MINERALOGY d F THE SCOTTISH ISLES; WITH MINERALOGICAL OBSERVATIONS MADE IN A TOUR THROUGH DIFFERENT PARTS OF THE MAINLAND OF SCOTLAND^ AND DISSERTATIONS UPON E A T AND KELP. IN TWO VOLUMES, Jllu Grated with Maps and Plates. B Y ROBERT JAMESON, FELLOW OF THE ROYAL AND ANTIQJJARIAN SOCIETIES OF EDINBURGH, LINlftEAN SOCIETY OF LONDON, PHYSICAL SOCIETY OF JENA IN SAXONY, 5sV. was, quam ingenlofiffliiias fiftioncs fcqiti praftat ; Nature myfteria pctius indagare qiuvn divinarc. BERG. De Form. Cryflallor. VOL. I. EDINBURGH: PRINTED BY c. STEWART & co. TOR B. WHITE & SON, FLEET - STREET, LONDON; AND \V. CRE.ECIT, ErlNr i 8 o o, EAR SCIENCES TO * EARTH JOHN WALKER, DD. MD. REGIUS PROFESSOR OF NATURAL HISTORY, AND KEEPER OF THE MUSEUM OF THE UNIVERSITY OF EDINBURGH ; THIS VOLUME, OF THE IS DEDICATED, OF HIS MUCH OBLIGED PUPIL, AND OBEDIENT HUMBLE SERVANT, THE AUTHOR. SHERIFF-BRAE, LEITH> ") 20. JULY, l8oO. 105 vi . PREFACE, icencry; ict him recoiled*, that to indulge in fuch defcrip- tions was incompatible with the defign of this work. I do not defpife thofc ornaments ; and I hope that I have not been in- .{enfible to the emotions which naturally arife from the retired and finking fcenes which often bur ft upon me in the unfre- quented tradls which my purfuits led me to explore : but I have thought it foreign to my purpofe to obtrude thefe things, upon the public. Another refolution I had formed to myfelf, and which partly indeed led me to choofe the form of a journal, was, to ihun the faf cinating evil of fpeculation .and hypothefis, which mars all faithful obfervation. It would ill fuit my talents to venture upon deep fpeculation, were I inclined ; and perhaps the ftate of mincralogical knowledge forbids it. It is a fitter tafk for me to record faithfully what I have myfelf examined, and to give a fair report of the materials which were collected, than to expofe myfelf, by the form or arrangement of the worfc^ to the danger of having the facls twifled and perverted by hy- pothefis, the rage for which is as remarkable in this as in the other fciences. While, in mineralogical purfuits, there is much to interefl a philefophical mind, the objed of true value is its application to PREFACE. to economical purpofes. I fear that the theories of the { tion of the earth, interefting as they are, often miflefc mind, and pervert the underftanding ; and thofe who yic them, become fo involved in delufive fpeculations, fo bji; fact and experience, that, like Archimedes, they find bii thing wanting to raife worlds. Of the utility of this fcience there can be no more particularly when it is freed from the vague fup tions of the theorift. It is a ground-work, without whijj obfervations of the geologift, and the labours of the m; will ever be uncertain, and of little utility. It is a fcif the cultivation of which will raife a country to importance exciting new fources of induflry, even in fituations the labours of the hufbandman will be employed in But, though I am well convinced that the importance of < thing in mineralogy is in proportion to its accuracy, I w not be underftood to reprefent thefe notes as a complete ac of the mineralogy of the countries of which they treat I them to the public as an imperfect outline. The mineralo hiftory of a xjountry is to be accomplifhed only by fludyi leifure all the varieties and difpofition of the flrata and and the appearances of the mountains and valleys : an in -gation which the utinoft care, in a rapid furvey, muft lea b 2 i particulars imperfect, efpecially when the nuneralogiit is xed with the difficulties of travelling among unfrequented iave in this, as in a former work, feparated the particu- :count of the ftrata and veins from that of the particular \ as the com-mon method of conjoining them appears of- > lead to confufioii, and can never be fufficiently correct. Scribing the foflils, the method and nomenclature of the jineralogifts has been followed. The chemical characters, ; form even the foundation of many mineralogical fyftems^ $ ieldom employed ; from a conviction that the chemical i>f mineralogy^ notwithstanding the late improvements i art of, analyfis, is ftill to be confidered as imperfecl. ave only to obferve the contradictory refults obtained by left chemiils in decompofing the fame foml, to be con- d that the analyfis of the prefent day, although much im- ,'d fince the time of Bergman, is ftill of no very great ?ji mineralogy. ;ie drawings of feenery, and the mineralogical plans, which mpany this work, were executed by the elegant pencil of friend Mr. Charles Bell. In the views of feenery, he has [>ily exprefled the different characters which the rocks a- je from the effects of the weather j a circumftance which render? CONTENTS, 1 VOLUME '. /. From Edinburgh, by Glajgow, to the Craig of Page i //. Defcription of the Fojfils mentioned in the pre- ' Chapter. III. Jin RAN. Size and Situation of the I/land. Mountains, Surface, Effir. Brodick Bay, and its ms ; comprehending Cory-gills, Glen-Cloy, Glen-Shir- Hoatfield, and Glen-Rofa. JV, Defcription of the Fojfils mentioned in the pre- i Chapter. ty. Cory, Cock of Arran, and Loch Ranzn, VI. Defcription of th#> Fojfils mentie&ed in the pre- Chapter* 44 67 xil CONTENTS. CHAP. VII. Glen-Catacol, Glen-Erf ay, Glen-Clachan, Shif- kin^ Tory-Lin, Benin-Head^ Whiting Bay, Lamlajh Bay, and Lamlaft I/land. - - Page 94 CHAP. VIII. Defcription of the FoJ/ils mentioned hi the preceding Chapter. 1 1 6 OBSERVATIONS to be made for the farther Elucidation of the Mincralogical Hiftory of Arran. 123 CHAP. IX. Outline of the Mineralogy of the I/land of Bute ; with Obfervations upon the Formation of the Bed of the Clyde, and an Account of the Route from Bute to the I/land of Jura. 12^ CHAP. X. Outline of the Mineralogy of the I/lands vf IJla and Jura. - - 148 CHAP* XL Defcription of the FoJJils mentioned in the prc- ceding Chapter. '.' * - 178 CHAP. XIL Voyage from Jura to the Slate I/lands of Sett and Eafdale ; thence .to Oban and the I/land of Mull. 1 9 1 CHAP. XIII. .Outline of the Mineralogy of the Ijland G Mull. - - : ' r. CHAP. XIV. Defcription of the FoJ/ils mentioned in foe preceding Chapter. *- - ^25 CHAP. XV. Obfervations on the Method of D if cover ing ' Coal. &> g? *r 236 P ' - INTRO- INTRODUCTION, CONTAINING An AbftracJ of the Wernerian Account of the different Kinds of Mountain Rocks ; with Geognojiic Obfervations on the Strata of the Scottift Ifles, and fuch parts of the Mainland as are mention- ed in this Work, I mall frequently have occasion to mention ill this work the divifion of rocks into Primary, Tranfition, and Stratified, it may be ufeful to many to know the chara<5lers by which thefe different rocks are diflinguiflied. I am the more anxious to do this, as we have not, as yet, in any Englifh publication, an ac- count of the divifion. To this I mall add a few geognoftic ob- fcrvations upon the different rocks to be found in the Scottilh C ifles, XIV INTRODUCTION. ifles, and in thofe parts of the Mainland which are mentioned in the following Outline. According to the latefl obfervations, all the ftrata, of which our globe is compofed, may be arranged under the follow- ing clafTes : The Primary, (Urgeburge) j the Tranfition, (Ubergangsgeburge) ; the Stratified, which comprehends what are called the fecondary ftrata, (Flotzgeburge) ; and the Volca- nic, Alluvial, (Aufgefchwemmte.) I mall now mention the diftindlion between thefe different kinds of ftrata ; and, fir ft, of the Thefe ftrata are characflerifed by their never containing the remains of animals or vegetables, nor alternating with fuch ftrata as contain thefe relics. Humbold has alfo obferved that the primitive ftrata in Europe are always inclined towards the N. E., while the ftrata of the fecondary mountains dip towards the S. E. It is to the celebrated mineral ogift John Gottlob Lehman that INTRODUCTION. XV that we are indebted for the very important difcovery of the divifion of mountains into primary and fecondary. Since he wrote, fucceeding mineralogifts have confirmed the truth of his obfervations, and have thus raifed geology, from a vague and confufed ftate, to a high pitch of certainty and utility. A few writers have tried to overturn this diftinclion, by averting that it is fanciful ; yet thefe fpeculations, like all others not founded on truth and accurate inveftigation, have funk into deferved oblivion. The primitive ftrata are the following : granite, gneifs, micaceous fliiftus, ardefia, iienite, porphyry, primitive lime- ftone, primitive greenftone, greenftone fhiflus, ferpentine, quartz, pitchflone, and topaz rock. Granite is confidered by Werner as the fundamental rock, or that upon which all others are laid, and it is but very rarely that it alternates with other rocks. It is difpofed in layers or ftrata, which are often enormoufly thick, and frequently horizontal, and ex- tend thus for many miles through a whole chain of moun- tains. All the other primary ftrata alternate with each other, but never with the tranfition or ftratified rocks. The green- ftone, wacken, and pitchftone are the only exceptions ; the two iirft being common to the three firft-mentioned formations, but the pitchftone only to the primary, and ftratified, or flotz- geburge. The c 2 TRAN- XVJ INTRODUCTION. TRANSITION, OR UBERGANGSGEBURGE comprehend all thofe rocks, the lowermoft ftrata of which contain few or no petrifactions ; in the higher they are more abundant ; but only petrifactions, the originals of which no longer exift. Thefe mountains alfo abound in metallic veins and in grottos. Thofe of Antiparos, Crete, &c. are in this kind of rock ; as are the Hartz metalliferous mountains, and thofe of Derbyfhire. They feem to have been formed af- ter the primitive, and earlier than the ftratifiecl (flotzgeburge) rock. The flrata of this formation are the following ; gra- wacken, grawacken flate, fandftone, fome fpecies of ardefia, greenflone, niandelftone, limeilone, and Dr Reufs conjectures that fome fpecies of fienite and porphyry * may belong to this clafs of rocks. The STRATIFIED (Flotzgeburge) appear to have been formed after the tranfition rocks. They confift of fandflone, limeftone, argillite, with numerous petri- factions ; * Mineralogifehe Geographic von Bohmen, ^ Band, $ 177, INTRODUCTION. XV11 factions ; alfo, bafalt, ihiftofe porphyry, pitchftone, greenftone, wacken, and the various coal ftrata. From the view of thefe three formations, we obferve that the greenftone and wacken occur in every one of them, but the bafalt is peculiar to the ftratified rocks. The VOLCANIC comprehends the various ftony fubftances altered by action ot fire : thefe are, lava, pumice, vocanic afhes, and volcanic tuff. The ALLUVIAL confifl of gravel, fand, clay, &c. and are the debris of the other ftrata. Having thus mentioned the divifion of the different rocks> according to their relative antiquity, I fliall now make a few general geognoftic obfervations on the rocks of the Scottish ides, &c. I {hall firfl mention the ERI- XVlll INTRODUCTION. PRIMARY ROCKS. GRANITE. This rock forms but a fmall portion of the Scot- tifli ifles, it being found only in the ifk of Arran, and in the low part of Mull called Rofs, and in the Shetland iflands. Upon the Mainland, however, I obferved it forming moun- tains in Sutherlandfhire, a confiderable part of the county of Aberdeenfhire feems to be formed of it, and alfo the lofty mountain of Cruachan upon the weft coaft. Granite veins are pretty frequent in feveral of the iflands, as in Arran where they traverfe the common granite, and in Coll, Tiree, Rona, the Orkney and Shetland iflands, &c. where they traverfe mi- caceous fhiftus, gneifs, or hornblende flate. Upon the main- land, in the route from Bernera to Perth, the granite veins are extremely common. GNEISS. This rock I obferved in Coll, Tiree, Rafay, Rona, in the Shetland iflands, and in feveral places upon the Main- land of Scotland; in particular it forms the fummit of the high mountain called Ben Lomond. It fometimes alternates with micaceous fhiftus and hornblende rock, and it is traver- fed by granite veins, as is the cafe in Coll, Rona, &c. MICACEOUS SHISTVS-. This rock forms a portion of the ifles of INTRODUCTION. Xix of Arran, Bute, and Mull ; it is juft to be obferved in Coll, but a very confiderable extent of the Shetland iflands are compofed of it. In the Mainland it appears to extend through the whole diftricl of Cowal, and to the extremity of the iflhmus of Cantyre, and in all the country from Bernera to Dunkeld ; and from Dunkeld to Loch Lomond by Inveraray, the micaceous fhiftus is the prevalent rock. Upon the eaft coaft it is frequent among the other primary ftrata. It alternates with fhiftofe quartz in the ifland of Mull, and with hornblende and gneifs in the ifland of Coll ; and it is to be obferved in feveral places pafling to ardefia, and it is traverfed by granite veins, and has pieces of granite enclofed in it. Primitive argillaceous fhiftus. This rock occurs in Arran, Bute, Ifla, Jura, Eafdale, and Seil. In Ifla there is a fpecies of it which contains pieces of granite, which, however, feem to have been formed at the fame time with the ardefia. In Eafdale, Seil, Bute, and Arran, it it quarried for economical purpofes ; but the flate of Eafdale is by far the befl.. SIENITE. A rock nearly allied to fienite feems to form the cralg of Ailfa ; it alfo forms part of the ifland of Arran, and the lofty Cullin moutains in the ifland of Skye. XX INTRODUCTION. PORPHYRY. I obferved fragments of porphyry among the granite mountains in the ifland of Arran, which is probably of primitive formation, and the porphyry, which forms fo con- fiderable a part of the hill of Glamofcard in Skye, feems to be of primitive formation. PRIMITIVE LIMESTONE^ or MARBLE. This rock^ occurs in vertical flrata at I-columb-kill, alfo in the ifland of Tirie, and in feveral parts of the Mainland. I obferved it alternating with primary rocks, particularly at Portfoy, where it is in vertical ftrata and alternates with talcaceous ihiftus and fer- pentine. PRIMITIVE GREENSTONE. I have not met with this rock in any part of Scotland excepting in the ifland of Iflay, yet I think it very probable that a careful examination may difcover it in many places. SERPENTINE. There are no ftrata of this rock in the He- brides, nor the Orkney iflands ; but in Shetland it forms ex- tenlive hills, and there it feems evidently to be of primitive formation. At the intere fling fpot, Portfoy, there are great vertical ftrata of ferpentine alternating with marble, talcaceous, and hornblende Ihiftus. INTRODtJCTION. Z. In the iilands of Ifla and Jura there are mountains of granular quartz, and it is there to be obferved alternating with, and pafTmg into micaceous fhiftus. In the ifle of Coll there are alfo confiderable rocks of granular quartz. In the ifl- and of Tirie I obferved the rare appearance of a vein of gra- nular quartz traverfing ftrata of micaceous fhiftus and horn- blende Hate. In Caithnefs the mountain of Scaraban is com- pofed of quartz ; and at Portfoy there is a hili which affords ihiflofe quartz. In many places veins of quartz are to be ob- ferved traverfing the primary ftrata, and in the ifland of Bute there is a quartz vein which prefents appearances irreconcile- able with the Plutonic theory. NE. The only fpecies of this ftone which I have ever feen, that may be confidered .as primary, is that upon the hill of Glamofcard in the ifland of Skye. It there feems to al- ternate with porphyry, but of this I am not as yet certain. In the ifland of Arran there are appearances of pitchftone in the form of veins traverfing the granite, but as all veins are of an after formation to the rocks which they traverfe, this cannot be reckoned equally old with the granite, or other primitive rocks. XXU INTRODUCTION. TRANSITION ROCKS, (Ubcrgangfgcburgc.) GRAWACKEN. This is a rare rock in the diftricts through which I paiTed. The only appearance I ever noticed was a fmall portion lying on ardefia in the ifland of Seil. GREENSTONE. The greenftone of the iiland of Mull appears to belong to this formation, as it is found near to limeflone that contains belemnites. LIMESTONE. This fpecies is found in the iiland of Mull, and contains in it cornu ammonis and belemnites ; hence I reckon it to belong to the traniition rocks. STRATIFIED ROCKS, (Flotegcburge.) SANDSTONE. Of this I obferved two kinds, the filiceous and argillaceous. The filiceous does not frequently occur. The fandftone of the ifland of Rume approaches nearly to this kind, and in the Orkney iflands there are ftrata of filiceous fandftone that al- ternate INTRODUCTION. XXlii ternate with argillaceous fandftone. Argillaceous fandftone forms the Cumbray iflands, the fouth extremities of Bute and Arran ; and it alfo appears in the iflands of Seil, Mull, Eigg, Skye, Rafay and Scalpa. Almofl the whole of the Orkney iflands are compofed of argillaceous fandftone, but it forms a very fmall portion of the Shetland iflands. It alfo fkirts the eaft coaft of Scotland from the Pentland Firth to the fmall fifhing town called Buckie ; and again this fandftone makes its appearance near to Aberdeen, and continues along the more all the way to the Frith of Forth. LIMESTONE. In the ifland of Arran there are considerable ftrata of limeftone which is covered by argillaceous fandftone ; and in fome places the limeftone and fandftone alternate. In the Orkneys limeftone is to be obferved covered by fandftone, and even traverfed by veins of fandftone. ARGILLITE with numerous fhells is found in the ifland of Arran, and in the ifland of Eigg. BASALT. This rock, which, as we have before obferved, is peculiar to the Flotzgeburge, is found in almoft every part of Scotland, either in ftrata, or in veins. I obferved it difpofed in ftrata in the ifland of Seil, at Oban, in the iflands of Mull, d 2 Eigg, liigg, Canna, and Skye ; and thefe ftrata either alternate with argillaceous fandftone, wacken, or greenftone. Frequently alfb veins of bafalt traverfe thefe ftrata. BASALT VEINS. Thefe veins are extremely common in mofc jf the Hebrides, but are rarely to be obferved in the Shetland >r Orkney iflands. I obferved them traverfing granite, gneifs, micaceous fhiftus, iienite, porphyry, hornblende ilate, fand- ftone, and limeftone. In the ifland of Arran there are feveral very remarkable veins which are partly formed of bafalt. Thus in Glencloy there is a vein^ (traverfing clay porphy- ry), which is compofed of bafalt in the middle, but, upon