.00 I. Boscampo Bridge, near Predazzo, Tyrol. Kjerulf, Christiania Silurbecken, 1855, 14. II. Dyke in largely-crystalline ' syenite.' Flesh-coloured base, with crystals of orthoclase, a few of light grey oligoclase, and greenish grains, probably of hornblende. Kjerulf, ibid. 15. III. Dark grey felspathic base, with rhomboid crystals of felspar (' Rhombic-porphyry '). Geological Ages. The highly silicated quartz- porphyries and felstone-porphyries have been chiefly developed amongst rocks of Primary, or Palaeozoic age, and are largely developed amongst the moun- tainous districts of the British Islands, formed of these rocks ; such as Galway, Sligo, and Donegal in the West and North of Ireland, and Wexford and 1 Wolff, ' Die. d'Anal. Chim.,' par Violette et Archambault. 2 Sterry Hunt, 'Logan's Geol. of Canada,' p. 654. F 66 PORPHYRIES. Wicklow in the East; in North Wales; Cumberland; the Southern Uplands and Highlands of Scotland; Devonshire and Cornwall in the South of England. They are also found penetrating the old crystalline rocks of Scandinavia ; the chain of the Oural moun- tains in Russia ; and the crystalline rocks near the first cataract of the Nile. CHAPTER II, BRITISH PORPHYRIES. Scotland. In this country porphyries are found imbedded with the Lower Old Red Sandstone, of the Sidlaw and Lammermuir Hills ; with the Upper, in the Pentlands ; l and in the vicinity of Lesmahagow. 2 One of these finely crystalline rose-coloured porphyries from this neighbourhood, which would make a beau- tiful stone for ornamental purposes, appears from examination under the microscope to be composed of red orthoclase and triclinic felspars, small hexa- gonal scales of greenish mica, and a few grains of quartz. Jameson mentions the occurrence of a beau- tiful porphyry, penetrating mica slate between Blair Athol and Dalnacardoch. 3 A handsome porpyhry, according to Dr. Bryce, occurs along the S.W. coast of the Island of Arran. Cornwall is rich in porphyritic rocks, many of the elvan dykes assuming this character having a highly silicated felspathic base, with crystals of 1 Geikie, ' Chron. Trap Rocks of Scotland/ Trans. Roy. Soc. Edinb. xii. 635. 2 Described by Sir K. Murcbison, Quart. Journ. G-eol. Soc. xii. 3 Syst. Mineralogy, iii. 137. F 2 BRITISH PORPHYRIES. felspar and quartz, sometimes schorl, and rarely mica. One of the most remarkable examples is the schorla- ceous porphyry from Luxullian, in Cornwall ; con- sisting of black schorl and a little felspar and quartz as a base, in which are distributed large crystals of red orthoclase felspar. The sarcophagus for the late .Duke of Wellington, now in St. Paul's, is formed of one huge mass of this rock, which has received the name of Luxullianite. 1 A handsome porphyry, suitable for polishing, may be obtained from Tremore, near Bodmin. It occurs as a dyke, extending in an easterly direction from this place to the south of Withiel and St. Wenn. The rock varies in colour, but those portions having a reddish or flesh-coloured base, with crystals of white felspar, and occasionally some schorl and quartz, are the most beautiful, and occur in large quantity at Tremore village, and in a ravine above Ruthan bridge. This porphyry has been cut and polished by water power at Fowey Consols Mine, for private use ; and it has a very handsome appearance, with the ad- ditional advantage of being capable of extraction from the quarry in large blocks. Another variety from the same neighbourhood is composed of light pink crystals of felspar, with others of quartz and schorl, in a brownish-red felspathic base ; and a third (but apparently only occurring in small quantity) is 1 Mr. R. Hunt, Descrip. Guide Mus. Prac. Geol. p. 20. BRITISH PORPHYRIES. 69 formed of greenish felspar crystals, in a light, flesh- coloured base, a combination of extremely rare occurrence. 1 A very beautiful reddish elvanite (a granitoid variety of quartz-porphyry) is found at Barton and Ennis, near the Indian Queen Inn, between Bodmin and Truro. Good varieties may be obtained from some of the Gwennap elvans ; that at Seveock Water, near Chasewater, with a grey granitic base, containing crystals of roseate felspar, and nests of radiating schorl, being specially worthy of notice. Other localities for ornamental porphyries, which may be mentioned, are May on, near the Land's End ; a rose-tinted rock between Tyecombe and Dowgas, near St. Austell ; others near Camelford, and between Penhale and Bochin, which latter is composed of white felspar crystals, in a very dark green base ; and lastly, the porphyritic greenstone of Boswednon Cliff, near Zennor. 2 The trap rocks here described either penetrate the stratified rocks in dykes, or occur as intrusive sheets nearly coinciding with the bedding, or strictly con- formable to them. In North Wales, on the other hand, they form beds of great horizontal extent and thickness, rising into the higher elevations, and fol- lowing all the inclinations and flexures of the lower 1 Sir H. T. De la Beche, Geol. of Devon and Cornwall, p. 502. 2 Ibid. pp. 156-192. 70 BRITISH PORPHYRIES. Silurian grits and slates with which they are truly interbedded; while enormous bosses protrude here and there through the sedimentary strata (as, for example, at Penmaenmawr), which may be regarded as portions of the old throats of the ancient volcanoes, from which these great lava streams probably sub- marine were poured forth. 1 The porphyrites, accompanied by melaphyres, are, for the most part, found imbedded amongst rocks of Devonian, Carboniferous, and Permian age, having been erupted and poured out in a liquid state over the bed of the sea in which these strata were in course of deposition, accompanied by volcanic ashes, scoriae, and agglomerate ; and thus presenting, as regards their mode of occurrence, the phenomena of more recent volcanic regions. In this manner, these basic plutonic rocks underlie the coal-measures of Scotland, and rise from beneath the coal-basin of the Clyde in terraced escarpments, forming the hills of Kilpatrick, Campsie, and Kinross on the north ; and of Largs, Gleniffer, and Neilston on the south; but finding their noblest exemplification in the mural cliffs of Arthur's Seat and Salisbury Crags, near Edinburgh. 2 These rocks are exceedingly varied 1 Ramsay, Geol. Survey Memoir on North Wales; Sedgwick, Quart. Journ. Geol. Soc. iii. 133, and iv. 216. 2 Murchison and Geikie, Geol. Map. of Scotland, text, p. 13 ; Geikie, ' Geology of Edinburgh/ Mem. Geol. Survey, p. 33. BRITISH PORPHYRIES. 71 in appearance, and contain numerous minerals, such as stilbite, prehnite, analcime, calc-spar, glassy quartz, &c. Ireland. In the South of Ireland, the porphyrites and porphyries of the Carboniferous basin are of a similar character to those in the centre of Scotland, forming two concentric zones, interstratified with the Carboniferous Limestone ; * in some places they as- sume the aspect of melaphyres. A very handsome porphyry (or porphyrite) is found at Lambay Island, off the eastern coast of Ireland, which is scarcely inferior in beauty to the porphyry called 'verde antico/ so frequently employed for decorative pur- poses on the Continent. 2 It consists of a dark green base, in which numerous light green crystals of ortho- clase felspar are distributed. This rock takes a fine polish ; a large block has been placed for exhibition in the Museum of the College of Science, Dublin, which deserves the attention of architects and sculptors. 1 Maps of the Geological Survey of Ireland, 144 and 154, with Explanatory Memoirs by Messrs. Jukes, Kinahan, and O'Kelly. Mr. S. Allport is now engaged in an examination of these rocks from the Limerick basin under the microscope, from which some interesting results may be anticipated. 2 Especially Italy. See p. 73. CHAPTEK III. POKPHYRIES OF THE CONTINENT. Sweden. At Elfdahlen, in the province of Delicar- bia, great varieties of porphyritic rocks are developed. One of these exhibits red, blue, violet, and grey colours, and contains in addition to crystals of felspar, others of garnet, titanite, magnetite, specular iron ore, and pyrites. It is manufactured into small ornaments. 1 This rock is extensively developed in the south of Norway. At the same place, mosaics of great beauty are produced, and fine specimens of ornamental art; 2 amongst which may be mentioned the large and beautiful vase placed in front of the Palace of Bosendal, near Stockholm ; and the sarco- phagus enclosing the remains of King Charles John. Germany. In Saxony, Thuringia, Westphalia, and the southern borders of the Harz, porphyries some- times contemporaneous with the Permian formation, sometimes irruptive, are largely developed, and occur both as quartziferous, basic, and amygdaloidal. 3 The 1 B. von Gotta, Petrog. p. 170. 2 A tazza of one of these porphyries is in the collection of the Royal College of Science, Dublin. 3 Murchison and Morris, ' Rocks of the Thuringenwald,' Ordinary. 59 Vellini . . . j 60 Campo Francisco . . Statuary. 62 Sponda . '* i. . Statuary. 63 Fondone. . . . Statuary. 64 Campanice . . . Statuary. 65 Crocicchia . . . . Statuary. 66 Monte Brugiana . . Ordinary. 67 Nido del Corvo . . Ordinary, red stalactite. 68 Al Ficale . . . Mischio. 69 Sordola .... Spotted white. 7 1 Cerignano . . . White, black bardiglio. Greece. How far the excellence of ancient Greek sculpture was due to the suitability of the material for high art which that country produced, it is un- necessary to discuss ; but no one can doubt that the presence of Parian and Pentellic marble exerted a certain influence upon the minds of the Athenian and Corinthian sculptors ; and that when they found at hand the material for embodying their ideas, in its greatest purity and suitability of texture, they were encouraged to aim at perfection in the design and execution. As Mr. Ruskin well observes of sta- tuary marble, it is exactly of the consistence best adapted for sculpture ; that is to say, neither hard, nor brittle, nor flaky, nor splintery, but uniform and delicately yet not ignobly soft ; exactly so soft as to allow the sculptor to work it without force, and CONTINENTAL MARBLES. 137 trace on it the finest lines of finished form ; and yet so hard as never to betray the touch, or moulder away beneath the steel. 1 In truth, the genius of Phidias, Scopas, and Praxiteles found in the island of Paros, and in the Mount of Pentelicus, a material admirably adapted for the embodiment of its highest conceptions. Parian and Pentellic marbles are composed of nearly pure carbonate of lime, with a finely crystal- line granular structure, doubtless due, as in the case of the crystalline marble of Carrara, to metamorphic action. The Parian stone, however, on being freshly fractured, presents a glistering play of light from the crystalline facets, of greater brightness than that from a similar surface of the Carrara stone. This distinction can be detected by the skilled Eoman workman of the present day, and is one means whereby he is enabled to determine the origin of a fragment of Greek or Italian statuary. The ancient quarries are situated in the island of Paros, and in Mounts Pentelicus and Hymettos. The Parthenon at Athens is' constructed of Pentellic marble. These quarries, besides others, in the islands of Scio, Samos, and Lesbos, afforded materials both for the construction and decoration of the temples of ancient Greece and Home, but are now rarely re- sorted to. The Pentellic quarries, however, have 1 Stones of Venice, III. i. 138 CONTINENTAL MARBLES. recently been re-opened, for the restoration of some of the buildings in Athens ; and, let us hope, for the use of sculptors all over the world. In illustration of the preference of sculptors for Greek marble, and its superiority to that of Carrara, the following anecdote may be related. 1 The sculptor Pacetti, having purchased a torso of a male figure, a Greek work of the best period, in Pentellic marble, and desiring to restore it, was unable to find marble of sufficient purity or fineness of texture to match the original, and was consequently obliged to destroy another Greek statue of inferior merit, in order to match it. Pacetti succeeded, and produced the sleeping figure known in art under the name of ' Barberini Faun/ 2 Any attempt to adequately illustrate the works of art to which the Greek marbles have been applied would be far beyond the scope of this work, even if it were within the ability of the author ; a very few examples, therefore, will here only be noticed. 1 See Recollections, by Massimo D'Azeglio, Eng. ver. 2 Poor Pacetti was not allowed to reap the reward of his successful labours. Having sold the work to a German Prince for several thousand scudi, the Pontifical Government forbade its removal from Rome, and actually sent an armed band to break into the studio of the sculptor and carry away the statue by force ! In vain did Pa- cetti appeal to the corrupt tribunals for restitution ; and thus cruelly wronged, took to his bed and died. It was only some years after that his executors were enabled by a process of law to come to some terms with the authorities. The whole case is related by Massimo D'Azeglio. CONTINENTAL MARBLES. 139 And first let us turn to the seat of ancient art itself, Athens, with its Acropolis grand and beautiful in its desolation, once adorned by the noble Par- thenon, 1 the Erechtheum, and the temple of Athene Nyke, together with the numerous shrines and statues, including the gigantic Athene Promachus of Phidias, 66 feet in height, clad in armour, with a lance whose gilded point formed a landmark to mari- ners as they approached the harbour of Piraeus from Cape Sunion ; the whole of this wonderful museum of art being approached by the Propylsea, the noblest gateway, perhaps, ever erected. With the exception of some small portions of these works of foreign mar- bles, the remainder were formed from the white crystalline rocks of Paros and Pentelicus. Ancient Eome was also adorned with architectural monuments in Greek marble, erected before the Christian era, of which the three Corinthian columns with their entablatures which belonged to the temple of Castor and Pollux, and which now stand in solitary gran- deur amidst the ruins of the Forum Romanum, are conspicuous examples. Although dating as far back 1 The Parthenon had stood almost intact down to 1684, when during a siege by the Venetians a shell exploded the powder magazine which it contained, and reduced it almost to ruins. In this state it was found by Lord Elgin, who in 1801 carried away to England a number of the metopes, a portion of the frieze, and the best statues of the tympana, the works of Phidias and Praxiteles. 140 CONTINENTAL MARBLES. as nearly 500 years before our era (B.C. 496), they are still in remarkably good preservation. Amongst the countless illustrations of the use of Greek marble in statuary, it is difficult to select even a few examples, especially after a visit to the galleries of Florence, Borne, and Naples; where, from the number of specimens recovered from the ruins of ancient cities, we may conjecture how numerous must have been those that are lost. As an example of the beautiful, the Venus de Medici, found in the villa of Hadrian near Tivoli, now deposited in the Galleria degli Uffizi, at Florence, would by many be considered as entitled to the first place ; an opinion in which I do not concur. Then the group of Niobe and her chil- dren, fourteen in number, which must originally have adorned the portico of a temple. This truly marvel- lous group of figures, when we consider the variety of attitudes they exhibit, supposed to be copies of works by Scopas or Praxiteles, was found in Rome in 1583, is now in the Uffizi Gallery at Florence. The group of Laocoon and his two sons, the original of which is in the Vatican Gallery at Eome ; the torso of Hercules, in the same collection; and the draped figure of Sophocles larger than life, found at Terra- cina in 1838, and now preserved in the Gallery of the Lateran at Rome, are all of Grecian marble. Admirable as are these works of art, they are not superior, as it seems to me, in boldness and largeness CONTINENTAL MARBLES. 141 of design to the group known as the ' Farnese Bull ' found in a mutilated state in the Thermae of Cara- calla at Rome, and now in the Museum of Naples. This group, consisting of seven distinct figures, if we include the bull and a dog, all larger than life, and in various positions and attitudes, is probably un- surpassed for boldness of design and vigour of execution by any group of statuary in the world. The whole group was originally cut out of a single block, which must have been of huge dimensions, by the Ehodian sculptors Apollonius and Tauriscus. When found, it was in a fragmentary state, but it has been admirably restored under the superintendence of Michael Angelo. 1 Sicily. The marbles of Sicily are but little used in this country. The following are some of the varieties : Marmo di Trapani, of a grey colour ; Marmo di Castelnuovo and di Segesta, of a yellow colour ; Marmo di Taormina and Ogliastro, of a red colour; and that of Castelaccio, of a grey colour. 2 Corsica produces a greyish variegated variety known as the bardiglio marble, similar in appearance to that of Northern Italy, and bearing the same name. France and Belgium. These countries yield several varieties of marble of great beauty; of the 1 The new portions are the head of the bull, the Antiope with the exception of the feet, the upper part of the Dirce, and a great part of Amphion and Zethus. 2 Gwilt, Encyc. Arch. p. 491. 142 CONTINENTAL MARBLES. colours red, rose, brecciated (breche), white statuary, and white-veined black of Saint Mont Clarie, and black and gold. The following are some of the locali- ties as given by Chateau. Gap in the Hautes Alpes ; greyish black, easy to work. Besancoii in the Doubs; tufaceous marble of different qualities. Combovin in Dr6me ; fine white marble employed in architecture and sculpture. Chartes in Ure-et-Loir ; beautiful con- glomerate, susceptible of polish. Montpellier in He- rault ; very hard, durable, and handsome stone. Lourdes in Hautes Pyrenees ; white and grey with black veins, of good quality. Chateau-Landon near Nemours ; grey, variegated with yellow, susceptible of good polish, and largely employed for decorative purposes in Paris : l this marble is derived from Tertiary strata. Spain. This country, from its geological structure, may be safely inferred to be rich in marbles, which in the period of her magnificence were employed in the interior decoration of her numerous splendid buildings. It is probable, however, that the marbles of Italy were largely employed in ecclesiastical edifices, since the architects of Spain during the middle ages seem to have had close intercourse with those of Italy. White marble from Machael in the Sierra di Bacares, 1 For example, in the pavement of the Pantheon ; the basement of the now prostrate Arc de Triomphe ; parapets of the bridge of the Tuileries ; the fountain of St. Sulpice ; the bridge of Ne'mours ; and the basins of the Chateau d'Eau. Chateau, Tech. d. Bat. i. 231, 2. CONTINENTAL MARBLES. 143 was employed in the Alhambra, and more recently in buildings of Madrid, and Baza. Similar marbles are obtained from Velez-Rubio in Andalusia, from Va- lencia, and from Rosas in the Eastern Pyrenees ; red marble veined from Murcia and Cueta in Leon ; shelly marble of a deep black ground from Badajos ; and statuary marble from Filabra in Grenada. Portugal, also, produces several good varieties of marble ; that known as the ' Emperor's Red/ of which a fine block was presented by the late Don Pedro, King of Portugal, to Queen Victoria for the royal mausoleum at Frogmore, being the most highly prized. White marbles are found at Estrennas and Vianna ; yellow and red at Alentejo and Troncao ; blue at Serpa and Villaviciosa ; and a peculiar variety called 'agate marble ' at Alentejo. Gibraltar. Amongst the caverns with which The Rock abounds, stalagmites and stalactites are found which have been formed by deposition from dripping water. These, when cut and polished, often afford a very handsome banded and concretionary marble, which has obtained some celebrity under the name of 6 Gibraltar stone ;' and is cut and moulded into small articles such as inkstands, cups, and candlesticks. Phrygian Marble. One of the most curious, as well as handsome varieties of marble with which I am acquainted, is largely used in Southern Italy in the internal construction of churches and buildings of 144 CONTINENTAL MARBLES. a higher class. It is known as * Phrygian ' marble, or ' Pavonazetta/ from its resemblance to plumage of a peacock. It consists of banded layers of silicious limestone of various shades of green, verging upon blue or grey, alternating with others of a pure white. These bands are sometimes contorted, waved, or foliated in a remarkable manner, characteristic of schistose rocks ; and in some instances the different layers are broken through and displaced by little 'faults' or slips, as may be observed in one of the four beautiful columns which adorn one of the courts in the Vatican Gallery. The finest examples of the use of this marble are to be seen in the Church of S. Maria sopra Minerva in Rome, in which the columns between the nave and side aisles are formed of it, and are beautifully polished. In these the wavy foliation and banded structure are brought out in perfection. The use of this species of marble reaches far back into Roman history. I observed a pillar of it amongst the ruins of Pompeii, 1 and the Corinthian columns in a dilapidated state, standing on the north side of the Forum Eomanum, which once formed the porch of the Temple of Faustina, but are now converted into a porch for the Church of S. Lorenzo di Miranda, sufficiently attest its use at the commencement of the Christian era. 1 Another of these columns of Phrygian marble from Pompeii is placed in the Museum at Naples. OHAPTEE III. MAEBLES OF THE AMERICAN CONTINENT. Canada. The crystalline limestones of the Lauren- tian series of rocks yield white marbles suited for decorative purposes, but not for statuary ; they are quarried at Calumet Falls on the Ottawa, Portage du Fort, and Fitzroy Harbour. Large blocks of pure white are obtained from Elzivir and Marmora ; and the statuary marble from Barrie would probably not be inferior to that of Carrara, were it not for grains and specks of quartz and tremolite, which detract from its excellence in quality. 1 Coloured marbles are obtained from the rocks at the mouth of the Madawaska, in Mac Nab county, on the Ottawa; the colours are grey, and dark grey variegated ; it can be raised in large blocks. A rich red variety is also found amongst the Quebec series of strata at St. Joseph on the Chaudi^re. 2 Nova Scotia, dc. Marble occurs sparingly in the eastern states of British America ; but coloured varieties are found amongst the Carboniferous lime- stone strata at Eraser's Mountain and Little Harbour 1 Logan, Geol. of Canada, p. 823. 2 Ibid. L 146 MABBLES OF THE AMERICAN CONTINENT. near New Glasgow ; at Plaistow Cove, in Co. Inver- ness ; and in Long Island, Cape Breton. White marble occurs amongst the metamorphic schists of Five Islands in Nova Scotia, together with coloured serpentinous marble. 1 United States. Statuary marble has been obtained in the U. S., but not of a quality equal to that of Europe. Good ornamental marbles are quarried at Sheffield, Great Barrington, and Lanesborough, in Berkshire, Mass. 2 The columns of the Girard College are from Sheffield, where blocks 50 feet long are sometimes quarried. The marble front of the City Hall, the Custom House, and University of New York, are built of stone from West Stockbridge ; that of the Capitol at Albany, from Lanesborough. At Stoneham there is fine statuary marble, but large blocks are not easily obtained. The variety from Great Barrington is handsome and clouded. There are marble quarries also in Vermont, in several counties in the State of New York, at Smithfield in Khode Island (statuary), near Hagerstown in Maryland, and and a fine clouded variety near Philadelphia. A dun- coloured marble is obtained at New Ashford and Sheffield, Mass., and at Pittsford, Vt. 3 Black marble used in the U. S. comes mostly from 1 Dawson, Acad. Geol. p. 593. 2 Hitchcock, Geol. Rep. p. 162. 3 Dana, Man. Miner, p. 363. MARBLES OF THE AMERICAN CONTINENT. 147 Shoreham, Vt., and other places in that state near Lake Champ lain ; there are also quarries at Isle La Motte, near Plattsburgh, and Glenn's Falls, New York. Grey and dove-coloured marbles are common throughout the Western States. There are also varieties of shell marble, encrinital marble, and madrepore marble from numerous localities. 1 1 Dana, Man. Miner, pp. 365-6. L 2 OHAPTEE IV. MAEBLES OF OTHER COUNTRIES. Egypt. Breccia di Verde. Between the Red Sea and the Nile, in lat. 26 8' N. (nearly), the celebrated Breccia di Verde, which has been largely used for ornamental purposes in Italy, is found. It reposes on slates in conformable thick-bedded strata, becom- ing more horizontal as it recedes from the central granitic axis. It is a beautiful rock, composed of angular, or rounded, pebbles of greenstone, gneiss, porphyry, slate, serpentine and marble, cemented together by a compact calcareous paste, varying from all shades of green to a purplish red. Between Siddt and Hummamet this breccia has been quarried by the ancient Egyptians, whose chisel-marks and hiero- glyphics are as sharp and legible as though only cut yesterday. The churches of Italy and the mosques of Constantinople contain numerous examples of this marble ; while one of the most perfect and beautifully sculptured specimens of art that remain in Egypt is the celebrated sarcophagus, supposed by Dr. Clarke to have contained the body of Alexander the Great. 1 1 Lieut. Newbold, from Geol. Soc. Lond. iv. 329. MARBLES OF OTHER COUNTRIES. 149 Onyx Marble. The re-discovery of the quarries from which the now justly-admired ' onyx marble ' was formerly extracted, by a French gentleman, M. Delmonte, in 1849, is an event of interest to petro- graphers. This stone, which is carbonate of lime, was formerly considered to exist only in a state of stalagmite in some limestone caves, but M. Delmonte discovered large beds of it amongst the Tertiary lime- stones of Blad Eecam ( ' Marble Country ' ) near the ravine of Oned-Abdallah. The old quarries which supplied the inhabitants of Rome and Carthage with this fine translucent marble, which was used in the internal decoration of their houses and monuments* were here situated. This marble, re-discovered after the lapse of more than a thousand years, is now imported into Paris, where it has assumed its former celebrity. 1 The onyx marble is translucent, faintly white, and iridiscent, of uniform texture and stalagmite structure bearing a resemblance to onyx, whence its name. It produces a beautiful material for the manufacture of timepieces, small vases, candlesticks and similar articles of every-day use ; 2 and was in ancient times cut into small vases for holding precious ointments. Onyx marble was one of the stones designated ' Oriental ala- 1 From MS. account by M. A. Gages, M.R.I. A., Curator of the Museum of the Royal College of Science, Dublin. 2 A cup ornamented with garnets is in the gallery of this museum ; some of the timepieces manufactured in this material in Paris are extremely handsome. 150 MAEBLES OF OTHER COUNTRIES. baster/but is of course altogether a different substance from the alabaster of the present day. ' Oriental ala- baster' is another variety of marble also derived from quarries in Egypt, and employed in works of art, ex- cept statuary, both in ancient and mediaeval times. Its stalactitic origin is at once apparent upon inspection. The colour is that of amber, or rich yellowish-brown, of various shades arranged in folds, or wavy parallel bands. Sometimes it is beautifully iridiscent, as in the case of the four columns, each about eight feet in height, which adorn the sala containing the cabinets of gems in the Galleria degli Uffizi at Florence. The mammillated structure, so characteristic of deposits due to filtration or percolation, is also not infrequent. This stone was largely employed by the ancient inhabitants of Egypt in the formation of canopi (or jars surmounted by sculptured images of the dog- headed god), in which were deposited the ashes of the dead, and of which examples may be seen in the British Museum, the Louvre, and the Galleries of Rome and Naples. 1 Besides these smaller objects, large cinneral urns were formed of this material; one of the finest I have seen being in the Museum of the Vatican at Rome, which measures about 9 feet in length, and 4 in depth. There is another in the Egyptian collection at Naples ; and the Galleria Pitti 1 One of these canopi is deposited in the Museum of the Royal College of Science, Dublin. MARBLES OF OTHER COUNTRIES. 151 at Florence contains tables of this material showing the banded and concretionary structure very beauti- fully developed. Palestine. Marbles were used without stint in the decoration of Solomon's Temple, and Palace, 1 and the buildings themselves were constructed of white marble 2 which glistened from afar in the blaze of an unclouded eastern sun. The situation of the quarries from whence the marble was hewn is uncertain ; but every block was shaped and polished before it left the quarry, and noiselessly let into its place. Heber has well expressed the silent growth of this the first permanent building erected for the worship of Jehovah, and as the central church of a whole nation : ' No hammer fell ; no ponderous axes rung ; Like some tall pine, the noble fabric sprung : Majestic silence ! ' Persepolis. The ancient capital of Persia, of which the ruins are situated in the great plain of Istakhr, destroyed by Alexander the Great, 2000 years since, contain amongst its tombs pavements of slabs of marble of great beauty, hewn from the neighbouring mountains. The palace of the Shah of Ispahan, the 1 i Chron. xxix. 3. 2 Josephus says, ' The body of the temple was built of white stone or marble / and contrasts this with the 'native stone,' pro- bably nummulite limestone, of the encompassing cloisters. Book viii. sec. 3. 152 MARBLES OF OTHER COUNTRIES. modern capital, is also adorned with twisted columns of Tabriz marble, while white and coloured marbles are profusely used in the interior of the building. British India. The marbles of India have been very largely employed by the inhabitants from remote periods, and used not only for statuary purposes, but in the construction of temples and palaces. The following are some of the localities from which marble of several varieties has been extracted. Statuary and white marbles of several kinds from the environs of Delhi, Gya, Syepore (of a very pure translucent kind), Tinnevelly, and the district of Nerbudda. 