one fide is fandftone breccia, and, on the other is hard filiceous fandftone. At Tormore, upon the weft, fide of the ifland of Arran, there are feveral other vei>y remarkable veins partly formed of bafalt. BASALT TUFF. I obferved this rock at Dumbarton caftle, and in the iflands of Mull and Canna, where it always accom- panies rocks of trap formation. In the ifland of Canna it is remarkable for having pieces of wood inclofed., . This curious foflil is found very frequently in the INTRODUCTION. XXV the ifland of Arran, but generally in the form of veins. Thefe veins traverfe the common argillaceous fandftone, and are of- ten of great magnitude, It is alfo difpofed in ftratified veins along with other fubftances at Tormore in Arran. In the ifland of Mull it feems to lie between fandftone and bafalt ; but in Eigg it forms confiderable veins traverfing bafalt. This foflil, which was before confidered as very rare, is thus fhewn not to be fo uncommon ; and I have lately learned that it has been obferved in veins traverfing fandftone in Morven, and ia veins traverfing bafalt at Ardnamurchan. GREENSTONE. The country between the primary ftrata at Dunkeld, and the banks of the Frith of Forth prefents many appearances of frotz greenftone ; and, in the fame tracl there is alfo wacken of a fimilar formation. COAL. In the ifland of Arran there is a flratum of blind eoal inclofed in fandftone. In Mull, Eigg, Canna, Skye, it is obferved always ftratified with bafalt or wacken. VOL- XXVI INTRODUCTION. VOLCANIC ROCKS* have never been difcovered in Scotland. ALLUVIAL. Of thefe there are examples in the Highland vallies, where the debris from the mountains are depofited in beds and cover- ed by heath. The great banks of fand, and the immenfe beds of peat which we find fometimes alternating with beds of clay or fand, are of this kind. MINE- * Of the pfeudo- volcanic rocks, which are different fpecies of rocks that have been expofed to accidental fire, we have inftances in Fifefliire. Upon the fhore between Dyfart and Eafter Wemyfs I picked up feveral fine fpecimens of porcella- nite, which feems to be the clay that accompanies the coal altered by fire, as mattes of fcorise and charcoal ftill adhered to it. MINERALOGY OP THE SCOTTISH ISLES. CHAPTER I. From Edinburgh, by Glafgow^ to the Craig of Atlfa* jLN travelling from Edinburgh to Glafgow, by the Living- ftone road, the country continues, for a confiderable way, pleafant and well cultivated ; but as we approach the Kirk of Shotts the fcene is much altered. In place of inclofed fields, exhibiting the operations of thriving agriculture, extenfive mofs grounds appear, forming a ftriking contrafl to the cul- tivated country through which we had juft patted. Happily, A however, j FROM EDINBURGH TO AILSA. however, thefe inofTes arc now viewed in a more favourable light than heretofore : the brown burnt-like afpect of a peat moor does not now flrike the mind with ideas of barenefs and fterility ; as we know, from experience, that labour and a little expence may foon convert them into luxuriant fields. A few miles after pafling this defert, we come in fight of Glafgow ^ but its low fituation, and the want of hills, render it, when compared with Edinburgh, far lefa interefting as a picturefque object. The nearer we approach the town the country im- proves, and is conliderably diverfified with wood and culti- vated fields. The rocks which occur in this tract are all of fecondary formation ; which is commonly the cafe where the country is low and flat. As our journey was- rapid, I can only fay, in general, that the ftrata are, fandflone, limeftone, bafalt, wac- ken, mandelflein, coal, with its accompanying fhiftofe clay, &c.. and iron-flone. The fandftone is generally ufed for the purpofes of build- ing j butj from different quarries it is more or lefs durable* This fact leads us to remark, that chemical trials, combined with correct mineralogical obfervations, might, in many in- fiances, enable us to determine, with fome certainty, as to the probable FROM EDINBURGH TO probable durability of (tones employed in building. Indeed, thofe who have been long in the habit of analyfiag and exa- mining fuch ftones, can, even by their appearance, judge of their probable durability * : a circumflance fufficient to encou- rage us to purfue a mode of inveiligation which has hitherto engaged little attention. The limefbone which occurs in this diftri(5l varies confiderably in its appearance : but we had not an opportunity of obferving it particularly. It is quarried in feveral places to a coniiderable extent, and then burnt, and ufed for manure, and for building. It is burnt for thefe pur- pofes in the common draw-kiln, which is ill conftrucSled, as there is not only a great wafte of heat, but, by expofure to all the variations of the weather, the burning is rendered preca- rious and uncertain. My father remedied thefe defects in a kiln which he built eight years ago, and which he flill conti- A 2 mies * We have a curious inftance of this related of the late Mr Bayen ; A gen- tleman who had paid much attention to the genera of marble and ferpentine. Walking one day in the Place de la Revolution, at Paris, with his friend and col- league Deyeux, he pointed out to him feveral of the marble pillars, which, he faid, notwithftanding their prefent folid appearance, would decay in a fhort time, and in the particular places he mentioned. Accordingly, a year had fcarcely elapfed when his predi&ion was fulfilled : many of the pillars began to decay, and even considerable hollows were quickly formed in fome of them drtnales de Chymtc* which certainly deferves to be tried : To us it appears objectionable, not only from the clofe attendance that the fires require, but alfo that a confiderable por- tion of heat is loft by its being open at top, See Rurnfcrd's E/ays* TROM EDINBURGH TO AILSA. 5 which has fometimes in-lying cryflals of felfpar, bafaltic horn- blende, augit, leucit, mica, and a few interfperfed parti- cles of quartz ; 2. bafalt porphyry ; 3. grunftein ; 4. lime- flone. The fhort time I could afford to fpend in Glafgow, and my anxiety to get forward to the Iflands, prevented me from examining the relation of the different flrata to each other ; which, however, I the lefs regret, as that circumflance is but flightly connected with my prefent object. ProfefTor Faujas de St. Fond has given us a fhort account of the mineralogy of the environs of Glafgow ; but his defcrip- tions are unluckily obfcured by a rigid adherence to a theory which has no foundation in nature. He confiders all the rocks we have now mentioned, as lavas ; and thofe he denominates bafaltic, porphyritic, and granitic lavas. I do not hefitate a moment in faying, that, in my opinion, there is not in all Scot- land the veflige of a volcano. I do not reft this afTertion upon my own authority, (for that would be prefumptuous ;) but upon that of Dr. Walker, who has examined more of the mineralogy of Scotland than any man now living, and whofe collection of Scotch foflils is the largeft that has ever been made. Befides, it wars with every principle of fyftematic clarification, to ar- range and denominate foflils from any theory we may adopt as to their formation* We 6 FROM EDINBURGH TO AILSA. We now purfued our journey from Glafgow to Greenock, down the river Clyde : a voyage which prefents the traveller with many fcenes of uncommon beauty. At Glafgow the ri- ver is narrow, with low formal banks ; but as we approach Dumbarton, the river becomes wider, the country more beau- tiful, and the fcene is foon rendered interefling by the appear- ance of the fingular rock of Dumbarton. From this the moun- tains of Cowal extend, along the north fide of the river, to Rof- neath ; forming a fine contrafl of Alpine wildnefs, with the comparatively low green hills which reach to Greenock upon the fouth fide of the river. Tlxe ftrata between Glafgow and Gree- nock, upon the fouth bank of the river, are, fandflone, lime- flone, bafalt, and wacken. Thofe of the north bank, to the town of Dumbarton, continue to be nearly of fimilar rock ; forming, in this rout, fome confiderable heights, particularly about Frifky Hall, where the rocks have a fine terraced appear- ance. Immediately below the houfe of Frifky, at the porter's lodge, we obferved a final! quarry of wacken, which is now celebrated as affording fine fpecimens of prehnite. The town of Dumbarton is fituated in a plain of confiderable extent ; and the rock upon which the caflle is built, rifes from it in a fimi- lar manner with Arthur's Seat, near Edinburgh, but is much more flriking, from the great flatnefs of the country. It is compofed of black bafalt ; but, upon the fide facing the town, we FROM EDINBURGH TO AILSA. 7 we obferved a bafalt tuffcovered by fandflone. ProfefTor St. Fond remarks that this rock is formed of a black bafaltic lava ; but upon the lower part, facing the town, there is to be obferved a current of muddy lava, having, intermixed, fragments of ba- falt, more or lefs altered. At different periods the rock of Dumbarton has been of confiderable confequence, on account of the flrong fortrefs which is built upon it. When Mary, the unfortunate and lovely Queen of Scotland, was imprifoned in England, and her kingdom wrefted from her, the folitary rock of Dumbarton held out againft every attempt to take it j and was the only place in the kingdom that dared to acknow- kdge her authority. If we glance over the country as it extends towards Lochlo- mond, we obferve it rifing gradually until the profpecl: is bounded by vaft mountains, marking, by their height and ihape, a change in the nature of the flrata, and forming the grand entrance into the Highlands upon this fide of Scotland. If we examine the country more particularly, we find our con- jecture right ; for at Lufs, upon the banks of this beautiful loch, ftrata of micaceous fliiftus, and other primitive rocks, make their appearance. Thefe flrata extend towards the Clyde,, and form a confiderable part of its north bank, from Dumbar- ton to Rofneath, a fmall village oppofhe to Greenock. Greenock, 8 FROM EDINBURGH TO AILSA. Greenock, a populous and flourifhing town, is fituated upon the fide of the river, at the bottom of hills of confiderable height ; and remarkable for the quantity of rain which falls during the year, which is faid to be more than in .any other part of Scotland. The ftrata in the immediate vicinity of the town are, bafalt, wacken, fandflone, limeftone : and in fome places the fandflone is to be obferved traverfed with bafaltic veins ; and the wacken, befides zeolite, contains a curious foml nearly allied to leucit. From Greenock our farther progrefs down the Clyde was more interefting, from the grandeur and variety of the objects which now occupied our attention. After pafling the Gouroch lighthoufe, we obferved the beautiful ifland of Bute, with the neighbouring and Cumbray ifles flretching acrofs the view ; and, farther diflant, the wild mountains of Arran appeared over the low part of Bute towering among the clouds. The hills upon the oppofite bank of the river are flrikingly con- trailed. Upon the Cowal more the country rifes into confi- derable hills of micaceous fhiflus, which are partly heath-clad, and join with the bare and flerile mountains that extend from this more through Argylefhire. Upon the oppofite bank of the river the country is much lower ; there are no deep hills upon thefhore; and the (trata^ which are horizontal, are, red and white FROM EDINBURGH TO AILSA. white-coloured argillaceous fandftone, fandftone breccia, bafalt, and frequently bafaltic veins traverfe both thefe flrata. The breccia, as is often the cafe with this kind of rock when it oc- curs upon the fea-fhore, forms beautifully wooded cliffs, which extend to the fweetly-retired village of the Largs. Thefe fe- condary flrata extend from the Largs to Saltcoats, and from thence far through Ayrfhire ; while the primary rocks, on the oppbfite bank of the river, appear to extend to the Mull of Cantyre. In a few hours after pafling the Cumbray ifles, and the majeflic ifland of Arran, we landed upon the great rock which is called THE CRAIG OF AILSA. This flupendous rock is faid to be 400 feet high, and is about two miles in circumference. It is fomewhat of a conical fhape, and very precipitous on all fides : the only landing- place being on the N. E. where there is a fmall beach, formed by the fragments which have fallen from the neighbouring rocks. It is much lower now than it was formerly ; as is evinced, not only by the numerous fragments lying on the beach, but alfo more fully by the nature of the bottom near it, which, according to the moft accurate foundings, is gra- velly to a considerable diflance. B After jO FROM EDINBURGH TO AlLSA. After having walked around part of it, and afcerided near to the fummit, I was forced to return, as the captain of the veflel was anxious to proceed to Arran. On this account, I was pre- sented from examining it fo accurately as could have been wifhed. This glance, however, was fufficient to fatisfy me as to the general nature of the rock of which it was compofed. The greater part feems to be formed of different fpecies of very compact fienite ; which, particularly on the eail fide, pre- fents imrnenfe groupes of columns, fimilar in appearance to the bafaltic columns that occur fo often in different parts of Scotland. In afcending towards the fuminit, and a little be- low the folitary ruin of a cattle, I obferved two confiderable bafaltic veins travelling the fienite, ' CHAP. CHAP. II. Defcription of the FOSSILS mentioned in the preceding Chapter. PREHNITE FriJky-Hall. SlLEX PREHNITES, Wem. JLtLB Z EOLITH^ Efthlier. Dr. Walker. It is either in flat mafTes, cellular, or botroidal, or partly af- fuming a mammillary figure ; is generally radiated and com- pofed of fmall prifmatic cryftals fometimes fo fmall, and fo near to each other, as to aflume, in fome degree, a compact texture, almoft resembling chalcedony. Colour. Varies, from apple green, to yellowifh green, pale yel- low, and white ; but, when affected by the weather, it ac- quires an ochry, or opaque white colour. Lujlre. The external luftre little gkncing* ; internal is pearly. Tranfparency. It is femi-tranfparent ; but, when acted upon by the weather, it becomes confiderably opaque, and much refembles certain fpecies of fulphat of barytes. Hardnefs. Gives fparks with fteel ; takes a pretty good polifh. B 2 Frafturc. * Wtnlg gtanzend. Germ. FROM EDINBURGH TO AILSA, Fratfure. The fracture in the direction of the folise appears fo- liated, but acrofs the radii approaches to the conchoidal. Fufibillty. Dr. Hope melted it, and, by flow cooling, had again a pretty regular cryflalline texture. It is contained in a fpecies of wacken, which, by its degree f induration, appears pamng to the ftate of bafalt. It is fre- quently accompanied by calcareous fpar. Another fubftance is often found with it, which is probably of the nature of zeolite. It is formed of long prifmatic radii, which have the follow- ing character. Colour. White. Luftre. Pearly. Tran/parency. Nearly tranfparent. Hardnefs. Difficultly fcratched with a knife. OBSERVATIONS. The Prehnite has received many denominations, by different mineralogifts : thus it has been called green felfpar, apple-green quartz, filiceous zeolith, cape-chryfolith, emerald, prafe, and cryfoprafe: a ftriking proof of the imperfection of mine- ralogical nomenclature. The juflly-celebrated Mr. Werner, to whom FROM EDINBURGH TO AILSA. whom we owe fo much of our moft accurate information, names it Prehnite, after Colonel Prehn, a Dutch officer, who found it at the Cape of Good Hope, and firffc brought it to Eu- rope. Since its difcovery at the Cape of Good Hope, it has alfo been found in Dauphine ; and Dr. Grofcke of Mittau firft difcovered it at Frifky-Hall. This is not the only place in Scotland where this beautiful foffil is found ; for I have ob- ferved it m the caftle rock and Arthur's Seat at Edinburgh, and we mail afterwards notice it in the ifland of Mull. LEUCTT GreenocL SARCITE, Dr. Townfon's Tracts in natural hiflory. BORAX MARGODES, Lin. ? This foflil is of a reddifh-brown colour, and generally cryftal- lifed in the form of a 24 edron : it is alfo, in fome inflances, amorphous, with an earthy fracture *.. It has always occurred opaque, and of fuch a hardnefs as to yield with difficulty to the knife. With the blow-pipe it lofes its colour, and melts like felfpar. It * Dr. Hope has in his pofleflion a very fine fpecimen of this foflil, which he. found at the Calton Hill. Dr. Townfon has figured it in his Trafts, j^ FROM EDINBURGH TO AILSA. It is found in the cavities of wacken, and fometimes im- bedded in calcareous fpar. Abbe Huay remarks that this foflll is considered as a zeo- lite *f ; and La Metherie, who had examined fpecimens of a fi- milar foflil from the Calton-Hill at Edinburgh, remarks, " On " trouve, au mont Calton-Hill, proche d'Edimbourg, un cri- " ftal a vingt-quatre facettes trapezoidales, comme celui-ci " II eft rougeatre, poreux, terne, comme de la brique. On " croit qu'il doit entrer dans la zeolite leucitique J." Dr. Townfon, in his lately-publifhed Traces in natural hiftory, coniiders it as a new genus, and names it Sarcite : this, how- ever, cannot be admitted, until the foflil {hall be regularly ana- lyfed. Mr. Camara of Lifbpn, a moft intelligent mineralogift, informed me, that he had frequently met with this foflil in other countries, but always confidered it as nearly allied to leucit. It appears, then, that it mould flill be reckoned of the nature of leucit, until it mall be more particularly examined in the way of chemical analyfis. SIENITE- Annales de Chyraie. Th orie de la Tcrrc, torn, 2 SIENITE Craig of Ailfa. CALOMACHVS, Dr. Walker's ClafTes FofGlium. So far as I can determine at prefent, this rock appears to be a very compact fpecies of fienite, in which the felfpar is the moft prevalent ingredient. Sometimes the felfpar feems pafling to the ftate of earthy felfpar ; and then it forms a bafis in which we obferve red or white-coloured cryftals of common felfpar and hornblende, and particles of quartz ; thus forming a fpecies of fienitic porphyry. A R R A N. CHAP. III. Size and Situation of the I/land. Cliff's , Mountains, Surface, Brodick Bay, and its Environs ; comprehending Cory-Gills, Glen Cloy, Gkn-Sbirreg, Goatfield, and Glen-Rofa. JL HIS ifland -is about thirty-two miles long and twelve broad ; fituated in the mouth of the Frith of Clyde, about eight miles from Bute, and lixteen from Saltcoats in Ayrfhire. Its fhape is irregular, but not fo much fo as many of the Weft- ern Iflands which are expofed to the Atlantic Ocean. Here, the vicinity of the Scottifh and Irifh fhores prevents any great de- ftruc~lion of land ; as is evident from the lownefs of the cliffs round the ifland, which have not the precipitous, rugged and bold afpecl of many of the Weftern Iflands. CLIFFS. The cliffs are feldom above two hundred feet high ; are generally precipitous : having frequently, however, an in- tervening THK &LAX1) cw AKRAN; i'cl For ai MINKRAMMJY '111, milt f/iirt/it h/iit/i/ A R R A N, 17 tervening bank between the cliff and die fea, formed by the definition of the rocks, which are either of fandftone or mi- caceous fhiflus. Confiderable fandy beaches frequently occur, formed of the debris of granite, fandftone, and micaceous mi- tus ; and fometimes we remark a confiderable extent of coafl covered with enormous mafTes, which have been torn away by torrents, or feparated from the neighbouring rocks by the vaft expanfive power of froft. MOUNTAINS. No regular ridge of mountains is to be ob- ferved : thefe being either in the form of groups, as Goatfield and the adjacent mountains, which prefent aftonimingly grand peaked fummits ; or irregular, forming round-backed hills, as thofe towards the fouth part of the ifland. SURFACE. The land is In general very high, particularly to- wards the north end, where the wonderful group compofed of Goatfield, Caime-na-callich, &c. prefent mountains near 3000 feet high. Here Nature exhibits to the aftoniihed eye the mod terrific and fublime fcenery ; to convey even a faint idea of which would require an able pen. The fouthern parts are lower ; and in place of the bare rocky appearance of the north, we have heath-covered hills, and a considerable portion of cul- tivated land. Q The 1 8 A R R A N. The ifland is divided into two parifhes, Kilbride and Kil- mory, belonging to three proprietors ; the Duke of Hamilton, Marquis of Bute, and John Fullerton, Efq. of Kilmichael ; and yields about 5000 1. of yearly rent. This indeed might be much increafed, were proper methods of cultivation followed ; and were long leafes and larger farms properly granted, more happinefs, induftry and wealth would be the natural con- fequence. In defcribing the ifland particularly, I mall begin with BRODICK BAY, fituated on the earl fide. This beautiful bay is bounded, on the S. by the hills of Cory-gills ; on the W. by the vales of Glencloy and Glenfliirreg, and, on the N. the tre- mendous Goatfield forms a lofty boundary. It is of an irregular fhape ; about five miles long, and four broad ; having about five fathoms water, with good anchorage ground : but it is on- ly in moderate weather that vefTels can ride in fafety. From this bay paflage-boats go to Saltcoats, about fixteen or eighteen miles diftant, which renders this the principal thorough-fare in the ifland ; fo that the population is confiderable. Many vi- fitors come from the mainland, during t}ie fummer months, to enjoy the free air, and admire the wonderful fcenery of this interefting ifland ; but the want of a good inn is much to be regretted. A R R A N. . 19 regretted. On the north fide of the bay (lands Brodick Caftle, an old ruinous building, inhabited occafionally during part of the furnmer by the Duke of Hamilton. It is lituated upon the fide of Goatfield, commanding a moil extenfive and de- lightful profpe<5l ; and might eafily be made a beautiful feat. About two miles diflant, in Glencloy, is fituated the pleafant feat of the worthy and mofl hofpitable family of Fullerton, of Kilmichael, who have now refided in the ifland upwards of 700 years. Mineralogy. The mineral hiflory of this part of the ifland is, in many refpedls, interefting ; not only on account of the variety of foffils which it affords, but alfo in prefenting to us, in a iliort fpace, a reprefentation of the flruclure and materials of nearly the whole ifland. On this account I fhall be minute in my defcription ; as I may have occafion to refer to this par- ticular part, when defcribing the other quarters of the ifland. The fouth fide of the bay is low immediately upon the more : it however rifes gradually ; forming the hills in the neighbour- hood of Cory-gills, and, towards the fea, cliffs of confiderable height, almoft entirely compofed of fandflone *. This fand- C 2 flone :> M. de C. LafTone has obferved, that the furface of a fandftone, which had the jo A R R A K. itone is pretty compact, of a reddifh colour, much refembling that found in Shetland ; and is here and there alternated with flrata of breccia, compofecl of rounded fragments of quartz, with fragments of fandflone, of various fizes and fhapes ; and both thefe flrata run at an angle of from 10 to 15. In ma- ny places there are very confiderable veins of bafalt, or what have been called Whin-dykes f> crofting die fandftone in va- rious the year before been left uncovered, was invefted with a filiceous cruft, nearly as hard as agate : the particles of which it was formed muft therefore have been eonveyed and depofited by water. Mem. Par. 1774. Kiribati's Geological Ejjays t p. 112. This is a proof of the folubility of filiceous earth in water : a facl: denied by the Plutonifts. It is more demonflrably confirmed by the following faft, from Mr. Kirwan's Geological Eflays, p. 140. ' About the year 1760, the Empeior * of Germany being defirous to know the length of time neceffary to complete a " petrifaction, obtained leave from the Sultan to take up and examine one of the " timbers of Trajan's bridge over the Danube at Belgrade. It was found to have < { been converted into agate to the depth only of half an inch ; the inner parts " were {lightly petrified, and the central flill wood." f The term Whinfton^ like many other popular denominations, does not convey a diftinft idea of any particular genus of foffils ; but is ufed by the inha. bitants of Scotland, and of the north of England, to exp refs thofe foflits which, are of trap formation* Mineralogifts, in many inftances, appear to have ufed it in a very vague manner : thus fome defcribe trap, others bafalt j and not unfre- quently wacken, greenftone and indurated clay ha^ve been arranged under this name, A R R A K 2 ! rious directions. Some may be obferved rifmg from the fea, and penetrating the fandflone. In other places, where the fu- perincumbent fandftone has been completely carried away, veins can be remarked running, with little variation in diame- ter or direction, for nearly a mile. Thefe veins are not only to be obferved upon the fea more, but can be traced running, in various directions, and of different diameters, through the fandftone and other rocks in the interior of the ifland, as we lhall afterwards clearly demonftrate. In afcending the hill to- wards Cory-gills, a very confiderable vein of dark leek-green ^itchftone makes its appearance, running from the cliffs upon the fhore, thro' the fandftone, to the Lamlam road, where we foon lofe it among the fandftone in the neighbouring hills. This vein is of various breadths ; in fome places, as at the Lamlaih road, being about eight feet. It does not appear to have altered the fandftone, where it is in contact with it ; but, in fome parts of the vein, the pitchftone, as it approaches the fandftone, lofes much of its luftre, and, in fracture and hard- nefs, approaches to the nature of bafalt. The name. It is much to be wiflied that it could be entirely laid afide ; particularly when we perceive that the great Werner has framed fatisfaftory characters for thefe different rocks, 22 A R R A K. The appearence of pitchftone in the form of veins, and in fecondary flrata, has not as yet been obferved by other mi- neralogifts. Mr. Werner, from his own extenfive knowledge, and the accumrmilated information of his numerous pupils, is of opinion, that pitchftone is always difpofed in ftrata, and entirely confined to primitive mountains. ^The late Abbe Spallanzani defcribes feveral veins of pitchftone lava that he obferved in the Euganean mountains ; but it is difficult to de- termine with certainty whether this be the true pitchftone *. Higher up, above the houfes of Cory-gills, I obferved a /number of columns which are compofed of clay - por- phyry. Thefe pillars are in various directions ; fome are perpendicular to the horizon ; others more or lefs inclined ; and I obferved, farther up, that they are quite horizontal. They are in the form of four or fix-fided columns, from fix to ten feet long, and two or three feet in diameter, having a whi- tifh cruft from decompofition. They are not jointed ; nor is there any appearance of balls, or what- the volcanifts call vol- canic bombs. I endeavoured to difcover the pofition of the por- phyry with regard to the fandftone, but could not detect them in contacl with each other ; yet, from the nature of the rocks all * Spallanzani's Travels in the Two Sicilies, vol. 3^, p. 251, &c. A R R A N. 23 all around, I am inclined to believe that it refts on the fand- flone. In defcending from this porphyry hill towards Lam- lafli, the fandftone again makes its appearance, but is foon loft ; being covered with a rock which is principally compofed of dark -green coloured hornblende, with a little felfpar and quartz, and anfwers nearly to the greenftone of the Germans. This greenftone forms the fummits of feveral hills in the neighbourhood, and may be remarked running towards the fea, forming high cliffs. In one place I obferved a great body of green-coloured pitchftone, which runs quite in an oppolite direction to the vein I obferved crofling the Lam- lafh road : in fhort, it appears to be ftratified, and to run immediately below the greenftone. About twenty yards lower, another mafs occurs, about ten or twelve feet thick; and which, fo far as I could determine, appears to form a ftratum, running between the fandftone and greenftone. I was inform- ed that this mafs of pitchftone had been traced to the face of a high cliff upon the fea-fhore, where it is faid to lie upon fand- ftone, which alfo covers it ; and that it was there alfo fplit into columns, like bafalt. Having now mentioned the pofition of the veins and ftrata upon the fouth fide j I lhall return to the fea-fhore, where we obfervc 34. A R R A N, obferve the bay rifing towards the weft, forming the one fide of Glencloy. GLEN-CLOY. This glen is nearly three miles long, and half a mile broad ; open towards the eaft, but bounded on the other fides by high hills. At the top, or weft part, of the glen, the hills are higheft, forming a very romantic groupe of rocks. The north and fouth fides, which are of confiderable height, become gradually lower as they approach the fea, where they form part of Brodick Bay. The bottom of the glen rifes gently from the fea, forming a fmall angle with the hills that bound it. Immediately under the peat mofs, or heather, we difcover boulder ftones, which form a thick bed, from three to thirty feet thick ; and in other places they are collected together in heaps, being thrown into this form by the force of water. Thefe bowlder ftones are not of very confiderable fize, and va- ry but little in that refpecl at the top or bottom of the glen ; which mews that the greater part of them have not received their rounded form by attrition in the water of the glen, but are derived from decompofed breccia. They confift of granite, porphyry, fienite, breccia and fandftone, which are all to be obferved in the neighbouring hills. Through the glen runs Glencloy burn, formed by the fpringa and rains from the the A R R A N. 2 the hills : it is narrow, but, during violent ftorms, it overflows a confiderable part of the glen, and has thus laid bare the rocks, and fhows us, in a fatisfaclory manner, the nature of the fub- jacent ftrata. The bottom of the glen is compofed of the com- mon red-coloured argillaceous fandftone, and here and there are ftrata of breccia ; and both are traverfed with veins of ba- falt, which run in very various directions, and are from three to twelve feet in breadth. Thefe veins, in their paflage thro' . the ftrata, (to ufe the Huttonian language,) do not appear to have occafioned in them any alteration with regard to hard- nefs : on the contrary, we often find a fpecies of femindurated clay interpofed between the fandftone and bafalt, thus form- ing a ftratified vein. Reufs, the celebrated German geologift, in his mineralogi- cal hiftory of Bohemia, defcribes two ftratified veins which he obferved in the Bunzlauer circle. As it is of importance to turn the attention of the young mineralogift to thofe curious,, and, I believe, rare, appearances, I will mortly mention the na- ture of thofe veins obferved by Reufs. One of the veins tra- verfes argillaceous fandftone, and is about a fathom wide ; its fides are of common argillaceous ironftone, about five or fix inches wide : to this fucceeds a layer of wacken-clay, about half a foot wide ; then a thin layer of wacken, or rather a rock D inter- 26 A R R A N, intermediate between wacken-clay and wacken ; laftly, the mid- dle of the vein is bafalt. The other vein has argillaceous iron- ftone for thefaalband or fides, but the middle is wacken clay. The fandflone, as it comes in contact with the vein, is remark- ably great-grained and iron-fhort *. The hills on the north and fouth fides of the glen are of the fame height ; and the pente of the hills appears to correfpond pretty nearly with the elevation of the flrata. The hills on the fouth fide are formed of fandilone and breccia, which, to- wards the upper end, form very lofty precipices. Many veins of bafalt traverfe the fandilone, and loofe nodules of brownifh- black and black pitchflone lie fcattered about here and there. On the north fide of the glen, near to Brodick wood, a confi- derable body of dark leek-green coloured pitchftone makes its appearance ; but it is fo much covered with grafs, that it is diffi- cult to fay whether it forms a vein or a flratum. It is well wor- thy the attention of thofe who may vifit Arran, to endeavour to determine this point. In afcending the hills upon this fide, after gaining a confiderable height, the fandftone difappears, when a clay ' Mineralogifche Geographic von Bohmen, von Franz Ambros Reufs, vol. 2. A R R A N. 27 a clay-porphyry is to be obferved ; and upon the brow of the hill, where the rains, &c. have broken down the porphyry, fe- veral curious phenomena appear. In the firft place, I obferved the porphyry in columns fimilar to thofe at Corygills : next, the bafaltic veins running in different directions through it. One great vein is to be obferved rifing from the neighbouring fandflone, penetrating the clay-porphyry ; and, as it rifes up- wards, getting a considerable curve, when it branches : one branch rifes to the top of the hill ; the other runs but for a ihort way into the porphyry, in the form of a wedge. Near to the fame place a curious Jlratified vein makes its appearance, running in an almoft oppofite direction to that we have juft mentioned, and terminating in a wedge-like form. On the upper fide it is formed of fandflone breccia ; the lower is hard filiceous fandflone ; but the middle is bafalt. The wefl or upper end of the glen is formed of fandflone pretty much traverfed with veins of bafalt, which are more or lefs in- clined, and of various diameters. Befides this fandflone, we obferve lofty precipices of fienite, which form ftrata elevated at an angle of about 30. This rock is not only very much varied in the nature of its conflituent parts, but alfo in the de- gree of intimacy of combination, which renders it very diffi- cult to diflinguifh its different fpecies. It is alfo traverfed with D 2 veins ..S A R a A N. veins of bafalt, but not fo much fo as the fandftone *. It- forms the higher part of feveral of the hills betwixt the top of this glen and the Shifkin, and is alt along traverfed with ba- faltic reins. It appears, from the defcription that has been now given* that the fandftone forms by far the greateft part of the glen ; the next in proportion is the porphyry, and laflly the fienite, The *' Dr. Hutton, in his fpeculations upon the theory of the earth, remarks, " k If it be by means of heat and fufion that ftrata have been confolidated, then, " in proportion to the degree of confolidation they have undergone from their, " original ftate, they fhould, cateris paribus, abound with more feparations in the mafs. But the conclufi^m is found confiftent with appearances. A ftratum of ''fandftone does not abound fo much with Gutters and veins as a fimilar ftratum " of marble, or even a fimilar ftratum of fandftone that is more confolidated : ** they are in general interfered with veins and cutters ; and in proportion as " ftrata are deep in their perpendicular feftion, the veins are wide, and placed at " greater diftances." This does not appear to be confiftent with the faft ; for it is to be obferved, in Arran, that the fandftone contains more veins than the fienite, which laft is harder than any fandftone in the ifland ; and we obferve that the.. fienite contains a greater number of veins than the granite, although it be fofter and lefs compact. A 31 R A N. 29, The determination of the relative pofition of flrata and veins is the great object of the geologift, and without it his labours will be of comparatively little value. It is, no doubt, of im- portance to know that a country is compofed of particular kinds of rock : yet this will be very unfatisfactory, if we know not whether thefe rocks be primary or fecondary, how they lie with regard to each other, and, confequently, if they be fa- vourable for the appearance of metallic veins, coal, &c. Ma- ny travellers, as my friend M. Camara de Bethencourt has ob- ferved f, fatisfy themfelves, in their geological obfervations, by following a very fuperficial and abfurd mode of inveftigation. Thus, fome are contented to fit in their carriage and view the rocks as they pafs along ; others, with more apparent curiofity, examine the debris at the bottom of the hills, and, by means of their telefcopes, determine the nature of the higheft moun- tain. It is plain that thefe practices muft be very detrimental to the advancement of true geological knowledge : they are the more fo, when we conlider, that the greateft labour and afli- duity is often employed in vain to delineate the true