1 In addition to the above we may mention the following : At Coimbatore in Madras, there is a marble varying in colour from pink to grey and white, which receives a fine polish, and is worked to a considerable extent. 2 The grey- veined marble of Assam. The black marble of Durha, Bengal. The marble of Bellary, of a canary, or cream colour, presenting varieties of depth of shade. It is extremely compact, and takes a fine polish. 3 1 The ' marble rocks ' in Nerbudda, formed of white saccharine marble, are celebrated for their beauty. Mr. J. G. Medlicott, Mem. Geol. Survey of India, vol. ii. 2 Mr. H. F. Blanford, Mem. Geol. Survey, India, vol. i. p. 247. 3 Chateau, Tech. d. Bat. ii. 573. OHAPTEE V. / AET ILLUSTEATIONS IN MAEBLE. PERHAPS the most ancient sculptures in marble which have been rescued from oblivion are those which decorated the majestic temple of Neptune at Paestum, which also exhibits, in its short crowded columns and gigantic entablature, that most charac- teristic specimen of the massy form of the older Doric style of architecture which prevailed amongst the Greek colonies of Sicily and Italy. 1 To the same period (B.C. 400-500) may be referred the sculptures on the metopes of the friezes of the three Sicilian temples in the citadel of Selinus, discovered amongst the ruins in i823, 2 and now in the Museum at Palermo. Of the character of these early works of art, a recent writer says : ' In the metopes of Selinus, while the lines are firm, and the general contour of the human figure is traced with a tolerable approach to truth, the proportions are ludicrously clumsy, the attitudes stiff and unvaried, and the expression of 1 Wilkins' Antiquities of Magna Grgeca, 1807. 2 By Mr. Harris and Mr. Angell. Casts are to be seen in the British Museum. 154 ART ILLUSTRATIONS IN MARBLE. all the countenances is a slight and almost silly simper/ 1 In advance both in truthfulness of detail, in vigour of design, and probably in the period of execution, are the sculptured figures on the tablets of the temple of Minerva at ^Egina, which were discovered in 1811, and after having been restored by Thorwaldsen, were deposited in the Eoyal Museum of Munich. The fidelity to nature, and simplicity and strength in design which these sculptures exhibit, have astonished artists, and seem to announce the approach to the succeeding period, when Grecian sculpture reached its zenith of excellence under the master minds of Phidias, Polycletus, Myron, Pythagoras, and Ca- lamis. Of the numerous and beauteous works of art which arose under the hand of these great masters, we are unhappily only acquainted with architectural sculp- tures ; but several antiques are recognised as being either copies, or more likely, free imitations of their designs, or of those executed by their pupils. The Amazon of the Vatican, a figure in the act of springing forward, with its repetitions, are regarded as copies or imitations of those of either Phidias or Polycletus. 2 1 Professor Spalding, Italy and the Italian Islands, vol. i. 153* 5th edit. 8 Of Phidias : by Miiller, Handbuch der Archaologie der Kunst, 417-2, 1885, 2nd edit. Of Polycletus : Gerhard, in the Beschrei- bung, vol. ii. 168. ART ILLUSTRATIONS IN MARBLE. 155 On the brow of the Quirinal in Rome stand two colossal and striking figures in marble, each reining in a horse. These statues bear on their pedestals, in Latin characters, the names of Phidias and Praxiteles ; artists are almost unanimous in considering them to be, not the actual handiwork of these masters them- selves, but copies of Greek works of the age in which those masters lived. But it is to the ' Elgin Marbles/ which once adorned the Parthenon, now in the British Museum, that we owe an acquaintance with the very- handiwork of Phidias himself, and of some of his con- temporaries : these consist (i) of the reliefs of the metopes, which ran along the frieze of the peristyle, or external colonnade ; (2) the uninterrupted series of reliefs which adorned the frieze of the cella ; (3) and the statues of heroic size, completely disengaged from the walls, which filled the triangular spaces (tympanae) of the pediments at both ends of the temple. The Phigaleian Marbles discovered in 1812, and also transferred to the British Museum, are evidently modelled after the sculptures of the Parthenon ; and though inferior in design and execution, as is gene- rally the case with imitations, they are works of high merit. The ascendancy of the Macedonian monarchy, and the luxury and magnificence to which it gave rise, called forth the powers of the successors of the Phidian 156 ART ILLUSTRATIONS IN MARBLE. age, and marble came into more general use for private as well as public works of art and sculpture. The names of Scopas, Praxiteles, and Lysippus adorn this age ; but few, if any, of the original works of these great masters have been preserved to us. The leading figures in the group of Niobe, which in 1 583 was found at Borne, and is now in the Gallery of the TJffizi at Florence, are supposed to be imitations of the group of Scopas commemorated by Pliny. Ancient writers mention numerous works of Praxiteles, chiefly like those of Scopas, in marble ; and they are described with sufficient minuteness to enable critics to identify some of those recovered from the ruins of Imperial Eome as free imitations, or copies. Of these may be mentioned the Satyr with the Flute in the Capitoline Museum ; Apollo slaying the Lizard, in the Villa Borghese at Eome; and the youthful Cupid, also preserved in Rome, and supposed to be an imitation of the Eros of Parion, or that of Thespiae. 1 The Venus de' Medici, which once graced the villa of Hadrian at Tivoli, and now adorns one of the Florentine galleries, is the work of Cleomenes of Athens, who is supposed to have lived about a century and a half after Praxiteles. This is justly considered a work of exquisite grace and beauty ; to the same period may be referred the statue called the Fighting Gladiator, found early in the seventeenth century 1 Spalding, Italy and the Italian Islands, vol. i. 166, 5th edit. ART ILLUSTRATIONS IN MARBLE. 157 amongst the ruins of the imperial palace at Antiurn, 1 and the Germanicus of Cleomenes. 2 With the conquest of Greece, Rome became en- riched with her spoils, and the conquerors transferred statues and works of art by hundreds or thousands into Italy. The result was the creation of love of art on the part of the Romans ; and the Graeco-Roman school arose, of whose works the most celebrated examples which have come down to us are the Apollo Belvedere, discovered about the end of the fifteenth century amongst the ruins of Nero's favourite villa at Antium ; 3 a colossal statue, unsurpassed in majesty and grace of proportion, executed in the reign of Nero about the year A.D. 54 ; the group of Laocoon and his sons, impersonating the scene so vividly de- scribed by Virgil, executed by the three Rhodian sculptors, Agesander, his son Athenodorus, and Poly- dorus, for the Emperor Titus, about the year A.D. 69 ; 4 and the colossal statue of Hercules, known as the Farnese Hercules, a copy of the original of Lysippus by the Athenian Glycon. 5 To a somewhat later period but prior to the accession of Constantine 1 Now in the Louvre, at Paris. 2 Also in the Louvre. 3 In the Museum Pio Clementino, Rome. 4 Preserved in the Museum of the Vatican. 6 In the Museum at Naples. A fine copy of this statue of colossal proportions, sculptured in Portland stone by Mr. C. H. Smith, stands in the Hall of the Museum of Practical Geology, London. 158 ART ILLUSTRATIONS IN MARBLE. belong the mutilated group of the Farnese Bull 1 and the Dying Gladiator. 2 From the accession of Con- stantine down to the middle ages, the art of sculpture gradually decayed with the decline and fall of the empire ; and the rise of the modern school, which attained such excellence under the hand of Thor- waldsen, Santorelli, Canova, Benzoni, Flaxman, G-ib- son, Engel, and Foley, may be dated from the revival of letters in the sixteenth century, and the excavations commenced by Pope Paul III, which brought to light the Farnese Torso, Hercules, Flora, and Venus Calli- pygos. From that time the search for antiquities has been uninterrupted, and many galleries formed, at the head of which stand those of Rome, Florence, and Naples. 3 1 In the Royal Museum at Naples. See p. 141, ante, 2 In the Museum of the Capitol. 3 Spalding, Italy and the Italian Islands, vol. i. 215. PART VII. OHAPTEB I. ALABASTEK. Gypsum, Gyps (Germ.) Chaux sulfate'e (Fr.) Spec. grav. 2.28-2.4. Hardness, 1.5-2. GYPSUM is a hydrous sulphate of lime, consisting in a pure state, of lime, 32.56, sulphuric acid, 46.51, water, 20.93. The name is derived from the Greek 71/^09, by which it was known to the ancients, who obtained their supplies chiefly from Cyprus, Phoenicia, and Syria, and applied the material to similar pur- poses as the moderns. 1 In its crystalline form it occurs as selenite, which is translucent and colourless, limpid or white ; or as satin spar, or fibrous gypsum, also colourless, and from its peculiar structure, in- 1 Bristow, Glos. Min. p. 167. Theophrastus, a Greek writer, who lived about 238 years B.C., in his work, History of Stones (' nepl At0o>i> '), of which there is an English version by Mr. John Hill (edit. 1774), gives a good account of the occurrence and use of gypsum and alabaster, cxii. to cxvi. 160 ALABASTER. dicated by the name, very beautiful when cut into necklaces or small ornaments ; in its massive form the stone is known as alabaster. Alabaster occurs in many formations from the Silurian down to the Tertiary ; but is especially abundant in the upper Triassic beds, known as the Keuper of Germany. According to Von Cotta, gypsum may have originated either by the wet or dry process, or by metamorphism from anhydrite ; but its most abundant source has been simple precipitation from water probably confined in lakes, and thus becoming supersaturated. On the other hand, beds of limestone may have been converted into gypsum by the per- colation through the strata of water charged with sulphuric acid. 1 Anhydrite. Anhydrit (Germ.) ; Chaux anhydro- sulfate*e (Fr.\ is a variety of gypsum free from water ; of the normal composition of lime, 41.18, sulphuric acid, 58.82, spec. grav. 2.8-3.0, hardness, 3-3.5, by which it may be distinguished from gypsum, which is much softer. Colour white, or tinged with grey, reddish, or dark-blue. It is generally found associated with massive gypsum, and in Bex, in Switzerland, the anhydrite is found at a depth of about seventy or a hundred feet underneath gypsum, which has been formed from it by absorption of water. Anhydrite, like gypsum, is found associated with rock salt, and 1 Bischof, Chem. and Phys. Geol. i. 419 (Eng. trans.) ALABASTER. 161 imbedded in clay, marl, and limestone. Its chief sources are Val Canaria, and Bex in Switzerland ; Osterode, Ilfeld, and Walkeuried in the Harz ; Mans- feld, Magdeburg, Sulz on the Neckar (of a fine blue colour), Luneburg in Hanover, Segeberg in Holstein, Hall in the Tyrol, Hallein and Auszee near Salzburg, Berchtesgaden in Bavaria, Vic in Lothringen, Bochnia and Wieliczka in Galicia. 1 Anhydrite, when com- bined with a small proportion of silex (Vulpinite), is sometimes cut and polished for ornamental purposes. British Localities. The chief source of British gypsum is the New Bed Marl of the Triassic forma- tion, from which it is derived in considerable quanti- ties, both in the central and north-eastern counties of England. In such positions it is frequently associated with rock-salt. Thus, at Droitwich, in Worcestershire, a bed of gypsum, from 40 to 100 feet in thickness, is penetrated, from beneath which brine ascends with force. This brine occupies a space of about 22 inch, in vertical depth, and rests on a floor of rock-salt, with a roof of gypsum, as already stated. The intervening space was doubtless once occupied by rock-salt itself, which has since been carried away, dissolved in water by natural and artificial processes, 2 1 Zirkel, Petrog. i. 268. 2 E. Hull, ' On the Triassic and Permian Rocks of the Mid- land Counties,' Mem. Geol. Survey, (1869) ; L. Horner, Trans, Geol. Soc. ii. 94. M 162 ALABASTER. The locality which probably yields the largest quantity of English gypsum, is Chellaston Hill, near Derby. Here the mineral occurs in a continuous bed, sometimes 12 feet in thickness, outcropping round the flanks of the hill. It is associated with beautiful bands of the fibrous variety, the ' fibres ' (or pris- matic crystals) being arranged in a position at right angles to the planes of bedding. The gypsum of this locality is seldom sufficiently pure to be em- ployed for ornamental purposes, and is chiefly used in the manufacture of 'plaster of Paris/ 1 Other localities are Orston, near Grantham; the neighbour- hood of Newark-on-Trent ; Fauld, near Tutbury ; St. Bees' Head, Whitehaven ; several localities in Nottinghamshire and Staffordshire ; Alston, in Cum- berland ; and in the vicinity of Watchet, in Somer- setshire, where it is occasionally collected on the coast, and sent to Bristol, Swansea, and some other places on the Bristol Channel. 2 Also, in the Isle of 1 This is done by calcining the stone in order to expel the water (temperature 200 C.), when it falls into a white powder. When water is again poured on the calcined stone, it combines to form a hydrate, and reassumes its original hardness and density. The aggregate annual consumption of gypsum in this country is esti- mated by Mr. R. Hunt at 30,000 tons, valued at 10,000, the largest quantities being used in the Staffordshire Potteries, where it is employed to form moulds of plaster ; hence it is there called ' Potter's stone.' Descrip. Guide Mus. Prac. Geology, pp. 26, 34. 2 Bristow, Glos. Min., art. Gyps. ALABASTER. 163 Purbeck, in Dorsetshire, forming large concretions in the lower Purbeck strata. 1 Ireland. Gypsum occurs in several localities in Ireland. At Carrickfergus, in Co. Antrim, it is found associated with rock-salt, in the Keuper marl of the Triassic formation. In the neighbourhood of Carrickmacross, Co. Monaghan, it forms a thick deposit in the same formation ; 2 and it has also been found on the banks of Lough Allen, County Leitrim. Alabaster has been largely used in the formation of ornamental tombs and statuary preserved in the Cathedrals and Parish Churches of England ; pro- bably much of the stone used for this purpose was brought from the Continent. France. The chief source of gypsum in France was formerly the fresh- water strata of the Tertiary formation of the Paris basin, chiefly at Montmartre and Pantin, associated with sulphate of strontia. It is from these quarries that the ' plaster of Paris ' is derived, and which is more valued than that from England, owing to its superior hardness. 3 These 1 Bristow, Glos. Min., art. Gyps. A large pedestal and tazza of alabaster from Fauld, Staffordshire, worked by Messrs. Hall, of Derby, is placed in the Hall of the Museum of Practical Geology, London. 2 A polished slab from this locality is deposited in the Museum of the College of Science, Dublin. 3 Gwilt, Encyc. Arch. p. 542. From these quarries the illustrious M 2 164 ALABASTER. quarries also yield a peculiarly pure variety of ala- baster, known by a sacred name I forbear to mention, and which is used in modelling in plaster. Gypsum is also found in New Red Marl (marnes irisees) of the east of France, and in the lacustrine deposits of Auvergne and Aix; in the latter containing an ad- mixture of 8 per cent, of carbonate of lime. 1 A fine saccharoid variety occurs near Salins and Lons-le- Saurier, in the department of the Jura. Spain. Some of the Spanish localities are Cer- vetto, Castelnau de Durban, in the Pyrenees ; San Jago ole Compostella, in Gallicia ; Paredes, in Guada- laxara ; Conilla, near Cadiz ; and Ternel, in Aragon, with mica as an accessory. 2 Germany, Switzerland, and Austria. Rittelsthal, near Eisenach ; Tonna, in Saxe-Coburg ; Golling, near Salzburg, in company with rock-salt ; as also at Segeberg, in Holstein ; Hasmersheim, in Baden ; and Lauenburg, in Hanover. It also occurs amongst the crystalline schists of the Alps and Tyrol; and, along with anhydrite, at Bex, and Val Canaria, in Switzer- land. Cuvier obtained the bones of extinct animals, from which he made the restorations described in his Ossements Fossiks, which laid the foundation of his fame as the greatest comparative anatomist of modern times. 1 Bristow, Glos. Min. Chateau, Technologic du Batiment, vol. i. pp. 88, 92. 2 Zirkel, Petrog. i. 260, i. ALABASTER. 165 Italy. Gypsum and alabaster occur in several parts of Italy, and in a state of much purity. In Tuscany it occurs at Miemo, with bitter-spar ; als at Fontibagni and Castellina, 1 and at Aosta, in Pied- mont. The alabaster of the Val di Marmolago, near Castellina, 25 miles from Volterra, is the purest of all the Italian varieties, and is cut into vases, statuettes, cups, tazze, &c. The alabaster of Vol- terra, or ( agate gypsum' (Marmo di Volterra), is also a fine variety, veined, and resembling white wax ; yellowish and red varieties come from Monte Catini; and a mottled variety, resembling granite (granite gypsum), is obtained from Carrara. Sculpturing in alabaster is carried on with great activity and success in Florence, Volterra, Pisa, and other cities of Central Italy. The art dates from ancient Etruscan times, when Volterra, the centre of this kind of sculpture, was a considerable fortress ; and it was the custom to inter distinguished citizens in sarcophagi or cinerary urns of alabaster, formed of a single block, with elaborate mythological sculpturings, and surmounted by a reclining figure of the deceased. The Etruscan Museum at Volterra contains a rich collection of such objects, and which are in excellent preserva- tion. 2 1 Hamilton, Quart. Journ. of the Geological Society, London, i. 283 (1845). 2 Mr. W. P. Jervis, Mineral Resources of Italy, 1862. 166 ALABASTER. The following is a summary of the Italian varie- ties : Statuary Val di Marmolajo. White Pomarance, Allacio and Ariano (with veined and spotted white). Agate Gesseri, Annunziata and TJgliano near Volterra; Fontebagni. Yellow agate and yellow . Cassaglia, S. Lorenzo. White and yellow . . . . Al Pozza, near Pomarance. Bardiglio Torricella, Ariano, and Menamuta, near Volterra. OHAPTEE II. British Possessions of America. Gypsum is found largely in the Lower Carboniferous rocks of the counties of Cumberland, Hants, and Colchester, in Nova Scotia ; as also in the same formation in the counties of Westmoreland, King's, Albert and Vic- toria, in New Brunswick. 1 In 1863, 8646 barrels of plaster were exported to the United States. 2 In Canada, the chief indeed, sole formation yielding beds of workable gypsum is the Onondaga formation of the Upper Silurian period. Large lenticular beds, interstratified with dolomite, have been traced for a distance of 35 miles along the course of the Grand Eiver, from Cayuga to Paris, and are exten- sively worked, while further discoveries to the north- west of Paris are anticipated. The rock is chiefly used for agricultural purposes. 3 United States. New York, near Lockport, affords beautiful selenite and snowy gypsum in limestone. At Camillus and Manlius, N.Y., and in Davidson County, Tennessee, are other localities. In the 1 Particularly on the river Tobequi ; Selwyn, Rep. Prog. Geol. Survey, Canada, 1866-9. 2 Logan, Geol. of Canada, pp. 459, 762. 3 Dawson, Acad. Geol. pp. 223, 249. 168 ALABASTER. Mammoth Cave, Kentucky, alabaster occurs in singu- larly beautiful similtudes of flowers, leaves, shrubs, and vines. Massive gypsum occurs west of Syracuse, in New York, and as far as the western extremity of Genessee County, accompanying the rocks which afford the brine springs ; also in Ohio, Illinois, Virginia, Tennessee, and Arkansas. 1 A fine blue crystallized anhydrite occurs, with gypsum and calc- spar, in black limestone, at Lockport. 2 Specialities. Though gypsum is of less value, and inferior in durability and beauty to some vari- eties of marble, it is extremely useful as an adjunct in the arts, and in making copies of works which are only within reach of the few. One of the most successful of these attempts at imitation is the copy of the Florentine Cup, by Benvenuto Cellini, which is in the Museum of Practical Geology. There are also means by which the plaster may be hardened, and coloured in imitation of marble, by processes which it would be out of place here to describe ; but which, in the instance of the model of the ' Dying Gladiator/ moulded in ' Parian cement/ in the hall of the same building, must be considered a successful imitation, though, like all imitations, far inferior in beauty to the original. 3 1 Dana, Man. Min. p. 113. 2 Ibid. p. 114. 8 For an account of these processes for making 'fictile ivory/ ' Keene's cement/ ' Parisian cement/ see Descrip. Guide M. P. G. PP- 34> 5> or Grwilt's Encyc. Arch. pp. 540-42. PART VIII, TIE BAKER OKNAMENTAL STONES. OHAPTEE I. FLUOR-SPAR Fluss-spath (Germ.)} Fluorine, Spathfluor (Fr.). Spec, gravity, 3.1-3.2 ; hardness, 4.0. A fluoride of calcium having a normal composition of fluorine, 48.72, calcium, 51.28. FLUOR-SPAR is a very handsome ornamental stone, and occurs either massive, or in well-known cubical or octohedral crystals ; of various colours, purple, blue, lilac, green, yellow, or (rarely) red. Perfectly limpid to transparent, with vitreous lustre. Fluor-spar, though locally plentiful, is but spar- ingly distributed. Its chief source in England is Derbyshire, where it is found in caverns, and mineral veins in the Carboniferous limestone. When cut and polished, it generally presents a series of banded hues, passing from deep purple to light yellow and limpid; and has been worked into vases, cups, obelisks, and various ornaments, with so much skill 170 FLUOR-SPAR. and success, as to have received the name of ' Derby- shire spar ' throughout the country. 1 Fluor-spar occurs in the mines of Cornwall, as at Huel Cupid, East Tamar, West Huel, Copper Hill, and North Gambler, near Eedruth ; Huel Mary Ann, Menhenniot, in fine blue bevelled cubes ; near St. Agnes, in translucent cubes of a rich lilac colour. Cumberland, at Cleator Moor, in large yellow, lilac, and green crystals ; also at Alston, in cubes which appear green by transmitted light, and blue by reflected light : this effect, termed by Professor Stokes f fluorescence/ is due to a peculiar refracting power of the first surface on which the light falls. 2 In Scotland, fluor-spar is found at Balater House, and Glenmuick, Aberdeenshire. In Ireland, in the Glendalough mines, County Wicklow. It is common in the mining districts of Saxony ; near Rottleberode and Strassberg in the Harz; 3 in the Thuringer Thai; in the Alten Liebenstein, Meiningen ; 4 Miinsterthal in Baden; the Lombardian Alps at Monte Presolana, and in the Val di Scalve, north-west of Lago Palzone 1 The name by which this mineral is known amongst the miners is ' Blue John.' In Bristow's Glossary of Mineralogy, figures of the various crystalline forms of fluor-spar are given. In 1858 about 1500 tons were raised from mines in England. Mr. R. Hunt, Mineral Statistics, 1 858, part ii. 2 Bristow, Glos. Min. p. 142. 3 Zirkel, Petrog. i. 192. 4 Breithaupt, Paragenesis der Minerallien, p. 200. FLUOR-SPAR. 171 in Italy. 1 It also occurs massive in the district of Auvergne, central France; as a recent deposit from springs of water at Plombieres ; and in crystals amongst the lava of Vesuvius. America. Cubic crystals of a greenish colour, over a foot each way, have been obtained at Mus- colonge lake, St. Lawrence, Co. N.Y. Near Shaw- neetown on the Ohio, a purple fluor in grouped crystals of large size is obtained from limestone ; other localities are Westmoreland, N.H., at the notch in the White Mountains, Blue Hill Bay, Maine, &c. 2 It is also met with sparingly in Canada, rarely massive, but generally in 'crystals of green and pur- ple colours, and associated with its favourite galena. The chief sources are mineral veins on Lake Superior, and in some of the islands ; also on Iron Island, Lake Nipissing, and at Bay St. Paul, and Murray Bay. 3 Specialities. Fluor-spar may be considered to have been formed by deposition from water either along the walls of fissures and mineral veins, or in a stalagmitic form in caverns and hollows in the rocks. In Derbyshire it sometimes forms the gangue of some lead mines, and its association with galena is a subject of common observation amongst mine- ralogists. The massive varieties receive a high polish, but are difficult to work on account of being 1 Bristow, Glos. Min. p. 142. 2 Dana, Man. Min. p. 122. 3 Dr. Bigsby, quoted by Logan, Geology of Canada, p. 463. 172 FLUOR-SPAR. brittle. It is usually turned in a lathe, and worked down, first with a fine steel tool, then with a coarse stone, afterwards with pumice and emery; and the crevices are sometimes filled with galena. 1 Fluor-spar supplies fluoric acid, which is employed in etching on glass ; it is also used as a flux for metallic ores, hence the name (fluere, to flow), for which purpose it is largely employed at the Mansfeld copper works in Germany. 2 Origin and mode of Occurrence. Fluor-spar occurs in drusy cavities in amygdaloids ; in veins and dykes in granite, gneiss, mica slate, porphyry, diorite, and granular limestone ; and as already stated, in the case of Vesuvius, in lava. Yet it cannot be argued from this that it is a product of plutonic or volcanic action, as it is also found associated with substances composed of carbon, hydrogen, and oxygen, that are not only not produced but decomposed under the influence of heat ; we must therefore conclude with Bischof, that, like the minerals with which it is associated in metallic veins, it has been formed in ' the wet way/ or by precipitation from water. 3 1 Rev. Dr. Haughton first drew my attention to this fact, when examining some specimens of minerals from Central France, 1871. 2 Vases and other objects of art in fluor-spar are so common that it is unnecessary to mention examples. These, however, may be seen in the Hall of the Museum of Practical Geology, South Kensington ; and the British Museum. 3 Bischof, Chem. Geol. ii. 5. CHAPTEE II. / ROCK-CRYSTAL. Quarzkrystall, Germ. (From xpvoraXAoy, ice.) Rhombohedral, usually occurs in six-sided prisms, terminated by six-sided pyramids. Spec. grav. 2.5-2.8; hardness, 7.0. QUARTZ GROUP. In treating on rock-crystal, we feel that we are on the boundary which separates the precious from the ornamental stones ; and it is ques- tionable with which of these divisions it ought to be classified, as it in some measure partakes of the character of both. Owing, however, to its use as an ornamental stone, especially by the Florentine artists of the sixteenth century, it is entitled to a place here, if only for a few lines. Bock- crystal is the transparent, colourless, and crystalline form of pure quartz. It is abundantly distributed in veins and geodes amongst crystalline and metamorphic rocks, but does not often occur in large crystals suitable for working into ornaments in the British Islands. Its limpid transparency and extreme hardness make it a valuable material for the manufacture of ornaments for the person, and lenses for spectacles ; and in no manner can it be dis- played to greater advantage than when set as cut 174 ROCK CRYSTAL. stones in a ground of bog-oak for bracelets or neck- laces, a branch of industry pursued with great suc- cess in Ireland, from which the stone takes its name of * Irish diamond/ Its chief sources in this country being Wicklow, Finglen mountain, and Killarney. Rock-crystal is an essential in many plutonic rocks, but generally occurs thus in an imperfect state of crystallization, as amongst the quartz-porphyries of Galway, Donegal, and Mourne in Ireland, and of North Wales. In the granite of the Mourne moun- tains it is well developed (as smoke quartz) in cavities along with topaz and beryl. The beautiful yellowish variety known as * Cairngorm/ from the mountain of that name in the Highlands of Scotland, is a highly prized ornament for brooches, the handles of dirks and knives (skian dhu\ which form ap- pendages to the Highland garb. The chief supplies of rock-crystal are from abroad. It is obtained from geodes in the granites of Switzer- land, amongst the marble beds of Carrara in Northern Italy, 1 and the sandstones of the Schwarzwald, Hun- gary ; India and Ceylon ; Quito ; Brazil ; Co. Herkimer, in New York State ; Diamond Island, Lake George ; Pelham and Chesterfield, Mass., U.S. Rose quartz, at Albany and Paris, smoke quartz at Goshen, amethyst at Bristol, and Kewenaw Point, Lake Superior. 2 The 1 Bristow, Glos. Min. ; Von Cotta, Eng. edit. 6. 2 Dana, Man. Min. p. 138. ROCK CRYSTAL. 175 trappean rocks along the northern shore of Lake Superior, yield amethysts in great abundance ; and the rock-crystals at Quebec, give rise to unusual modi- fications of form. Large crystals are also found in the quartz veins of Bruce mine and Harvey's Hill mine of Lower Canada. 1 Varieties. Smoke quartz. This is a clouded variety, with a brownish tint becoming deep, when it is termed morion. Rose quartz. A pink variety, the colour being probably due to a slight admixture of oxide of manganese. 2 (b) Amethyst. Violet or purple colour from oxide of manganese. The finest specimens are obtained from Ceylon, India, Persia, and Siberia. (c) Chalcedony (from Chalcedon, in Asia Minor). A milk-white or wavy, translucent variety, approach- ing smalt-blue, the latter being most rare and highly esteemed. The stone is an intimate mixture of crystalline and amorphous silica; or, according to Fuchs, of silica and some opal disseminated through it. 3 It generally occurs in mammillated and bo- tryoidal forms, exhibiting in cross section parallel layers of slightly varying tints and degrees of trans- 1 Logan, Geol. of Canada, p. 500. 2 Hunt, Descrip. Guide M. P. G. p. 141. 3 Poggend. Annal. xxxi. 577. Bischof concurs in this view, Chem. and Phys. Geol. (Eng. vers.) ii. 464. 176 ROCK CRYSTAL. parency. From its hardness and toughness it forms an excellent material for the engraver, and is worked into vases, brooches, and ornaments for the person. Fine specimens are procured from Monte Verdi in Tuscany, the amygdaloidal volcanic rocks of Iceland, and the Faroe Islands. Specimens of sponges in chalcedony from the Chalk formation are found on the sea-coast at Bognor, Selsey, Littlehampton, and Worthing. 