geological character of fome parts of a country. In the courfe of my li- mited travels I have experienced the truth of this obfervation ; for, after having fpent many days in endeavouring to deter- mine f Neues Bergmannifches Journal. B. i. 272, 30 A R R A N. mine the relative poiition of certain ftrata to each other, I have been obliged to reft fatisfied with a general conclufion drawn from the nature of the furrounding rocks. Thus, in Glencloy, I could not difcover the porphyry and fandftone at their junc- tion ; yet, if we confider that the porphyry, both here and at Corygills, is found upon the fummit of 'fandftone hills, and that, in this place, we obferve the fame bafaltic vein apparently traverfing the fandftone and porphyry, we may prefume that they are of the fame formation, and that the porphyry covers the. fandftone. We have more certainty with regard to the iie- nite, which appears to be of an origin anterior to the fand- ftone ; as is pretty well {hewn from the appearance of a brec- cia that lies upon its furface, which had been interpofed be- tween it and the fandftone, before the caufes which formed the glen had removed the fandftone. GLENSHIRREG. This glen is of considerable extent, bounded upon one hand by Glencloy, and on the other by Glenrofa. The hills towards the W. are not fo rugged as thofe at the top of Glencloy, and both the bottom and fides are formed of the common fandftone, much traverfed with veins of bafalt ; but towards the S. W. we obferve a clay -porphyry, which forms part of the rocks higher up than the fandftone, and is, in facl, part of the mafs we obferved before in Glencloy. GOAT FIELD. A R R A K. 31 GOATFIELD. This mountain, according to ProfefTor Play fair, is about 2945 feet above the level of the fea, and is reckoned the nighefl in the ifland. It rifes pretty rapidly from the fouth fide of Brodick Bay, until we arrive at the region where the mi- caceous fhiftus difappears. At this height there is a kind of irregular plain, from which the mountain rifes in the form of an obtufe pyramid, and is very precipitous, being entirely formed of granite. On the W. where it forms part of Glen- rofa, it is extremely deep, which is owing in a great meafurc to the want of micaceous fhiftus and fandftoue ; for, in general, wherever thefe occur the declivity is lefs fudden.. On the eafl fide the pente is more gradual ; marking, according to the fteep- nefs, the prefence of granite, micaceous fhiftus, or fandflone. It declines a little towards the N. but it rifes again, forming one of the boundaries of the rude Glen-Sanicks : it alfo fopms- the top of the bare, rugged and flerile Cory-Glen, and the top of the, other two great hollows between the Cory-Glen and Glen-Sanicks. The lower part of Goatfield is compofed of the ufual red- coloured fandftone, and is traverfed by veins of bafalt ; this continues for feveral hundred feet up the mountain, when it at laft difappears : the micaceous fhiftus rifes from under it, fe- parated only by a ftratum of breccia, thus fhewing the relative pofition 0^ A R R A N. pofition of the fandftone and micaceous miftus. The micace- ous miftus continues until we arrive at the plain formerly mentioned ; but the fide of the mountain, in fome places, is fo covered with the debris of granite, micaceous miftus, &c. that it is only by the appearance of the granite, in the neighbour- hood of this plain, that we are aware of its exiftence, as the afcent is hardly more fteep over the micaceous fhiftus than the fandftone, which is not generally the cafe ; for we find, when the ftrata are not covered with debris, that the fandftone is far lefs fteep than the micaceous miftus, and this laft than granite. Even in this way, we have a kind of general rule for judging i)f the nature of mountainous ridges. If they be neaked, and very precipitous, we may prefume that they are of granite ; if they be lefs lofty, and not peaked, but ftill fomewhat ap- proaching to the conical fhape, we may fuppofe them to be compofed of micaceous fhiftus ; and, laftly, if we obferve thefe fkirted by lower mountains, with a trifling pente, we may con- clude that they are compofed of fandftone and limeftone. Al- though thefe obfervations may hold true in general, yet they will fometimes be found liable to confiderable variations : thus we know that the fhape, and other appearances, of moun^ tains compofed of fimilar rocks, are apt to be varied by feve- ral circumftances, particularly by the horizontality or verti- cality of the ftrata, their degree of compadnefs, and their aptnefs A R R A N. 33 apthefs to be weathered. It would be an addition of fome confequence, if we had a few general rules on this fubject. SaufTure well remarks, " Les fignes qui peuvent donner ; qualque indice de la nature des montagnes, a de grandes " diftances, et au travers des plantes qui les couvrent, font en " petit nombre, et meritent d'etre etudies et confacres par des " termes propres." The pyramidal part of the mountain has a very fterile and wild afpeft ; being completely covered with loofe blocks of gra- nite, and deftitute of all vegetation, excepting a few lichens, which only add to its bleak appearance. Thefe blocks differ very much in fize, fome being twenty feet long *, and gene- rally of a quadrangular fhape ; and are fo heaped upon each other, as to render the afcent very difficult. Having, however, gained the fummit, we are well repaid for our labour by a moft extenfive view of a wonderful diverfity of country. To the E northward * Dr. Walker has obferved immenfe folid mafles of granite in different parts of the Highlands : but thefe are vaftly inferior to others that have been found in other countries. About thirty miles from the Cape of Good Hope there is a large mafs of granite, called the Pearl Diamond, which is about half a mile in circumference, and 400 feet high. Ph'd. Tranf, 1778, p. 102, 34 A R R A N. northward we look down upon the peaked fummits and deep glens in the neighbourhood of Goatfield, whofe arid and reddifh appearance fuggefls to our minds the effects of a dreadful conflagration. Beyond thefe, the iflhmus of Cantyre, the ifland of Ifla, the lofty and dreary paps of Jura, the long mountainous ridges of Argylefhire, and the far-diftant moun- tains of Mull, which are faintly defcried, prefent a view rather to be felt than defcribed. On the E. the well cultivated ifland of Bute, the frith of Clyde, the Cumbray Iflands, backed with the beautiful coafts of Renfrewfhire, form a mofl piclurefque fcene. Towards the S. we have, below us, the lower part of the ifland fpread out like a map, forming a fuigular appearance of heath-covered mountains and cultivated glens : farther di- tant, the charming coafts of Ayrfhire, the mores and moun- tains of Galloway, aa far as the Mull, the ftupendous craig of Ailfa, rifing from the bofom of the ocean, all delight the eye and raviili the imagination. Laftly, on the W. the coaft of Ireland,, from Fairhead to Belfaft Loch, concludes the amazing view from this interefting height. GLENROSA. This very finking glen, fituated upon the weft ' and fouth-weft fides of Goatfield, is about five miles long, and half a mile broad, bounded by very high mountains. The bottom. A R R A N. 35 bottom forms a confiderable angle with the fides, rifing gradu- ally towards the upper, or north end, where it is formed part- ly by the mountain called Keid-voe, and partly by Goatfield. The mountains on the oppofite fides of the glen are of differ- ent heights, (being far higher on the eafl than weft ;) but the inclination of the oppofite flopes is the fame, being about 70. At its entrance upon the fhore at Brodick Bay, it has Goatfield on the north, and Glenfhirreg on the fouth. Oil the fouth fide, the ftrata are common argillaceous fandftone, traverfed by bafaltic veins ; but this continues only for a fliort way, as the micaceous fhiftus foon makes its appearance. Upon the north fide, a very little fandftone is to be obferved at the bottom of the hill, the upper part being formed of micaceous fhiftus. Amongft the debris of the micaceous fhiftus I obferved great blocks of a rock, which is principally compofed of hornblende, and now and then intermixed with quartz, and a fubftance that appears to be the fame with the paliopetre of SaufTure. The micaceous rocks upon both fides of the glen lie upon granite, which foon prefents itfelf as we proceed up the glen, and forms the mountains upon both fides to its further extre- mity. This granite, which is fimilar to that of Goatfield, ap- pears to be difperfed in great ftrata, that run N. and S. which is nearly in the direction of the glen. If we view them from E 2 the *6 A R R A K. the bottom of the glen, they appear like great perpendicular walls, which are fplit in many places into rhomboidal maiTes j but if we clamber upwards for fome hundred feet, we at length difcover the edges of the ftrata, extending for a great way, and emerging here and there from above the loofe blocks of granite, which have fallen from the mountains, or have been formed by the fplitting of the banks themfelves. It was long believed, by geologifls, that granite never occur- red in ftrata, but merely formed great maffive mountains. This has been mown to be erroneous by many later obfervers ; yet La Metherie, in the laft edition of his Theorie de la Terre, fpeaking of granite mountains, remarks, " Les mafTes ne font " ni par banes, ni par couches, comme 1'ont pretendu de fa- " vans naturaliftes. J'ai parcouru une grande quantite de ter- " reins primitifs, et je n'y ai jamais vu de couches. Quelque- " fois on appercoit des mafles affez confiderables de granites, " ayant une figure prefque rhomboidale, fuperposes les uns " fur les autres. Mais on ne fauroit regarder ces luperpoli- " tions pour des couches, puifqu'elles n'ont rien de regulier, " et que ces malTes, prefque rhomboidales, ne fe rencontrent " que tres rarement. Le plus fouvent ces granites font fen- " dues, en differens fens, Ces fifTures fe correfpondent ** quelque- A R R A N. 37 " quelquefois j ce qu'on prendroit, au premier coup-d'ceil, " pour des efpeces de couches ; mais un exameii plus appro- " fondi en fait bientot reconnoitre la difference f." To thefe obfervations we will oppofe that of feveral geologifts who have obferved ftrata of granite, fimilar, I imagine, to thofe which occur in Arran, in different parts of Europe. The late cele^- brated M. Sauffure, whofe accuracy of obfervation is not to be queftioned, difcovered granite difperfed in ftrata in many parts of Europe ; as may be feen by confulting his moft inte- refting and elegant volumes. Reufs, in his mineralogical geo- graphy of Bohemia, has detailed minutely many fimilar ap- pearances ; and my learned friend Dr. Mitchell informs me, that the Reifenbergs, a chain of mountains which feparate Si- lelia from Bohemia, are compofed of granite, for above fifty miles, and in this long courfe it is invariably difpofed in ftrata nearly horizontal J, Upon the eaftfide of the glen feveral curious appearances are to be obferved. Of thefe, the moft interefting are the bafaltic veins, f Tom. iv. p. 352. J Mr. Kirwan, in his Geological Effays, refers to feveral other authors who defcribe granite difpofed in ftrata* 3$ A R R A N. veins, which traverfe the granitical flrata, as they do the por- phyry and fandflone *. The firft vein which I difcovered, be- ing between three and four feet in diameter, is to be obferved rifing through the granite, feveral hundred feet above the bot- tom of the glen. Its lower part is hid by the heather, and loofe blocks of granite, which cover the fides of the mountains. As it rifes upwards it becomes gradually narrower, and at laft di- vides into two branches, which run through the granite, con- tracting and enlarging their diameter from a few inches to more than two feet. The extremity of one of thefe branches appears either to have been broken, or fo funk inwards as to caufe one part of the branch to appear feparated from the other, as is reprefented in the plate ; where A is the granite, B the ba- i ^HA ' / fait vein, C the branch having the appearance of being fepara- ted from D by intervening granite J. In the body of the great vein * However commonly we obferve bafaltic veins traverfing the granite in this ifland, yet it appears to be a rare occurrence in other countries. Reufs never ob- ferved it in Bohemia ; and Sauflure, in a late communication to the Bibliotheque Britannique, affures us that he never obferved any bafaltic rock among granite. Bibl. Brit. vol. vii. t Rocks which are difpofed in flrata prefent fimilar appearances with the vein above defcribed, and of this we have a curious example in Saliflmry Craigs near Edinburgh. This hill, which is entirely compofed of rocks of trap forma- tion. A R R A K 39 vein there is immerfed a confiderable wedge-maped piece of gra- nite, marked in the plate at E ; which has the ufual liardnefs, colour, &c. of that fpecies of which Goatfield is formed* The granite and bafalt are not intermixed at their junction ; no mat- ter is interpofed ; and they are not altered in the leafl by being in contact with each other. In the neighbourhood of this vein were found fpecimens of rock cryflal in cavities of the granite ; and fome of the cryflals were of confiderable fize, but generally of a fmoke colour. I alfo picked up a fpecies of granite fimilar to the pierre graphic which is found at Portfoy *; alfo a (lone much refem- .- tion, affords fome fine views of its ftratification, in a lofty cliff that extends around a confiderable part of it. Towards the north extremity of this cliff, the red-co- loured fandftone, which lies below the bafaltic rock, is much waved in its courfe, and, at one place, a part of the fandftone ftratum, appears detached and immerfed in the bafaltic rock. The inclofed piece of fandftone is of great fize, ftill pre- ferves its ftratified-like afpeft, only it is very hard. Dr. Hutton reckons it a ftrong proof of the truth of his theory : but Mr. Deriabin, an intelligent mineral ogift, who examined it along with me fome time ago, thinks, that the ftratum is not broken, only that it finks behind the bafalt, as I have conjectured may be the cafe with the vein above defcribed. Dr. Hope informs me that feveral fimilar ap- pearances are to be obferved in the neighbourhood of Edinburgh. * I found a fimilar rock among fome foffils fent me from Hudfon's Bay ; and, by a late memoir of Patrin in the Bibliotheque Britannique, (vol. 8. p. 78.) it proved alfo to be a produ&ion of Corfica,' 4 o A R R A N. refembling the veined granite of M. SaufTure ; and likewife a curious fpecies of granite, where the quartz, felfpar and mica were diflributed in a radiated form, as is the cafe with many zeolites. Near to the fummit of Goatfield I picked up Several pieces of rock, which is evidently the fame with the paliopetre of SaufTure, which he found loofe near to the fummit of Mont Blanc in Switzerland f. Lower down, but upon the fame fide of the glen, many fragments of bafalt are to be obferved, lying upon the fides of the mountains, mowing the prefence of bafalt veins ; and at the Keid-voe a great vein is to be feen, rifing perpendicularly through the granite. Nearly at the fame place, I was much furprifed to find feveral columns of dark leek-green coloured pitchflone lying amongft the debris of the granite ; but, after confiderable labour, I was not able to dif- cover its fituation. Not far diflant from this, in afcending towards the fum- mit of Goatfield, amongft the loofe blocks of granite which cover its fides, I obferved a curious appearance. Upon breaking f Voyages dans les Alpes, torn. 70*6, p. 275. A R R A N. 41 breaking thefe rocks, with an expectation of difcovering rock cryflal, I found in feveral of them mattes of compact granite, of different fizes, either rounded or angular. Somewhat fimi- lar appearances have been obferved by other mineralogifls : thus Mr. Werner has in his pofleflion a mafs of granite which contains pieces (gefchiebe) of gneifs * ; Mr. Rofter found be- tween Ellbogen and Schlackenwalde, in Bohemia, a great- grained granite f ; and Mr. SaufTure obferved a mafs of granite which contained an oval piece of gneifs J. Mr. Werner rec- kons his fpecimen a proof that the gneifs is of earlier forma- tion than the granite ; in other words, that the pieces of gneifs have been broken off a ftratum which was depofited before the granite. Mr. SaufTure, however, is of an oppofite opinion : he is inclined to believe that thefe pieces of granite or gneifs have been formed fimultaneoufly ; and that they have, by fome peculiar circumflance, affected a rounded form, which is not manifefted in the other parts of the rock. This conjecture is rendered more probable from the following fact : " I have of- " ten ieen, fays he, in veined granite, rounded pieces of a far F " finer * Werner, Kurze Klaffification der verfchiedenen Gebirgsarten, f Emmeiling Lehrbuch der Mineralogie. B. 3. J Voyages dans les Alpes, 4.2 A R R A N. " finer grain, which neverthelefs had been formed fimultane- " oufly, fince we obferved the continuity of the layers of the " fine-grained, with that of die granite in great grain and " thick layers." The weft fide of the glen is formed in part by a granitical mountain, named Ben-echleven, which prefents to us the great flat fides of the granitical ftrata. Its top is covered with enor- mous blocks of granite, which reft upon it in a moft fantaftical manner. This mountain declines rapidly towards the N. E. forming a tremendous hollow, named Cory-dain, whofe bot- tom is far elevated above that of Glenrofa, but is lower than the bottom of the next hollow, named the FeUn-hody, which is raifed far above either, prefenting to the bewilder'd eye an amazing fcene of ridged and peaked rocks of granite. In the Cory-dain, the granite, at firft fight, appears to be ftratified ho^ rizontally ; but an examination mews us that is owing to the fplitting of the granite. Here alfo we obferve the granite di integrating, in the form of fand, and, what is more rare, de- compofing in the manner of fome fpecies of bafalt, that is, in crufts *. SaufTure, fpeaking of this kind of decompofition, re- marks ;. * Granite decompofes in concentric layers Charpcntier Mineralogifche Geographic Lin. SALTES COLUMNARIS, Waller. ARGILLA BASALTS, Werner, COMMON T&AP, Kirwan, BASALT-*- f Journal de Phyfique. Vol. 40. p. 215. $ Lehrbuch der Mincralogie. B. i. J 264. it R A is. BASALT South Side. <-.f Gkuch\\ Colour. Black. Luftre. A number of fhining particles difperfed through it, which is probably hornblende *, ^Tranfparency. None. Hardncfs. Scarcely gives fire with fleel. Frafture. Even earthy, but is very compact;. By decompoiition acquires a brownifh-coloured tegmen. BASALT, which forms a vein running in the porphyry Head of Glencloy. Colour. Lavender blue, intermixed with yellowifh green ; by decompofition, red. Lujire. None. 