1 (d) Agate. (From aydco, to admire), or from the E. Achates, whence, according to Theophrastus, agates were first brought. 2 Translucent coloured owing to combinations of common quartz, amethyst, jasper, carnelian, and other varieties of quartz, arranged in alternate stripes, or irregularly mixed together. 3 The moss agate is a well-known variety, with moss- like delineations due to oxide of manganese or iron. The chief sources are India and the Brazils. (e) Jasper, derived from the Greek "laann?, is another of the many forms under which quartz is presented to us. It differs from agate chiefly in being opaque. Its colours are extremely varied, and are due to the presence of foreign substances, chiefly oxide of iron ; which is, indeed, the great colouring agent which nature employs for stones as well as 1 Bristow, Glos. Min. p. 75. 2 Ibid. p. 4. 3 B. von Cotta, Rocks class, p. 6. BOCK CRYSTAL. 177 rocks and mountains. 1 It may be described as a dense, opaque, siliceous rock, of red, purple, blue, and greenish tints, with their modifications ; and according to the arrangement of these we have the following varieties: i. Riband jasper ; in which the colours are arranged in parallel bands. 2. Egyptian jasper ; found imbedded in trap, or as pebbles on the banks of the Nile, in which shades of wood-brown, alter- nating with red, are arranged in concentric wavy zones, which are usually cut across and polished. 3. Ruin jasper; a variety presenting a fanciful resemblance to ruins. There are also, 4. Yellow jasper ; found at Yourla in the bay of Smyrna ; and, 5. pebbles of Red jasper ; on the plains of Argos. 2 (f) Blood stone, or heliotrope, has a deep green base, slightly translucent, containing spots of red, which have some resemblance to drops of blood. In the Louvre at Paris, there is a bust executed in this stone, in which the spots are so arranged as to represent drops of blood. 3 Jasper is not uncommon amongst the more ancient geological formations. It is abundant in large pebbles or boulders amongst the conglomerates of Mweelrea mountain in the West of Ireland ; along the shores of Co. Wexford; and in sinaller ones, 1 A fact well expressed by Mr. Buskin in ' The Two Paths/ Lect. 5. 2 Bristow, Glos. Min. p. 195. 3 Dana, Man. Min. p. 137. N 178 BOCK CRYSTAL. amongst the conglomerate beds of the New Red Sandstone of England. A fine bed of red jasper is found on the eastern shore of Loch Lomond, north of the pass of Balmaha ; in bog iron ore at Briesgau in Germany ; in the form of pebbles from the sand of the Nile or Desert of Egypt. 1 Fine specimens of riband and other jaspers are obtained from the river Korgon in the Altai, and Orenburg in Siberia. 2 Heliotrope from the Island of Eum, Scotland ; Ice- land ; and Silesia. 3 At Sherbrooke in Canada there is a large bed passing into jasperry iron-ore ; and another at Riviere Quelle. Fine pebbles are found in the jasper conglomerate of the Huronian series on the north shore of Lake Huron, 4 In the U.S. red jasper occurs on the banks of the Hudson at Troy, and at Sangus near Boston, Mass. ; yellow jasper along with chalcedony at Chester, Mass. ; heliotrope occupies veins in slate at Bloomimgrove, Orange County, N.Y. 6 (g) Opal being a precious, rather than an orna- mental stone, its description here would be foreign to the purpose of this treatise. 1 B. von Cotta, Rocks class. Eng. ver. p. 6. 2 Of which there are specimens in the Museum of Practical Geo- logy. In the mountains near the river Korgon in the Altai is a mass of jasper 300 feet thick resting on a mass of porphyry. 3 Hunt, Descrip. Guide M. P. P. p. 142. 4 Logan, Geol. of Canada, p. 834. 5 Dana, Man. Min. p. 138. ROCK CRYSTAL. 179 Onyx is an ornamental siliceous stone, resembling agate, and consisting of layers of opaque white, alter- nating with others of a yellowish brown, dark brown, or umber colour ; when it consists of sard and white chalcedony in alternate layers, it is called sardonyx. 1 The tints of onyx may be heightened by boiling it for several days in honey and water, and then soaking it in sulphuric acid to bring out the black and white layers, or in nitric acid, to bring out the red and white layers. 2 Onyx is found in Perthshire ; in the Isle of Syke ; in the amygdaloid of Antrim ; at Oberstein in Saxony ; in the South of Russia ; Yemen in Arabia ; and Guzerat. Aventurine (or Aventurine quartz) is a vitreous variety of quartz, usually translucent, variegated with tints of grey, brown, reddish-brown, or rose colour, and spangled throughout with scales of golden- yellow mica, or, according to Gahn, by metallic copper, crystallized in the form of flat segments of a regular octohedron. It is obtained from Siberia, Silesia, Bohemia, Cape de Gata in Spain, Egypt, and India. The name is derived from the artificial gold-spangled glass, the art of which was accidentally (par aventure) discovered by a workman having let some brass filings fall into a pot of melted glass, which he thereupon named Aventurine. 3 1 Dana, Man. Min. p. 136. 2 Bristow, Glos. Min. p. 266. 3 Ibid. p. 31. N 2 OHAPTEE III. AET TLLUSTEATIONS. SCULPTURING. Sculpturing in various ornamental stones of the quartz family has been practised from very early ages. Descending from the times of Jewish history through the period of high art in Greece and Eome, down to the comparatively modern times of the sixteenth and seventeenth centuries, the glyptic art was practised largely and most suc- cessfully by Italian artists, as also those of Germany, France, and England. 1 Many of these gems of art have been preserved to the present day ; a circumstance, as Mr. J. C. Eobinson has remarked, 2 due not only to the intrinsic value and beauty of the objects themselves, but to the imperishable nature of the material out of which they have been formed ; for while thousands of sculptured rings and personal ornaments have come down to us from the days of the Eoman emperors, it is not improbable that thousands more 1 The art of sculpturing and fashioning jasper, chalcedony, rock- crystal and other stones was practised during the fourteenth cen- tury by French and German artists. Some beautiful specimens of their work is in the collection of the Marquis of Salisbury. 2 Catalogue of the Special Exhibition of Art-treasures at South Kensington, 1862. ART ILLUSTRATIONS. 181 are hidden beneath the soil, retaining the sharpness of original sculpture, and only awaiting some accident to bring them to light. During the sixteenth century, the Italian artists, especially those of Florence, exhibited great skill and taste in fashioning cups, vases, ewers, and similar articles in rock-crystal, jasper, agate, chalcedony, and lapis-Tazuli ; while they also re-mounted and decor- ated with jewels and enamel similar objects which had been preserved from the days of ancient Greece and Rome. Of this, the onyx ewer, taken at the sack of the summer palace of the Emperor of China, which I shall presently more fully describe, may be cited as an illustration. Many of these beauteous examples of industry and skill adorn British and foreign cabinets, especially those of the Queen, of the Dukes of Marl- borough and Devonshire, of Lords Carlisle and Salis- bury, and were freely lent by the owners to the South Kensington Museum for special exhibition in I862. 1 The Museum of the Louvre, rich in works of art sculptured in precious stones which have formed part of the treasures of kings and princes of France, is especially rich in examples fashioned . in rock-crystal. The Imperial Treasury of Vienna, and the Green Vaults of Dresden are also the repositories of similar examples of handiwork ; amongst which fine crystal 1 Fuller descriptions will be found in the catalogue drawn up by Mr. J. C. Robinson, F.S.A., and Mr. G. W. Chaffer, F.S.A. 182 ART ILLUSTRATIONS. cups by a Milanese artist may be specially noticed. I now proceed to briefly notice a few, from amongst the many, splendid examples of glyptic art exhibited at South Kensington in 1862. 1. Fragment of a magnificent antique cameo in onyx of three layers; representing a head and bust of Jupiter with the aegis. When complete this gem must have measured about three and a half inches high by two and a half in width. It is engraved in the ' Dactyliotheca Smithiana.' 2. Large cameo, executed in sardonyx of many strata ; a laureated head and bust of an emperor, with the segis, surrounded by a raised border enriched with ovolo moulding. It is, perhaps, the largest in ex- istence, being seven and a half inches high by five and a half wide, and belonged to King Charles I. It was unfortunately broken by a lady of the court, and was afterwards rather badly set, but none of the frag- ments are lost. 1 3. Large cameos with busts of Henry VIII, and Queen Elizabeth. 4. A crystal vessel in the form of a flying fish, the body and fins of one large piece ; the head and tail joined by silver mounts, set with stones carved with 1 According to Van der Doort, who made an inventory of the articles belonging to the King, the culprit was Lady Somerset, wife of the Lord Chamberlain. It is to be feared that her husband did not take sufficient care of his master's property ! ART ILLUSTRATIONS. 183 incuse scrolls, the whole supported by a crystal figure of Pan kneeling. This object was brought from the summer palace of Pekin. 1 5. A splendid variegated onyx ewer, cut out of a single pebble, set in gold with rubies and enamelled work. The ewer itself is of antique Roman date, while the mounting and adornment was added by an Italian artist in the sixteenth century. The ewer was taken at the sack of the summer palace of Pekin, and it may be well supposed that few works of art have undergone such strange vicissitudes. Originally formed by a Roman sculptor, probably before the Christian era, it descends through sixteen centuries or more, to be re-mounted and decorated with gems by an Italian worker in jewelry. It afterwards finds its way who can tell by what strange changing of hands ! to China, and is deposited amongst the treasures of the monarch of the Celestial Empire. It is afterwards seized by a * barbarian* army of invaders, carried back to Europe, and becomes the property of a British commoner. 2 6. Jasper cup of triangular escalloped form, carved at the base with upright leaves ; it has a stem and foot surrounded with two belts of painted enamel scroll and flowers. The cup is a work of the seventeenth century. 1 It now belongs to the Duke of Buccleuch. 2 Mr. T. M. Whitehead. 184 ART ILLUSTRATIONS. 7. Large oval sardonyx bowl, carved out of a solid mass of rich, deeply shaded stone, with striped spots of a lighter shade. It is fluted inside, and on the outer surface has a series of vertical lines arched above. This large and noble pebble measures nearly ten inches in longer diameter, and is three and a quarter inches in height. It is mounted on a stem and foot of gold, chased and enamelled with cinque- cento designs, supported by twelve upright bars with festoons between. 1 8. The ' Cellini ewer' is cut in sardonyx ; it is of a flattened oval form mounted in enamel, and adorned with gems taken from the crown jewels of France before the first revolution. These are described in detail in an inventory made by decree of the National Assembly in 1791 ; the ewer itself is a work of the sixteenth century. A figure of Constantine the Great on horseback, brandishing his lance against his prostrate enemies ; cut in sardonyx, and now in the cabinet of antiquities in the Eoyal Library deserves special notice. 2 In the Galleria degli Uffizi at Florence, one of the chambers contains no less than 400 gems and works of art in precious stones, such as jasper, agate, chalce- dony, rock-crystal, and lapis-lazuli, once the property of the Medici. Amongst these is a jug of rock-crystal 1 The property of the Duke of Hamilton. 2 Nouv. Manuel d'Arche'ol. par P. Nicard, 1842. ART ILLUSTRATIONS 185 fourteen inches by eight, on a gold pedestal, by Benvenuto Cellini ; two bas-reliefs in gold on a ground of jasper, and a large basin of lapis-lazuli about fifteen inches in diameter. The art of sculpturing in jasper, agate, crystal, and aventurine is successfully practised in Eussia, and several magnificent examples, in the form of vases, bowls, &c., were contributed to the Industrial Exhi- bition of 1 85 1. 1 One of the finest works which has proceeded from that, or any other, country in modern times, is the polished vase formerly in the possession of the late Sir R. I. Murchison, and presented to him by the Emperor Nicholas I, in recognition of his services as ' the explorer of the geology of Russia/ This noble vase measures four feet in height, by six feet in circumference, and is supported by a pedestal of polished grey porphyry. The prevailing tint is pearl-grey, clouded with delicate rose-tints, and it is remarkable both for the beauty of the material, the elegance of its form, as well as for its excessive rarity ; the difficulty of procuring a stone of such large dimensions, and of polishing so hard a substance being such that only one other similar vase has been made. This was presented to the late Baron Humboldt, and is now in the Royal Museum, Berlin. 2 1 The chief seats of this industry are the Imperial Polishing Manufactories of Perm and Tomsk. 2 Bristow, Gloss. Min. p. 31. 186 ART ILLUSTRATIONS. With such examples we may be allowed to call in question Mr. Dana's statement that the artificial imitations of this stone are more beautiful than natural aventurine. 1 1 Man. Min.p. 134. Sir R. I. Murchison bequeathed the aventu- rine vase to the Museum of Practical Geology, London. The name of this stone is sometimes written avanturine; but I have preferred to follow that which is suggested by the origin of the word as described above, p. 179. PART IX. CHAPTEE I. MALACHITE. MALACHITE. (Molochites, Pliny.) This is one of the few metallic ores capable of being used with success for ornamental purposes in place of marble. It is a green carbonate of copper, and occurs essen- tially in a stalagmitic form, generally devoid of crystallization. It effervesces freely with heated nitric acid, and has a specific gravity of 3.57-3.68 ; hardness, 3.5-4.0. The composition varies, but the two following analyses will serve to give the general result : Klaproth.i Phillips. ?W" 58 ' } Protoxide of Copper ..^ Oxygen I2.O J Carbonic Acid .... 18.0 18.5 Water 12.0 9.3 i oo.o i oo.o Malachite is a very handsome mineral when cut and polished ; presenting various shades of apple to emerald green, and various degrees of translucency 1 Brongniart, Trait^ de Min. p. 223. 188 MALACHITE. down to complete opacity. The shades are arranged in globular concentric folds around a central nucleus, or in a wavy strata the differently-shaded layers arranging themselves in accordance with the sinuosi- ties of the adjoining layers. The mass is made up of fine globules, which often show a radio-concentric structure ; and in most cases has been formed from a cupriferous solution which has successively deposited its residue in a stalagmitic form. 1 Concretionary mala- chite occurs in mammilated masses of undulating parallel beds, striated in the direction of their thick- ness, the surfaces of contact being often overspread with pulverulent malachite, or decorated with black dendrites, which have a very pretty effect on the greenish ground. The masses are rarely homogeneous and compact, often containing cavities which render the mineral unfit for ornamental use ; but large masses free from such defects have occasionally been procured : one piece, especially cited, having been fashioned into a table eighty-five centimetres long, and forty-five broad. 2 The largest masses of this ore of copper have been obtained from the Ural mountains; one of which is described by Murchison, and his companions in travel, as having been found at Nijni Tagil sk, occupy- ing a fissure between schaalstein on the one side, and 1 Murchison, Geol. of Russia, i. p. 374. 2 Brongniart, Trait de Min. ii. 223. MALACHITE. 189 Silurian limestone on the other ; the upper surface presented an area of eighteen feet by nine, and pene- trated to an unknown depth. 1 It is also obtained in Bohemia, Saxony, Hungary, and the Tyrol. In Britain it rarely occurs except in small quantities, associated with other ores in Cornwall, &c. From Australia, however, enormous masses of this ore have been obtained from the celebrated Burra-Burra mines, situ- ated about ninety miles N.E. of Adelaide. These rich deposits of carbonate of copper resemble in their shallower portions the malachite formations of .Russia. In a great basin formed in an amphitheatre of hills is an immense deposit of clay, resulting from the decomposition of the clay slate, of which the sur- rounding hills are formed. In this clay the deposit of malachite is found. There are some evidences which appear to show that the earliest condition of the mass was that of oxide and native copper ; and that this has been changed into a carbonate, in all probability, by water charged with carbonic acid. 2 In the United States, it occurs at the copper mine of Cheshire, Conn. ; also at Morgantown, Penn., and Schuyler's mine, New Brunswick. 1 Murchison, Geology of Russia, i. 374. This mass has since been excavated in large blocks. See Catalogue, Exhibition 1851, art. 'Russia.' 2 Descrip. Guide Mus. Prac. Geol. p. 95. The Burra-Burra mines were opened in 1845. 190 MALACHITE. Art Illustrations. Ornamental and decorative works in malachite are peculiarly Eussian, and the sculptur- ing is carried on with great success in that empire. Of this branch of art several magnificent examples were displayed at the Industrial Exhibition in London in 1851, and in subsequent international exhibitions. These works consist of large vases, tables, timepieces, fireplaces, and ornaments, of which there is a cele- brated manufactory in St. Petersburg. 1 It is also advantageously employed for inlaying. At the palace of Versailles, there is (or was) a room furnished with tables, vases, and similar articles, all of malachite ; it is also largely used in the palaces of royalty, both in Russia and other countries of Europe. One of the most beautiful of the malachite tables I have ever seen, stands in one of the chambers of the Galleria Pitti in Florence. It is six feet in length and was originally brought from Russia. 1 That of Messrs. Demidoff, who were the chief exhibitors in 1851. PART X. CALCAREOUS GROUP OF BUILDING STONES. OHAPTEK I. LIMESTONE. LIMESTONE of several varieties is largely employed as a building material. These varieties depend very much on differences of origin and composition, and correspond to successive geological periods. Amongst the oldest formations, limestones are comparatively rare, at least in the British Islands and Europe, and it is not till we ascend into the Devonian, and es- pecially the Carboniferous periods, that they assume a high importance as compared with the other strata. From this period forwards into Tertiary times they are proportionately more fully developed, till amongst the Cretaceous and Lower Tertiary formations, they become the most conspicuous members. This gradual augmentation in volume, as compared with the associated sedimentary strata consisting of various forms of sand or clay, appears to be intimately connected with the development of those classes of 192 LIMESTONE GROUP OF BUILDING STONES. marine animals which form for themselves calcareous shells or skeletons by the vital process of assimilation ; by which the calcareous matter dissolved in the waters of the ocean by carbonic acid is seized upon, and con- verted into the stony skeletons of the inhabitants of the deep. That all the great marine limestone formations have been derived either directly, or in a secondary manner, from organic agency is a view which is capable of demonstration, if we suppose that the proportion of carbonic acid in sea- water was as high in geologic times as in the present day. For Bischof l has shown that there is in existing seas about seven times as much of this acid as would be necessary to hold in solution the carbonate of lime contained therein ; hence it could not be precipitated on the sea-bed in a solid state unless by vital forces. The composition also of the generality of marine limestones bears out this view of their origin. In the great majority of them remains of fossil shells, or internal skeletons, are visible to the eye, often in a fragmentary form. And even where this organic structure is not apparent, it does not follow that there has been no organic agency originally in operation ; as the observations of Pro- fessor Jukes on the formation of coral reefs show that the organic structure of the reef is often obliterated during the very process of formation. 2 1 Chemical Geology, vol. iii. 2 Voyage of H.M.S. 'Fly.' LIMESTONE GROUP OF BUILDING STONES. 193 When we examine the characters of those animals which were the most industrious of the limestone- builders of the different geological periods, we find that they were, for the most part, of simple structure, and low organisation ; for the higher forms of mol- lusca, such as the Cephalapoda and Gasteropoda, con- tributed but an inconsiderable share to the formation of limestones. The most important workers were Foraminifera, the Polypi (or coral-animals), the Echinodermata (including crinoids, starfish, and sea- urchins), the Bryozoa, together with the Brachi- opoda amongst the mollusca ; the remaining classes of the mollusca played a secondary part. Taking a rapid survey of the great limestone deposits, from Silurian down to Tertiary times, we find that in each case the forms of life which were the most active agents in their formation were the following : Silurian and Devonian. Corals (Zoantharia tabu- lata, and Z. rugosa), 1 crinoids, and brachiopods. Carboniferous. Corals (Z. tabulata, Z. rugosa, and Z. tubulosa), crinoids, and brachiopods. 2 Permian. Corals (not abundant ; Z. tabulata, and Z. rugosa), bryozoa, and conchifera. 1 These groups of corals are here arranged according to the classification of Milne- Ed wards and Haime. 2 Some of the limestones of Scotland of this period are largely formed of the skeletons of entomostraca as shown by Mr. J. Young. O 194 LIMESTONE GROUP OF BUILDING STONES. Jurassic, or Oolitic. Corals (Z. aporosa), foramini- fera, echinoderms, bryozoa, and mollusca. Cretaceous. Foraminifera, corals (Z. aporosa, Z. tabulata, Z. rugosa), bryozoa, and echinoderms. Tertiary. Nummulite limestone, composed of skeletons of foraminifera, and of corals (Z. aporosa, Z. perforata, Z. tabulata). * 1 Dr. T. Wright, on ' Coral Reefs Past and Present/ Trans. Cotteswold Nat. Club, 1866. OHAPTEE II, BRITISH LIMESTONES. THE limestones chiefly employed in the British Islands for building purposes are derived from the Carboniferous, Permian, and Oolitic formations. Those from the Purbeck and Wealden formations have already been described under the head of Marbles, as also those from Devonian rocks. We shall now examine these building stones in the ascending order above stated. Carboniferous Limestone. This formation com- prises the main portion of the lower division of the Carboniferous series ; being the foundation on which has been reared that great superstructure of sedi- mentary deposits, including the Yoredale series, Millstone Grit, and Coal-measures, which in Lanca- shire attains the enormous thickness of 18,600 feet. 1 In Derbyshire the limestone consists of very pure granular, or crystalline, carbonate of lime, of grey, blue, and (when dolomitic) of yellow colours ; with 1 E. Hull, ' Thickness of the Carboniferous Rocks, &c.,' Journ. Greol. Soc. Lond. xxiv. 322. O 2 196 BRITISH LIMESTONES. occasional lenticular bands of a siliceous stone called ' chert.' Its upper beds are dark, and produce black marble ; some beds are reddish, and variegated. The whole mass attains a thickness estimated by the Government Geological Surveyors at 5000 feet, and appears to be composed of remains of corals, crinoids, and molluscs. 1 Towards the North of England the Carboniferous limestone is split up into several separate layers, with intercalated beds of shale, sandstone, and coal, 2 which in Scotland assume a high degree of importance, giving rise to the Lower series of coal and iron- stone measures ; while the beds of limestone dwindle down to a few thin bands, chiefly useful for affording hydraulic lime and cement. 3 Throughout this region, the Carboniferous limestone is rarely employed to any extent as a building stone ; its chief use being for the manufacture of mortars, cements, marbles, and for fluxing iron-ore. As the grits and sandstones of the Millstone and Yoredale beds generally occur in the neighbourhood of the limestone, they are generally preferred as a material for building, for which they are better adapted. 1 Hull, C 0n the Distribution of the Carboniferous Strata, &c./ Journ. Geol. Soc. Lond. xviii. 137. See also Horizontal Sections of the Geol. Survey, Sheet 42. 2 Professor Phillips' Geology of Yorkshire. 3 Such as the Arden limestone, near Paisley, and the Garnkirk, and Burdiehouse limestones near Coatbridge, and Edinburgh. BRITISH LIMESTONES. 197 The Carboniferous limestone of Denbighshire and Flintshire is similar in appearance and composition to that of Derbyshire ; its thickness varies from 1000 to 1 500 feet, and it is extensively quarried for lime and cement. In the South-west of England it forms an encircling zone around the Somersetshire coal-basin, and rises into the table-land of the Mendip Hills. It also forms a similar zone round the margins of the South Wales and Forest of Dean coal-fields ; and from its tendency to form mural cliffs and terraced escarp- ments, it produces, along the valleys of the Wye and the Avon, features at once bold and beautiful. OHAPTEE III. MAG-NESIAN LIMESTONE OF THE PERMIAN FORMATION. THIS formation ranges in a nearly north and south direction through the North-east of England, from Tynemouth to Nottingham ; disappearing, however, beneath the New Bed Sandstone for a few miles in the neighbourhood of North Allerton ; and generally forming the escarpment of an elevated plateau, over- looking towards the west the coal-fields of Durham, Yorkshire, Derbyshire, and Notts. The formation is interposed between the Carboniferous rocks below, and the Triassic rocks above, and is unconformable to both. Hence the Permian strata may be found resting in some parts on upper beds of the Coal-series ; in others, on lower beds of the Millstone Grit; while, on the other hand, the New Eed Sandstone rests on dif- ferent members of the Permian series, or (as already observed) passes over and rests directly on Carboni- ferous strata. The Magnesian Limestone series of Durham has a thickness of about 300 feet, and is overlaid by red marls with gypsum ; it reposes in turn upon marl slate, and Lower Permian Sandstone, the whole series MAGNESIAN LIMESTONE, PERMIAN FORMATION. 199 attaining a thickness of about 600 feet. 1 In the neighbourhood of Mansfield the series consist of an upper and lower bed of Magnesian limestone, with intermediate marls and sandstones. 2 The lower lime- stone is the more important, attaining a thickness from seventy to one hundred feet ; it is variable in quality, and at Mansfield passes into a white calca- reous sandstone, with which the terrace in Trafalgar Square in London is paved. The following analysis, by the late Mr. Eichard Phillips, 3 will give a general idea of the composition of this and the Mansfield ' red stone ' which it strongly resembles except in colour. White and red siliceous dolomites of Mansfield, Derbyshire. White. Roseate. Brown. Silica 51-40 4940 49-40 Carbonate of Liine 26.50 .... 26.50 .... 26.50 Carbonate of Magnesia .... 17.98 .... 16.10 .... 16.10 Iron, Alumina 1.32 .... 3.20 .... 3.20 Water and loss 3.80 .... 4.80 .... 4.80 100.00 100.00 IOO.OO The stone from these quarries is largely employed in building and paving, as also for making troughs and cisterns. The excellence of the stone is testified on the high authority of Sir Gilbert Scott. In the 1 According to the observations of Professors Sedgwick and King. 2 W. F. Aveline, ' Geology of parts of Notts and Derbyshire/' Mem. Greol. Survey, p. 5. 3 Ibid. p. 6. 200 MAGNESIAN LIMESTONES direction of Nottingham the formation deteriorates, and passes into a friable calcareous sandstone. The stone from the Mansfield Woodhouse quarries is a massive, but irregularly-bedded, crystalline lime- stone of a fine yellow colour, in some places speckled with black. It is hard and durable, as testified by the good condition of Southwell church, and it has been employed in the foundation and lower portions of the Houses of Parliament, and in the construction of the Martyrs' Memorial at Oxford. 1 The stone from Bol- sover Moor quarries, nearly identical in geological position with that from Mansfield, was selected by the Commissioners for the New Houses of Parliament, but not used in the building. It is a yellowish-brown dolomite, compact and fine-grained, but variable in quality, and requiring careful selection. The stone from Anston quarries, Yorkshire, is of excellent quality, and has been used "or the front of the Museum of Practical Geology, London, in which there is not a single bad block. The other important quarries of Magnesian limestone are situated at Brodsworth, Cadeby, and Park Nook near Don- caster, Huddlestone near Sherburne, and Smawse near Tadcaster, all in Yorkshire ; while in Derbyshire the same stone is obtained at Bolsover, and in Notts at Mansfield Woodhouse, already referred to. 1 W. F. Aveline, ' Geology of parts of Notts and Derbyshire/ Mem. Geol. Survey, p. 8. OF THE PERMIAN FORMATION. 201 The following are analyses of the Bolsover (i), and the Mansfield Woodhouse stones (n). i. ii. Carbonate of Lime 51.10 51.65 Carbonate of Magnesia 40.20 42.60 Oxide of Iron and Alumina i .80 trace Silica 3.60 3.70 Water and loss 3-3O 2.50 100.00 100.45 The sp. gr. of a dry mass of the Bolsover stone is 2.316 ; the weight of a cube of two inches, 4890.8 grains in the ordinary state ; when dried, 4881.4 grains ; when saturated with water, 5042 grains ; J one specimen from Cadeby absorbed one-fourth its bulk of water. General Observations. From the above description and analysis, it will be seen that this rock is of variable quality and composition, the proportions of carbonate of lime, magnesia, and silica, rapidly varying and influencing the durability of the rock as a building stone. In general it may be affirmed that the dolomite of the north-east of England is more dense than the oolite limestones, and stronger than the Portland stone, but that it disintegrates rapidly in a smoky atmosphere ; especially where deeply cut into mouldings, as those of the New Houses of Parliament unhappily evince. On the 1 R. Hunt, Descrip. Guide M. P. G. p. 31. 202 MAGNESIAN LIMESTONES other hand, the colour of the stone is pleasing to the eye; and if care be observed in the selection of the blocks in the quarry it will prove an excel- lent stone for architectural purposes, and for build- ings erected beyond the influence of the smoke of towns. Amongst the edifices constructed of Magnesian limestone which have well resisted the effects of time, may be mentioned the choir of Southwell church of the twelfth century ; the stone is similar to that from Mansfield, being a siliceous dolomite, while the Anglo-Norman portions, built of a stone similar to that from Bolsover Moor, are in a very perfect state ; the mouldings and carved work retaining the sharp- ness of the original sculpture. The keep of Koningsburg Castle, built of Magne- sian limestone from the vicinity, is in a perfect state, although the joints of the masonry are open in conse- quence of the disappearance of the mortar. Tickhill church of the fifteenth century, Huddlestone church of the same period, and Huddlestone Hall of the sixteenth century, are in a good state of preser- vation ; and the stone of Eoche Abbey of the thir- teenth century is for the most part intact. On the other hand, the churches and minster of York, Howden church, Doncaster old church, and others in that part of the country, all built of Magne- sian limestone, have suffered severely from atmo- OF THE PERMIAN FORMATION. 203 spheric influences, the mouldings having often been entirely effaced. 1 The Commissioners appointed to report on the best building stone for the New Houses of Parlia- ment concur in stating, that in proportion as the stone employed in Magnesian limestone buildings is crystalline does it appear to have resisted the decom- posing effects of the atmosphere ; and Professor Daniell observes that the nearer the composition of Magnesian limestones approaches to equivalent pro- portions of carbonate of lime and carbonate of mag- nesia, the more crystalline and better they are in every respect. 2 1 Report of the Building Stone Commission, i5th July, 1839. New edit. 1845. The Commissioners included Sir Charles Barry, Sir H. De la Beche, Mr. William Smith, and Mr. Chas. H. Smith, assisted by Professors Daniell and Wheatstone. 2 Ibid. These proportions are 45.7 per cent. carb. of magnesia and 54.3 of carb. of lime. Cotta (Rocks class, p. 245) proposes that all lime-stones containing upwards of 23 per cent. carb. of magnesia should be classed as dolomites. CHAPTER IV. OOLITIC, OE JUEASSIC LIMESTONES. THE Oolitic group of rocks lying above the great argillaceous formation of the Lias, yields varieties of building stones more largely in request, and better adapted, perhaps, for ordinary architectural purposes than any of the other British formations. This group of strata extends in a band of varying width from the coast of Dorset to that of Yorkshire ; through Somersetshire, Gloucestershire, Oxfordshire, Northamptonshire, and Lincolnshire. North of the Humber it is gradually overlapped and concealed for a distance of fifteen miles by Cretaceous strata, but emerges again at New Walton, and rises into the higher escarpments of the Cleveland Hills. Nature of the Limestones. The limestones of this group, though varying somewhat according to locality and geological position, are generally soft, uniform in texture, either white, cream-coloured, or yellow, and composed either of fragments of shells cemented by calcareous oolitic material, or of small grains, or ovules, of carbonate of lime firmly bound together. It is owing to this structure that the formation has received its name of ' Oolite/ but as OOLITIC, OR JURASSIC LIMESTONES. 205 these strata are nobly developed in the picturesque range of the Jura, lying on the borders of France and Switzerland, geologists both of Britain and the Con- tinent are now inclined to adopt the territorial name, 'Jurassic/ in preference to the petrological term, ' Oolitic/ when speaking of this series of strata. Structure and Specialities. On examining a speci- men of Bath or Cheltenham Oolite, we find that the spherular grains are either hollow, or contain as a nucleus a grain of sand, or a fragment of a shell, or other foreign substance. The size of other spherules is about that of the roe of a small fish ; but in a few instances they are much larger. 1 Fragments, or whole shells, or skeletons of molluscs, crinoids, and corals are enclosed ; and, not unfrequently, the strata present in a conspicuous degree the phenomena of oblique-lamination, arising from the action of cur- rents in the waters in which they were deposited. All these Oolitic limestones are of marine origin. They are composed of carbonate of lime, with various proportions of carbonate of magnesia, silica, alumina, and iron. When used for buildings not subjected to the smoke of cities and manufacturing towns, they often last for lengthened periods. But different beds have very different powers of resisting 1 As in the case of the pisolite, at the base of the inferior oolite at Cheltenham. See ' Geology of the Country around Cheltenham/ Mem. Geol. Survey, p. 32 (1857). 206 OOLITIC, OR JURASSIC LIMESTONES. the influence of the atmosphere ; of which instances will be presently adduced. When first quarried it is often sufficiently soft to be cut with the saw ; but hardens on exposure. This is the case both at Bath and at Cheltenham. Geological Position of the best Building Stones. The Jurassic series contains four distinct formations of Oolitic limestone, some of which are divisible into distinct bands, with varying petrological characters. These, in ascending order, are (i) The Inferior Oolite ; (2) The Great, or Bath, Oolite ; (3) The Coralline Oolite, or Coral Bag ; (4) The Portland lime- stone. A short description of each of these will now be given. i. Inferior Oolite. This formation is more fully developed in the Cotteswold Hills in Gloucestershire than in any other part of England, attaining at Leck- hampton Hill, near Cheltenham, a thickness of 2646;., and furnishing two courses of a building stone which has probably been used in the construction of Gloucester Cathedral, the Abbey Church Tewkes- bury, Sudeley Castle, and several of the ecclesiastical buildings which adorn the Vale of the Severn. From this spot as a centre, the freestones of the Inferior Oolite thin away towards the north, east, and south. The following is the section of the strata at Leckhampton Hill: x 1 E. Hull, 'Geol. of Cheltenham/ Mem. Geol. Survey, 1867. OOLITIC, OR JURASSIC LIMESTONES. 207 Feet. ' Ragstone ' A rough, shelly, oolitic limestone, not used for building 38 Upper Freestone White or light yellow oolitic limestone, used for ordinary buildings 34 Oolite Marl Soft chalky limestone and marl 7 Lower Freestone Fine-grained, compact oolitic freestone, white or light yellow, used for build- ing purposes 147 Pisolite, or Pea Grit. . Largely oolitic, friable limestone, shelly and coralline, unfit for building pur- poses 38 The principal quarries are at Bourton, Broad- way, Guiting, Stanway Hill, Cleve Cloud, Painswick Hill, Sheepscomb Hill, Syreford, Brockhampton, and Loughborough. The stone from Painswick is of specially fine quality, approaching in texture the celebrated Caen stone of Normandy. The presence of this Oolitic limestone has imparted a special character to the domestic architecture of the hilly districts as contrasted with that of the plains, which are formed of Lias clay, and in which brick houses set in wooden frame-works abound. Some of the farmsteads and manor houses of the Cotteswold Hills, as old as Henry VIII or Elizabeth, are good speci- mens of the style of the period, and are built ex- clusively of Oolitic limestone. 2. Great or Bath Oolite. This formation has a much more extensive range than the Inferior Oolite, from which it is separated by a clayey stratum, called 1 Fuller's earth/ which is absent in Oxfordshire. 208 OOLITIC, OR JURASSIC LIMESTONES. The Bath Oolite has an average thickness of 200 feet 1 , and is divisible into two members or zones ; the lower including the * Stonesfield slate ' and Oolitic freestones of Burford and Tainton ; the upper being formed of a compact white, brittle, or chalky lime- stone, not suitable for architectural purposes, in Oxfordshire. The lower member, however, produces a white Oolitic freestone of excellent quality in this county. It has been used in the ecclesiastical buildings of the I3th, i4th, and I5th centuries, in the city of Oxford, which have stood the assaults of time better than the more modern buildings, erected in the last century, of Coralline Oolite, from the neighbouring quarries of Headington Hill ; proving the care which the architects of those days exercised in the selection of building stone. This stone is quarried at Tainton Downs and Burford ; and it has also been used in the building of Blenheim Palace, 2 and the ulterior of St. Paul's Cathedral. 3 This Oolitic freestone, forming the * lower zone ' of the Great Oolite, in certain directions entirely alters its character, and at Stonesfield, and Sevenhampton Common, near Cheltenham, passes into flagstones 1 E. Hull, < On the S.E. thinning out of the Secondary Rocks/ Quart. Journ. Geol. Soc. Survey, xvi. 74. 2 E. Hull, 'Geol. of Woodstock/ Mem. Geol. Survey, p. 16. 3 Gwilt, Encyc. Arch. p. 468. The recent additions and restora- tions completed in Lambeth Palace in 1833, at a cost of 83,000, are of Bath Stone. OOLITIC, OR JURASSIC LIMESTONES. 209 and tiles, which have been largely worked for roofing purposes, but have now been generally superseded by the lighter and more durable slates from North Wales. The most important quarries, however, are those situated along the range of the Somersetshire hills, at Stinchcombe, Minchinhampton near Stroud, Bath- ampton, and Bath Baynton near Box, Chippenham, and Doulting. The stone is here largely worked by tunnelling under ground, and is of a fine grain, com- pact, slightly shelly, and soft when first extracted, but afterwards hardens. In colour it is nearly white, passing into yellow ; and is capable of receiving sculpturings to a degree of sharpness only surpassed by Caen stone. At Bathampton the upper beds for a depth of 30 feet appear to be chiefly worked. From these quarries the stone for most of the beautiful ecclesiastical structures of the West of England has been extracted, including the Abbey Church at Bath, Glastonbury Abbey Church (nth century), and Wells Cathedral (i2th to isth cen- turies) ; all of which are in good preservation. 1 On the other hand, the church of St. Mary HedclifFe, Bristol, constructed of Inferior Oolite of Dundry Hill, 2 and, exposed to the smoky atmosphere of a 1 The Oolitic limestone used in the interior of Christ Church Cathedral, Dublin, has all the appearance of Bath stone. 2 Gwilt, Encyc. Arch. p. 471. P 210 OOLITIC, OR JURASSIC LIMESTONES. populous city, has suffered much from exfoliation of the stone, chiefly in the ornamental portions. The following is an analysis 1 of the average Bath stone from Box: Garb. lime, 94.52, carb.mag.,2.5o, iron and alumina, 1.20, water and loss, 1.78, bitumen, a trace. The Great Oolite ranges throughout portions of Oxfordshire, Northamptonshire, and Lincolnshire, and is quarried for building purposes in several localities along its course. The principal quarries are at Barnac and Casterton, in Northamptonshire, producing a light brown, oolitic, shelly limestone, which has been largely employed in all the mediaeval structures of Cambridgeshire, the Isle of Ely, and North Suffolk. It has stood remarkably well when care has been taken to select for the more exposed portions the less earthy varieties. 2 The Kelton stone, from quarries near Stamford, is a rich cream-coloured Oolite ; rather harder, and more uniform than the Barnac stone, and has been largely used in the numerous beautiful churches of North- amptonshire. It has been also used for the modern restorations of the Peterborough and Ely cathedrals, and in St. Dunstan's-in-the-East, London. 3 1 By Professors Wheatstone and Daniell. ' Report of Commis- sioners,' &c. 2 G. B. Burnell, C.E., On Building Stones,' Journ. Soc. Arts, March, 1869. 3 Gvvilt, Encyc. Arch. p. 467. The range and character of these Oolitic formations in Central England have recently been admirably OOLITIC, OR JURASSIC LIMESTONES. 211 Haydor, near Grantham, has produced an Oolite used in Lincoln Cathedral, Boston, Grantham, and Newark parish churches, Culverthorpe House, and Belvoir Castle. The stone is of a brownish cream- colour, and large blocks can be raised from the quarries. 1 The Ancaster quarries, near Sleaford in Lincoln- shire, produce compact, fine-grained, cream-coloured Oolite, largely employed in the churches of Lincoln- shire, and in private residences, such as Wollaton Hall and Belvoir Castle ; blocks from 3 to 5 tons may be raised from their beds. Its specific gravity is greater than that of the Barnac stone, and it is also more cohesive; in Lincolnshire and the Midland counties it has well stood the test of time, and is in good repute from its agreeable colour, and the ease with which it may be worked. 2 2. Coralline Oolite. This formation has a compara- tively limited range, being interrupted throughout a large section of its course from Dorset to Yorkshire. It ranges from Berkshire, along a series of calcareous hills, into Oxfordshire, and again recurs near Scar- borough, forming some noble cliffs along the coast south of that town. It is seldom, however, that it described and illustrated by Professor Phillips, F.R.S., in his work, < The Geology of Oxford,' p. 141 et seq. (1871). 1 Gwilt, Encyc. Arch. p. 466. 2 G. B. Burnell, C.E., < On Building Stones/ Journ. Soc. Arts, March, 1869. P 2 212 OOLITIC, OR JURASSIC LIMESTONES. produces a building material, as it is generally of too incoherent a nature for that purpose. The stone of this formation from Headington Hill, near Oxford, was unfortunately employed to a large extent in the building and restoration of the colleges and ecclesias- tical structures of that city during the last and pre- ceding centuries ; and ,often laid with the bedding- surface outwards, in total disregard of the recognised principles to be observed in setting stones in masonry. The result has been, that these modern structures present lamentable examples of weather- ing ; and are in striking contrast to those of more ancient date, built with a stone brought from a greater distance, but with far greater power of resisting decay. 1 The best example of the use of Headington stone is that of Wadham College,which had excep- tional means of selecting material from the quarries. 2 4. Portland Stone. The Portland limestone forms the uppermost member of the Jurassic series, and, like the lowest, is largely in request as a building material. Its uses, however, are somewhat different ; for as the Inferior and Great Oolite seem especially adapted to receive the delicate chiselings of the Gothic 'styles, so the Portland limestone is employed to greatest advantage for the massive and more 1 The stone from Tainton Downs from the Great Oolite for- mation, see ante, pp. 207-8. 2 Professor Phillips, Geology of Oxford, p. 299, OOLITIC, OR JURASSIC LIMESTONES, 213 uniform structures of classic and Italian architec- ture. Thus, while Portland limestone has been ad- vantageously employed in the construction of St, Paul's Cathedral, the churches of the reign of Queen Anne, and the massive columns and portico of the Bank of Ireland, it would have been totally unsuited as a material for the restoration of Henry the YII's chapel in Westminster Abbey, or for the New Houses of Parliament; this is owing to peculiarities of texture which I shall now describe. Texture and Composition. In composition the stone is a nearly pure carbonate of lime, containing 95 per cent, of this mineral, and i per cent, each of silica and carbonate of magnesia. It is superior to the Oolitic limestones in hardness and durability in the presence of a smoky atmosphere, and is also less absorbent of moisture ; at the same time, its texture is far from uniform ; it contains numerous large shells, and is not devoid of flaws, on which account it is unfitted for elaborate and delicate carvings. The following is an analysis, by Professors Daniell and Wheatstone, of the average composition of Port- land stone : Per cent. Silica i.ao Carbonate of lime 95.16 Carbonate of magnesia .... 1.20 Iron, alumina 0.50 Water and loss 1.94 100.00 When dry aborbs 8.86 per cent, of its weight of water. 214 OOLITIC, OR JURASSIC LIMESTONES. This stone is obtained from numerous quarries in the Isle of Portland, near Weymouth. 1 The best stone is in the north-eastern part of the island, the worst in the opposite side; the section in different localities also varies, but the following will serve to give a general view of the succession of strata. 2 Sections of Quarries in the Isle of Portland. Weat side. Feet. 2. Stone brash and two beds of Cap increased to 4. Roach, in one bed 4 feet thick, and i feet united to the white bed 5. White bed. Marketable free- stone Layers of flint, &c., unsale- able 6. Two beds of roach full of oyster-shells, replacing the middle bed 7. Third bed of saleable stone, not equal to the white bed in quality 5 2 East side. Feet. 1. Vegetable mould i 2. Stone brash. Cream-coloured limestone 3 3. Dirt bed. Clay with vegetable remains I 4. Cap. Hard cream-coloured limestone and clay, in three layers ... 10 5. White bed. Marketable free- stone 5 Parting of flinty material . . ^ 6. Middle bed. Marketable free- stone 5 Parting of shelly limestone . 2 7. TJiird bed with few shells, best freestone, varying from 7 -I 4 43 History, and illustrations of Use. Previously to 1623 this stone does not appear to have attracted any attention; but from 1660 it has gradually grown into use. Inigo Jones restored a portion of 1 The principal are < Trade Quarry,' ' King Barrow East End,' ' Yernstreet,' * Castle's,' ' Waycroft,' 'Gosling's/ and ' Grove' quarries. 2 Conybeare and Phillips, Qeol. of England and Wales, p. 173. OOLITIC, OR JURASSIC LIMESTONES. 215 old St. Paul's, 'casing the outside, and adding a grand Corinthian portico to the west part, all of Portland stone/ St. Paul's Cathedral, and many of the churches in London erected in the reign of Queen Anne, were constructed of stone very superior to that now generally employed, as far as regards durability. The quarries from which this stone used by Sir Christopher Wren was obtained have long since been deserted ; the only reason assigned being that the merchants find they cannot sell that stone on account of its being a little harder, and therefore more expensive to work. 1 Amongst the other public structures in London built of Portland stone, may be mentioned, the old Westminster and Blackfriars bridges, the Custom House, opened in 1817, Goldsmith's Hall, the Reform Club, and the colossal statue, a copy of the Farnese Hercules sculptured by Mr. C. H. Smith, which stands in the hall of the Museum of Practical Geo- logy, of which the original is in the Museum of Naples. Portland Oolite has been largely employed in the more prominent portions of some of the finest build- ings in the City of Dublin ; amongst them are the columns and portico of the Bank of Ireland, formerly Parliament House, founded 1729, and com- 1 Mr. R. Hunt, Descriptive Guide Museum of Practical Geology, p. 30. 216 OOLITIC, OB JURASSIC LIMESTONES. pleted exactly ten years after ; the Custom House, founded in 1781, also ten years in completion; the General Post Office, the Royal Exchange, the frontage and some of the buildings of Trinity College. 1 Ireland, like Scotland, being deficient in those for- mations producing soft calcareous freestones agree- able to the eye, and fitted for fine sculpturing, has been obliged to have recourse to England and France for building stone of this quality. That this was done from very early times is shown by the example of Christ Church Cathedral, founded about the year 1038, and built in the Anglo-Norman style. The interior of this venerable structure, now undergoing restoration or rather reconstruction, is built of cream-coloured Oolitic limestone, which is apparently identical with that of the West of England. This view is corrobo- rated by the opinion of Mr. Street, founded on pecu- liarities in the original plan of the building, that the original architect was an inhabitant of South Wales or the border counties of England. Oolitic stone, derived either from Normandy or England, was not uncommonly employed in Ireland, in structures of the nth and I2th centuries. 2 1 For some information on the matter I am indebted to the Rev. Dr. Haughton, F.R.S. 2 Mr. G. Wilkinson, M.E.I.A., Ancient Architecture of Ireland, pp. 84-5. OHAPTEE V, CBETACEOUS LIMESTONE, OR CHALK. THIS well-known formation is a finely granular white carbonate of lime, formed for the most part of the microscopic shells of foraminifera, or the calcareous mud derived therefrom. It also contains fossil shells of molluscs, starfishes, and echiDoderms. The lower beds consisting of the 'Chalk Marl/ and * Lower Chalk/ are devoid of layers of flint, which characterise the ' Upper Chalk/ and the whole formation attains a thickness of about i ooo feet. Range of the Formation. ' The Chalk escarpment ranges from the coast of Dorset to the entrance of the Wash, producing one of the most striking physical features in England ; consisting of a smooth, dry ridge, forming the margin of a table-land every- where intersected by narrow valleys, often water- less and steep-sided. North of the Wash the same escarpment reappears, and, crossing the Humber near Kingston-on-Hull, terminates in the bold promontory of Flamborough Head. South of the valley of the Thames the Chalk-downs form a nearly oval 218 CHALK. range, stretching from the cliffs of Dover westward into Hants, and again eastward to Beachy Head. The white cliffs of Kent and Sussex have given to England the old Norman name of * Albion/ Chalk as a Material for Building. Generally, throughout its range, the formation is much too soft, and liable to atmospheric waste to be used as a build- ing stone. At the same time, the harder varieties were formerly sought after for this purpose over the South- east of England ; and when protected by an outer coating of flint, or other durable material, have been found to last very well. The ruins of St. Pancras Priory, near Lewis, which have stood for 800 years, may be cited in illustration. 1 St. Alban's Abbey Church, the longest in the kingdom, and some of the older portions of Windsor Castle, are in part con- structed of Totterntive stone, a hard band at the top of the Chalk Marl. 2 1 Dr. Mantell, Geology of the South-east of England. 2 On the authority of Mr. W. Whitaker, F.G.S. CHAPTER VI. LIMESTONES OF IEELAND. THE Carboniferous limestone occupies the greater part of the central plain of Ireland, and has been largely used both in the ancient and modern buildings of this region. It is divisible into three members. i. Lower limestone; 2. Calp, a Middle limestone; 3. Upper limestone ; the whole attaining a thickness from 2000 to 3000 feet. The marbles from this formation have already been described. As a building stone there is much variety. The lower and upper divi- sions produce a good, crystalline, greyish limestone, sometimes dolomitic, and in a few instances oolitic. This later variety occurs along the shores of Killala Bay ; and has been used in the construction of the beautiful, but ruined, Abbey of Moyne, where the sharpness of the sculpturing is still retained. 1 The Calp, or Middle division, consists of dark carbonaceous or earthy grey limestone, alternating with beds of dark shale and chert, and is very irregular in the stratifica- tion. The Upper limestone resembles the lower, but is more evenly bedded and flaggy. These general 1 Mr. G. Wilkinson, Anc. Arch, of Ireland, p. 37. 220 LIMESTONES OF IRELAND. divisions are not capable of being recognised over the entire country. 1 Limestone has been employed in some of the most ancient structures in Ireland, the details of which have been carefully collected and faithfully deline- ated by Mr. G-. Wilkinson. Amongst these may be mentioned the Bound Towers of Cashel, Clondalkin, Clones, Donoughmore, Fertagh, Kilree, Swords, Timahoe, and the Seven Churches. Many of these structures present, in the doorways or windows, excellent examples of the Norman mouldings and ornamentations belonging to a period anterior to the introduction of this style into England. 2 As regards the object for which the Eound Towers were built, a visit to Italy has led me to adopt the view of those who consider them to have been campaniles, or belfries ; their Italian representatives being such structures as the campaniles of Florence, and of Pisa, generally known by the name of the Leaning Tower of Pisa. Sandstone seems to have been the favourite material for the sculptured portions of ecclesiastical and monastic structures until the introduction of pointed architecture of the early English style, when limestone was more generally employed. The cathe- dral structures of Christ Church, and St. Patrick in 1 According to the opinion of Professor Jukes. 2 Mr. Wilkinson's views on this subject appear to me to solve a problem which has been a source of difficulty to archaeologists. LIMESTONES OF IRELAND. 221 Dublin, and of Kilkenny, Cashel, and Limerick present interesting examples of this transition period. Amongst the examples of domestic architecture of a past age is the ruined Castle of Trim, of huge pro- portions, and of the Norman style of construction. The walls are upwards of 13 feet thick, constructed of the limestone of the locality, roughly squared and coursed, but not dressed ; sandstones being used in the angles of the openings and the arches, in accordance with the Norman practice of building. 1 Muckruss Abbey, standing by the Lakes of Killarney, displays some good examples of limestone sculpture. Limestone of a bluish tint has recently been employed with excellent effect in ecclesiastical structures in Dublin and its vicinity, when combined with granite, or Portland oolite, for the angles and mouldings of doors and windows. The dark-coloured beds from the ' Calp ' are liable to rapid decay, and have a gloomy aspect. 2 In some localities, however, they yield a hydraulic lime, and were employed by the Shannon commissioners for this valuable species of mortar. * The ordinary limestone of Ireland weighs in average per cubic foot I7olbs. ; the extremes of weight being 159 and iSolbs. The average weight 1 Wilkinson, Anc. Arch, of Ireland, p. 117. 2 As shown by the state of the walls of the Library of Trinity College, Dublin. 222 LIMESTONES OF IRELAND. of water absorbed by immersion is one-fourth of a pound ; the greatest being one-half a pound. The chalk of Antrim weighs i6olbs. per cubic foot, and absorbs 3 Ibs. of water ; the impure shaly calp weighs 1 60 Ibs., and absorbs from one to four pounds of water per cubic foot. As compared with the Oolitic limestones of Eng- land, the Carboniferous limestone contrasts unfavour- ably as regards colour. It is also harder, and more expensive to work ; and not so well adapted for receiving with facility the delicate mouldings and ornamental sculpturings of Gothic architecture. It is chiefly as a source for the production of marbles that the formation is to be valued in an architectural point of view, and as such has already been described. THE CHALK FORMATION. The Chalk is extensively developed around the basaltic plateau of County Antrim. It is very similar to the Upper Chalk of England, and contains numerous layers, and large sponge-like masses of flint. It is generally tolerably hard, but very brittle, and subject to atmospheric waste ; on which account it is Seldom or never used as a building stone, though largely quarried for lime. 1 Scotland. This country is devoid of calcareous strata suitable for architectural purposes. The meagre representatives of the Carboniferous limestone are solely employed either for the manufacture of 1 Sir R. Kane, Industrial Resources of Ireland, p. 277. LIMESTONES OF SCOTLAND. 223 hydraulic or ordinary mortar, or for the smelting of iron-ores, and the stone is far too valuable for these purposes to be used as a building material. The principal limestone quarries are those of the Roman Camp Hill, Burdie House near Edinburgh, Garnkirk, Hurlet, and Arden near Glasgow. In the Western Highlands there are occasional bands of crystalline limestones amongst the Lower Silurian strata, which might be used as marble of inferior quality. OHAPTEK VII. CONTINENTAL LIMESTONES. France and Belgium. The limestones belonging to that part of the Continent adjoining England, are analogous in composition, and in geological distri- bution, to those of England itself. They may be arranged under the following heads, from the earlier geological periods downwards : (a) those of the Si- lurian, and Devonian, (b) those of the Carboniferous, (c) those of the Triassic, (d) those of the Jurassic, (e) those of the Cretaceous, and (/) those of the Tertiary periods. Some account will now be given of each of them, as far as they bear upon the subject before us. (a) The rocks of the Silurian, .Devonian, and Car- boniferous series occur chiefly in Brittany, and south of the Meuse. They are all conformably inclined to each other, 1 and contain limestones of grey, blue, or dark colour, sometimes magnesian, or becoming true dolomites. They are frequently employed for build- ing purposes, and often produce marbles; and these of several varieties. 1 Sir R. I. Murchison, Siluria, 4th edit. p. 407. Chateau, Tech. du Batiment, i. 129. CONTINENTAL LIMESTONES. 225 (6) The Carboniferous limestone, used largely -in Belgium, comprehends two varieties : the compact grey, blue, or black variety, and the finely granular (' petit granite 'J. 1 The former is largely quarried on the banks of the Meuse, and in the environs of Tournay ; the quality is variable. The second variety is more highly prized as a building ma- terial. It is formed of the debris of shells, corals, and crinoids, and is both quarried and shaped with ease. It offers a great resistance to crushing force, and is not liable to be attacked either by frost or rain. It is worked in Belgium at the quarries of Soignies, Ecaussines, Arquesnes, Felny, and Ligny, &c. ; and in France at the quarries of Lille. 