'Tranfparency* None. Hardnefs. Yields pretty eafily to the knife. Frafture. * Hornblende having been found to contain charcoal, or probably carbone, as a conftituent part, has been ingenioufly mentioned by Dr. Walker, as one fa&, to fliew the tranfition from plumbago to hornblende, which he imagines he has obferved in feveral other inftances. r i A R R A N, FracJure. Rather uneven fine fplintery. Fufibility. Melted at 103. BASALT, which forms veins traverfmg the granite Eajl Side of Glenrofa. Colour. Greyifh, or black. Lujire. A number of cryftals of hornblende, difperfed through it, give it a flight degree of luftre. Transparency. None. Hardnefs. Gives a few fparks with fteel. FracJure. Uneven earthy. Gives a grey trace. Fufibility. Melted at 58. This fufibility diftinguifhes it from the fpecies of bafalt examined by Mr. Kirwan. He found them fufible from 120 to 130; and the figurate trap, or columnar trap, melted at 100. It contains yellow-coloured olivin, and in greater quantity than I have obferved in other fpecies. In the former edition of this work, I conjectured that both the pitchftone and bafalt might contain potafh. Since that pe- riod, Dr. Kennedy has analyfed bafalt, wacken-porphyry and greenftone, and thefe he finds to contain a fmall portion of foda A R R A N. 55 foda and muriatic acid J. Dr. Mitchell, to whom I commu- nicated Dr. Kennedy's experiments, has lately repeated them upon the famous bafalt of Stolpen, but obtained a very diffe- rent refult. Having detected a fmall portion of muriatic acid, he then powdered a quantity of the ftone, and mixed it with fulphuric acid ; then diftilled to drynefs, and lixiviated the folu- tion : the folution was decompofed by the acetite of lead ; the fu- pernatant liquor was then evaporated to drynefs, and the acetous acid burned off. The refidue, which was pure alkali, afforded, vrith nitrous acid, prifmatic nitre : a decifive proof of potafh. S I E N I T E. , Marmor. PrROPOEcrLus, Plin. et Al. Dr. Walker's ClaiT. Foffil. GRANITES SIENITES, Gmelin. Syft. Nat. This rock we have remarked forming ftrata at the head of Glencloy, and it occurs in many other parts of the ifland : I mall now mention its external characters. To prevent repeti- tion, I will fhortly detail the different fpecies, placing the in- gredients in their order of proportion. i. Felfpar; * Tranfa&ions of the Royal Societj of Edinburgh, vol. 5th. A R R A N* \n< i. Fellpar; reddiili. Hornblende ; green, and fometimes black. Quartz ; white, and fometimes brown. This fpecies is more or lefs compact, and is ibmetimea fhiftofe. a. Hornblende ; green* Quartz. Felfpar. This aggregate, which is almoft entirely compofed of horn- blende, has the following characters : Colour. Dark leek-gren. Luftre. A mimber of mining points difperfed through the the mafs, owing to the hornblende. Tranfparency. None. Hardnefs. Gives fire with fleel, but not very plentifully. Leaves a grey trace. It is difficultly diftinguiihable from many fpecies of bafak, and is often intermixed with patches of the firft fpecies* 3. Quartz. Felfpar. Hornblende. This fpecies, oxving to the great proportion of quartz, has much the appearance of a fandftone. .}. Horn- A R R A J^ 2 4. Hornblende. Quartz. Felfpar ; greenifli-coloured. The hornblende, in this compound, has fometimes a metal- lic iuftre, approaching to the nature of fchiller fpar ; and the felfpar is tinged green, owing to the difFufed matter of the Jiornblende. OBSERVATIONS. The different fpecies of fienite were long confounded with bafaltic and granitic rocks : a circumflance which was owing, not only to the want of an appropriate name, but to the diffi- culty of diftinguimiiig the gradations. Werner firfl named it greenftone ; but he now calls it Sienite, from a conviction that it was a fimilar flone which Pliny defcribed as being found at Sienna in Upper Egypt. In antient times it was quarried in great quantities at Sienna ; and from thence was brought to Rome for the building of great public edifices, and for the ufe of the flatuaries, who worked it into pyramids, obelilks, &c. The famous Sarcophagus of Cheops, and Porsapey's Pillar at Alexandria, are now known to be of fienite. H 5$ A R R A K. As the difcovery of metallic veins is one of the great objects of mineralogy, we think it not out of place to introduce, among the general obfervations we may have occafion to make during the courfe of the work, a fhort account of the different veins of ore which have been obferved traverfing fimilar rocks in other countries. In purfuance of this plan, we may re- mark, that fienite, in fome places, is rich in metals : thus, at Schauffenberg there are veins of filver and lead, and part of the productive Altenberg mine-works are in fienite : we believe that the veins of Strontian in Argylefhire run in a U milar rock. CLAY PORPHYRY Cory-Gills. PORPHYRY, German. Colour. Brownifh bafis j by decompofition, acquires a white tegmen. Lujlre. None. 'Tranfparency. None. Hardnefs. Is difficultly fcraped with a knife. Fra&ure. Splintery. Smell. Strong earthy fmell, when breathed on. FELSPAR AURA FELSPAR Is of a brownifli colour; fometimes white and cryftallized. Is of various colours, white, yellow, or fmoke ; of different fhapes, angular, rounded, or regularly cryftallized, prefenting often fix-fided pyramids, which is a rare appearance in porphyry : it is alfo fometimes difperfed through the bails in the form of firings. Po R P H y R Y Glencloy* The bans of this porphyry differs, in general, but little from that of Corygills : in particular inftances, however, we obferve it nearly in the ftate of hornftone, and having the following characters : Colour. Grey. Lujlre. None. Tranfparency. A very flight degree at the edges, Hardnefs. Gives a few fparks with fteel. FraElure. Even. SmelL A ftrong Imell, when breathed on. H 2 The R R A The cryftals of felfpar are much larger than in the clay- porphyry ; and, befides, I obferved it to contain a foftifh Jub- ilance, probably fteatitical. The true porphyry was long confined by mineralogifls to a particular flone which was fuppofed to have a jafpideous bafis * r but Werner has extended its fignification much farther, and now reckons eight different kinds. It would be ufeful here to follow the Linnaean mode, by dividing them into diflindl ge- nera ; and then the fpecies might be defcribed in fhort charac- ters, as has been done in botany. This will probably be rec- koned ufelefs labour by thofe who think that foflils are not capable of fuch arrangement : we are well convinced, however r that r in the prefent inflance, as well as in many other parts of mineralogy, much good may be done by fuch attempts. In modern times, porphyry has been principally ufed for ornamental purpofes ; and, where compact, it has been found to anfwer well for millflones. The Greeks and Romans ufed it for the conftrudlion of their finefl edifices ; and the ftatuary often cut it into burls, vafes, 6cc. of the mod exquilite work- manfhip. The A R R A N, 6l The porphyry in this ifland, fo far as my experience goes, does not afford any veins of ore ; yet in other countries it is fometimes productive. Thus, in different parts of Germany, a fpecies, fimilar to what we obferve in this ifland, has been found to contain veins of tinilone, iron ore, manganefe, ga- lena, and molybdsena. SILICEOUS SHISTUS. GEMEINER KIESELSCHIEFER, Wern. HORNFLINT. Among the debris which covers the bottom of Glencloy, I discovered fpecimens of a rock which feems to be filiceous fhi tus ; but I could not difcover it injtttt. It prefents the follow-, ing characters : Colour. Grey, or greyifli black. Luftre. None. Tranfparency. Tranfmits extremely little light at the edgesv Hardnefs. Gives fire plentifully with fteeL Fraflure. In the grofs, flaty ; of the fingle plates, more or lefs fine fplintery, inclining to the even. It has difperfed through it grains of quartz, and very mi- nute A R R A N, mite particles of a fofter fubftance, whofe nature I could not determine. GRANITE. GRANITES GENVIXUS, Lin. GRJNI ES DURUS, Cronfted. SAXVM quartzo, fpato fcintillante et mica in diverfa proportions mixtis, compofttum; Waller, Syft. Miner, vol. i. p. 407. The granite of this ifland is, in general, pretty compact ; of a whitim-brown colour, owing to the flight-brown tinge of the felfpar. To defcribe all the varieties that occur might be ufe- ful ; but that is more adapted for a fyflematic treatife of mine- ralogy than an outline of this kind. I {hall only, therefore, give a particular account of two fpecies ; the Great-grained, or Common Species, and the Small-grained. I. GREAT-GRAINED GRANITE. This fpecies is not only remarkable by its forming a very confiderable part of the folid materials of the ifland, but alfo on account of the peculiarity of its compofition ; as it frequent- ly contains three fpecies of felfpar, and the quartz is often cry- ilallized. A R R A K. ifl Species i FELSPAR Is of a white colour, with a flight ten- dency to the brown; having the ufual luflre, tranfparency, and hardnefs. id Species^ ADULAHIA f Colour. White. Form. Either in amorphous mafTes, or cryftallized in hexa>- haedral prifms, bevelled at both ends. Liiflre. External, like that of cryftals not much polifhed ; in- ternal, fame. tranfparency. Sometimes objects can be feen pretty diftinclly through the cryftals j but when they are a little decompofed, opacity is produced. Fr attar e. Plain foliated, and fometimes ftriated. Hardnefs. Gives fire, plentifully with fleel. Fufibility. At 1 00 the furface was formed into a. yellow-co- loured enamel. $d Species Is of a white colour, having nearly the ufual hardnefs, fracture, &c. of the common felfpar ; differing prin- cipally in the luftre, which is like that of polilhed metals, re- fleding, in certain directions, a filver light. A R R A tf, 5 Is frequently colourlefs ; alfo greyifh, pale yellow, pale, or dark brown, and fometimes nearly black, when it is called Morion. Is very often cryftallized ; and either in the form of hexan- gular prifms, terminated by hexangular pyramids at one or both ends, and the prifms are feamed acrofs. The cryftals are fometimes found feveral inches long, and from two to three inches diameter; of a pale brown, or rather fmoke colour. Thefe lafl are much valued by the lapidaries. MICA Is often black; fometimes golden yellow, tombac brown, or green. It is generally in the form of irregular plates ; and pretty frequently hexagonal plates occur, which, being fuperimpofed upon each other, form a hexagonal figure of fome magnitude. It is the mica lamelleuse hexagone of Rome d'Ifle, (vol ii. p. 509.) and the hexagonal mica of the Abbe Huay, (Miner, vol. v. p. 296.) The confiituent parts of the granite are very various in their proportion ; but, in general, the felfpar forms the moft confi- cu iAAVING now given a pretty extended description of the ftrata and foflils in the neighbourhood of Brodick Bay ; I hall, in the next place, proceed to trace the flrata round to Loch-Ranza, which is fituated upon the north-weft fide of the ifland. Trom Brodick Bay, the cliffs all around are low, and, for a great way, compofed of the ufual red fandftone, which is much traverfed by veins of bafalt, of various widths, and run- ning in different directions. Coves occur in feveral places, but none are of confiderable fize : frequently calcareous ftalac- tites hang from their roofs. The action of the fea upon the fandftone has given a fingular afpecT: to the whole fhore ; owing I 2 tO 68 A R R -A N. to foft fandflone being warned away, while the more compact and hard, which appears to have been formed in fifTures, is left {landing in long ridges, or criflae. The fandflone, as it rifes upwards, forms part of the lower region of Goatfield, in the vicinity of the micaceoxis fhiflus, which it, in all probability, covers. About a mile from the Cory, nearly one hundred feet above the level of the fea, there is a flratum of limeflone, about twelve feet thick, running at an angle of 20, and co- vered with red-coloured argillaceous fandflone ; but, below:, interpofed between the limeflone and fandftone, there is a layer of a red fhiflofe clay. In this clay I obferved regular fe- ries of fliells, depofited in layers, (all appearing of the fame fpecies,) with their convex fides regularly downwards. The flratum is fometimes flraight, but often waved and twifled. It alfo frequently contains radiated calcareous cryflals, which are of a reddifh colour, owing to the admixture of iron. In a nfTure of the fandflone, above the limeflone, I obferved fla- lactites of peat, of confiderable fize and confiflence, which ap- pear to have been formed by the infiltration of the foluble peat- matter through the fandflone. To the N. of this flratum there is a confiderable ravine, which luckily afforded me an opportu- nity of obferving the junction of the different ftrata. Here I traced the common red-coloured argillaceous fandflone from the more to a confiderable height, and, in fome places, ob- ferved A R R A N. 69 ferved it intermixed with fragments of quartz ; thus forming a kind of breccia. As we approach the primitive rocks, the fandflone flrata become more elevated ; and, at length, I ob- ferved it lying on a compact fhiftofe rock, which appeared to be of the nature of micaceous fhiflus ; but it was fo much de- coinpofed by the action of the weather, that I could not well de- termine exactly as to its particular defignation. This micaceous miftus ? continues but for a fhort way, when it is to be feen lying on the granite, which rifes upwards, forming a very deep afcent, which leads to the rugged and flerile-looking Coryglen. This glen is very precipitous on all fides ; is broader than any in the Goatfield groupe> but is comparatively fhorter : its. bottom is higher than that of Glenrofa, but not fo much ele- vated as that of the Cory-dam or Feun-hody. It is entirely eompofed of granite ; whicll'is here fplit, as ufual, into im- menfe blocks, that are piled in vaft tumuli upon the tops of the furroundiiig mountains, or cover the fides and bottom of the glen, as with ruin and defolation.. Having returned again to the fea-fliore, I continued my journey j and, as I approached the Cory, obferved a vein of foft, red, fhiftofe fandflone, containing rounded pieces of ar- gil running through the fandfhone N. E. and S. W. At the Cory, where there are a few houfes, I obferved quarries of fandftone v *j7O A R R A N, iandftone, of a beautiful white colour, and of good confiftence for building. Thefe quarries are now worked, by a company, for the conftruction of the Crinan Canal. Here there is alfo a ilratum of limeftone, about thirty feet thick, confiderably in- clined to the horizon, running N. N. W. and divided into ftra- tulse, as the ftratum formerly mentioned, with intervening clay and {hells, but the clay is more or lefs indurated. From this towards Weft Sanicks, the more is compofed of the com- mon red-coloured fandftone, interfered here and there with veins of bafalt ; but it is often fo covered with bowlder ftones of different kinds, as to render travelling very difficult. The rounded mafles of granite, fcattered up and down here, are of a moft aftonifhing fize ; fome of them hundreds of tos weight. Near to theSanicks, there is an immenfe ftratum of breccia, which is compofed of rounded fragments of quartz, and micaceous ihiftus, cemented by an arenaceous ground. The breccia is in many places much broken. Immenfe mafles of it, many hund- red tons weight, lying feparated from the ftratum only a few feet, render it probable, that thefe mafles were difunited by froft. In one place, I obferved, a confiderable fection of the breccia, which I examined very carefully, in order to difco- yer if the mafles of quartz, were comprefled and fmaller at the lower than the upper part, but no difference could be ob- . vcd, Very remarkable inftances of this kind have been ob- ferved A R R A N. ~i ferved in other countries; thus in Bergm. Erde-Befch. 