2 (c) The limestone of the Trias is called Muschel- kalk, or Calcaire Conchylien. It is interposed between the grds ligarre below, and the marnes irisees above, in France and Germany, but is absent in Britain. It is a shelly limestone, compact, grey, greenish, or yellow, or variegated. It is well developed in Lor- raine and other places, as Grasse and Toulon. (d) The Jurassic formation of France produces a building stone unsurpassed by that of any country for purity of colour, fineness of texture, and fitness for receiving the most elaborate and delicate chisel- ings of ornate architecture. The Caen stone of Nor- 1 Chateau, Tech. du Bailment, i. 129. 2 Ibid. i. 130. Q 226 CONTINENTAL LIMESTONES. mandy stands in the same relation to architecture as Carrara marble does to sculpture. Both occupy the highest position as materials for their respective uses in art, and both have been valued from a re- mote, though not equally remote, antiquity. Range of the Jurassic Formation. This formation stretches in a broad band along the western flanks of the Vosges mountains into Central France, passing by Nevers and Bourges to the borders of the Atlantic at La Eochelle. 1 From Poitiers a narrow band ex- tends in a northerly direction to the British Channel at Caen in Normandy. Along the east of France these rocks compose the picturesque range of the Jura mountains, forming the rocky frontier of Switzerland. The formation is interposed between the Liassic shales with their bluish earthy limestones below, and the Cretaceous rocks above. It includes similar di- visions to those established in England, and de- signated by the English names only slightly modified by MM. D'Orbigny and Omalius D'Halloy. 2 It would, however, be impossible, within the limits of this work, to follow these in detail. We shall confine 1 MM. Elie de Beaumont and Dufrenoy's Geological Map of France. 2 Dr. S. Wright has shown how clearly the fossils of these different stages throughout the Oolites correspond in England, France, and Germany. ' On the Correlation of the Jurassic Hocks, &c.,' Trans. Cotteswold Naturalist Club, 1869. CONTINENTAL LIMESTONES. 227 our attention to a few of the localities producing the more valuable of the building stones. Inferior Oolite (Etage Bajocien, D'Orb). The following are sections of this formation at Sainte- Honorine, Calvados, in Normandy ; and at Niort, Deux Sevres, given by M. D'Orbigny as typical sections of the formation as it occurs in France. 1 Sainte-Honorine. Niort. (d) Not stated. (c) Limestone white as chalk, and of very fine texture, worked for building stone (freestone). Several metres in thickness. (6) Yellow limestone, argillaceous, enclosing sponges. (a) Compact, very hard sandstone, with the same ammonites as (6) and (d) of Sainte-Honorine. The above series are separated by a band of blue shale (corresponding to the Fullers earth of England) from the overlying beds of the Great Oolite, now to be described. Great, or Bath, Oolite (Etage Bathonien, D'Orb.) This is the formation which yields, at Banville and Caen, the building stone of greatest excellence. It extends without interruption throughout the Depart- ment of Nievre by Nevers, by Dun-le-Roi, to Lucy- le-Bois ; also in the C6te-d'0r, the Saone-et-Loire, and Herault. It is found on both flanks of the Vosges ; 1 Cours &m. de Palseont. et Gol. ii. 483. Q 2 (d) Blue limestone, compact, hard, full of ammonites and stems of trees, i metre, (c) White limestone, oolitic (grenu), with fossil sponges, &c. 10-12 metres. (6) Ferruginous oolite, characterised by numerous ammonites. 2 metres. (a) Thin band of earthy ironstone. 228 CONTINENTAL LIMESTONES. in the Department of the Meuse, at Montainville, and in that of the Aisne, at Eparcy. In Brittany it is especially developed ; along the coast of Cal- vados we may follow the strata, without interruption, from the upper beds of Port-en-Bessin, by Saint Aubin, to B,anville. The thickness of the strata is considerable, from fifty to sixty metres, and the formation varies much in character and composition. The beds most important as freestones are near the bottom ; consisting of fine-grained, white limestone, glossy, and filled with fragments of crinoids. They are nearly horizontal, and the thickness is about eight metres. 1 The following is a short account of the special qualities of different kinds of Caen stone. 2 (1) Quarries of Caen, Allemagne, La Maladrerie, and Quilly. Very handsome limestone, and white ; of good quality, fine-grained, and uniform in texture. This stone is employed for fine sculpture in Nor- mandy, England, and the United States of America. (2) Quarries of Villers- Card vet, Aubigny, and Cauvicourt. This stone is the purest and most esteemed. 3 It is largely exported, and weighs 1 50 Ibs. per cubic foot. 1 D'Orbigny, Cours dldm. de Palaeont. et Ge*ol. ii. 49 6. 2 Chateau, Tech. du Batiment, pp. 211-12. 8 Mr. G. B. Burnell considers that it will not stand exposure ; quoted by Gwilt, Encyc. Arch. p. 480. The mediaeval buildings of Falaise, a town situated near the Aubigny quarries, are in a dilapidated condition. CONTINENTAL LIMESTONES. 229 (3) Quarries of Amblie, Fontaine, and Henri. This stone is used in hydraulic constructions of the country, but is not exported. (4) Quarries of Banville, Fontenay, and Aucrais. The Eanville stone is especially useful in structures exposed to moisture and rain, as it is practically non- absorbent. It weighs 142 Ibs. per cubic foot; and is, therefore, the most dense, with the exception of the Aubigny stone, of all the Oolitic limestones of Caen. Specialities and Illustrations. Caen stone re- sembles that of Bath and Cheltenham, but is finer in texture, rather lighter, weighing in general about 1 20 Ibs. per cubic foot, generally non-oolitic, and only less white than chalk. It is supposed that the quarries worked several centuries ago yielded a stone more durable than that raised at the present day. These quarries were situated amongst the upper beds, which have a finer and more crystalline texture than those at present quarried for exportation. It must be admitted, however, that the objections which have been urged against the employment of limestones of the granular varieties in exterior work, are also applicable to the beautiful calcareous free- stones of Caen. They are sadly liable to decay from atmospheric causes, which are intensified if combined with the smoke of towns. The present condition of the elaborate Anglo-Norman decorations of the exterior of Canterbury Cathedral, built by ' William 230 CONTINENTAL LIMESTONES. of Sens/ succeeded by his pupil ' English William/ in the twelfth century, sufficiently attest the truth of this observation. 1 It is, however, eminently adapted for use in the interior of buildings ; and no stone is more capable of being wrought into all those intricacies of ornamental art which the fancy of man can invent, or his hand can execute, when employed on designs of Gothic architecture. The introduction of Caen stone into Britain is curiously interwoven with history. It was probably introduced shortly after the Norman Conquest, having been a favourite stone with the architects who fol- lowed the fortunes of William, duke of Normandy, and his successors. Its introduction into Ireland may have been of a still earlier period, corresponding to the introduction of Norman and Lombardian styles of architecture into that 'country. 2 In England, how- ever, it was largely used in cathedrals and other buildings down to the middle of the fifteenth century (1448), when Normandy was lost to Britain ; and it is only in modern times that its use has been revived. Of its use in the earlier periods, the Cathe- dral of Canterbury and Westminster Abbey may be cited as examples ; and, amongst .modern structures, 1 Mr. William Whitaker, F.G.S., of the Geological Survey, in- forms me that the restorations now in progress are being executed with the same stone as that originally used. 2 See ante, p. 220. CONTINENTAL LIMESTONES. 231 the new facade of Buckingham Palace, and Mr. Hope's mansion in Piccadilly. Of the other quarries in France yielding Jurassic limestone the following may be mentioned : Those of St Vivien, St. Vaise, and St. Sorlin, near La Rochelle ; those of Bourges Montbart and Chatillon, near Bourges, Dijon; those of Brillon, Mont St. Marie, Ville, Issey, Enville, and Mecrin, near Bar-le-Duc. From these quarries the Military Hospital of Vin- cennes, the Hotel de Louvre, the Church of Eosny, the Cathedral of Toul, and the Viaduct of Nogent- sur-Marne have been constructed. 1 Portland Oolite (Portlandien D'Orb). Occurs round the Paris Basin ; though sometimes locally absent, owing to denudation previous to the deposition of the Cretaceous strata. It rests upon the Kimmeridge clay, and is composed generally of white compact fossiliferous limestone, often cavernous. It is largely quarried in the Pas-de-Calais, and at Hanoringhen, It occupies extensive tracts in the Department of La Meuse, Haute - Marne, L'Aube, LTonne, La Nievre, and L'Oise. 2 (e) Chalk of France (Terrains Cretaces). The Cre- taceous rocks of France form a nearly oval ring round the Tertiary basin of Paris, dipping away gently from the circumference, towards the capital 1 Chateau, Tech. du Bailment, ii. 222. 2 D'Orbigny, Cours el^m. de Palseont. et G^ol. ii. 562. 232 CONTINENTAL LIMESTONES. as a centre. They consist of seven members, 1 cor- responding generally to those of England. The formation also occurs in the South of France, and along the base of the Pyrenees. Some of the lower beds, consisting of ' tuffeau/ and ' craie tuffeau/ more or less arenaceous, are sufficiently hard for ordinary building stone ; but it is seldom that the Chalk itself can be used except for interior work of buildings. 2 In the valley of the Lower Seine, however, it is extensively used in the best buildings, as at Eouen, Vernon, and Louviers. 3 It is also quarried and extracted by tunnelling amongst the vine-clad hills at Sens, along the line of railway from Paris to Versailles, about seventy miles from the former city. (/) Tertiary Limestones of the Paris Basin. The Tertiary series of the Basin of Paris includes varieties of strata, both of marine and freshwater origin, consisting of limestone, sandstone, gypsum, and lig- nite. Some of the marine limestones yield blocks of great size and thickness. In colour the stone has a pale yellowish tinge, admirably adapted for street architecture under a smokeless sky ; and no 1 D'Orbigny's Stages: i, ' N^ocomien ;' 2, ' Aptien;' 3, ' Albien;' 4, ' Ce'nomanien ;' 5, ' Turonien ;' 6, ' Senonien ;' and 7, 'Danieii.' Cours 16n. de Palseont. et Gol. ii. Fig. 393, p. 384. 2 Chateau, Tech. du Batiment, ii. 132. 3 G. B. Burnell, Journ. Soc. Arts, 1860. CONTINENTAL LIMESTONES. 233 one can fail to observe how much, of the beauty of the noble public buildings, and scarcely less noble ranges of houses, in the principal streets of this queen of cities, is due to the chaste purity of the stone, and its capability of being employed either in massive structures, or in those of a more ornate character. These limestones also abound in the South of France, and most of the buildings of Marseilles, Montpelier, and Bordeaux, are constructed of these materials. The Tertiary limestones have been largely quarried along both banks of the Seine for use in Parisian buildings ; and the quarries situated along the line of the Northern Eailway (Chemin de fer du Nord), about twenty miles out of Paris, are now being vigorously worked for the restoration of the build- ings recently destroyed by the Commune. The large caverns left under portions of the city, after the ex- traction of the stone, are now used for the remains of the dead collected from the city churchyards, which formerly abounded. The gypsum quarries in the vicinity of Paris have already been described. 1 1 The following is the order of succession as given by Sir C. Lyell. LOWER EOCENE : Argile plastique et lignite. MIDDLE EOCENE : (a) Soissonnais sans, or lits coquilliers ; (b) lower calcaire grossier ; (c) middle and upper calcaire grossier ; (d) gres de Beau- champ, or sables moyens ; (e) calcaire siliceux ; (/) gypseous series and calcaire lacustre moyen. UPPER EOCENE : Calcaire de la Beauce, and Gres de Fontainebleau. Man. Elem. Geol. 5th edit. 234 CONTINENTAL LIMESTONES. The beautiful city of Brussels is also constructed of Tertiary limestone ; the materials for the more important structures having been brought from the vicinity of Lille. Of similar materials are built the Louvre in Paris, the Cathedrals of Amiens and of Kouen, from quarries at Bonneleau and Vernon respectively. These lime- stones contain bands of siliceous material, and the consequence is that, the progress of decay being un- equal, the siliceous bands project in various forms to the great disfigurement of the architecture. This decay generally takes place where the rain reaches the limestone indirectly, as underneath cornices, niches, and entablatures. Similar cases of unequal weathering have been observed in the cases of the Arc de Triomphe, the Cathedral of Notre Dame de Paris, and we may add that of Bristol ; but in this case arising from the use in the same edifice of sand- stone and limestone indiscriminately. Prussia (Rhenish). Carboniferous limestone, like that of Namur, is quarried at Aix-la-Chapelle. Wilrtemberg is very rich in building limestones, derived both from the Muschelkalk of Friederichsthal and Rottweil ; the Jurassic limestones of Urspring, p. 223. The gypsum of Montmartre yielded those remains of extinct mammalia which the illustrious Cuvier has described in his great work, ' Ossements Fossiles.' CONTINENTAL LIMESTONES. 235 Arnegg, Schnaitheim (interior work) ; and the reddish and yellow marbles of Kirchheim and Zwiefalten. There are also the calcareous tufas of Geisslingen and Untertiirkheim. The calcareous tuff of Wiirtem- berg, of a yellow colour, is so soft as to be cut with the saw when just quarried, but upon exposure hardens, and is much sought after for the construc- tion of arches, tunnels, towers, and fortifications. 1 Spain. Limestones belonging to the Carboniferous, Jurassic, and Cretaceous formations are extensively developed in Spain. Madrid is chiefly built of a siliceous dolomite, termed Piedra de Colmenar, from the name of the district in which it is quarried. 2 Italy. Limestones are largely developed amongst the Austrian Alps and the Apennines, belonging to the Jurassic, Cretaceous, and Lower Tertiary forma- tions. 3 In some portions of this tract, as for instance opposite the bay of Spezia, and amongst the Alban and Volscian mountains, these rocks constitute the main mass of the range, and frequently produce marbles of considerable variety, some of which have already been described. Many of the buildings of 1 Delesse, Materiaux de Construction de 1'Exposition Universelle de 1855. 2 As I am informed by Professor O'Reiley ; an analysis of this stone is given by Dr. Sullivan in Atlantis, 1863. 3 Sir R. I . Murcbison, ' On the Geological Structure of the Alps, Apennines, &c.,' Journ. Geol. Soc. Lond., vol. v. Sir C. Lyell, Manual of Geology, 5th edit. p. 230. 236 CONTINENTAL LIMESTONES. Verona, Venice, Padua, and some of the towns of Tuscany, are largely constructed of limestones, such as the Nummulitic, which are capable of receiving a polish, and thus become ' marbles/ Africa and Asia Minor. The great formation of Nummulite limestone occurs in full force in the north of Africa, as for example in Algeria and Morocco. It has been traced from Egypt, where it was largely quarried of old for the building of some of the pyramids, and notably the great Pyramid of Cheops (as stated by Herodotus), into Asia Minor. 1 Of this stone the ruins of Baalbec are formed ; and it is also the building stone of Aleppo, and some of the cities of the Holy Land. The range of mountains between Aleppo and Antioch is largely composed of cream-coloured lime- stone containing Nummulites. 2 This wonderful for- mation has also been traced across Persia, through the Himalayas to the frontier of China. 1 Lyell, Man. of Geol. 5th edit. p. 230. 2 Specimens of this stone were shown to me by Mr. W. J. Maxwell, C.E., who was employed in 1870 on the survey for the Euphrates Valley Kailway. PART XL SANDSTONE GROUP OF BUILDING STONES, CHAPTER I, SILICEOUS FEEESTONES. Sandstein (Germ.) Grbs (Fr.) SANDSTONE, sometimes called ' freestone/ is very largely employed as a building material in some portions of the British Isles, especially the northern ; and it possesses this advantage over limestones and dolomites, that it is better able to resist the chemical action of the smoky atmosphere of large towns. Some varieties, however, are, on the other hand, equally liable to the influence of atmospheric dis- integration, depending very much on the nature of the cementing matter; and quite as much judgment is necessary in the selection at the quarry of a good and durable sandstone, as of any other kind of building material. Of the injurious effects produced by simple weathering on sandstones of inferior quality, the venerable cathedral and churches of Chester, 238 SANDSTONE GROUP OF BUILDING STONES. until recently restored, afforded a lamentable ex- ample. Geological Formations. Sandstones for building, paving, and flagging purposes in the British Islands are chiefly derived from three great formations, the Devonian or Old Red Sandstone, the Carboniferous, and the Triassic. These formations are largely developed in England, Ireland, and Scotland, and in a manner often highly advantageous to the growth of architecture. Sandstones of the Wealden forma- tion of Kent and Sussex from the neighbourhood of Tunbridge Wells, Godstone, and Maidstone, have been, to some extent, used in London and its vicinity ; but in durability they are inferior to those from the older formations. Composition and Texture. Sandstones are com- posed of grains of quartz and other materials, of variable size, bound together by some cementing material such as silica, carbonate of lime, or oxide of iron; sometimes pressure, and a high terrestrial temperature, have been the chief agents in the con- solidation of sandstones. Along with the quartz-grains, which form the essential constituents of these rocks, other ingredients are often present in large proportions, such as flakes of mica, argillaceous matter, fragments of limestone, agate, or jasper, felspar, fossil shells, or wood. When mica is abundant, and is distributed in SANDSTONE GROUP OF BUILDING STONES. 239 layers over the planes of bedding, the rock is called a micaceous sandstone. If carbonate of lime is abundant, it is a calcareous sandstone; and if the materials are composed of the debris of felspathic rocks (such as granite, gneiss, porphyry, or trap), the rock is termed a felspathic sandstone. In texture, sandstones have extreme variations, from the impalpably fine-grained to the coarsest grit, in which the grains may reach the size of a pea, or small bean. On the other hand, when the rock is composed of distinct pebbles, rounded, or waterworn, and which may vary in size from that of a bean, to a diameter of three feet, it receives the name of a conglomerate, and passes beyond the limits assigned to a building stone. When the component fragments are angular, or nearly so, the rock becomes a breccia. Of the former, the Old Bed conglomerate of Argyleshire offers the finest example ; of the latter, the brecciated limestone of Alberbury in Shropshire, belonging to the Permian system, may be cited as one of the most remarkable illustrations in the British Isles. 1 Sandstones are often highly porous, and are capable of absorbing large quantities of water, ac- cording to the degree of porosity. In the elaborate series of experiments undertaken by Mr. Wilkinson 1 Murchison's Silurian System, p. 63. Hull's ' Triassic and Permian Rocks,' Mem. Geol. Survey, p. 21 (1869). 240 SANDSTONE GROUP OF BUILDING STONES. on sandstones from various parts of Ireland, 1 it was found that some specimens absorbed as much as 1 1 Ibs. of water per cubic foot, while others scarcely imbibed as much as i Ib. As a general result it may be assumed that sandstones of ordinary softness and porosity absorb from 5 to 6 Ibs. of water per cubic foot. As regards crushing weight, Mr. Wilkinson found it to vary from 1680 Ibs up to 14,600 Ibs for a cubic inch ; the most tenacious specimen being a white ' quartz -rock, open and porous, semi-granu- lar/ from Muckish in Donegal. 2 Similar experiments were made by the Commis- sioners for the selection of stone for the New Houses of Parliament, 3 and are given in the Appendix. Chemical Analysis. The following are analyses of samples taken from some of the best-known quarries of sandstone - 3 it is almost unnecessary to remark that no two specimens would give exactly the same results, but those here stated may be considered to represent a fair average description of the workable stone in each quarry. 4 1 Prac. Geol. and Arch, of Ireland. Tables of Experiments. 2 Ibid. This seems to have been a quartzite rather than a sandstone. 3 Report (1839) Appendix D. 4 Report (1839) Appendix C. The light-red, yellow, and white sandstones of the ' Lower Keuper ' division of the New Red Sand- stone of England, appear to have been strangely overlooked by the Commissioners. SANDSTONE GROUP OF BUILDING STONES. 241 Chemical Analysis of Sandstones. Darley Dale Mansfiel Craigleith. (Stancliffe). Heddon. Kenton. (Lindley'sl Silica 98.3 .... 9640 .... 95.1 .... 93-1 .... 49.4 Carb. lime i.i .. .. 0.36 0.8 .. .. 2.0 .... 26.5 Carb. magnesia . . o.o .... o.o .... 0.0 O.O .... 16.1 Iron, alumina .... 0.6 .. .. 1.30 .... 2.3 4.4 .... 3.2 Water and loss.. . . o.o .. .. 1.94 .... 1.8 .... o-5 .... 4.8 IOO.OO IOO.O IOO.O IOO.O Colour. Sandstones are extremely variable in colour ; having various shades of purple, red, brown, yellow, and grey passing into pure white. Some- times these tints alternate, and produce variegated sandstones not uncommon in the Triassic, Permian, and Carboniferous formations both of Britain and Europe. The most widely distributed colouring agent is iron, often occurring in company with manganese ; and there are very few sandstones entirely destitute of the former metal, either as a carbonate, protoxide, or sesquioxide. On the nature of the colouring matter, Mr. G-. Maw has made some very interesting experiments, founded on the chemical analysis of differently-coloured por- tions of the same rock ; and he arrived at the con- clusion, that in the case of red, and reddish brown, the colour is due to the presence of iron in a state of anhydrous sesquioxide ; in the case of yellow colours, to iron in the state of hydrous sesquioxide ; and that the blue or grey tints are due to carbonate, or pro- 242 SANDSTONE GROUP OF BUILDING STONES. toxide of iron. 1 These colours either pervade the mass of the rock uniformly, or are distributed along the planes of bedding; but examples occur, chiefly amongst the Carboniferous rocks, of variegated colours, disposed in concentric rings, or envelopes ; while we frequently observe in some portions of the New Hed Sandstone, blotches of yellow or white in the midst of a rock otherwise uniformly of a red colour due to the deoxidation of the iron at these places. Forms of Stratification. Sandstones may be either massive, thin-bedded, lenticular, or flaggy, according to the conditions under which they have been formed. When massive, the rock is of uniform composition throughout a considerable vertical depth, and is then suited for the production of large blocks for founda- tions, engine beds, and piers ; such blocks are to be obtained from the Millstone Grit of England and Wales. When thin-bedded, the original layers, or beds, are parted into strata of moderate thickness, often by bands of shale or micaceous laminae ; such strata produce stones for ordinary buildings, walls, and paving. When lenticular or wedge-shaped, the rock is seldom so uniform in texture as when the bedding is even, and the blocks are more difficult to shape, owing to the want of parallelism in the upper and lower surfaces. When flaggy, the strata split 1 ' On the disposition of Iron in variegated strata/ Quart. Journ. Geol. Soc. xxiv. 355. SANDSTONE GROUP OF BUILDING STONES. 243 up into thin layers ; a kind of bedding especially characteristic of laminated micaceous sandstones, such as are to be found amongst the Millstone Grit series of the North of England, and the Lower Keuper sandstones of the central counties. Not unfrequently the surfaces of flaggy sandstones present the phenomena of ripple-markings, similar to those we may see on a flat sandy shore, over which a gentle current has drifted ; and * oblique lamina- tion/ also due to current action, is of frequent oc- currence amongst sandstones of nearly all geological periods. In laying courses of masonry care is necessary that the stone be placed in the same manner in which it was originally deposited ; in other words, that the laminae occupy a horizontal position. Otherwise, the atmosphere acting with greatest effect along the planes of lamination, the stone will flake off along the face of the building. Many instances might be cited where disregard of this evident rule has been attended with destructive consequences. E, 2 OHAPTEE II. SECTION I. SANDSTONES OF ENGLAND AND WALES. THE building sandstones of England are abundant, and sometimes of excellent quality, and are princi- pally distributed throughout the central and northern counties. A brief account of the more important, arranged according to their geological position, will now be given. It seems unnecessary to refer specially to the great sandstone beds of the Cambrian and Silu- rian formations of Wales and Shropshire, as they are not employed, except locally, for building purposes. (a) Old Red Sandstone. (Devonian.) The sand- stones of this system have not been much employed for buildings of a higher class, with the exception of Tintern Abbey, an edifice of the i3th century, part of the stone of which is in good preservation. 1 They are distributed throughout parts of Devonshire, Herefordshire, and Monmouthshire. In colour they vary from deep red, or purple, through shades of green, yellow, and grey, to almost white ; and though largely used for local buildings, are not at 1 Built of stone from ' Barbadoes Quarry/ in the vicinity. Gwilt, Encyc. Arch. p. 459. SANDSTONES OF ENGLAND AND WALES. 245 present in request for finer architectural purposes at a distance. In Devonshire building sandstones occur at the Hangman Hills, the Foreland, North Hill, Newnham Park ; as also in the vicinity of Liskeard, and of Bodmin in Cornwall. 1 North of the Severn the sandstone has been quarried in the neighbourhood of Chepstow, Monmouth, and Ledbury. Those portions of Chepstow Castle, of the nth and I2th centuries, constructed of red sand- stone of this formation, are generally much decom- posed ; while the remaining portions, built of Carboniferous limestone, are in a state of good preservation. 2 (b) Carboniferous Series. The building sand- stones of this group are referable to the Yoredale Beds, the Millstone Grit, and the Coal-measures. They occupy large tracts of the North of England, extending from Derby into the high moorlands of Yorkshire and Lancashire, being thrown off on either side from the great anticlinal axis of the Pennine Chain. The building stones of the Millstone series occur either as coarse massive grits, finer siliceous grits, or flaggy sandstones, suitable respectively for foundations, bridges, piers, engine beds, ordinary building stones, paving, and flagging. The stone is generally hard, durable, and of greyish or light 1 De la Beche, Geol. Rep. p. 490. 2 Report of Commis. Build. Stones, p. 21, Table B. 24$ SANDSTONES OF ENGLAND AND WALES. brown colours, and is used in many of the towns and villages of the North of England to a large extent, such as Manchester, Bolton-le- Moors, Blackburn, Haslingden, Burnley, Skipton, Bradford, Sheffield, and Leeds. The stone is admirably adapted for resisting the effects of the smoky atmosphere of these large manufacturing towns, as very little lime enters into its composition. Flagstones of the Lower Coal-measures. Imme- diately over the Millstone Grit there occurs in Lancashire, Derbyshire, and Yorkshire, a series of strata, varying from 1000 to 2000 feet in thickness, known as the * Lower Coal-measures ' or ' Gannister Beds/ 1 which produces excellent flagstones, generally micaceous, evenly bedded, and parted by bands of shale. These are largely worked in some parts of the country, as at Whiston near St. Helens, Orrell, Billinge and Up-Holland near Wigan, Bradshaw near Bolton, at Eochdale and Oldham, at Kerridge and Shrigley near Macclesfield, and Wingfield Manor in Derbyshire. These flagstones are also largely quarried along the margin of the Yorkshire coal-field through- out a semicircular range of hills, from the valley of the Aire, near Leeds, by Bradford, Halifax, Hudders- 1 A name given by Mr. E. W. Binney, F.R.S., and Professor Phillips to the series of the Lower Coal-measures, from the pe- culiarly hard siliceous rock, which forms the floor of the principal coal-seam. See Phillips' Manual of Geology, pp. 183-5 SANDSTONES OF ENGLAND AND WALES. 247 field, and Peniston, to Sheffield; and from these quarries both the internal demand of the country, and that of the eastern and southern coasts is supplied. (c) Coal-measures. The sandstones of the Coal- measures, on the other hand, are generally of a more destructible nature, containing as they do more ar- gillaceous matter, as well as iron, than is the case with those just described. They are also rather softer, generally of purple, yellow, or greyish colours, and are very apt upon exposure to become iron-stained. The Pennant Grit sandstones, however, of Somerset- shire and South Wales, occupying a central position in the Coal-series, 1500 to 3200 feet in thickness, more nearly resemble those of the Millstone Grit. * SECTION II. EXAMPLES AND ARCHITECTURAL ILLUSTRATIONS. Out of the vast number of quarries scattered over the country formed of Carboniferous rocks, it will be impossible to do more than give a selection of the most important. Quarries in Carboniferous Sandstones. i . Bakewell Edge, Derbyshire. Yoredale Grit ; a very handsome stone, of which the fronts of Chats- 1 De la Beche, ' On the Formation of Rocks of South Wales, &c./ Mem. Geol. Survey, voLi. Hull, Coal-fields of Great Britain, 2nd edit. pp. 69, 80. 248 SANDSTONES OF ENGLAND AND WALES. worth, Bakewell Church, and the Crescent at Buxton are built. 1 These rocks sometimes assume the ap- pearance of ornamental wood. 2 2. Boltoris Quarry, Aislaby, Yorkshire. Warm light-brown, moderately fine siliceous grit, micaceous, with specks of carbon, used in Whitby Abbey, New University Library, Cambridge ; Scarborough Pier, and St. Catherine's Docks. 3. Duffield Bank, Derbyshire. Millstone Grit ; dark and light-brown, or white, quartzose sandstone. This stone has been used in the construction of the Grammar School, Birmingham ; and some of the public buildings in Derby. 4. Elland Edge, Yorkshire. Fine micaceous grit and flagstone of a light greyish -brown colour, slightly micaceous; worked for paving, flags, and building. From the Gannister Beds, or Lower Coal- measures. 5. Gatherly Moor, Yorkshire. Cream-coloured micaceous sandstone, moderately fine-grained, and sometimes obliquely laminated, and in thick beds ; used in Aste Hall, Eichmond, Purse Bridge over the Tees, Skelton Castle, and Darlington Town-hall. 6. Harrock Hill, Lancashire. Coarse-grained massive grit, grey and yellow in colour, about one 1 Geol. of parts of Derbyshire and Yorkshire, by Messrs. Green, Foster, and Dakyn, Mem. Geol. Survey, p. 88 (1869). 2 Report of Comrais. Build. Stones. Table A. SANDSTONES OF ENGLAND AND WALES. 249 hundred feet thick ; quarried for paving, millstones, engine beds, and foundation stones. 7. Haslingden, Lancashire. Greyish micaceous flag- stones, belonging to the Millstone Grit series. Nu- merous quarries in the neighbourhood producing flagstones and ashlar. 8. Heddon, near Newcastle-on-Tyne. Light-brown Coal-measure sandstone, spotted with oxide of iron, mixed with laminations of carbonaceous matter ; used in Heddon Church, and buildings at Newcastle. 9. Kenton, near Newcastle-on-Tyne. Light-brown ferruginous sandstone, which can be raised in large blocks ; used in modern buildings at Newcastle. 10. Knockley, Nag's Head, &c., Forest of Dean, Gloucestershire. Grey, micaceous sandstone from the Coal-measures, or Millstone Grit ; used in the New Pier at Cardiff, and for troughs, grindstones, &c. 1 1 . Leeds, Yorkshire. Coarse - grained massive greyish grit of the MiUstone series, yielding blocks of large size for foundations, piers, and buildings. 12. Longridge Fell, Lancashire. Yellowish and greyish sandstone, not very coarse-grained. Worked along a system of joints, and of about 550 feet in total thickness. The rock belongs to the Yoredale series of the Carboniferous system, and is opened out in six quarries, some of which show a section of one hundred feet in depth. The stone weathers well, and has been largely employed in the churches and 250 SANDSTONES OF ENGLAND AND WALES. public buildings of North Lancashire, amongst which Preston Town-hall may be mentioned. 1 13. Meanwood, Leeds. Coarse-grained, light-brown, micaceous grit, yielding blocks up to 8 or 9 tons. 14. Osmotherley, Yorkshire. Dark-brown sandstone, moderately fine ; formerly worked for railway chairs. 15. Parbold, Lancashire. Coarse-grained massive grit from the Millstone series, yielding large blocks. 1 6. Peniston, Yorkshire. Greyish and light-yellow flagstones, sometimes rippled and micaceous. Several other quarries of these flags are in the neighbour- hood of Sheffield, Elland, and Bradford. 1 7. Up-Holland, Billinge Hill, Lancashire. Fine- grained micaceous flagstone, largely quarried for flags and paving stones, which are sent to Wigan, Liverpool, Preston, and all parts. 1 8. Scotgate Head, Huddersfield. Light-greenish grey, thin-bedded sandstone, used in York Castle, and Bath Hotel, Huddersfield. 1 9. Stancliffe and Darley Dale, Derbyshire. Light- yellowish brown, micaceous, moderately fine sand- stone ; used in the construction of Darley Abbey, Stancliffe Hall, Birmingham Grammar School, and numerous other buildings. 20. Stenton, Durham. Light yellowish brown grit, in beds from two to eight feet thick, yielding large 1 For these details I am indebted to Mr. De Ranee, of the Geological Survey. SANDSTONES OF ENGLAND AND WALES. 251 blocks ; used in the round keep of Barnard Castle, and modern buildings in the town of Barnard Castle. 21. Stanningley, Yorkshire. Light-brown fine- grained sandstone, suitable for steps, landings, and fine work, such as pinnacles, &c. 22. VineyHill, Gloucestershire. Fine-grained purple and grey sandstone, used in the New Pier, Cardiff. 23. Wheatwood, Addingley, Yorkshire. Medium grained light-brown sandstone, and strong coarse grit, yielding large blocks ; used in parts of Whitby Abbey, Sleights Bridge; the New Library, Cambridge; Town-hall, Whitby, and Market House, Exeter. (d) PERMIAN SANDSTONES. In the midland counties and Shropshire the Lower Permian formation con- sists of purple, reddish, or brown, speckled sandstone, interstratified with red marls, breccias, and calcareous conglomerates ; but the sandstones are seldom of sufficient consistency or uniformity of texture to be useful for any but common buildings, and the colour is decidedly objectionable. In Lancashire, Yorkshire, and Durham this for- mation consists of very soft bright-red and variegated sandstone, only fit for foundry purposes ; but where it occurs in the valley of the Eden, and along the cliffs of St. Bees Head, it is rather firmer in texture, and has been almost exclusively used for buildings in the pretty town of Penrith, including the church and ruined castle. An examination of the older 252 SANDSTONES OF ENGLAND AND WALES. portions of these structures will, however, be suf- ficient to show that it is not a durable stone, though sufficiently well suited for ordinary houses, walls, and cottages. Professor Harkness regards the Penrith sandstone as the lower, and the St. Bees sandstone as the upper, member of the Permian series of the North of England. 1 Of these sandstones the beautiful ruined abbeys of Calder and Furness have been built, a careful selection of the stone having been the chief cause of their state of partial preservation. (e) TBIASSIC, or NEW EED SANDSTONE SERIES. The building stones belonging to this formation are widely distributed over the central and north-western counties, and are obtained both from the Bunter and Keuper divisions ; but chiefly from the latter, and only in Cheshire and Lancashire. Bunter Sandstone. This forms the lower division of the Trias in England, and consists, when in its complete form, of three members : 3. Upper Bed and Mottled sandstone. 2. Pebble beds, and conglomerate. i. Lower Bed and Mottled sandstone. Of these, the upper and lower members consist of soft, fine-grained, red or mottled sandstone, unfitted 1 Journ. Geol. Soc. Lond. xviii. 105, and xx. 144. The sand- stone of St. Bees Head is described as stony and hard, of reddish- brown, whitish, and yellowish colours, p. 158. SANDSTONES OF ENGLAND AND WALES. 253 for building purposes, and chiefly useful as moulding sand for foundries. The middle member, throughout the central coun- ties, consists of dull red, coarse, pebbly sandstone, passing into quartzose conglomerate, and is only fit for very rough and second class work, such as walls for fields, gardens, or cottages. When traced into West Cheshire and Lancashire, however, it becomes less pebbly, and assumes a more compact structure, so that it is capable of yielding a very fair building material of a light reddish colour, sometimes varie- gated with light yellow or grey bands, and is largely quarried at Liverpool, for buildings in that town and the vicinity ; these quarries are situated along the eastern side, from Walton to ^Everton, Kirkdale, and West Derby. There are also quarries at Roby, Hale, and Woolton. 1 Lower Keuper Sandstone. This division of the Trias, lying at the base of the red marl, and above the Bunter sandstone, produces the best building material for the nobler kinds of architecture of the central counties, combining lightness of colour with durability, and fineness of grain with uniformity of texture. The general succession of these beds below the Keuper marl in Cheshire, Staffordshire, and Worcestershire, is as follows 2 : 1 Hull, on ' The Triassic and Permian Rocks,' Mem. Geol. Survey, p. 58 (1869). 2 Ibid. p. 66. 254 SANDSTONES OF ENGLAND AND WALES. General Section of the Lower Keuper Sandstone. 1. Water stones, (passage beds into the red marl). Brownish laminated, micaceous sandstones and flags, rippled, with beds of sandy marl or shale. 2. Building Stones. Fine-grained, light-red, brown, yellow, or white freestones, regularly bedded, with occasional bands of marl or shale. In Cheshire and Worcestershire these occur at the base of soft red sandstone which underlies the ' Waterstones/ 3. Basement Beds. Coarse, irregularly -bedded, pebbly sandstones, calcareous breccia, and conglo- merate with bands of marl and brecciated limestone (corn-stones). This group of strata ranges from the estuary of the Severn northwards along the eastern base of the Malvern and Abberly Hills, to the banks of the Stour at Stourport. Throughout the midland counties it follows the margin of the red marl, and in Shrop- shire, Derbyshire, and Cheshire, often rises into remarkably picturesque escarpments or groups of scarped hills, such as those of Penn, Oreton, and Tattenhall, near Wolverhampton ; the Hawkstone and Grinshill Hills, near Shrewsbury, the Peckforton, Delamere, and Frodsham Hills in Cheshire ; and the Alton, Ramshor, and Okeover Hills on the bor- ders of Stafford and Derbyshire. 1 The stone has 1 The structure of these ranges of hills has been worked out by the Government Geological Surveyors, and is shown on the maps SANDSTONES OF ENGLAND AND WALES. 255 been largely employed in the construction of many of the churches and mansions of the midland counties, and more recently in their restoration. Its fitness for use in the nobler ecclesiastical struc- tures may be illustrated in the cases of Worcester and Chester cathedrals ; the latter of which, renovated under the judicious superintendence of Sir Gilbert Scott will be more beautiful than it ever was before. Out of the large numbers of quarries in this sub- formation scattered over the country, the following deserve special mention : Chief Quarries of the Lower Keuper Sandstone. 1. Belton, Muorton, near Market Dray ton, Salop. White and light red compact sandstone. 2. Bidston Hill, Cheshire. Light yellow and white freestone of good quality. 3. Colwich, Staffordshire. White, rather soft free- stone, used in churches and mansions of the vicinity. 4. Colton Mill, Eugeley. White, soft, compact freestone, suited for finer kinds of architecture. 5. Crumpwood, Alton, Staffordshire. White free- stone of good quality, yielding large blocks, similar to that used at Alton Towers. and sections of the Survey. A description of the strata will be found in the Memoir on the Triassic and Permian Kocks, pp. 67-97. 256 SANDSTONES OF ENGLAND AND WALES. 6. Fulford, near Cheadle, Staffordshire. Light brown sandstone. 7. Grinshill, near Shrewsbury. White, light yellow, and reddish brown freestone ; flaggy at the top, with courses of massive stone yielding large blocks, presenting altogether a section of nearly 100 feet. 1 A stone well adapted for highest kinds of architectural work. 8. Grug Hill, Baschurch, Salop. Bather soft, fine, white sandstone, in lenticular beds. 9. Helsby, Delamere Forest. Light red, fine- grained, sometimes flaggy sandstone. 10. Hollington, Uttoxeter, Staffordshire. Light brownish grey, to white, freestone, fine grained, yielding blocks from 30 to 40 feet square, and 8 feet thick; used in Trentham Hall, Drayton Manor, Heath House, Town-hall, Derby, and Meer Hall, Cheshire. 1 1. Mauley, near Dunham, Cheshire. White and light red freestone of good quality, and yielding large blocks. With the light-reddish freestone from this locality Chester Cathedral is now being re- stored. 12. New Brighton, Wallasey, Cheshire. Yellowish freestone, rather soft and fine grained. 1 3. Orribersley and Hadley, near Worcester. Eed- 1 A section of this quarry is given by Sir R. Murchison in the Silurian System, p. 40. SANDSTONES OF ENGLAND AND WALES. 257 dish, light brown, and white freestone of good quality, thin-bedded in the upper part, massive below. Worcester Cathedral is now being restored with stone from these quarries. 14. Oreton Hill, near Wolverhampton. White and light brown freestone. 15. Overton Scar, Edge Hill, Chester. White freestone. 16. Park Quarry, Tixall, Staffordshire. Light brown, or grey sandstone, sometimes micaceous, in beds from 4 to 8 feet thick ; used in old mansions at Tixall, TixaU Hall, St. George's Church, Birming- ham, Sandwell Hall, Staffordshire. 17. PecJcforton, Cheshire. Massive light red sand- stone, durable, rather hard ; used in the construction of Peckforton Castle. A similar material is used in Beeston Castle, now a ruin. 1 8. Stanton, near Ashbourn. White and light red freestone, similar to that of Hollington. 19. Tixall and Weston, Eugeley, Staffordshire. Light brown, compact sandstone ; sometimes mica- ceous. 20. Weston, near Shrewsbury. White and light grey sandstone. 21. Weston Cliff, Donington Park, near Derby. White and light brown sandstone. 22. Woodhead, near Cheadle, Staffordshire. Light brown sandstone. s 258 SANDSTONES OF ENGLAND AND WALES. Sandstones of Formations newer than the Trias. With the exception of the sandstones belonging to the Lower Oolite formations of Yorkshire, the Wealden, and the Kentish Eag of the Lower Green- sand formations, there are no sandstones of any importance overlying the Trias in England ; and even these just named are only .local and compara- tively unimportant. (f) The Yorkshire Jurassic Sandstones, containing bands of coal and jet, are considered by Professor Phillips as the littoral representatives of the marine limestones of the centre and south of England. 1 They are finely displayed in the sea-cliffs of Gris- thorpe, Scarborough, and along Stainton Dale, and Haiburn Wylie ; interstratified with shales, iron- stones, coal, and ferruginous or calcareous bands. The stone has been largely worked at Aislaby, near Whitby, where it is of a light brown colour, mode- rately fine grain, and can be extracted in large blocks. 2 It has been used in Whitby Abbey, New University Library, Cambridge, and Scarborough and Bridlington Piers. Tunbridge Wells Sandstone. This rock is included in the lower division of the great Wealden group, lying at the base of the Cretaceous system, and con- sisting of the following members : 3 1 Manual of Geol. p. 297. 2 Report of Commis. Table A. 3 Mr. Drew, Mem. Geol. Survey (1833). SANDSTONES OF ENGLAND AND WALES. 259 /" S J V Feet. 5. Weald clay, with some local beds of stone ........ 600 4- Tunbridge Wells sand, with * Grinstead clay' .... 150 to 200 3< Wadhurst cla y ^k i 115 * 0116 ................ 100 i 60 2. Ashdown sand, with bands of clay and ironstone.. 160 250 i. Ashburnham beds, clays and sandstones (over). . .. 330 The sandstone is quarried at Calverley quarry near Tunbridge Wells. It is fine-grained, with a slightly calcareous cement, and of a variegated brown colour. The beds vary from i to 3^ feet in thick- ness, and can yield blocks from 80 to 500 cubic feet. It has been used in the new church, Eoman Catholic chapel, and other buildings at Tunbridge Wells. 1 (g) Kentish Rag. The stone known by this name forms a portion of the Lower Greensand group, and may be best observed at Hythe and Folkestone, on the coast of Kent. 2 The stone is variable in character ; and may be described as a calcareous sandstone, of a brown or light yellow colour, and often shelly. It is quarried at Godstone, Maidstone, Boughton, and the vicinity of Folkestone, and is used to a considerable extent in the. more recent ' gothic' churches of London and the neighbourhood, as I am informed by Mr. W. Whitaker. The sandstones (or ' firestones ') are how- ever ill adapted to resist alternations of wet and dry 1 Report of Commis. Table A. 2 See Memoir on sheet 4 of the Geological Survey, by Mr. F. Drew (1864). The name given to this formation by Dr. Mantell was ' Shanklin Sand,' Geol. South-East of England (1833). S 1 260 SANDSTONES OF ENGLAND AND WALES. weather, nor are they suitable for internal work, as they are apt to ( sweat.' When used for building they require to be kept above ground, and also to be pro- tected from rain. If these precautions are observed, these stones do not rapidly decay, and in some of the oldest parts of Westminster Abbey and the Temple Church, specimens of them may be observed in a fair state of preservation. 1 1 Mr. Burnell, C.E., Journ. Soc. Arts, 1860. See also Gwilt, Encyc. Arch. p. 564. OHAPTEE III. SANDSTONES OF SCOTLAND. THE chief sources of building sandstones in Scot- land are the Old Red and the Carboniferous forma- tions, which are largely developed between the Cheviot Hills and the Grampians, and yield some excellent building freestones, as well as others, suitable for flags and paving. The grits and conglomerates referable to the Silurian period require no special mention. (a) Old Red Sandstone. This formation has been divided by Professor Geikie into three members, the central one of which is unconformable to the other two, while the lower graduates into the Upper Si- lurian rocks of Lesmahagow, and the upper into the Carboniferous series. 1 The lowest division 2 includes the grey sandstones and paving stones of Dundee and Arbroath in Forfarshire, much used in the streets of Edinburgh, Glasgow, London, and other large towns. 3 The middle division comprehends the 1 Siluria, 4th edit. p. 250. 2 To the north and south of the Clyde basin it consists of chocolate-coloured sandstones, and boulder conglomerates. 3 In these flagstones, the remarkable featherlike thoracic ap- pendages of a huge crustacean, called by the quarrymen ' Seraphim, 262 SANDSTONES OF SCOTLAND. flagstones of Caithness, Cromarty, and Nairn ; and the upper, the yellow sandstones of Dura Den, re- markable for the abundance of fish remains. In reference to the use of these sandstones for building purposes, Mr. Burnell observes as follows : The Dundee and Arbroath stones are sometimes employed in London, the former as an ordinary building stone, the latter principally as a flag-pave- ment. The colour of the Dundee stone hitherto brought to London is rather disagreeable, for it is of a dark brown colour, or of a deep oxide of iron tint ; but the stone is hard, and resists weather very satis- factorily ; in consequence of the colour, however, this material is never used in ornamental buildings. The Arbroath stone is of a denser character than that obtained from Dundee, but it is more decidedly ' flakey,' to use a workman's phrase, and it is there- fore almost exclusively used for the purpose above mentioned. Occasionally, however, blocks of the largest dimensions, and of a very uniform character, are obtained from the Arbroath quarries. They are hard ; they resist weather satisfactorily ; the stone is easily worked, and its colour (a light greenish grey) is far from being disagreeable. 1 were discovered by the late Mr. Hugh Miller, and referred to their true origin by Prof. Agassiz. The crustacean is known as Ptery- gotus Anglicus, Ag. ' Poissons fossiles/ &c. 1 Ibid, supra cit. p. 260. SANDSTONES OF SCOTLAND. 263 (b) Carboniferous Sandstones. The sandstones of this series are the most valuable in Scotland for building materials, and are largely developed on both sides of the valleys of the Clyde and Forth. Their presence in the immediate vicinity of Edin- burgh and Glasgow has greatly contributed to the substantial character of the dwelling-houses, as well as of the public buildings, of these cities; a character which strikes the eye of a visitor on arriving from the great brick-formed cities of England. The geological position of these building stones is far down in the Carboniferous series; a position, in fact, corresponding to the mountain limestone of England ; the formation having completely altered its physical character in its extension into Scotland. As here developed, it consists of light yellow, or white, sandstones and grits, of various degrees of fineness, interstratified with shales, beds of ironstone, and coal, together with several bands of limestone. The sandstones when first extracted from the quarry are often beautifully white, but ere long, after being placed in position, assume a sombre aspect, due to the smoke of thousands of chimneys. The following are some of the principal quarries in the neighbourhood of Edinburgh and Glasgow : 264 SANDSTONES OF SCOTLAND. Quarries of Lower Carboniferous Sandstone. Binnie, near Uphall, Lirilithgowshire. Fine- grained, light brown or grey siliceous sandstone ; durable, and suitable for decorative purposes. Used in the New Club House, Princes Street, Edinburgh; the ornamental fountain in front of Holyrood Palace; and numerous private houses in Glasgow and Edinburgh. Bishop BriggSj near Glasgow. Light brown to white freestone, in thick beds, moderately fine- grained, and yielding large blocks. Stone used in Glasgow for building purposes. Cat Craig, Carridon. Light grey, fine-grained, siliceous stone, regularly bedded. Craigleithy near Edinburgh. Light grey, or brown, approaching white, fine-grained freestone, in beds varying from a few inches to twelve feet, interstra- tified with shales, and showing a vertical depth of about 250 feet. This stone has been largely em- ployed in the public, as well as the private buildings of Edinburgh, including the University, Law Courts, Royal Exchange, ' National Monument/ and numerous churches. It has also been used in London and ex- ported to the Continent. Good specimens resist crushing to the extent of 5000 Ibs. to the square inch. Crawbank, Borrowstounness, Linlithgowshire. Light yellowish brown, fine-grained freestone, yield- SANDSTONES OF SCOTLAND. 265 ing blocks of large size. Used in a Roman bridge, A.D. 140, and the old church of Kinneil, I2th century. Other quarries in the neighbourhood. Dunmore, Stirlingshire. Light grey, fine-grained sandstone of good quality. Giffneuch, near Glasgow. Pale grey to white, generally fine-grained freestone, of good quality, and adapted for the higher classes of public and private buildings. Used extensively in Glasgow, and in the more ornamental portions of the New University buildings in that city. Humble, Linlithgowshire. Pale grey and light brown sandstone, fine-grained, sometimes micaceous, and yielding large blocks. Used in Newliston House, Dun das Castle, additions to the Eoyal Institution, Edinburgh, the spire of Tron Church; and also in the Royal Exchange, Glasgow. Paisley. To the north of this town there are numerous quarries of white, or light brown, freestone, sometimes coarse and massive, at other times fine- grained, and apparently well calculated to withstand the action of the atmosphere. They belong to the Lower Carboniferous series. OHAPTEE IV, SANDSTONES OF IEELAND. THE sandstones of Ireland, suitable for building purposes, belong to the Old Red Sandstone, the Car- boniferous, and the Trias, or New Eed Sandstone, systems ; and are distributed chiefly in the north and south of that country, the central portions being formed of other materials. (a) Old Red Sandstone. The sandstones of this system are distributed chiefly throughout the coun- ties of Cork and Kerry, and consist of greenish, purple, red, and greyish grits, flagstones, and con- glomerates ; the uppermost member producing fine- grained flags and tiles, which, at Kiltorcan, yield im- pressions of fern- like plants in a state of remarkable preservation. 1 Amongst the best building stones of the counties of Cork and Kerry are the following : 2 Mallow. Hard sandstone; brown colour, and yield- ing flagstones, and blocks suitable for steps, window sills, &c. Kanturlc, and Macroom. Hard brown, and liver- coloured sandstones; expensive to work, but durable. 1 See Memoirs Geol. Survey of Ireland. Maps 147 and 157, p. 14. 2 Mr. G. Wilkinson, Prac. Geology, p. 172. SANDSTONES OF IRELAND. 267 Youghal. Sandstone of a reddish grey colour, capable of being dressed. Ardmore, on the borders of Waterford. Red sand- stone, changing on exposure to grey ; very durable, as shown by the condition of the Round Tower. Skibbereen, and Sherkin Island, Baltimore. Grey- ish sandstone, soft on being cut, but hardening on exposure. Glandore. Greenish sandstone, or hard grit ; used in many of the mansions of the country, as also in ancient buildings, as Ballymoney Castle. (b) Carboniferous Sandstones and Flags. The Lower Carboniferous rocks, lying below the limestone, produce either yellowish grits and conglomerates, as in County Longford, or greyish and yellowish flag- stones, as in County Mayo. In a higher geological position, we have a series of flaggy sandstones, ex- tensively distributed through portions of the counties Clare, 1 Limerick, Tipperary, Carlow, Kilkenny, and Queen's County, 2 occupying a position immediately under the Coal-measures ; while towards the north- west we find, in Leitrim and Fermanagh, massive grits and conglomerate sandstones occupying a similar geological position ; and,, in all probability, 1 Mr. F. J. Foot, Expl. Mem. Geol. Survey. Maps 114, 122, and 123, p. 9. 2 Messrs. J. B. Jukes and G. H. Kinahan. Expl. Mem. Map 137, p. 10. 268 SANDSTONES OF IRELAND, referable to the Millstone Grit formation of England. Yellowish and reddish sandstones, capable of pro- ducing good building stone, are distributed through- out parts of Londonderry, and Tyrone. 1 Near Cookstown, in this county, a fine-grained white free- stone, belonging to the Lower Carboniferous series, is quarried and extensively used for finer kinds of architecture in Belfast and neighbourhood. Along the coast of County Antrim, at Ballycastle, large blocks of reddish, yellow, and white freestone might be quarried, and shipped to any port in England, Scotland, or Ireland. 2 Carlow Flags. These flagstones are largely worked in portions of Carlow and the adjoining counties. They consist of hard dark-blue and grey flagstones, sometimes micaceous, and showing tracks of annelids, and, probably, of Crustacea or molluscs. They are imported into Dublin by canal ; and amongst other quarries those in the parishes of Shankill and Old- leighlin, of Kilrush and Money Point in Clare, may be specially named, 3 These flags all belong to the Carboniferous formation. Millstones and grindstones were formerly obtained from the Millstone Grit for- 1 Portlock's Geol. of Londonderry, Tyrone, &c. 2 For details of the building sandstones of different parts of Ireland, the reader is referred to the useful work of Mr. G. Wilkinson, already quoted. 8 Explanation of sheets 147 and 157 of the Maps of the Geol. Survey, by Messrs. Jukes and Kinahan. SANDSTONES OF IRELAND. 269 rnation of Cuilceagh, a high ridge on the borders of Leitrim and Fermanagh ; and from Drumdowney in Kilkenny. 1 (c) New Red Sandstone. (Bunter.) This formation is extensively distributed along the southern and western borders of County Antrim, occupying the rich and fertile valley of the Laggan, and stretching for some distance along both shores of Belfast Lough. In this district, it consists for the most part of soft red marly sandstone unfit for buildings, except those of a temporary character, and is more adapted for the production of moulding sand for foundry purposes. There are, however, a few places near Holywood and Newtown Ards where this red sandstone, after having been quarried, hardens on exposure; but its dura-, bility may well be questioned. All these beds belong to the Bunter sandstone the lowest member of the Trias. 2 (d) Lower Keuper Sandstone. At Scrabo Hill, however, which rises to a considerable elevation above the surrounding country from the northern shores of Strangford Lough, sandstones belonging to the upper division of the Trias the remnants of a once more widely extended formation are to be found ; very similar in appearance, and identical in geological position, to the freestones of Bidston Hill, 1 Sir B. Kane, Industrial Resources, p. 233. 2 Expl. Mem. Geol. Survey, Ireland, Map 36, p. 8. 270 SANDSTONES OF IRELAND. New Brighton, and Manley in Cheshire. 1 These sandstones are harder and more durable than those of the underlying Bunter division ; and are also of an agreeable colour, varying from light reddish- brown, to grey, yellow, and white ; they are easily worked, and suited for ornamental sculpturing ; these quarries also yield flagstones. The sandstone is overlaid by a great sheet of basalt and dolerite, and numerous horizontal and vertical dykes of similar igneous rocks perforate the beds, so as not only to interfere with the excavations, but also seriously to injure large masses of the stone itself. Notwithstanding this natural drawback, I know of no sandstone in the North of Ireland so well fitted for architectural purposes of an ornamental cha- racter; and for such purposes it is largely used in Belfast, Newtown Ards, and the adjoining country. The crushing weight of this stone has been ascertained by Mr. Wilkinson to vary from 2240 Ibs. up to 10,570 Ibs. to the -cubic inch. The average being about 4000 Ibs, 2 1 Expl. Mem. Geol. Survey, Ireland. Maps 37, 38, 39, p. 13. 2 Prac. Geol. &c. Table of Experiments. CHAPTER V. CONTINENTAL SANDSTONES. France. The principal sources of sandstones fit for building in France are the Devonian, Triassic (gres bigarre), the Jurassic, containing the gres de Lux- embourg, and the Tertiary series of the Paris basin, which yields the gres de Fontainebleau. In the Vosges there are the sandstones of the Permian and Trias in a position of almost relative conformity. 1 Quarries. The most important quarries are those of Villery, and those on the borders of the canal of Languedoc, by which large blocks are carried to Toulouse and other towns. The stone belongs to the class known as psammite, formed of siliceous grains in an argillaceous cement, often with flakes of mica. The town of Carcassonne is entirely built of sandstone from the quarries of Villery. 2 The sandstone of Fontainebleau, often called gres Uanc, or gres commun, is chiefly found at the town of that name, at Longjumeau and Pontoise. The quarries of Busagni, near Pontoise, furnish a stone in 1 M. A. D'Orbigny, * Cours &&nentaire, &c.' ii, 392. 2 Chateau, i. 184. 272 CONTINENTAL SANDSTONES. much request for hydraulic structures ; for although friable in the quarry, it becomes exceedingly hard under water. 