182, we are told that in the mountains of Quedilia? and Portfiasllet in Norway, which confifl of an' argillaceous puddingftone, the filiceous pebbles it contains, are obferved to be compreffed to the thicknefs of the fourth of an inch, in the lower parts of the mountains, but to increafe in fize and roundnefs in proportion as their fituation is higher. Alfo in the Yivarois, the lowed ftrata of primitive limeftone, have been found of the thicknefs of one-tenth of an inch ; but in proportion to their elevation in the mountain their thicknefs increafes, until at its fummit, it arrives at thirty or forty feet. i. Soulavie, 178. Ferber made the fame obfervation in England. At a little di fiance from the more, is the entrance into the deep South Glen-Sanicks, which is about four miles long, running nearly E. and W., and bounded on both fides by lofty mountains. As I obferved a confiderable flream of water running through this glen, I determined to examine it, as it was probable that the ftrata would be well expofed. Having walked for upwards of a mile in the direction of the glen, 1 defcended into the ravine formed by the water, but found 1 ftill the ufual red-coloured argillaceous fandftone. As we con- tinued clambring upwards, I obferved feveral veins of fulphat o barytes, fome nearly four feet wide, travelling the fand- ftone ; J2, A R R A N. ftone ; and, by a little care, I obtained fpecimens pretty well cryftallized. About a quarter of a mile further on, a very compact arenaceous breccia (principally compofed of rounded pieces of quartz, and a fpecies of bafalt, which has, interpofed, grains of felfpar, and a yellow fubflance,) makes its appear- ance ; and this extends to a confiderable diftance ; but it is at length apparently interrupted by a flratum of hornblende rock. This flratum of hornblende rock is only a few feet wide ; and it appears to lie immediately on the granite. I have to regret that I could not obtain more fatisfaclory views of the junction of thefe ftrata, owing to the great covering of debris. I am fomewhat confident, however, that the difpofhion of the ftrata is pretty nearly as now ftated, viz. that in the lower parts, and for a confiderable way upwards, is argillaceous fand- ftone ; next, arenaceous breccia ; then a bed of hornblende rock ; and, laflly, granite. The glen is now bounded by lofty granite mountains : on the N. is the Caimes, with part of Caime-na- caillich ; and, towards the S., Keich-na-hien and Goatfield form boundaries awfully grand. Its fides are much furrowed by the action of the rain : which circumflance, with the red colour of the decompofing granite, the immenfe granitic blocks which cover the fides and tops of the mountains, form alto- gether a fleril and tremendous fcene. In . A R R A N, 73 \ In lonely regions, here, retired From little fcenes of Art, great Nature dwells In awful folitude. Here I obferved feveral veins of bafalt traverfing the gra- nite ; and, in fome places, I could trace the perpendicular veins from the top to the bottom of the mountains. At the top of this glen, is the hollow called Cory-na-huave, which is bounded by Caime-na-callich and Keid-voe. Its bottom is higher than that of G len-Saiiicks ; and is entirely compofed of granite, traveried with veins of bafalt, fome of which have a confi- derable degree of curvature. Having examined this glen as far as my time would permit, I was again proceeding toward the fea-fhore, when , I thought it might be interefling to examine the junction of the granite and fliiflus in fome of the neighbouring glens. I therefore changed my courfe, as foon as we came to the rock of breccia which I have jufl defcribed ; and from this I crofTed over a hill of fimilar rock to North Glen-Sanicks. Here we obferved a ilream running through the glen, and in it I found the fhif- tus in immediate contact with the granite. The miflus appear- ed to be a very compact micaceous rock ; but the granite was not intermixed with it at the junction, nor were there any veins K to 7-f A R R A N to be obierved fhoocing from the granite into the micaceous rock. We now crofled over the hills into another glen, where I obferved another junction of the granite and fhiftus, but it prefented nothing remarkable. I now returned again to the fhore, below the entrance of South Glen-Sanicks ; fo that I might proceed regularly on my tour through the ifland. After pafling the Sanicks burn, I found the fandftone, breccia and bafaltic veins flill continuing ; but the appearance of the mountains was much changed. The peaked fummits, and almoft perpendicular, furrowed fides, now difappeared : the mountains were cloathed with heather to their fummits,^ which were more or lefs round-backed: inti- mating an alteration in the materials of which they are compo- fed ; which is really the cafe, as the granite had now difap- peared, the fummits of the largeft hills being of micaceous fhiflus, which, in fome places, alternated with talcaceous fhiflus. I now wandered along a mile or two of fhore compofed of fandftone ; when my attention was arrefted by the remains of workings for coal, at a little diflance from the fea-mark the Cock of Arran. This coal flratum, which is but of fmall extent, runs in the fandftone, accompanied by the ufual coal metals, as, argillaceous ironftone, fhiftofe clay containing numerous vegetable impreflions, &c., and at the bottom of a mountain A R R A ST. 75 mountain of micaceous fhiftus. It is fimilar to that which is found at Kilkenny in Ireland, and is called blind-coal*. I obferved two pits, about fifteen feet deep, which had been dug in cutting the coal ftratum ; but, as the coal foon difap- peared, the pits were left, and the falt-pans which had been erected were rendered ufekfs. The fituation of this ftratum is fuch, as to preclude all hopes of finding any confiderable quan- tity of coal, although frefli fe&ions were made : for we inva- variably find it to be the cafe, that wherever coal ftrata come into the vicinity of high mountains, they then moil certainly decreafe in breadth, and become bad, owing to the great ad- mixture of earthy matter. Thus, many of the feams of coal which have been found in France are trifling, and continue but for a fhort way ; owing to their fituation, being found in rallies that are bounded by granite, or other primary rocks f , K 2 The * Dr. Button conceives that this fpecies of coal prefents an irrefragable proof of the truth of his theory. Here, fays he, is a coal having all the properties of that which has been fubmitted to the aclion cf heat; the bitumen is feparated, and charcoal remains. To the Neptunifts, this affords one of the ftrongefl ar- guments againft the theory. The feparation of bituminous matter fhows a Want of immenfe compreffion, which is the grand fundamental bafis of the hypothefis. It is indeed this circumilance, principally, which diftinguifhes it from, the vol- canic theory, and has led Mr. Kirwan to name it the Plutonic. f Journal des Mines, 76" A R R A N. The great frequency of bafaltic veins is another caufe which may render the coal, if it fhould again be deemed worthy of attention, of an indifferent quality, and difficult to work. From this ftratum to the Cock, which is the mo ft northern point of the ifland, the more is covered with immenfe mafles of fandftone and breccia, w r hich have tumbled from the neigh- bouring hills by the adlion of the weather. Ironftone is found fcattered upon the more, and is probably connected with the coal workings. The Cock is not, as I expecled, a headland, but merely an enormous mafs of fandftone, lying loofe upon the fhore, having a fancied refemblance to the head of the cock. Here the cliffs are of confiderable height, compofed of fandftone and breccia, traverfed with veins of bafalt of various fizes. One of thefe veins is compofed of a reddifh brown-co- loured bafalt, with, interfperfed, white-coloured, apparently cryftallized fpecftein of Werner ; and the bafalt, where it is in contact with the fandftone, is hard, and much refembles horn- ftone. After leaving this, a ftriking appearance prefents itfelf to our view, of the whole face of an immenfe ftratum of breccia, which was {nattered to pieces, and rolled towards the fea, by an intenfe froft fome years ago : the crafh of its fall was heard far off. The fandftone upon this part of the coaft is alternated layers of fhistofe clay ; and where the clay is wafhed away A R R A K. 77 away, the fandstone lies expofed, having the appearance of a regular pavement. If we examine it more nearly, we find the fandstone strata fplit into two, four, or fix-fided irregular fi- gures, and connected together by the clay, which gives it an artificial afpect ; by the decomposition of the clay, the pieces of fandstone are feparated, and lie fcattered on the more, and are apt to be taken for the work of art. From this to within a mile of Loch Ranza, the fandstone, as ufual, forms the cliffs upon the more, and is backed by mountains of micaceous fhistus, upon which it rests. Here, however, the fandstone difappears, and the micaceous fhistus now forms the cliffs, which become higher as we approach Ranza. At the place where the fandstone difappears, there is a great bafalt vein, about thirty feet wide, running in a rock inter- mediate between ardefia and micaceous fhistus. As we ap-r proach nearer to Loch Ranza, the fea has expofed feveral other fimilar appearances, but far more distinct than the first. Thefe veins are of various fizes ; fome are curved in their direction ; one, in particular, is forked, or divided into two branches, which run in very different directions through the micaceous fhistus. A few hundred yards from the en- trance of the Loch, the fea has formed an interefting fec- tion of the ftrata, which demonftrates, in a Satisfactory man- ner, the relative pofition.of the fandftone,- limeftone, and mi- caceous, 78 A fc R A N. caceous miftus. The micaceous miftus which forms the iliore, is inclined at an angle of 45 and dips to the S. E. ; the fecondary ftrata, are inclined at an angle of 45, but dip to the N. W. fo that the two kinds of ftrata meet together, iimilar, as Hutton remarks, to the two fides of a lambda, or the roof of a houfc. The fecondary ftrata are of red colour- ed argillaceous fandftone, (which fometimes appears pamng into breccia :) which alternates with limeftone. This lime- ftone fometimes contains mafles of hornftone, a fact, fome- what fimilar to the occurrence of flint in the chalk beds of England. Sauffure remarks that hornftone is confined to the fecondary limeftone, quartz being the fporadic matter which he has obferved in primitive limeftone. Many other veins may be obferved traverfing the micaceous fhiftus, before we arrive at the entrance of Loch Ranza, but any detailed ac- count of thefe would be but a repetition of what has been already mentioned. GLEN-RANZA. This glen is about two miles long, and half a mile broad, running nearly north and fouth, bounded on both fides by lofty round-backed mountains, that rife at a very confiderable angle, and are nearly of the fame height on both fides of the glen. The inclination of the oppofite mountains is the fame, and the ftrata run at the fame angle. The i ./r.\cTjf>.v f>t \ A .\'/i/ir/ \ft//i I) Hrt.Ht/f/f I'fltl B 11 /.//n, .\'/r/n .\'fmf'ft n.i\.\:\ Ji, A R R A N. 79 The bottom of the glen is but little elevated, and nearly le- vel ; about one half is covered with a fait water loch, which adds greatly to the beauty of this romantic fpot. The hills are compofed of micaceous miftus, containing a greater or lefler proportion of quartz and mica ; indurated chlorite is alfo difperfed through it, and towards the mouth of the loch there is a conliderable ftratum of ardeiia, or primitive argil- laceous fhiftus, bounded by the ftrata of micaceous miftus. GLEN-ES-NJ-BIRACH. From the top of Glen-Ranza, we en- ter, by a narrow paffage, into a long deep glen, running near- ly in the fame direction, called Glen-es-na-birach, bounded on both fides, with mountains of compact micaceous miftus, which lie upon the granite. The granite and miftus are often intermixed at their junction, and fometimes fmall granite veins are to be obferved ifTuing from the mailive granite, and tra~ verfing the miftus. This latter appearance was confidered by Dr Hutton, as a demonftration of the truth of his theory, with regard to the formation of granite. I will not now make any obfervations on this particular opinion, as I intend to consider it fomewhat fully in a fubfequent part of the work. As we ad- vance further up the glen, the micaceous miftus difappears, when both fides are formed of granite, of the fame kind with that of Goatfield. The bottom is alfo formed of granite, as is well demon ftrated 8o A R R A N. dcmonftratcd by the ft ream, or burn, which has laid bare the rocks through the whole extent of the glen ; it is indeed by rivulets of this kind that we are often enabled to have a dif- tinct view of the mineral ftruclure of highland countries. From the further extremity of this glen, is the afcent to Caimc- na-caillich, which is in feveral places rugged and difficult, from the number of loofc blocks of granite fpreading all around. Upon afcending, we firfl flop at the edge of what is called the Garife-hodie : Here a wonderful and moft tremendous fcene prc fonts itfelf to our view. An immcnfc hollow, many hund- red feet deep, dreadfully rugged and broken, almoil entirely furrounded with mountains, whofe ferrated fummits arc cover- ed with immcnfe tumuli of granite, exhibits to us, in very le- gible characters, the vaft operations of nature, in the forma- tion and decompofition of our globe. What man, poiTefled of rcafon, contemplating this awful fcene, could doubt of the ex- iftence of that BEING, whofe power and wifdom are far be- yond the reach of human comprehenfion ? If fuch a man exift, vanity, not foundnefs of judgment, is the diftinguifhing fea- ture of his character. Few, indeed, of thofe who deny, or even doubt the cxiftciice of Deity, have ever beheld, far Icfs lludied, the ftupendous and awful works of nature. It is not, then, much to be wondered at, that the pride and arrogance, which fo often characterifc the clofet philofopher, fhould find their A R R A K. Si their way to mix with their daring and impious fpeculaii which have for their end the propagation of the worfl princi- I pies, the clifTolving of all the bonds, and deftroying the fwect- eft endearments of human fociety. Upon the edge of the hollow, I obferved feveral fragments of porphyry, but I could not difcover any fixed rocks of it, owing to the blocks of granite fcattcred all over the fides of the mountains. In afcending from this, to Caime-na-callich, fc- veral other appearances of porphyry, and alfo fragments of ba- falt and pitchftone, prefcntcd themfelves. After considerable fatigue I was fo fortunate as to difcover two veins of bafalt, upon the fide of Caime-na-caillich looking into the Garife- hodie ; and, between thefe, there appeared a perpendicular vein of pitchftone, all running in the common granite. This pitch- flone, is of a green colour, much refembling that from Bro- dick wood. It forms a vein, about two feet wide, and, what is remarkable, it is formed into two regular columns, from two to twelve inches diameter, and having from three to fix irregular fides *. I could not, however, difcover the fituation of L the f It would be worthy the attention of future travellers to determine whether the bafalt be not included in the fame rein with the pitchftone, thus forming a ftratified vein. J2 A * R A N, the porphyry, although it was fcattered in fome places of the mountains in confiderable quantities. Having gained the 9 i'ummit of this great mountain, which is nearly of an equal height with Goatfield, I had a very grand view ; yet not fo extenfive as that from Goatfield. Its fummit has a moil fingular appearance, owing to its be- ing covered with enormous piles of quadrangular maiTes of granite, which reft upon each other in a moft fantaftic man- ner, and have much the appearance of artificial tumuli. Such appearances are by no means peculiar to Caime-na- callich, for I have already remarked them upon the top of fever al of the granite mountains in the ifland. Here we can trace the granite in its various ftages of decompon- tion, from the folid rock to the loofe fand ; in its begin- ning difintegration it fplits into mafTes, having a greater or lefler tendency to the quadrangular form; but thefe mafles have flill a degree of connection amongfl themfelves, as is the cafe upon the mountain top. The next flep is the enlarge^- inent of the fiflures, by which the mafles are loofened from, their connection, and tumble down from their elevated fitua- tions, upon the fummits of the neighbouring mountains, or are hurried with impetuous velocity down the mountain fide, covering the bottom of the glens with thefe ftupendous ruins. - Laflly A R R A N, 83 Lafcly, thefe detached mattes, by the action of the weather, are completely difintegrated, forming a loofe fand, which is left upon the tops or fides of the mountains, or is carried in great quantities to the fea more by the torrents *. SaufTure, at fec- L 2 tion * Dr Hutton remarks, that the flony matter of this globe has been formed "by the decay of a former world, whofe debris has been colle&ed by various means, at the bottom of a former ocean. This part of the Huttonian theory differs but little from that of Count Buffon, yet it is fo material for the general fupport of the whole, that if it (hall be difproved, the folidity of the theory in general will be much impaired. If we examine a few of the numerous fals on this fubject, we mail find no proof of the debris being carried to the fathomlefs depths of the ocean ; on the contrary, we will obferve it difpofed of in a very different way. Thus in fome cafes, the loofe materials warned from the mountains, are obferved filling up great hollows ; and in other inftances, rivers depofit their earthy matters, and form extenfive plains, and not unoftcn the debris having reached the fea more, is thrown back upon the fame or other mores. The following fails are in proof of thefe remarks. The plains of Crau and Camarque, in lower Languedoc, were formed by depofitions from the Rhone, and the plains of Lombardy from that of the river Po ; the lands of Holland and the Delta of Egypt, feem alfo to -be depofitions of the debris, brought to the fea more by great rivers. In Egypt, the gathering of debris is very great, as is well authenticated by hiftoric evi- dence : thus, we are told, that the town of Damietta, in lower Egypt, about the year 1243, was upon the fea more, but is now about twelve miles from it: and the town of Foc-ah which, three hundred years ago, was fituated at the mouth of the Nile, is now fevn miles diftant. The country about the Baltic is alfo gradu- ally 84. A R R A N. tion 604 of his Voyages dans les Alpes, remarks, that gra- nite is difpofed in ftrata, but that they are not always to be diftinguifhed, particularly in the granite of low countries and plains. This he conceives to be owing to the granite of low hills containing a great quantity of pierre de corne. This ally incroaching upon the fea. Linnaeus remarks that the fca ports of eafl and weft Bothnia are every year decreafing, and becoming incapable of admitting veffels ; the inhabitants of the ports are obliged to change their feats, and fometimes re- move a quarter of a mile nearer the fea. On the eaflern fide of Gothland, near Hoburg, the increafe of the continent for thefe laft ninety years, is about two or three toifes annually. The inhabitants of weft Gothland remark that the fea de- creafes every ten years four or five lines perpendicularly, which, amounts, to for- ty or fifty lines in a century. According to this calculation, 6co years ago the fea was 25 inches deeper than it is at prefent. In Arran we have alfo a ftriking proof of the formation of land by the accumulation of debris. Innumerable other inftances might be mentioned. But we will not cite more, but conclude this note with the following ingenious obfervations from Mr Kirwan's Geological E flays. f< Mariners were accuflomed, fays he, for fome centuries back, to difcover their fituation by the kind of earth or fand brought up by their founding plummets, a method which would prove fallacious, if the furface of the bottom did not con- tinue invaiiably the fame. Fortis in his Travels through Dalmatia, p. 285, re- lates that urns thrown into the Adriatic upwards of 1400 years, fo far from be- iag covered by mud, were