1 Luxembourg. The sandstone of this name (gres de Luxembourg) is referable to the lower portion of the Jurassic series. On a rock of this sandstone the strong fortress of Luxembourg is built. The red sandstone at Hommartin (Meurthe) has furnished most of the stone for the churches and buildings of Lorraine, such as those of Saint Wandel and Sarre- brtick, remarkable for their rich brown colour. Germany. The New Red Sandstone (Bunter Sand- stein) is much employed for building in some parts of Germany. At Heidelberg it rises into the lofty ridge of the Kaiserstuhl, and from the quarries of the vicinity the grand old castle, together with many of the buildings of the town, have been constructed. The stone has a reddish tint, which affords a pleasing contrast to the green of the forests which rise behind the buildings along the banks of the Neckar. The gres de Wurtemberg, belonging to the Bunter Sandstein formation, is quarried in the Black Forest. It is of excellent quality, generally fine- grained, and the grains being cemented by silica it is exceedingly durable. Of this stone the beautiful gothic Cathedral of Cologne is chiefly constructed. 1 Chateau, i. 185. CONTINENTAL SANDSTONES. 273 The specific gravity varies from 2.22 to 2.36. 1 The Keuper formation also yields a useful sandstone, varying from red to white, sometimes coarse-grained, and refractory. It is quarried at Tubingen, Mertin- gen, and Stuttgart ; the finest quality is produced at Schlaydorf, and Holsteinbruch. The Bunter Sandstein of the neighbourhood of Treves furnishes excellent material for building pur- poses ; the quarries are situated at Beilinger, Lorig, Udelfang, Wasserliesch, and Hiltengend. Near Aix-la-Chapelle there is a white sandstone of great beauty, being composed of grains of pure quartz. It is easily worked, and suitable for sculpture, while it can be obtained in blocks of large size ; the quarries are situated at Herzogenrath. The sand- stone of Phalsburg is of a similar character. 2 Switzerland. The Tertiary formation known as the 'Molasse/ is largely developed in the great valley of Switzerland, and produces a greenish sand- stone, largely employed for building purposes at Geneva, Berne, and Lausanne. The quarries from which the building stone of Geneva is supplied, are situated on both banks of the lake ; those for Lausanne and Berne are close to these cities respectively. Italy. Sandstone is not largely employed as a 1 M. Delesse, quoting from M. "Wagner, Matdriaux de Constr. de 1'Expos. Univ. de 1855. 2 Chateau, i. 190. 274 CONTINENTAL SANDSTONES. building stone in this country. The chief sources being in Tuscany, the capital of which province is largely constructed with a dark greenish sandstone, quarried along the banks of the river Arno some miles below Florence itself. This stone, which when fine-grained is called ' mascigno/ when coarse, ' cicer- chia or cicerchina/ is variable in quality and composition, passing from a flag and paving stone into a massive building stone, and from a fine-grained sandstone into a conglomerate. It is used for paving and building both at Florence and Pisa ; and accord- ing to the observations of Sir E. Murchison belongs to two geological periods, namely : the Cretaceous on the one hand, and the Eocene Tertiary stage on the other, the two masses being separated by beds of nummulite limestone. The upper beds attain to a great thickness in the hills south of Santa Martino. 1 Large quarries of macigno sandstone, similar to that near Florence, are opened near Agosta along the valley of the Teverone amongst the Sabine Hills. 1 ' On the Geol. of the Alps, Apennines/ &c. Journ. Geol. Soc. Lond, v. 277. CHAPTER VI. SANDSTONES OF INDIA. SEVERAL formations of Northern India produce excellent sandstone for building purposes, which have been largely used. Amongst these, the stone derived from the ' Vindhyan' series is the most valuable. It is very widely distributed in the Nerbudda Valley, and neighbouring districts, and consists of several thick masses of sandstone of a light colour, uniform texture, and, while durable, it is not difficult to work. Of this stone many of the chief cities and build- ings in the north-west provinces, the Punjab, and the Ganges Valley are partially constructed. Allahabad, Benares, Agra, and Delhi have all drawn their supplies from thence ; and of this material have been erected the proudest monuments of the Mogul dynasty. It was used by Akbar for his palace of Futtipursikri, and the forts of Agra and Allahabad ; by Shah Jehan for portions of the Taj at Agra, as well as for the Jumna Musjid at Delhi, and by Aurungzebe for the palace at Benares. More recently, some of the largest engineering works, including the piers of the T 2 276 SANDSTONES OF INDIA. East Indian railway bridges over the Jumna at Allahabad and Delhi, have been constructed of this material. 1 Excellent building sandstone is also obtained from the Lower Damuda group, and Ranigari beds in Bengal. 2 *Mr. F. R. Mallet, F.G.S., Mem. Geol. Survey of India, vol. vii. part i. 2 Mr. W. F. Blandford, F.G.S., Mem. Geol. Survey of India, vol. iii. CHAPTER VII. SANDSTONES OF NORTH AMERICA. Canada. Sandstones suitable for building pur- poses, are to be found in the Huronian series, as yet little in demand, and in the Potsdam formation. This latter, in its extension eastward of Kingston, furnishes a white freestone, durable and fireproof, but rather hard. At Lyn, near Brockville, massive beds of superior quality have been worked for material with which to construct the new Parliament Buildings of Ottawa. Other localities in which the Potsdam formation yields serviceable freestones are Beauharnois, Hemmingford, Veaudreuil, Nepean, Eamsay, and Pakenham. The Quebec group affords building stone used in the city of that name, as also does the Chazy forma- tion. One of the most valuable is the ' grey band/ extending from Queenstown to Collingwood; it varies from 10 to 20 feet, and furnishes excellent building stone, which is largely used in many towns of west Canada. Of this stone the University College at Toronto, and many of the buildings at Hamilton, are constructed. 278 SANDSTONES OF NORTH AMERICA. The Oriskany sandstone of the Devonian age furnishes millstones, besides white freestones for building, as do also the Gaspe and Hudson Biver group of the Upper Devonian series. 1 United States. Only a few of the most valuable building sandstones can here be noticed. New Jersey and Connecticut contain a dark red sandstone, which is serviceable when fine-grained and compact ; of this etone Trinity Church, New York, is built. 2 At Chatham, on the Connecticut, and along the river are numerous quarries which supply the towns on the coast. A variety in North Haven, and at the east end of Mount Carmel, has been commenced for orna- mental architecture. The stone of Longmeadow and Wilbraham in Massachusetts, that at the mouth of Seneca Creek, Maryland, and the white and coloured freestones of Sugarloaf Mountain in the same county are largely used. The sandstone of the Capitol at Washington is from the Potomac, but of inferior quality. 1 The above details are condensed from Logan's 'Geology of Canada/ 1863. 2 Dana, Man. of Min. p. 361. ; PART XII. EAKEE BUILDING STONES. OHAPTEE I. TRAVERTINE. TRAVERTINE, anciently called lapis Tiburtinus, is the principal building stone of ancient and modern Rome. According to the views of Lyell, Bischof, and other observers, this rock has been formed by the precipitation of calcareous matter from water charged with carbonic acid gas ; and the enormous masses accumulated at Tivoli were deposited in an extensive lake, which existed at the close of the period of volcanic activity, during which the lavas and tuffs of the Roman territory were formed. 1 Its manner of formation may still be witnessed at the Lago di Zolfo in the Campagna, and at the cataract of the Anio at Tivoli. The travertine used in Rome is chiefly derived from quarries at Tivoli. It is a straw-coloured, 1 Lyell, Principles of Geol. loth edit. i. 405. Also Bischof, Chemical Geology, i. 155. 280 TRAVERTINE. tufaceous limestone, cellular and porous, and exhibit- ing in section lines of wavy lamination. When first extracted from the quarry it is sufficiently soft to be cut by the saw, but hardens on exposure, and under an Italian sky seems to be almost indestructible. It is laid open in sections along the banks of the great chasm, into which the waters of the Anio precipitate themselves, and shows horizontal beds of alternating tufa and travertine, attaining a thickness of nearly 500 feet. From the days of the Emperor Augustus, who selected it, and white marble from Carrara, for the numerous buildings and restorations undertaken under his auspices, this rock has been largely em- ployed in Roman buildings ; and is still in use. Architectural Illustrations. First, amongst the buildings of ancient Rome constructed of travertine, must be named the Amphitheatrum Flavium, or Colosseum, the largest theatre in the world, capable of seating 87,000 spectators ; founded by Vespasian in the middle of the first century. The exterior of this truly colossal structure was entirely built of traver- tine, and of an elliptical form, consisting of four tiers of arches, the three lowest being embellished with half columns of Doric, Ionic, and Corinthian orders. The interior was almost entirely formed of brick- work. During the i5th and i6th centuries the Colosseum was regarded, and treated, as a sort of quarry, from which materials were obtained for the TRAVERTINE. 281 construction of more recent edifices. Here Paul II procured materials for the Palazzo di S. Marco in Venice ; Cardinal Rlario for the Cancelleria ; and Paul III for the Palazzo Farnese. 1 Subsequent popes, however, have come to the rescue of the structure, and averted the fate which their predecessors had intended for it, by building massive buttresses at either end of the portion of the uppermost story which still remains. 2 Of modern structures in Borne built of travertine are the external walls of nearly all the churches, in- cluding St. Peter's, together with the grand colon- nades of Bernini, which partially enclose the Piazza. Of similar stone are built the palaces and public, as well as private, buildings of Home, including the Museum and Church of the Lateran, the Castle of St. Angelo, the Quirinal, and portions of the walls of the city, in which however brick was most gene- rally employed. The building stone of Naples is a species of calca- reous tuff, or travertine, from the vicinity, formed, in all probability, by the deposition of volcanic mate- rials over the former bed of the sea. It is scarcely equal in quality to that of Kome, being rather softer, 1 Bsediker, Central Italy, p. 177. 2 That travertine was used from very early times in ancient Rome is shown by the Arch of the Cloaca Maxima, which is partly formed of it. 282 TRAVERTINE. and of a yellowish-brown colour. Of this stone the colonnade of the Piazza del Plebiscite is formed. For the more exposed and stronger kinds of masonry grey lava from the base of Vesuvius is used in Naples. Amongst the most ancient cities of Southern Italy travertine has been in use. Thus we find it occa- sionally amongst the ruins of Pompeii, where it was used for corner stones and pillars to houses built of concrete. The walls and columns of Paestum, con- structed of a similar material, are still in a remarkable state of preservation. From the manner in which the buildings and monuments of Italy, formed of calcareous materials, have retained to a wonderful degree the sharpness of their original sculpturing, unless disfigured by the hand of man, it is clear that a dry and smokeless atmosphere is the essential element of durability. In this respect, therefore, the humid sky and gaseous air of British towns must always place the buildings of this country at a comparative disadvantage as regards durability. CHAPTER II. / VOLCANIC TUFF, OR PEPEEINO. THIS material, formed of lapilli and ashes ejected from modern volcanoes, and bound together by various cements, such as carbonate of lime and silica, has been occasionally employed in France and Italy as a building material for structures of secondary importance. It is very light, of a specific gravity of 1.22-1.95, an( i consequently adapted for vaults or small arches. It is found abundantly in the volcanic district of Central France, and in the Haute-Loire has been used in the construction of churches and dwelling- houses. The Peperino of the Campagna of Home and Naples is a volcanic tuff, which has been used in some of the less important buildings of those cities ; and it has also been used in the houses of Hercu- laneum and Pompeii. Varieties of tuff from Monte Verdi have been quarried and used at Rome to some extent. 1 LATEEITE OF INDIA. This is a peculiar formation, 1 Specimens presented by Mr. W. W. Smyth, F.R.S., are deposited in the Museum of Practical Geology. 284 VOLCANIC TUFF, OB PEPERINO. occupying large portions of the plains of Madras and Bengal. It appears to be an ancient alluvial forma- tion of gravel and conglomerate, cemented more or less by a ferruginous paste ; and in the Madras Pre- sidency Mr. Bruce Foot, of the Geological Survey, found it to contain works of human art, in the form of flint implements. In Midnapore and Orissa, as well as at Tanjore and Trichinopoly, it has been employed for building purposes from early times ; having been used in the construction of temples and other ancient structures as well as dwellings. When first taken from its bed it is very soft, but hardens on exposure, and is very durable. 1 1 Mr. Blandford, Mem. Geol. Survey of India, vols. i. and iv. PART XIII. KOOFING SLATE, OHAPTEK I. CLAY-SLATE. Gemeiner Thonschiefer (Germ) ; schiste argileux commun (Fr.). CLAY -SLATE is a sedimentary argillaceous rock, generally compact and fine-grained, of colours vary- ing from grey to purple, green, and even black, and splitting along planes of cleavage which only ac- cidentally coincide with those of bedding. These slates are chiefly used for roofing houses and public buildings, and are valuable in proportion to their compactness and durability, the smoothness of the surface which they present, their uniformity of colour, and incapacity for absorbing water. Cleavage. The phenomena of cleavage have en- gaged the attention of physical geologists, both in our own country and abroad, and especial light has been shed on its origin by the observations of Mr. D. Sharpe 1 and Mr. Sorby, 2 who, having subjected cleaved 1 Journ. Geol. Soc. Lond. iii. 74, and v. 3. 2 Edinb. New Phil. Journ. iv. 137 (1853). 286 CLAY -SLATE. rocks to microscopical examination, found that the component particles had undergone elongation and a certain degree of re-arrangement, which is obvious to every one who has examined cleaved fossiliferous strata, and which can only be attributed to me- chanical pressure. Mr. Charles Darwin has observed, with reference to the relations of cleavage to foliation, that in the Andes the dip and strike planes coincide, and has concluded that the latter may be the extreme result of the process of which cleavage is the first effect. 1 Professor Ramsay, after having observed these phenomena in North Wales and Anglesea, showed that in this latter country cleavage had followed metamorphic action, resulting in foliation, and that there is, therefore, no necessary connection between them ; * but that if rocks be uncleaved when meta- morphism occurs, the foliation-planes will be apt to coincide with those of bedding ; and that if intense cleavage has preceded, we may expect that the planes of foliation will lie in the planes of cleavage/ 2 The mechanical theory of cleavage, as illustrated 1 Geology of South America. An excellent summary of the views of Sedgwick, Herschel, Phillips, &c. will be found in Lyell's Elements of Geology. 2 Journ. Geol. Soc. Lond. ix. 172. Mr. G. H. Kinahan, of the Geol. Survey of Ireland, from an examination of the foliated rocks in Galway, seems to have arrived at similar conclusions. Expla- natory Memoir on sheets 105, 114 (Galway). CLAY- SLATE. 287 by Professor Phillips, Mr. D. Sharpe, and Mr. Sorby, is that which is now generally adopted by geologists ; and is one which seems to explain most readily the various appearances connected with the presence of cleavage itself. According to this view, the terrestial forces acting in a lateral direction have not only contorted the beds, but by changing the dimensions of the rocks have so re-arranged the laminae or particles, as to cause a very great majority to He in a plane perpendicular to the direction of the forces themselves. Geological Formations. As far as the British Isles are concerned, cleaved slates are confined to the Palaeozoic formations, from the Cambrian down to the Carboniferous inclusive. On the Continent, how- ever, it is otherwise; and both in the Pyrenees, the Alps and Apennines strata belonging to the Mesozoic and even Tertiary periods present the phenomenon of cleavage, which is altogether independent of geological age. It seems probable, however, that unless a great resistance due to the weight of large masses of strata has been offered to the forces acting in a lateral direction, the result will be not cleavage but simply crumpling or contortion of the strata ; and from this it follows, that the older rocks are generally those in which cleavage has been developed, and that we may suppose that enormous masses of material have been removed from off the surfaces of those districts 288 CLAY-SLATE. in which cleaved rocks are to be found. 1 We may therefore infer, that the Lower Silurian rocks of North Wales, the Devonian and Carboniferous slates of Devon and Cornwall, and those of the Lower Car- boniferous age of the South of Ireland have been subjected to denudation on a large scale. Results of Cleavage on the structure of the Rocks. The direction of the planes of cleavage is indepen- dent of that of the planes of bedding ; and we, there- fore, have these planes intersecting each other at various angles, or accidentally coinciding. In general, however, the tendency of the rock to split along the planes of cleavage predominates, so that a slab of slate is equally strong throughout, though crossing several divisional layers of original stratification. This is the case in all good roofing slates, in which we may frequently observe the layers of bedding crossing the surface in a series of parallel bands indi- cated by faint shades of colour, or slight differences of texture. At the same time, it has been fre- quently observed, that amongst strata composed of various materials, such as sandstone and slate in alternate bands, the cleavage planes take different directions in the different beds, depending on the amount of resistance the materials have been able to offer to the lateral forces. 1 Professor Ramsay, Descrip. Catalogue of Rock Specimens M. P.G. p. 122 (1858). CLAY- SLATE. 289 Uses of Slate. It is scarcely necessary to attempt an enumeration o the uses to which slate, such as that of North Wales, is applicable. The superiority both in durability, and especially in regard to light- ness (or less weight), of Welsh slate for roofing pur- poses, has caused it to supersede, since the introduc- tion of canals and railways, those bedded fissile tile- stones (sometimes erroneously called /slates') which were in use in many parts of the country, and which were derived from the Upper Silurian, the Carbonife- rous, and the Oolitic formations. 1 But while in some respects this has been an advantage, it has been otherwise as regards architectural taste ; for while the heavy tilestones were employed, high pitched roofs were a necessary consequence, but the introduc- tion of the Welsh slates has been generally accom- panied by the construction of flattened roofs ; an alteration certainly not in the direction of architec- tural beauty. Besides its use as a roofing material, slate is very properly applied to the construction of cisterns for holding water, thus doing away with the objectionable use of lead for such purposes. It is also used for ornamental structures, and as a substitute for marble ; but although it is capable of receiving a fair polish, 1 Viz., the tilestones of the Upper Ludlow, the thin flags, or tiles, of the Millstone or Yoredale series, and the Stonesfield and Collyweston slates of Gloucestershire, Oxfordshire, &c. U 290 CLAY- SLATE. its density and absence of crystalline structure are obvious, and it is very inferior in beauty to true marble, which is properly a crystalline carbonate of lime ; in fine, the use of slate as an imitation marble is very much to be deprecated, as long as we have abundance of genuine marbles at our command. OHAPTEE II. SLATES OF GKEAT BEITAIN. SLATE is one of the most dense of stratified sedi- mentary rocks, one cubic foot weighing from 170 to 1 80 Ibs. per cubic foot. Mr. Wilkinson found that one cubic inch of Killaloe slate required in one case as much as 30,730 Ibs. in order to crush it; but the average crushing weight was considerably less, say about 20,000 Ibs. 1 The transverse strength of Welsh slate is greater than that of any other mineral product of the stone-kind ; and for such qualities as strength, space, and cleanliness, no other material is superior to slate. 2 The following analysis of an average sample of Welsh roofing slate, serves to show, that as compared with the composition of granite, it contains less silica, and, on the other hand, more alumina. Analysis of Welsh Roofing Slate. 100 parts. Percentage. Oxygen. Silica 60.50 32.27 Alumina 19-7 9- A 9 Iron (protoxide) 7.83 1.74 Lime 1.12 0.32 Magnesia 2.20 0.88 Potash 3.18 0.54 Soda 2.20 0.57 Water 3.30 2.71 100.03 48.22 1 Practical Geology of Ireland. Table of Experiments. 2 Gwilt, Encyc. Arch. p. 522. U 2 292 SLATES OF GREAT BRITAIN. The finest roofing slates in Britain, perhaps in the world, are obtained from North Wales, and are de- rived from three formations : First : The Cambrian, producing generally green and purple slates. Second : The Llandeilo beds of the Lower Silurian, producing generally black, or dark, slates. Third : The Caradoc, or Bala beds of the same period, producing generally pale-grey slates. (a) Cambrian Slates. These are quarried in im- mense excavations at Llanberris Pass and vicinity, following the northern outcrop of the strata from the flanks of the Snowden range in a N.N.E. direction. The Penrhyn quarries are worked in successive ter- races in the form of an amphitheatre ; the rock is detached in immense masses by blasting, and is then sorted and cut to the various sizes suitable for the market. From the quarries in this neighbourhood the demands of London and the northern towns are supplied, while large quantities are exported to Scot- land, Ireland, and even America. 1 (b) Lower Silurian Slates. These are quarried near Ffestiniog, and shipped at Portmadoc; also at Machynlleth, Aberdovey, Barry Island, Dol- wyddelan, and at Llangollen. These last named 1 See account of these slate rocks by Professor Sedgwick, Journ. Geol. Soc. Lond. iii. 540, and iv. 213. Also Prof. Ramsay, 'On the Geol. of North Wales,' Mem. of Geol. Survey, p. 155. SLATES OF GREAT BRITAIN. 293 quarries are remarkable for the size of the slates they are capable of producing ; a slab from the quarry of the Llangollen Slate Company having been sent to the International Exhibition of 1862 which was 20 feet long, 10 feet wide, and weighed 4^ tons. The Welsh Slate Company, whose quarries are at Ffestiniog, sent several slabs, averaging 14 feet by 7 or 8 feet. All the slate from this neigh- bourhood possesses the remarkable quality of splitting with great facility, and with wonderful accuracy of surface, into thin laminae, or sheets. Some of these thinly divided sheets are obtained 5 to 10 feet long, and from 6 to 1 2 inches wide, and not more than the 1 6 th of an inch in thickness ; they are so elastic that they bend like a veneer of wood. 1 Amongst the numerous slate quarries of North Wales, worthy of especial notice may be mentioned the ' Dorothea West/ in Carnarvonshire, supplying green, blue, and red slates ; those of the ' Llanfair Green and Blue Slate Company/ and the ' Eoyal Slate Company/ near Bangor. The following is a list of the Slate Quarries of Wales in the year i86o 2 : 1 Mr. R. Hunt, Handbook to Exhibition of 1862. 2 From Mr. R. Hunt's Mineral Statistics for 1858, part ii. (1860). 294 SLATES OF GREAT BRITAIN. Name of Quarry. Nearest Railway Station or Shipping Port. Name of Stone. Buildings in which used, and Purposes to which applied, and Remarks. RADNORSHIRE. Abbey-cwm-hir | Rhayader | Slate. CAERMARTHENSHIRE AND PEMBROKESHIRE. Pontarllechan | Llangodog | Slate | Building stone. MONTGOMERYSHIRE. Llanervnosr . . Slate Tuno or Braichgoch . . Tvn-v-berth . Machynlleth Blue slate .. Roofing slates. MERIONETHSHIRE . BraichDhu Braich Goch CemCam Craig Dhu, Ffestiniog Maen-Twrog .... Tal-y-llyn Barmouth River. . Slate and slab Slate Slate and slab Blue slate .. Slate DifiVys ii Ffestiniog Four more quarries of the same name .... Hollands Slate and slab II t! II II II II II 91 Blue slate .. Slate and slab rHSHIRE. Slate Rhiwbach ii ...... Tvn v-Oopd "Vnttv Portmadoc DENBIG Llangollen Roofing slate and large slabs. Roofing slates. Greenish, very durable slate. Roofing slates. Roofing slates and slabs. > Roofing slate, slabs, &c. Roofing slates. Roofing slates and slabs. Roofing slates. Roofing slates and slabs. Roofing slate. Roofing slates and slabs. SLATES OF GREAT BRITAIN. 295 Name of Quarry. Nearest Railway Station or Shipping Port. Name of Stone. Buildings in which used, and Purposes to which applied, and Remarks. CARNARVONSHIRE. Bangor . Bangor Slate "R fi 1 ^ 1 Vv Braichrhydd Bwlch-y-Gwes " Cofn-du " Cilgwyn ' " " Cloddfar L6n Cwm Eigia .... Tal-y-Cafh " Dinorwic " Dorothea " )) It Hafodlas MoelTryfan Trefriw & Conway Slate and slab Slate i Talysarn Vron . (c) Cornwall. The Delabole quarries, from strata belonging to the Devonian formation, have been worked for a long period. The colour of the slates is grey or blue, and they are shipped from Tintagel, and Boscastle. The Wellington College at Sand- hurst is roofed with Delabole slate. 1 The Tavistock slates from Devonshire were once in much demand ; 1 De la Beche, Geological Rep. of Devon and Cornwall, p. 502 296 SLATES OF GREAT BRITAIN. there. are also quarries at Ingsdon, near Bickington ; East Down, between Ogwell and Ashburton; at Bow, near Staverton; at Tigley and Moor, near Battery; and at Cann Quarry, near Boringdon Park. (d) Lake District. 'Westmoreland Slate/ from the Upper Silurian rocks of the neighbourhood of Kendal, of a pale blue and green colour, is much esteemed ; similar slates are also quarried at Ulver- stone in North Lancashire. 1 From the Lower Silurian rocks of Skiddaw, sea-green slates are extracted, and shipped from Maryport. (e) Scotland. Owing to the metamorphic condi- tion of the Lower Silurian rocks of the Scottish Highlands, they are rarely capable of producing good slates for roofing purposes. The most important quarries are those of Ballachulish in Inverness-shire, and from which from five to seven millions of slates are annually extracted, 2 the weight of which may be estimated at 10,000 tons. The refuse, amounting to five or six times this quantity, is thrown directly into the sea. 3 Slates are also worked at Benledi and Birnam, in Perthshire. The latter quarries yielding about 300,000 roofing slates yearly ; also at Craiglea and Drumahern, near Perth ; at Dalbeattie, near Dun- keld ; at Glenalmond and Laurick, near Crieff ; and 1 Gwilt, Encyc. Arch. p. 522. 2 Ibid. * Ibid. SLATES OF GREAT BRITAIN. 297 at Tully beagles near Tynedrum. In Forfarshire, slates are also worked at Hoyston and Turin, near Forfar; and in Aberdeenshire at Fondland, near Aboyne ; and at G-artley and Troup Head, near Inverary. 1 (f) Ireland. The principal quarries are those of Killaloe, Co. Tipperary ; Valencia, Co. Kerry ; Ben- duff, near G-landore Harbour, Co. Cork ; those near Carrick-on-Suir ; also Ashford Bridge, and Rathdrum, Co. Wicklow. The Killaloe slate quarries are situated at Cor- bally, and are worked in strata belonging to the Lower Silurian rocks. 2 These quarries lay open a vertical section of over 350 feet, and produce slates from ten feet square downwards, of a dull bluish - grey colour, and of good quality, though somewhat rough. The slates of Valencia, from the Devonian series, somewhat resemble those of Killaloe, but have a greener tinge. Mr. Wilkinson states that they are also inferior in quality to those of Killaloe, being thicker, and splitting with a less even surface ; but from this locality flagstones for cisterns, baths, &c., are largely exported to England. There are also 1 Mr. R. Hunt, Mineral Statistics, part ii. 1858. 2 See Map of the Geol. Survey, sheet 134, with Explanation, by Messrs. Kinahan and Wynne, Mem. Geol. Survey, p. 25 (1861). Also Kane's Industrial Resources, p. 230. 298 SLATES OF GREAT BRITAIN. quarries in the Lower Carboniferous slate of the south-east of Co. Cork at Clonakilty, and at the Old Head of Kinsale, yielding roofing slate of a good quality, exceedingly light and durable. 1 The slates of Ashford Bridge resemble those of Bangor in Wales, 2 while those of the Victoria Slate Company, near Carrick-on-Suir, are not unlike those of Keswick or Penrhyn, being smooth, of a light green colour, and of excellent quality. It is not improbable that the West and South of Ireland may be found capable of yielding far larger quantities of this valuable commodity than hitherto ; but which, for want of capital and perseverance, have not been rendered available. Amongst the Lower Silurian rocks north of Hillary harbour, and along the valleys of the Erriff and Doo Lough, in Co. Mayo, are certain beds, which, if opened up at sufficient depth, might be found to produce excellent pale-grey or bluish roofing slate ; and to this district I ven- ture to direct the attention of capitalists. 1 Kane's Industrial Resources, p. 231. 2 Mr. Wilkinson has experimented on varieties of micaceous, talcose, and chloritic schists from Donegal, which cannot, however, properly be included amongst ordinary roofing slates. CHAPTER III. SLATE ROCKS OF THE CONTINENT. Schistes Ardoisieres (Fr.). France. Roofing slate is obtained at several localities in France ; but the two principal centres of quarrying are Angers, Poligny, &c., in the De- partment of Maine-et-Loire, and the Ardennes on the north-eastern borders of the country. The quarries of Angers have been worked from very ancient times ; the slate is of a blue or dark-blue colour, and is extracted both in open work and in subterranean galleries ; it is also of good quality. It has afforded fossils which have enabled MM. E. de Beaumont and Dufrenoy to refer its age to that of the Llandeilo formation (Lower Silurian) of Britain. 1 The schistose rocks of the Ardennes, on the other hand, have been determined by Professor Sedgwick and Sir R. Murchison to belong to the Devonian system. 2 They are very largely quarried in some places, particularly at Rimogne, Fumay, and Deville. Slates are also obtained in the departments of La Sarthe, Mayenne, Finisterre, Calvados, and Les Landes. 