found in the fame fituation, as they could have been fuppofed to have been the firft day of their fall ; therefore, notwithflanding many jparticles of earth are, by rivers, conducted to the fea, yet none are conveyed to any A R R A N. gj This pierre de corne, he continues, contains a great proportion of argillaceous earth ; and as mod ftones, which have this earth as a coiiftituent part, and in confiderable proportion, fplit into rhomboidal mafTes, fo he concludes that it is the earth of the pierre de corne which is the caufe of the fplitting of granite, thus forming the numerous mafTes which prevent us from obferving the ftrata. This explanation, however inge- nious, does not hold true with regard to the granite of this ifland : no argillaceous ftone of that kind enters into its com- pofition, yet ftill it fplits into very numerous rhomboidal maffes. GLEN-HALIMIDEL. Upon the eaft fide of Glen-Ranza there is an opening leading to a glen, named Halimidel, which is about any diftance, but are either deposited at their mouths, or rejected by currents or by tides j and the reafon is, becaufe the tide of flood, is always more impetuous and forcible than the tide of ebb, the advancing waves being prefied forwards by the countlefs number behind them ; whereas the retreating are preffed backward by a far fmaller number, as muft be evident to an attentive fpe&ator ; and hence it is, that all floating things caft into the fea, are at lad thrown on more, and not conveyed into the mid regions of the fea, as they mould be, if the reciprocal undulations of the tides were equally powerful." Kirwan's Geological EfTays >Xi p. 440, 441 = S'6 A R R A N. about two miles long, running W. N. W. and E. S. E. but which foon changes its direction, running nearly in a line with Es-na-birach. It is narrow at the bottom, but widens upwards, owing to the inclination of the fides, which form an angle of about 60 ; and the bottom alfo rifes, forming a confiderable angle with the fides. It is compofed of various fpecies of mi- caceous fhiftus and quartz. In feveral places bafalt veins may be obferved traverfing the micaceous fhiftus, many hundred feet above the level of the fea : even in the bottom of the glen, where the burn has expofed the micaceous fhiftus, we obfervc bafalt veins crofling it. Upon the eaft fide of the glen, feveral hundred feet above the level of the fea, there are two quarries, which were formerly worked for ardefia, but are now difconti-^ nued. The ardefia is of various colours ; generally bluifh or green, and is intermixed with white quartz ; the fiflures often contain cryftals of aclynolite, and a fpecies of quartz penetra- ted with actynolite, forming a ftone fomewhat refembling prafe* A R R A N. CHAP. VI. * Defer ipt ion of the FOSSILS mentioned in the preceding Chapter. XIMESTQNE Cory. Colour. Grey. Lujlre. A very faint degree of luflre* Transparency. None. Hardnefs. Scrapes with a knife. Smell. Emits a ftrong earthy fmell. Frafture. Even, fine, fplintery, and very compact. Fufibility. At 140 Wedgewood, no appearance of fufion. Another fpecies is alfo found at the Cory; of a dark-brown colour, minutely foliated, difficultly fcraped with a knife, and wanting tranfparency. 1 LIME- 88 A R R A N. LIMESTONE near the Cock. Colour. Brick red. Liiftre, A flight degree of luftre from fome difperfed folias. Tranfparency. None. Hardnefs. Pretty difficultly fcraped with a knife. Frafture. Generally foliated, paffing to the compadl earthy. INDURATED LITHOMARGA? -found loofe on the Jhore between Brodick Bay and the Cory. Colour. Light blood-red. Luftre. None. Tranfparency. None. Hardnefs. Yields to the knife with confiderable difficulty; gives a pink flreak. Frafture. Even, bordering upon fine fplintery Does not {lain the finger ; feels dry j does not acquire a polifh by friclion ; after immerfion in water for two days, no ap- pearance of difintegration, BASALT A R R A N. BASALT -from a vciti near the Sanicks* Colour. Greyifh green. Luftre. None. Traj2fpare?icy. None. Fragments. Uneven earthy. Hardnefs. Pretty eafily fcraped with the knife. Fufibility. Melted at 58, BLIND - COAL. KOHLENELENDE, German. NATIVE MINERAL CARBON, Kirwan. Colour. Black ; when frefli broken, reflects a golden yellow, or violet colour. Lujlre. That of metals not much polifhed. Hardnefs. Yields rather with difficulty to the knife. Fratture. Plain foliated. Is not coated with illinitions, as that from Kilkenny in Ire- land. It does not {tain the fingers. Hardly burns until wholly ignited, when it confumes flow- M ly, iy, \vith a light, lambent, blue flame, which continues for a iliort time. According to Mr. Kirwan' s method, it contains, in the 100 parts, 93 of carbon and 7 of aflies. Mr. Kirwan, in the fecond volume of his Mineralogy, re"- marks, that coals are not foluble in acids. I have obferved, however, that the coal of Arran is rendered foluble in wa- ter, by means of the nitrous acid, the carbonaceous bails ap- pearing to be converted into an oxyd.. This fubftance has been placed in various parts of the mine- ral fyftem, as with black-lead, molybdama, manganefe, &c. ; but the lat correct analyfes that have been made, mow it is carbon nearly in a pure ilate. Mr. Kirwan, upon consideration of its great purity, places it at the head of the coals, with the name of Native Mineral Carbon. ARDESI A. ARGILLITE, Kirwan. PRIMITIVE ARGILLACEOUS SHISTVS, DACHSCHIEFER, Emmerling* ARDESI A TEGVLARIS, Linn. Colour. Greyifh blue, or greyifh green ; fometimes both co- lours are intermixed in the fame fpecimen.. LuJIre. A R R A N. 9 1 * Silky. Tranfparency. None. Fratture. Streight, flaty. Fragments. Tabular. Hardnefs. Yields pretty eaiily to the knife. Streak. Grey. Does not adhere to the tongue ; feels rather greafy, particu- larly the green-coloured ; does not ftain the fingers. There are often contained in the filTures, cryflals of glafTy ac- tynolite. MICACEOUS SHISTUS. LEPIDOTES, Dr. Walker. SHISTOSE MICA, Kirwan. GLIMMER. SCHIEFER, Werner. GNEISSUM MICACEUM, Gmelin. The few obfervations I have to make on this genus of rock fhould, in Uriel order, have been introduced in chapter fecond ; but I wifhed previouily to examine a greater number of fpeci- mens, fo as to be better able to give a general idea of the whole. It would be inconfiitent with the brevity of this outline to M 2 defcribe 2 A R R A N. defcribe all the fpecies of this rock: I fhall therefore only mention it in general. MICA. The mica, in general, is of a grey, or black co- lour; the fcales very fmall, and indeed often hardly diftin- guifhable. Is of a white colour ; is fometimes difpofed in lay ers ; and, in fome fpecimens, has a granulated appearance. TALKERDE, Werner; TALCITE^ Mr. Kirwan; LEPIS, Dr. Walker. This fubftance occurs very frequently, indeed more fo than the mica ; yet, as I am not well acquainted with the names given to its admixture with other foflils, I Hill retain the term Mica for the whole, in fpeaking in general. Thefe three fub fiances are often conjoined, forming a fpe- cies of flate ; in other examples we obferve only quartz and mica conjoined, or quartz and talcite ; and, laftly, felfpar, in- durated chlorite and hornblende add to its variety. In ge- neral, the rock which thefe fubflances make is very com- pact ; and often they are fo intimately combined, that it is difficult to determine whether it be mica, talcite or chlo- rite that is intermixed with the quartz. Frequently we fee the A R R A N. 93 I the quartz a~wanting, when the mica pafTes to the ilate of ardeiia. . Several kinds of this rock, particularly the quartzy, have been ufed for the building of ovens and furnaces, on ac- count of their great infufibility. No rock is more favourable for metallic veins ; indeed, many of the richeft mining coun- tries are formed of it : we may inflance the vaft mines of Sweden, which are almoft entirely fituated in micaceous fhiftus. A R R A K A R R A N. CHAP. VII. Glen-Catacol, Glen-Erfay, Glen-Clachan, Shi/kin, Tory-Lin, Benin- Head, Whiting Bay, Lamlajh Bay, Lamlafh I/land. JL~1AVING glanced over the glens and flrata in the neigh- bourhood of Loch-Ranza, I will now proceed around the ifland by Glen-Catacol, which is about a mile and a half from Ranza. The mores in this direction are bounded by cliffs, which are neither very high nor rugged, but beautifully adorned with low mrubs, giving a richnefs of appearance feldom obferved upon the fhores of this ifland. The cliffs and mountains in the vi- cinity are formed of micaceous fhiftus, of various degrees of hardnefs, owing to its being more or lefs intermixed with quartz. They are feparated from the fea by low beaches, of confiderable extent, which, in forne places, are cultivated. The entrance to the glen is bounded by lofty, precipitous moun- tains A R R A N, tains of micaceous mill us ; but this foou difappears, as the glen changes its direction, running N. N. E. and S. S. W. .: then the mountains are formed of granite llmiiar to that of Goatfield. In feveral places of the glen fragments of bafalt oc- cur ; demonftrating the prefence of veins traverfing the gra- nite, as we have already obferved upon Caime-na-callich and Glenrofa. Upon one fide of the glen we obferved a narrow valley, into which we entered, but found that the granite was fall the prevailing rock. At one place, indeed, I difcovered great maifes of porphyry ; but I could not detect them in fitu. It is probable, however, that it forms veins running in the granite, as the quantity of debris is too fmall for fuppoiing the exiftence of flrata. After a very fatiguing walk, . I reached the top of the glen, when I obferved a confiderable plain, in which is fituated a lake, about a mile long and half a mile broad, which is named -Loch-Tan. It is bounded upon two tides by lofty granite mountains ; but is open towards the others ; one leading to Glen-Erfay, the other to Catacol. The margin of this partakes much of the flerility of the furround- ing fcenery : vegetation hardly mews its head : a few lichens and tufts of heather are the only ornaments of which it can boaft : _______ A joylefs coafl. Around a flormy lake, . Yet 56 A R R A N. Yet here the grandeur and fublimity of the furrounding gra- nite mountains, envoloped in clouds and mift, excited in my mind a vaft variety of ideas ; for, Surely there is a hidden power that reigns 'Mid the lone majefty of untam'd nature, Controlling fober reafon. Upon afcending the granite mountains on the eafl fide of the loch, I obferved confiderable quantities of the debris of bafalt upon the top of the mountains, mowing that the veins had reached to the very fummit *. I walked onward to Glen-Erfay, and, in my way, obferved large blocks of a beautiful dark leek-green coloured pitchftone- porphyry, remarkable not only for the number, but alfo for the fize and beauty, of the cryflals of felfpar. I was not fo fortunate as to find it forming a fixed rock in the neighbour- ing granite mountains ; yet it is probable that future obfervers may difcover it in veins, fimilar to that obferved on the fide of Caime- * SaulTure obferved fragments of greenftone upon the fummit of Mont Blanc j very probably originating from a vein of greenftone which reached to the fummit of this great mountain. Voyages dans les Alpes, torn. 7me, p. 280 288, A R R A 97 Caime-na-callich. Some mineralogifts will rather be inclined to lufpect that it alternates with granite : as this is faid to be the difpofition which it affects when among the granite moun- tains of other countries. According to Charpenfcier j% who made this obfervation, porphyry containing pitchflone alter- nates with granite near MeifTen in Saxony. Dr. Mitchell, who "was lately on the particular fpot described by Charpentier, in- forms me, that he could not obferve any fuch alternation, and therefore prefumes that the obfervation of Charpentier is erro- neous. Having reached the lide of Glen-Erfay, I obferved it taking its rife from the lower part of Caime-na-callich and the neighbouring mountains, and running, in an irregular .courfe, towards the fea. It is faid to be nine miles long, and is reckoned the mofl extenfive glen in the ifland. Its fides and bottom are formed of granite, which continues un- til we come within a mile of the lower extremity of Loch- Erfay, when flrata of micaceous and talcaceous fhiftus make their appearance. Thefe ftrata continue to the entrance of the glen on the fea-fhore ; and here they are covered and fucceeded by red argillaceous fandflone andfandftone breccia. 4 Charpentier Mineralogifche von Churfachfen, 63. 98 A R R A N. As I had an opportunity, upon my former vifit to this ifland, of walking along the more from Catacol to the entrance of Glen-Erfay, I will now fliortly mention the nature of the rocks that occur in this tract, and then continue the defcription oil- wards to the other parts of the ifland. From Catacol to Whitefarland, a farm belonging to Fuller- ton of Kilmichael, the cliffs are low, compofed of micaceous ihiftus, but defended from the action of the fea by intervening fea-banks fimilar to thofe noticed between Catacol and Loch- Ranza. Near to the farm of North Tundcrgay, I obferved a re- markable vein of bafalt penetrating the micaceous fhiftus. The micaceous fhiftus is much waved ; but, as it approaches the fide of the vein, it lofes its mining glimmery appearance, breaks in- to thick plates, and, where in immediate contact with the ba- falt, it forms a compact kind of ardefia. The vein, as it rifcs from the fea, is fairly croffed by a fpecies of micaceous fhiflus approaching to breccia ; and here alfo the bafalt and micaceous fhiftus are much jumbled together, and fome pieces of the vein are apparently infulated in the micaceous fhiftus.. Here, then, we have two facts ; the former, the apparent tranfition from micaceous fhiftus to ardeiia ; the other, maffes of bafalt im- merfed in. the micaceous fhiftus, in a fimilar manner to the ba- falt I obferved embedded in the granite upon the eaft fide of Glen-Rofa. At Whitefarland there is a considerable extent of natural A R R A N. 99 natural wood, which adds greatly to the beauty of its appear- ance, which is much heightened by the lofty granite mountains that bound it on one hand, with the fea and long-extended ifthmus of Cantyre on the other. From this to Imachar the fame micaceous ftrata continue, forming beautiful cliffs and coniiderable fea-beaches. At Imachar the micaceous fhiflus is undulated, and traverfed with quartz, fo as to give the whole a kind of maculated afpecl ; and it continues to form cliffs until we come to the ftream which iffues from the entrance of Glen- Irfa. Upon one fide of this flream I obferved primitive fhiflus, but iipon the oppofite fide fandftone cliffs make their appearance. Thefe cliffs have a confiderable beach interpofed between them and the fea ; and the flrata of fandftone and fandftone breccia are elevated at a greater angle than any I have obferved in the other parts of the ifland. The retreat of the fea from thefe cliffs is not only marked by the confiderable beach we have juft mentioned, but alfo by the caves which are difperfed in them. Thefe cliffs foon difappear, when porphyry is to be ob- ferved ; but we can only trace it a little way, the covering of grafs preventing any further examination. The country is now low and flat, fo that we have an eafy walk to the houfe of the Shifkin ; and the only rock I noticed was the red argil- laceous fandftone, which I obferved in the bottom of feveral burns : thus intimating that the whole ftrata over which I had N 2 paffed, AURA N palled, aita- leaving the porphyry, was fandilone. At the Shifkin tlie land is low and flat. The mountains in the neigh- bourhood have a different appearance from thofe about Loch- Ranza -j. are lower ; their fides lefs precipitous ; in fhort, have much of the general afpedl of thofe about Glencloy, all an- nouncing a change in their competition. We have a good op- portunity of determining the truth of this conjecture, in the Clachen glen, which is but a fhort diftance from the Shifkin, The fandflone flrata, which we have jufl mentioned as form- ing the low country around the Shifkin, flretches up the glen for a confiderable way. At one place, on the fouth fide, I ob- ferved a confiderable flratum of limeflone, which is covered, and even, in fome places, intermixed, with fandflone breccia ; and, nearer the upper extremity of the glen, fhiflofe clay, richly impregnated with iron, makes its appearance. As we proceed upwards the glen becomes very deep ; and, upon the north fide, confiderable rocks of clay-porphyry occur, appa- rently covering the fandflone, as I conjectured may . be the cafe at Glencloy and Corygills. As we approach flill nearer to the upper extremity of the glen the fandflone difappears, when: a fienite, fimilar to that at the head of Glencloy, is to be ob- ferved, and, fo far as I could determine, rifes to the fummit of the neighbouring hills, About A R R A N, 1OI About two miles N. \V. from the Shifkin, after pamng through a moorifh flat, we come to Tormore, which is the promontory of this plain. Here are cliffs of confiderable ex- tent, which contain a range of extenfive caves, celebrated by tradition as the reding place of Fingal, the father of our great Oman, who, it is faid, ufed to retire here after the fatigues of the chace. In the farther extremity of the greatefl, or what is called the King's Cove, are a few fcratches, made by idle fi- fhermen or fmugglers, which, by fome, have been referred to the Fingalian age. As the appearances at this promontory are very interesting, I fhall make the defcription as diflincl; as poflible ; and, to be regular, I fhall begin at the north-eafl end, or Machry Bay, and fo on to Drumoodon point. The bay is of confiderable extent ; and the fhore, all around to Irfa, is formed of fand- flone. The bottom of the bay is a low fandy beach ; but, to- wards Tormore, it rifes, forming cliffs, which are continued all around to Rue-varey, or the columnar promontory, for the fpace of about a mile and a half : and thefe cliffs are from forty to one hundred feet high. Between the cliffs and the fea there is a confiderable fandftone beach, which is remarkable for the great variety and the number of veins that traverfe it, in different directions : thefe, at firft fight, appear confufed ; but a little. IO2 A R R A N, a little attention iboii difcovers a beautiful and diflinct difplay of a mofl curious difpofition of rock. As the pitch- Hone veins are the principal objects of curiofity, I will defcribe thefe firfl ; and, to make the detail accord with the engraved plan, I will begin from the extremitv of the great pitchflone vein as it rifes from the fea, ancl-ib trace it back to near Ma- chry Bay. The great vein of green-coloured pitchflone, D, as it rifes from the fea, is feveral feet wide, has a confiderable inclina- tion to the horizon, is (lightly bent in its courfe, and traverfes the common red-coloured argillaceous fandflone. It has, for fome yards, the character of a Jlratified vein ; that is, it con- tains layers or flratulae of different fubflances depoiited in the fame nfTure along with the pitchflone. Upon the fide of the *ein next the fea, there is a layer, A, of a fubflance which appears inclined at an angle of 60, dips in the fame direction with the pitchflone D, and has a fimilar curve. It is not untike a com- pact fandflone ; but it is probably of the fame nature with B on the oppofite fide of the vein, only more altered by the ac- tion of the weather and the fea. Upon the oppofite fide of the pitchflone, we obferve a layer, B, which appears to be of the nature of hornflone, or, rather, verging to quartz : it has a fi- rnilar curve and dip with the pitchflone. Immediately befide it there A R R A N. IO3 j there is a thin layer of bafalt, C, which is decomposing in balls ; and this, again, is boxinded by the common argillaceous fandftone ftrata. The vein continues thus flratified for about twenty yards, when the layers, A, B, C, appear to come nearly horizontal, and foon they entirely difappear under the debris. Further on, where the pitchftone is almoft free from the cover- ing of debris, it appears to be bounded on both fides by the common argillaceous fandftone ; yet this is doubtful, as there may be finall portions of the other ftratula?, which the debris prevents us from obferving. At a little diftance from where the fandftone appears to form, the fide of the great vein D, we obferve E, which is a vein of r ock fimilar to that of B, is from fix to eight inches wide, and is waved in its courfe. At fome diftance from this, there is a vein of bafalt, P, about five feet wide, running nearly E. and W. which is much the fame direction with the laft mentioned vein. The next vein which we meet with is about thirty feet feet wide ; runs N. W. and N. and N. E. and E. which is nearly in an oppofite direction to the great vein., Upon one fide, there is a layer, F, of a wax-coloured fubftance, intermediate between hornftone and pitchftone ; next, is a layer, G, of high olive- green coloured pitchftone, about two feet wide ; again, we have a layer, H, about half a foot wide, of the fame pitchftone- hornftone,. 