3 Belgium, &c. The slates of Luxembourg belong to 1 Murchison's Siluria, 3rd edit. ch. xv. 2 Trans. Geol. Soc. Lond. vol. vi. 3 Chateau, ii. 268. 300 SLATE ROCKS OF THE CONTINENT. the same geological series as those of the Ardennes. They are extracted in large quantities, and used both in Belgium and France, the chief localities being those of Geripont, Herbeumont, Bertrix near Neufchateux. According to M. Chateau, the slates of Luxembourg are inferior in quality to those of the Ardennes. 1 Germany. Roofing slates are obtained from the Devonian and other formations of Nassau, Wiirtem- berg, and Westphalia. Austria and South Germany. Slates are obtained from the older Palaeozoic formations of Moravia and Silesia extending throughout an extensive tract of country, the chief seat of the industry being Walters- dorf, near Olmiitz. The slates vary from grey to blue and black, and are receptive of a good polish, on which account they are not only employed for flagging and roofing purposes, but also for tables, boxes, and cisterns. Italy. The Liassic strata of some portions of the Apennines have undergone metamorphism to such an extent, especially in that part known as the ' Apuan Alps/ that they have assumed the outward character of Palaeozoic rocks. In this manner we find roofing slates extensively quarried at Cardosa, in the valley of the Vezza, above Seravezza in Tuscany, and at Lavagna and Chiavari, not far from Genoa, the latter being most esteemed. In the capital of 1 Chateau, ii. 279. SLATE ROCKS OF THE CONTINENT. 301 Tuscany, however, red artificial tiles are almost ex- clusively in use for roofing purposes ; except in the case of the beauteous cathedral, the roof of which is formed of thin slabs of marble. Savoy possesses beds of roofing slate, but of little importance, and difficult to work and transport. The chief quarries are those of Cevins, in Haut-Savoie, and those of Bellecombe in Tarentaise. These slates are probably referable to the Liasso- Jurassic series. Sweden and Norway. Slate quarrying has not until recently been extensively carried on ; and it is only since 1850 that the use of slates has become pretty general. In 1855, there existed only four quarries in Sweden : l 1. That of Glava, in Vermland, which is the oldest ; 2. That of Gyfkihlen, near Gothemburg ; 3. That of Halla, in Vermland and Dahlsland ; 4. That of Kjellsvik, in Dahlsland. The three first produce slates generally thick ; that of Kjellsvik, on the other hand, is sufficiently im- portant, giving, in 1855, employment to 400 work- men. The slates from this quarry (situated near Lake Wener, or Wenern) are fine-grained, l 10 / 127 ja Q Hawkswortli ^Vood Leeds Linlithgowshire .... 1 o7 *4 13 jog 2 rt Roche A.bbey Bawtry Yorkshire Ancaster Sleaford Lincolnshire . *39 2 S Re derate 'Wolsingham. Durham . . *39 4 13 Yorkshire X 39 9 9 Scullcap Portland . . Dorsetshire J oy *4 o Humbie light Edinburgh 1 4^ I o Stanley Bewdley Shropshire . *4 3 o Catcraig Borrowstounness 141 7 O Wass soft .... Thirsk I4 1 ii o Edinburgh . . . . Edinburgh 141 ii i 1A.I 12 n Ham Hill Yeovil Somersetshire . * Bramley Fall Leeds .... Yorkshire . Barnard Castle 1 4* 3 o Hookstone Harrowgate 142 5 Weetwood Leeds 1A1 ft O Giffneuk Glasgow . . . . . Lanarkshire Anston, Norfall Quarry . . South Anston . . Yorkshire X 43 X 4 13 Anston, Stone-ends Quarry 144 o 9 1 .1.1 5 8 Duke's Quarries Cromf ord A 44 6 Newcastle-on-Tyne X 44 o 5 Victoria Leeds 145 i o Curf, Groove Quarry, Port- land W ey mouth A 45 3 Mansfield I 45 9 9 Craigleith, liver rock Edinburgh .... 145 12 4 Gun Barrel Bewdley 1 45 J 4 5 Mansfield, white Mansfield .... Corby Corby Chepstow New Leeds Yorkshire 146 12 5 TA 1 ? 8 n W^eymouth . i4/ o o Darley Dale Bakewell . IjQ /; 9 Warwick Huddersfield 4 3 3 T/l8 Tr> ft Mansfield, red Mansfield Amygdaloid Crediton Talacre Holy well .. *49 9 5 1^0 A A 320 APPENDIX. Name of Quarry. Nearest Post Town. County. Avoirdupois Weight per Cubic Foot. Purbeck Dorsetshire Ibs. oz. dr. 151 o 4. Leeds Yorkshire 151 I 12 Chilmark Trough Bed .... Wiltshire 151 6 12 Hoyle House Clough .... Huddersfield 151 7 I Chilmark, Penney Bed .... Wiltshire iej. n e Bolsover Moor . . Chesterfield Derbyshire . . .... 151 n o Ellaiid Edge Halifax Yorkshire . jca A Q Huddersfield 153 7 o Crossland Hill T f C A T Ketton Rag Bed TCpttrvn Rutlan d shire I5C jo 1 3 Yiney Hill Coleford Gloucestershire .... 155 II 12 ChiLtnark Hard White Bed Wiltshire 157 6 o Scotgate Head Huddersfield 158 o *o Hopton \Vood .. Derbyshire 158 7 4. Forfarshire 158 ii o 1^8 14. 5 Lioch 150 3 I Knockley Gloucestershire .... 150 5 4- Mylnefield Dundee . 160 o 13 Munlochy . . Munlochy . . . Ross-shire 160 9 ii Forfar Forfarshire 161 2 8 Wass Hard Bed Thirsk .... Yorkshire 162 8 o Pvotdvkes Forfarshire 162 8 13 Granite Sterling Hill .... Peterhead Aberdeenshire .... 165 14 5 Granite, High Eock, 1 66 o Q Glamorganshire .... 166 3 12 Kentish Rag Kent 1 66 o o Black Hill Granite 166 10 4 Monmouthshire . 167 i J> 168 i o 168 2 8 Dublin Dublin 1 60 7 Granite Bars Breadalbane Perthshire 160 ii *> Cenfas Swansea . ... Glamorganshire I7O 2 4 I7O 7 o Black Marble Kilkenny Ireland 171 6 o Tiree Marble . . Hebrides. . , Scotland .. 172 .5 o INDEX, ABERDEEN, granite of, 3. - city of, 33. Acropolis, of Athens, 139. Agate, 176. Agglomerate, composition of, 1 1 . Agosta, sandstone quarries of, 274. Aillemore, granite of, 42. Aislaby quarry, 258. Aix-la-Chapelle, sandstone of, 273. Alabaster, 160. composition of, 16, 159. sculpturing in, 165. Albert Memorial, Hyde Park, 45. Alhambra, stone used in, 109, 142. Alie Hills, serpentine of, 104. Alps, granite of the, 24, 49. serpentine of the, 105. Alston, in Cumberland, fluor-spar of, 170. gypsum of, 162. Amazon of the Vatican, statue of, 154- America, fluor-spar of, 171. granites of, 57. gypsum of, 167. Amethyst, 175. Amiens Cathedral, 234. Analysis (chemical) of dolomite, 201. Analysis of granites, 28. of greenstones, 82. of basalts, 89. of oolitic limestone, 2 1 o, 2 1 3. of serpentines, 100. of Carrara marble, 1 30. of Welsh roofing slate, 291. of sandstones, 240. Ancaster stone, 211. Andernach, lava of, 95. Anglesea, serpentine of, 102. marble of, 120. Anhydrite, 160, 161. Ansted, Professor, on granite, 30. Anston quarries, 200. Apollo Belvedere, statue of, 129, 157- Arbroath sandstone, 261, 262. Ardmore, quarries at, 267. Armagh, variegated marble of, 122. Arran, granite of, 33. Arranmore Island, granite of, 40, 46. Arthur's Seat, trap rocks of, 70. Athens, quarries of marble near, 137, 139- Augitic rocks, 85. Aurelius, marble column of, 129. Australia, malachite of, 189. 322 INDEX. Auvergne, fluor-spar of, 171. granitic plateau, 47. basaltic rocks of, 89. architectural features of, 47. gypsum of, 164. Avallon, granite of, 47. Aventurine, 179. vase of, 185. BAKEWELL EDGE quarry, 247. Church, 248. Ballachulish slate quarries, 296. Ballyknockan, granite of, 43. Ballymoney Castle, 267. ' Barberini Faun/ the, 138. Bardiglio marble, 131, 141. Bardon Hill, rocks of, 81. Barford, granite of, 58. Barnac, stone of, 210. Barnard Castle, stone of, 251. Barnston, granite quarries of, 57. Barton, Cornwall, porphyry of, 69. Basalt, composition of, 9. mode of occurrence, 85. sheets of North of Ireland, 88. art illustrations of use, 90. uses of, 91. Basses lighthouse, stone used in, 37- Bath, Abbey Church, 209. oolite, 206, 207. quarries in, 209. Bathampton quarries, 209. Baveno, granite of, 29, 47. where used in buildings, 48. Belfast, stone used at, 270. Belfay, France, melaphyre of, 91. Belgium, marbles of, 141. carboniferous limestone of, 225. Belleek, orthoclase granite of, 46. Belton quarry, 255. Belvoir Castle, stone used in, 2 1 1 . Bengal, sandstones of, 276. Bex, anhydrite of, 160, 161. Bidston Hill quarry, 255. Binnie quarry, 264. Birkenhead Docks, granite used .in, 33, 3 6 - Birmingham Grammar School, >24 8. Birnam slate quarries, 296. Bischof, Mr., on the origin of ser- pentine, 99. on fluor-spar, 172. on limestones, 192. Bishop Briggs quarry, 264. Blackenstone, granite of, 35. Blackfriars Bridge, stone used in, 215. Blackstairs mountain, granite of, 29. Blandford, Mr., on age of basalts of India, 90. on laterite of India, 284. Blanford, Mr. W. F., on sandstones of India, 276. Blenheim Palace, stone used in, 208. Blessington, granite of, 43. Bodmin, sandstone of, 245. Bolsover, magnesian limestone of, 200, 201. Bolton-le-Moors, stone used in, 246. Bolton's quarry, Aislaby, 248. Boston (America) granite build- ings of, 57. (England) church, stone used in, 211. Box, analysis of stone from, 210. Breccia, composition of, 13. Breccia di Verde, 148. Bristow, Mr., on the use of Pur- beck marble, 118. British Museum, objects of art in, 150. Brittany, porphyritic granite of, 47- Brixen, granite of, 49. Brussels, city of, 234. INDEX. 323 Bryce, Dr. J., on porphyry of Arran, 67. Buckingham Palace, 231. Building stones, physical charac- ters of, 304. chemical characters of, 309. Bunsen, on classification of rocks, 5- Bunter sandstone, 252. Burdie House limestone, 223. Burford, oolitic freestone of, 208. Burnell, Mr., on building stone, 262. CADEE IDEIS, columnar green- stone of, 8 1. Caen stone, 225, 228. use in England, 230. use in Ireland, 230. Cairngorm stone, 174. Caithness flags, 262. Calcareous rocks, 14. Calder Abbey, 252. Calverley quarry, 259. Canada, basalt of, 90. granite of, 57. gypsum of, 167. jasper of, 178. marbles of, 145. sandstones of, 277. slates of, 302. syenite of, 61. Canary Islands, volcanic rocks of, 90. Carboniferous limestones, 195, 219. sandstones, 238, 245, 263, 267. Carlingford, granite of, 45. syenite of, 60, 61. Carlow flags, 269. Carlton Club House, London, 32. Carpathians, granite of, 28, 49. Carrara, marble quarries of, 126. Carrickfergus, gypsum of, 163. Carrickmacross, gypsum of, 163. Y Castle Kuthen, stone used in, 120. Castlewellan, granite of, 45. Casterton quarries, 210. Castor and Pollux, temple of, 1 39. Cat Craig quarry, 264. Cellini ewer, 184. Chalcedony, 175. Chalk, composition of, 15, 217. of England, 217. of Ireland, 222. - of France, 231. chalcedony from, 176. Channel Islands, granite of, 37. Chantrey, tomb of, 130. Chatham, granite used at, 36. Chatsworth, 247. Chellaston, gypsum of, 162. Chelmsford granite, 57. Cheesewring, granite of, 35. where used, 37. Cheltenham, oolitic limestone of, 205, 206. Chepstow, sandstone of, 245. - Castle, 245. Chester, City of, 2. Cathedral of, 255. Chichester Cathedral, stone used in, 119. Churchtown, Co. Cork, marble of, 122. Clay-slate, 285, 287. geological age of, 287, 292. economic uses of, 289. of Wales, 292, of Cornwall, 295. of Lake District, 296. of Scotland, 296. of Ireland, 297. of France, 299. of Belgium, 299. of Italy, 300. - of Sweden and Norway, 301. Cleavage in slate, 285, 288. Cleopatra's Needle, granite of, 56. Clifden, Connemara, graphic gran- ite of, 30. 324 INDEX. Coal-measure sandstone, 247. Cologne Cathedral, 272. Colosseum, at Rome, 280. Colton quarry, 255. Colwich quarry, 255. Compact limestone, 15. Conglomerate, 13. Connecticut, granite of, 57. Connemara serpentine, 102. Constantine, Arch of, 129. Coralline oolite, 206, 211. Cornegie, granite of, 33. Cornwall, fluor-spar of, 170. granites of, 35. porphyries of, 67. slates of, 295. Corsican porphyry, 74. serpentine, 106. marble, 141. Cotta, B. von, on the origin of serpentine, 99. on the origin of gypsum, 160. Cottanello marble, 132. Cotteswold Hills, limestone of, 206. Craigleith quarry, 264. Crawbank quarry, 264. Cronstadt Palace, granite of, 50. Crump wood quarry, 255. Cumberland, minettes of, 84. slate of, 296. Custom House, London, stone used in, 215. Dublin, stone used in, 216. DALKEY GRANITE, 43. Dalmore, granite of, 34. Daniell, Prof., on dolomite, 203. Darley Dale quarry, 250. Dartmoor, granite of, 26, 35. Darwin, Mr. C., on cleavage and foliation, 286. Delabole slate quarries, 295. De la Beche, Sir H., on Cornish porphyries, 69. on Cornish serpentines, 100. Delesse, Prof., on French por- phyries, 73. on Grecian porphyry, 73. on serpentine, 99. Derby Town Hall, 256. Derbyshire, marbles of, 119. fluor-spar of, 169, 171. Devonshire, marbles of, 116. sandstones of, 245. Diabase, composition of, 8, 80, 82. Diallage-rock, 12. Diorite, composition of, 9, 80. Dolerite, composition of, 9, 85, 86. of Fair Head, Antrim, 88. Dolomite, composition, 16, 201. Donard, Slieve, granite of, 44. Donegal, Co., analysis of syenite of, 61. crystalline limestones of, 123. granite of, 26, 29. serpentine of, 103. Doochary Bridge, granite of, 29, 40.^ Doulting, oolitic limestone of, 209. Drayton Manor, 256. Dresdner Falsterstein, syenite of, 61. Droitwich, gypsum of, 161. Dublin, stone used in the buildings of, 43> 213, 215. Christ Church Cathedral, stone used in, 209. Dufneld quarry, 248. Dundry Hill, stone of, 209. Dunmore quarry, 265. Du Noyer, Mr. G. V., on Killiney granite, 44. Durham, magnesian limestone of, 198. Durocher, on classification of rocks, 5. Dykes of basalt, 87. EDINBURGH, stone used in, 261, 263, 264. INDEX 325 Egypt, granite of, 29, 51. red porphyry of, 75. serpentine of, 109. marbles of, 148. Elba, granite of, 48. white marble of, 130. Elfdahlen, porphyries of, 72. Elgin marbles, 155. Elland Edge quarry, 248. Ely Cathedral, stone used in, 210. Eozonal serpentine, in. Erechtheum, the, 139. Euphotide. 108. Eurite, 7. FARNESE BULL, statue of, 1 4 1 , 1 58. Hercules, statue of, 215. Felspathic ash, 10. Felstone, 8. porphyry, 8, 64. Ffestiniog slate quarries, 292. Finland, granite of, 49, 51. Fishmongers' Hall, granite pillars of, 32. Flagstone, 14, 246. Florence, building stones of, 107, 274. works of art in, 184, 190. fluor-spar, 169, 171. Fontainebleau, sandstone of, 271. Foot, Mr. B., on laterite of India, 284. Forum Romanum, 139, 144. Fox Rock, granite of, 28, 42. Fragmental volcanic rocks, 10. France, granites of, 47. gypsum of, 163. Jurassic limestones of, 225. porphyries of, 73. serpentines of, 106. marbles of, 141. limestones of, 224, 226. sandstones of, 271. Freemasons' Hall, New, stones used in, 117. Fremator, granite of, 35. Fuchs, on chalcedony, 175. Fulford quarry, 256. Furness Abbey, 252. GrABBRO, 82. Gages, Mr. A., on onyx marble, 149- Gallery of the Uflizi, works of art in the, 91. Gal way, granites of, 41. black marble of, 121. Gannister beds, 246. Garvary Wood, granite of, 41. Gatherly Moor quarry, 248. Geikie, Prof. A., on Scotch por- phyries, 67. on rocks of Salisbury Crags, 70. on age of basaltic dykes, 87. on Old Red Sandstone, 261. Geneva, building stone of, 273. Genoa, serpentine of, 108. Germany, porphyries of, 72. sandstones of, 272. Giant's Causeway, 88. Gibraltar Stone, 143. Giffneuch quarry, 265. Gladiator, statue of the, 157. Glandore, quarries at, 267. Glasgow, stone used in, 263. Glastonbury Abbey, 209. Glencullen, granite of, 43. Gloucester Cathedral, stone used in, 206. Gneiss, composition of, 1 1 . Gothland, granite of, 50. Granite, composition of, 6, 20. foliated, 7, 23. Galway, 23, 24. geological ages of, 24. Donegal, 23, 24, 38. mode of occurrence of, 24. mode of formation of, 25. specific gravity of, 80. varieties of, 22. the proper uses of, 25. 326 INDEX. Granite, veins, origin of, 21. of Syene, composition of, 51. Granulite, 12. Graphic granite, 23. of Schloitzbachthal, 30. Great Oolite, 207. quarries in, 209, 210. Greece, porphyries of, 73. serpentines of, 108. statuary marbles of, 136. Greenstone Ash, 10. Greenstones, 78. Greenwich, granite of, 57. Griffith, Sir K., on Donegal granite, 39, 46. on Carlingford granite, 45. Grinshill quarry, 256. Grug Hill quarry, 256. Guernsey, syenite of, 60. Gypsum, composition of, 16, 159. quarries of, 233. British localities, 161, 162. Gwennap, elvans at, 69. Gwilt, Mr., on Marbles of Isle of Man, 1 20. HABKNESS, Prof., on the Penrith sandstone, 252. Harrock Hill quarry, 248. Harz Mountains, granite of, 49. Haslingden quarry, 249. Haughton, Rev. Dr., on Galway granite, 21. on Aberdeen granite, 33. on Donegal granite, 40, 46. on Peterhead granite, 32. on the classes of granite, 25. on the syenite of Donegal, 61. Hawkshaw, Mr. J. C., on Egyptian granite, 53. Haydor, stone from, 211. Headington stone, near Oxford, 212. Heddon quarry, 249. Church, 249. Heidelberg, granite near, 28. Heidelberg, sandstone of, 272. Heliotrope, 177. Helsby quarry, 256. Hercules, torso of, 140. the Farnese, 157. Highlands, granite of, 24. Himalayas, granite of, 38. Hollington quarry, 256. Hornblende-rock, 12. ' Horse-tamers,' statue of the, 155. Houses of Parliament, West- minster, 200. Huddlestone Hall and Church, 202. Humbie quarry, 265. Hunt, Dr. Sterry, on granite veins, 21. Hunt, Mr. R., on Luxillianite, 68. on Cornish serpentine, 101. Hypersthene Eock, 9. IGNEOUS ROCKS, 6. India, granite of, 58. basaltic sheets of, 90. serpentines of, no. sandstones of, 275. lona Marble, 123. Ireland, marbles of, 120. gypsum of, 163. syenite of, 61. porphyries of, 71. minettes in, 83. sandstones of, 266. serpentines of, 102. roofing slate of, 297. Isle of Man, marbles of, 120. Italy, alabaster of, 165. serpentines of, 106. statuary marble of, 126. sandstones of, 273. limestones of, 235. JAMESON, Prof., on porphyry of Blair Athol, 67. Jasper, 176. INDEX. 327 Jasper, varieties of, 177. works of art in, 180. Jersey, syenite of, 60. Jervis, Mr. W. P., on marbles of Italy, 134. Jukes, Prof. J. B., on the forma- tion of limestone, 192. Jurassic formation of England, 205. of France, 226-231. Jurassic limestones, 205. sandstone, 258. KELTON STONE, 210. Kentish Rag, 259. Kenton quarry, 249. Keuper sandstone, 253. range of, 254. Keynham Docks, granite used in, .3 6 ' Kilgobbin, granite of, 43. Kilkenny marble, 121. Killaloe slate quarries, 297. Killarney, marble of, 122. Killin, Perthshire, serpentine of, 104. Killiney granite, 31, 43. schorl in, 30. Kinahan, Mr. G. H., on Gal way granite, 41. Kindrum, granite of, 40. King, Professor, on serpentine, in. Kirkcudbrightshire, granite of, 33. Knockley quarry, 249. Koningsburg Castle, 202. Kynance Cove, serpentine of, 101. LAMBAY PORPHYRY, 71. Lammermuir Hills, porphyries of, 67. Lamorna, granite of, 36. Lancashire towns, stone used in, 246. flagstone, 246. Laocoon, statue of, 140. Lateran Museum, works of art in, 77- Laterite, 282. Lavas, 93. as a building stone, 95. Leckhampton Hill, oolite of, 206. Leeds, stone used in, 246, 249. Lenne-Gebiet, porphyry of the, 73. Lessines, porphyry of, 73. Leucite rock, composition of, 9. Limestone, bored by Pholas, 117. builders of marine, 193. composition and origin, 14, 191. compact, 15, 225. crystalline, 13, 15, 225. Carboniferous, 195, 219. hydraulic, 16, 196. magnesian, 198. of Ireland, 219. of the Continent, 224. Lincoln Cathedral, stone used in, 128, 211. Liskeard, sandstone of, 245. Liverpool Docks, granite of, 33. buildings of, 33. quarries at, 253. Lizard, serpentine of the, 100. Llanberris, slate quarries, 292. Llangollen, slate quarries, 292. Logan, Sir W., on Laurentian serpentine, in. London Bridge, granite used in, 35, 37- Churches, 259. Docks, stone used in, 37. Longridge Fell quarry, 249. Lough Lomond, jasper of, 179. Louvre, the, works of art in, 91, 150, 177, 181. stone used in, 234. Lundy Island, granite of, 38. Luxembourg, sandstone of, 272. Luxor, Obelisk of, 54. Luxullianite, 68. 328 INDEX. Lyell, Sir C., on granite at Land's End, 36. on volcanic rocks of the Canary Islands, 90. on the origin of travertine, 279. MAEN MIDGEE, serpentine of, 101. Magnesian limestone of England, 199. buildings of, 200. Malachite, 187. Mallow, quarries at, 266. Malvern Hills, syenite of, 60. Manchester, stone used in, 246. Manley quarry, 256. Mansfield, magnesian limestone of, 199, 201. Marble, 114. of Anglesea, 120. of Great Britain, 115. of Greece, 136. of Ireland, 120. of Italy, 126. of Isle of Man, 120. of Scotland, 123. Marmolite of Bodoken, 113. M armor Laced, viride, 73. Martyrs 1 Memorial at Oxford, 200. Mayo, diabasic rocks of, 83. Massachusetts, granite of, 57. Meanwood quarry, 250. Medlicott, Mr., on the granite of Shillong, 58. Meineckenberg, granite of, 29. Melaphyre, composition of, 8. geological position of, 8, 70. of Scotland, 70. of Haute Sa6ne, 91. Mica-schist, 12. Milan, Cathedral and buildings of, 48, 134. Mill Hill, Cornwall, granite of, 36. Millstone Grit, building stone from, 245, 267. Minerva, temple of, 154. Minette, composition of, 9, 83. Mittelgebirge, basalt of the, 89. 'Molasse' of Switzerland, 273. Mont Blanc, granite of, 29, 49. Monte Kosa, granite of, 49. Montmartre, gypsum of, 163. Moravia, serpentine of, 105. Mourne mountains, granite of, 22, 26, 29, 44. Moyne, Abbey of, 219. Muckruss Abbey, stone used in, 221. Mull, granite of, 34. basalt of, 88. Murchison, Sir R., on Lesmahagow porphyry, 67. on Carrara marble, 127. on mascigno sandstone, 274. Muschelkalk, 225. Museum of Geology, London, 32, 112, 200. of Naples, works of art in, 90, 141, 150. South Kensington, London, 181. Museums of Florence, 1 50. of Rome, works of art in, 141, 150. Mweelrea Mountain, jasper peb- bles of, 177. NAPLES, building stone of, 281. Napoleonite, 74. Napoleon's tomb, stone used in, 91. National Provincial Bank, stone used in, 116. Neckar, granite of region north of the, 49. Nelson's pillar, Dublin, 43. Nerbudda, granite of, 58. sandstones of, 275. Neva walls, granite of, 50. New Brighton quarry, 256. New Brunswick, granite of, 58. INDEX. 329 Newbold, Lieut., on Egyptian granite, 53. on Egyptian marble, 148. New Hampshire, granite of, 57. New Red Sandstone, 252. New York, granite buildings of, 57. marbles used in, 146. Newfoundland, serpentine of, 112. Nicolett, granite quarries of, 57. Niobe and her children, statues of, 140, 156. Normandy, architectural features of, 47. North America, granite of, 57. Notre Dame de Paris, Cathedral of, 234. Nottingham, magnesian limestone of, 230. Nova Scotia, granite of, 58. syenite of, 62. marbles of, 145. Nummulite limestone, 15. of Italy, 132. of Africa, 236. of Asia, 236. OBAN, granite of, 34. O'Connell's monument, stone used in, 43- Odenwald, granite of, 49. Old Red Sandstone, 238, 239, 244. Ombersley quarry, 256. Onyx, 179. Onyx marble, 149. Oolites of England, 204. of France, 227. Inferior, 206. Oolitic limestone, 15, 204. of Killala Bay, 1 5. Opal, 178. Ophicalcite, 109. Oreton Hill quarry, 257. Oriental alabaster, 150. Oriskany sandstone, 278. Osmotherly quarry, 250. Ottawa, buildings of, 277. Oughterard granite, 41. Overton Scar quarry, 257. Oxford, building stone used at, 208. PACETTI, the sculptor, 138. Paestum, ruined temple of, 153. Painswick, oolitic limestone of, 207. Paisley, quarries near, 265. Palace of the Doges, Venice, 133. Palestine, marbles used in, 151. Pantheon, granite pillars of, 55. Parbold quarry, 250. Parian marble, 137. cement, 168. Paris Basin, limestone of, 233. City of, 234. plaster of, 163. Park quarry, Tixall, 257. Parthenon, the, at Athens, 137, 139. Pavonazetta marble, 144. Peckforton quarry, 257. - Castle, 257. Pelham, granite of, 57. Penmaenmawr stone, 70, 81. Pennant Grit, 247. Penrith sandstone, 251. Penryn, granite of, 36. Pentellic marble, 137. Pentland hills, porphyries of, 67 Peperino, 283. Permian limestone, 198. sandstone, 351. Persepolis, marble used in, 151. Peterborough Cathedral, stone used in, 210. Peterhead, granite of, 32. Peter the Great's Statue, granite of, 51. Phigaleian marbles, the, 155. Phillips, Professor, on slaty- cleavage, 286. Phonolite, composition of, 10. 330 INDEX. Phrygian marble, 143. Piazza of St. Mark, granite columns of, 54. di St. Pietro, pavement of, 95- Pilla, Professor, on Carrara marble, 127. Pisa, Cathedral and buildings of, 48, 131. building stone of, 274, Pitchstone, 10. porphyry, 10. Plymouth breakwater, stone used in, 117. Pompeii, works of arts found in, 77, H4- street pavement of, 95. building stone of, 282, 283. Pompey's Pillar, granite of, 55. Porphyrite, 8, 64, 70. analysis of, 65. Porphyry, origin of the name, 63- analysis of, 64. geological age of, 65. ornamental use of, 77. Portland breakwater, granite used in, 36. limestone, 231, 212. quarries in, 214. Portsoy, granite of, 34. serpentine of, 104. Portugal, marbles of 143. Prato, serpentine of, 107. Preston Town Hall, 250. Propylaea, the, 139. Provincial Bank, Dublin ; granite pillars of, 32. Prussia, Carboniferous limestone of, 234. Purbeck marble, 117. Isle of, gypsum of, 162. Pyramid of Cheops, granite lining Pf, 56. stone used in, 236. Pyrenees, granite of the, 24, 49. QUARTZ-PORPHYRY, 7, 63. Quartz -schist, 12. Quebec group, sandstones, of 277. RAMSAY, Professor, on foliation, 286. Rhine, volcanic rocks of the, 89. Rhode Island, granite of, 57. Rhyolite, 10. Riesengebirge, granite of the, 49. basalt of the, 89. Rock-crystal, 172. foreign sources of, 174. Rocky mountains, granite of, 57. Roman, ancient quarries at Fan- tiscritti, 128. Roman Camp Hill, Scotland; stone of, 223. Rome, building stones of, 279, 281. Rose, Mr. G., on the origin of serpentine, 99. * on the serpentines of the Ural, no. Rose-quartz, 175. Rouen, Cathedral of, 234. Round Towers of Ireland, 220. Ruskin, Mr., on imitation marbles, 115- on statuary marble, 136. Russia, sculpturing in stones, 185. malachite of, 188, 190. SALINS, in the Jura ; gypsum of, 164. Salisbury Crags; basaltic sheets of, 88. Sandstone, 13, 137. colour of, 241. for building, 238. stratification in, 242. Sardinia, granite of, 48. Saxony, minette of, 84. serpentine of, 105. Scandinavia, granite of, 24. Scarborough Pier, 248. INDEX. 331 Schwarzwald, granite of, 49. Scotgate Head quarry, 250. Scotland, granites of, 32. syenite of, 61. porphyries of, 67. minettes of, 85. serpentine of, 104. marbles of, 123. slate quarries in, 296. limestones of, 222. sandstones of, 261. Scott, Mr. K. EL, on Donegal granite, 38, 46. Scrabo Hill, dolerite of, 89. sandstone of, 269. Sculpturing in marble, 136. in ornamental stones, 181. Sedimentary rocks, 13. Selinus; ruined citadel of, 153. Septimus Severus ; Arch of, 129. Serpentine, composition of, 12, 97- . varieties of, 97, 98. origin of, 99. of Cornwall, i oo. Seveock Water; prophyries of, 69. Shap granite, 23, 38. boulders of, 38. Sharpe, Mr. D., on the structure of Mont Blanc, 49. on slaty-cleavage, 285. Sheets of basalt, 87. Shetland Islands, serpentines of, 104. Shillong, composition of granite .of, 58. Sicily, marbles of, 141. Sidlaw Hills, porphyries of, 67. Skelton Castle, 248. Skye, syenite of, 61.* marble, 124. Slate quarries of Wales, list of, 294. Slieve Croob, granite of, 7, 44. syenite of, 60. Sligo, Co., serpentine of, 104. Smith, Mr. C. H., experiments on building stones, 317. Smoke-quartz, 175. Sophocles, statue of, 140. Sorby, Mr., on cells in granite, 21, 22. on slaty-cleavage, 284. Sorel, Mount, granite of, 37. syenite of, 60. Southwell Church, 202. Spain, serpentines of, 106, 109. marbles of, 142. building stones of, 235. gypsum of, 164. Sphinx, granite of the, 52. St. Alban's Abbey Church, stone used in, 218. St. Angelo, Castle of, 281. St. Bees Head, gypsum of, 162. sandstone of, 251. St. Catherine's Docks, 248. St. George's Hall, granite pillars of, 3 2 - St. Mary,Redcliffe Church, Bristol, 209. St. Pancras Priory, stone used in, 218. St. Paul's Cathedral, stones used in, 120, 208, 213, 215. St. Peter's, Rome, granite columns of, 55- building stone of, 281. St. Petersburg, granite of, 49. Stancliffe quarry, 250. Stannington quarry, 250. Stanstead, granite quarries of, 57, 58. Stauton quarry, 257. Statuary marble, 128, 133, 136, 146. Stenton quarry, 250. Stockholm, granite quarries of, Stonesfield slate, 208. Strata, classification of, 17. Streitberg, granite of, 28. Strontian, granite of, 34. 332 INDEX. Strontian, syenite of, 61. Superior, Lake, rock-crystal of, 175. Sussex marble, 117. Swansea docks, granite used in, 33- Sweden, granite of, 49. porphyries of, 73. Switzerland, alabaster of, 164. granite of, Syenite, composition of, 7, 59, 61. of Plauenschen Grund, 59. Syenitic granite, 7, 29, 51. TAVISTOCK slates, 295. Temple Church, marble used in, 118. Tewkesbury, Abbey Church, 206. Thames Embankment, stone used in, 37- Three Rock Mountain, granite of 43- Thuringer Wald, granite of the, 49. marble of, 123. Tintern Abbey, 244. Tiree, granite of, 34. Tivoli, travertine quarries at, 279. Tixall quarry, 257. Tomb of the Duke of Wellington, stone used in, 37. William Kufus, 118. Tory Island, granite of, 46. Totterntine stone, 218. Trachyte, composition of, 10, 93. porphyry of Antrim, 10, 94. Trajan's marble column, 129. Travertine, 279. Tregala, serpentine of, 102. Trelo warren, serpentine of, 101. Tremore, porphyry of, 68. Trentham Hall, 256. Treves, sandstone of, 273. Triassic sandstone, 252. Trichinopoly, granite of, 58. Trim, ancient Castle of, 221. Trinity College, ^Dublin, granite specimens in, 36. stone used in, 43, 216. Tuff, volcanic, 283. Tunbridge Wells sandstone, 258. Tyrol, granite of the, 28. statuary marble of the, 134. UNITED STATES, gypsum of the, 167. jasper of, 178. serpentines of, 1 1 2. marbles of, 146. sandstones of, 278. - roofing slates of, 303. Up-Holland quarry, 250. Ural mountains, serpentine of the, 109. VALENTIA slates, 297. Vatican Museum, works of art in, 74, 76, 129, 150. Venice, public buildings of, 133, 236. Venus de Medici j statue of, 1 40, 156. Verde Antico, of Italy, 107. Verde di Pegli, 108. Verona, marble of, 132, 236. ^ Amphitheatre of, 133. Cathedral of, 133. Via Sacra (Home), pavement o .95- Vicenza, beds of basalt, 9 o. Viney Hill quarry, 251. Volterra, sculpturing in alabaster at, 165. Vosges mountains, syenite of, 60. minettes of, 84. serpentine of, 105. Vulpinite, 161. WALES, porphyries of, 68. slates of, 291. syenite of, 61. Warmbrunn, granite of, 29. INDEX. 333 Washington, the Capitol at, 278. Waterford, granite of, 57. Waterloo Bridge, stone used in, 37. Weights, per cubic foot, of build- ing stones, 317. Wellington Monument, Strath- fieldsaye, 36. - Dublin, 43. Wells Cathedral, stone used in, 209. Westminster Abbey, marble used in, 1 1 8. stone used in, 230. Westminster Bridge, stone used in, 37, 215. Westmoreland slate, 296. Weston quarry, 257. Wexford, granite of, 42. Wheatwood quarry, 251. Whitby Abbey, 248, 251, 258. Wicklow mountains, granite of, 26, 42. Wilkinson, Mr. G., experiments on granite, 31. Wilkinson, Mr. G., experiments on sandstone, 239. on Irish limestone buildings, 220. Wolf Kock, Cornwall, 9 . Wollaton Hall, stone used in, 21 1. Woodhead quarry, 257. Worcester Cathedral, stone of, 255. Wiirtemberg, building stones of, 234, 272. YOKK Minster, stone used in, 202. Yorkshire towns, stone used in, 246. flagstone, 246. Youghal, sandstone of, 267. ZENNOB, porphyritic greenstone of, 69. Zirkel, on classification of rocks, 5- OXFORD : BY T. COMBE, M.A., E. B. GARDNER, E. PICKARD HALL, AND J. H. STACY, ' PRINTERS TO THE UNIVERSITY. THIS BOOK $%**** * _lOOw- YC 18682 224207,