104 A R R A hornftone as F; then, a layer of indurated clay, K; and, after this, the whole vein is formed of bafalt, L. The fandftone which bounds this vein, in place of being red, the ufual colour, is partly a yellowifh-white colour. I endeavoured to difcover its j unction with the great vein D, but without fuc- cefs, owing to the great covering of debris : I obferved it, how- ever, upon the oppofite fide of D, but at a diftance, entering into the neighbouring fandftone cliffs. At a little diftance from this, we meet with another remarkable vein : the fides, M, M, are of bafalt * ; but the middle, L, is of breccia f. Still nearer to Machry Bay, another curious vein is to be feen : it is about eight feet wide ; the fides, P, P, are of fine white-coloured argil- gillaceous fandftone J; next, are two layers, O, O, of bafalt ||, which * This bafalt does not differ from that from the fouth fide of Glencloy, defcribed at page 53. f This breccia is formed of varioufly-fhaped maffes of common and arena- ceous quartz, and indurated clay, connected by a bafis which is only an agglu- tination of fmaller particles of the fame kind. t This fandftone only differs from the ilratified kind by its having a white colour. H This bafalt has a black colour j and 4ias, difperfed through it, cryftals of .hornblende, calcareous fpar, aud iron pyrites : this laft, by decompofition, often gives the whole a brown colour. A R R A N. IOJ which decompofes in balls ; and the middle, N, is formed of a rock which has cryflals of felfpar and rounded pieces of quartz, immerfed in a bafis that feems one of the gradations from pitch- done to hornflone. The laft vein, Q^, which I obferved run- ning, in a crofs direction, to the great vein of pitchflone D, is about ten feet wide, and entirely compofed of green-coloured . pitchftone. The great vein continues vifible for a little way after pafling the vein Q, and is nearly of the fame diameter ; but, as we approach very near to Machry Bay, it is not to be further tra- ced, on account of the covering of debris. Near to its termi- nation, however, I obferved the hornflone pitchflone fubflance forming a layer upon one fide, and even, in fome places, intermixed with it. I have to regret that this interefting piece of mineralogy is fo imperfectly detailed ; yet I trufl it will ferve to excite others, better qualified, to give it a more particular examination. I would particularly recommend an attention to the appearances prefented by the junction and croffing of the veins ; which I had not an opportunity of exploring, on account of the great covering of debris : a hindrance which fome future aftion of the fea may remove. O The A R R A N. The next objeft which claims our notice, is, the determina- tion of the rektive pofition of the fandftone and porphyry. The cliffs, befides the fandftone, of which they are principally compofed, are, in fome places, varied by a clay-porphyry, very fimilar to that of Glencloy ; with this difference, that the cry- ftals, felfpar and quartz are larger. The porphyry, fo far as I could determine, does not feem to lie on the fandftone, but merely to fkirt it. Several bafalt veins are to be obferved tra- veling it, in different directions. One vein, about feven feet wide, runs through it in a perpendicular direction, and gra- dually narrowing towards the top of the cliffs, when it is loft among the fandftone that lies behind. Another runs more, in a horizontal direction, and between the fandftone and clay- porphyry. Another vein, which is nearer to Machry Bay than the other two, is to be obferved running with porphyry on the one fide, and fandftone on the other : it foon divides ; one branch penetrating the porphyry, the other ^running between the fandftone and porphyry. To the \V. of the King's Cove, I obferved great mafles of green-coloured pitchftone fcattered upon the more ; but I could not difcover whether they belonged to the great vein D on the other fide of the caves, or had been feparated from other veins or ftrata. Upon the top of the cliffs, at the fame place, I ob- ferved A R R A N, 107 ferved a variegated pitchftone, which was decompofed, in fome fpecimens, almoft to a brownifh-white earthy powder, cropping through the grafs j but I could not difcover whether it formed a vein or ftratum. From this to within a fhort diftance of the columnar promon- tory of Drumoodon, the cliffs are of fandftone ; but, in fome pla- ces, they appear covered with a porphyry : of this, however, I can- not fay any thing fatisfactory. I obferved many bafaltic veins traverfing this fandftone ; and, upon examining the connection of the veins and ftrata, I found the bafalt and fandftone, at; their junction, in feveral places, intermixed; and alfo the ba- faltic veins, belides the angle they form with the horizon, had a confiderable inclination of themfelves. At a little diftance from the columnar promontory, I ob-- ferved low, fhelving rocks of clay-porphyry, which extend be- yond the point Rue- Varey on the one hand^ and ieem to be connected with the porphyry on the other. The promontory is a ftriking object ; is pretty high ; and cornpofed of red-co- loured argillaceous fandftone, which is> covered by irregular columns of a porphyry which, in fome places, has much refem- blance to bafalt-porphyry, in others is evidently clay-porphyry. This fact is a prefumptive proof that the conjecture I have O a made*. io A R R A N. made, with regard to the fituation of the porphyry of Glen- cloy and Corygills, may be true. Having pafTed Rue-Varey, which is the mod weftern point of Arran, we came to the farm of Drumoodon, which is fitua- ted upon the fea-iliore, with a confiderable fandy beach before it, and, behind, the fandflone cliffs are ftill continued. Here we find, refling upon the fandflone, a curious fpecies of rock, having a tendency to fplit into columns ; but of which I cannot give a determinate opinion, as I do not find any defcription, in the mineralogical works I have confulted, that correfponds with it. I have marked it, in the fliort defcription that is detailed in the following chapter, as intermediate between bafalt and fandftone, Thefe cliffs become gradually lower, and at length difappear, being fucceeded by an extenfive beach covered with fragments of the neighbouring rocks. After pafling this beach, which forms one fide of the plain of the Shifkin, confiderable cliffs now rife before us, which are formed of clay-porphyry of confiderable height, but much fplit by the adlion of the wea- ther, which gives an indiflincl idea of Gratification, fimilar to the granite obferved in the Cory-Dain, at the head of Glen- Rofa. Thefe cliffs contain feveral caves, but none of them are of any confiderable fize ; and the fhore is covered with great .maffes. A R 11 A N. mafTes, which have been feparated from the cliffs by the ac- tion of the fea and weather. Thefe mafTes have a peculiarity of form, which characterifes the rock from which they have been feparated. This remark may appear fanciful ; but feve- ral circumflances lead me to imagine, that one, accuflomed to obferve with attention the debris upon the fea-coafts, &c. may often guefs as to the peculiar nature of the rocks themfelves, by obferving the fhape of the fragments. The whole more, to Tory-Lin, appears to be compofed of clay-porphyry, and in foine places fandftone is to be obferved, and both are traverf- ed with veins of bafalt. I picked up fragments of dark leek- green-coloured pitchflone, in different places, among the debris of the neighbouring rocks ; but had not leifure to determine its fituation. From the Shifkin to Tory-Lin,there is a to- lerable road ; which is a rarity in this ifland, and extreme- ly agreeable to the traveller, after having fcrambled around the more from Brodick Bay. The .land now becomes lower, and has more of the rural appearance of the Lowlands of Scotland : agriculture is followed with fome fpirit, and even many of the fea-beaches are cultivated. Tory-lin confifts of a few houfes, pleafantly fituated in a hollow, at a little diftance from the fea fhore, and furrounded with . 110 A R R A N. with fandftone hills. In the burn which runs by the hoxifes, I obferved veins of bafalt traverfing the fandftone in different directions, and amongfl the bowlder ftones which cover its bottom, fragments of a light blackifh green-coloured pitch- flone prefented themfelves, (bowing the exiftence of veins or flrata of that foflil in the neighbourhood. Upon the fhore a curious fpecies of porphyry, (different from waeken-porphyry,) makes its appearance, and feems to be traverfed with veins of common bafalt, which are here of very great fize. On my fecond vifit to Arran, I walked a-crofs from Tory- Lin to Lamlafh harbour, which gave me an opportunity of obferving a part of the iflands, with which I was before un- acquainted. I will therefore ihortly mention what occurred in that route ; before proceeding to mention the very few ob- iervations I made on the fouthern part of the ifland. After leaving Tory-Lin, we afcend for fome time over the ufual red-coloured argillaceous fandftone, it at length difappears, and the higher grounds are formed of porphyry. This porphyry continues until we come to the farm of Achariach, when red- coloured argillaceous fandftone is to be obferved in the bot- tom of a burn, and is apparently travefed by a vein of white- coloured fandftone. As we proceed onwards, we afcend fome high grounds, where the porphyry again appears, and it now continues ARRAN. HI continues all the way to the hills upon the fide of Lamlafh bay. Thefe hills are compofed of white-coloured fandftone at the top, but lower down of common red-coloured fandftone. The more from Tory-Lin to the Benin-Head, the mod fouth- ern part of the ifland, is principally compofed of fandftone, traverfed with veins of bafalt, which are fometlmes of great fize, and run in a great variety of directions. The hills back from the fhore appear to be entirely compofed of porphyry*, but are not of any great height. The whole country to the Benin-head is confiderably cultivated, and is here and there diverfified with fmall villages, which give to the whole a pic- turefque feature, which we have feldom an opportunity of ob- ferving in this ifland. At the Benin-head, the cliffs are of coniiderable height, and are compofed of fandftone, porphyry, and bafalt. The porphyry and bafalt have a tendency to the columnar form, and both are traverfed by bafalt veins, which are often of a great fize. From this to Whiting Bay, the cliffs are low, formed of fandftone, and traverfed with bafalt veins, which run in a great ' * I find in my notes, that fienite is marked as one of the rocks of this part of the country. I am now fomewhat doubtful of that fad, and will therefore leave it as an objeft for future enquiry. AURA N.. great \ ariety of directions. The hills, however, up from the ihore,. now change their appearance, prefenting broad, bare> perpendicular faces, fimilar to thofe which occur in all bafaltk countries ; and upon examination, we find them to be com- pofed of various fpecies of bafalt,* lying upon a red-colour- ed fandftone, which is intermixed with grunerde, and a grey thiftofe clay. This bafalt is often columnar, and the perpen- dicular crags, being fcattered in various directions, and often riling in 'groupes above each other, have a pleafing effecl:. Near to Whiting bay, there are confiderable rocks of green- ftone of nearly the fame fpecies with that found near Cory- gills ; it is not in any confiderable quantity, and appears to i be the rarefl rock in the ifland. At Whiting bay, the clifFs difappear, and are not to be ob- ferved until we come to the entrance of Lamlam bay; in their place we have an extenfive beach, bounded by gradu- ally rifing. fandftone hills> much traverfed with bafaltic veins. When the tide ebbs, the bottom of the bay exhibits a moft a- ili^iifhing collection of bafaltic veins, which have been laid bare * v Stucke, a German chemift, on breaking a certain cellular bafalt, found the cells to contain water. He analyfed 20 ounces of this watet, and found it to contain fourteen and a half grains of filex. Stuck Unterfuch. 119, Ktfwan t Geo- Ifigical Eflays, p. A R R. A N. j j ,j bare 'by the action of the fea ; here they are to be feen run- ning in every direction, meeting and crofTmg each other in a nioft curious manner ; in fhort, this is one of the befh parts of the ifland for obferving the various crofTmgs, &c. of thefe fingu- lar appearances *. At the entrance of the bay of Lamlam, the fandflone forms coniiderable cliffs, which continue a fhort way of confiderable height, but are gradually lower as we approach the village of Lamlam, where there is an extenflve flat beach. Thefe cliffs are alfo traverfed with veins of bafalt, and in fome places a few hundred yards from the more, I obferved many detach- ed maffes of green pitchftone, indicating its exiftence in the neighbourhood. Lamlam bay, which is the befl harbour in the ifland, and one of the beft in the Firth of Clyde, is of a femi-circular fhape, and is formed in part by Holy ifland or the ifland of Lamlam, which lies acrofs it, leaving two entrances, one from the north, the other from the fouth, which laft is always pre- P. ferred * It will be fomewhat difficult to explain the appearance of fo many veins in fo fmall a fpace of ground as Whiting bay, according to the Wernerian Theory. For furely had all thefe been at one time open fiffures, the fandftone would not at. the fame time have fupported itfelf. Sauflure, imagines, that this objection be removed, by fuppofing, that thefe fifTur.es were formed fucccffively* II^. A R R A W, fcrred by mariners. It is bounded upon the Arran fide by hills of red and white fandftone, traverfed by bafaltic veins. Upon the eaft fide of the bay, attempts have been made to xlifcover coal, but without fuccefs. Lamlafh or Holy ifland, is about three miles long, and half a mile broad, precipitous on the eafl, alfo confiderably abrupt on the weft fide, but the north and fouth ends are low. It is compofed of red-coloured fandftone, which is in fome places formed into fmall caves; one is celebrated for being the refi- dence of the holy difciple of St. Columba, St. Mool-jos^ or the fervant of Jefus. This fandftone is covered in ma- ny places with a fpecies of bafalt, very fimilar to that near Whiting bay, -and with difficulty diftinguifhable from fandftone. I have been very much -at a lofs with regard to the particular denomination to be given to this rock ; and I muft ftill remain in doubt f. It forms in many places regular columns, generally fix-fided, which rife range above range, giv- ing a faint idea of the ftupendous icenery of St.afFa or Bo-fhe- la, T SauiYure mentions a bafalt much refembling fandftone, having . a prifmatic rhomboidal form, and containing hornblende cryftals. Obfervations fur les lines du Brifgau Journal de Phyfique, An Deuxieme, p. 329. Nay, even fandftojie has been found columnar : thus the columnar boulaflein, fourul In Iceland, is a fandflone. Eggert Olaf&er. Reife durch Iceland, A R R A N. lie ' la. Upon the weft fide, the columns are of greater fize than upon the eafl, and the fame matter appears to form the fum- mit of the ifland, which is reckoned about feven hundred feet high. Upon the fouth-eaft part of the ifland, I obferved a rock principally formed of cryftals of hornblende, which is in fome places traverfed by bafalt veins *, and alfo ftratified with the common fandftone ; and towards the fouth-weft ex- tremity, bafalt veins are feen traverfing the fandftone* P 2 * This bafait has a very great fpecific gravity, owing to its being abundant ii* iron> A R R A N. CHAP. VIII. Dcfcription of the Foffils^ occurring in the preceding Chapter. PITCHSTONE F rom Tormore. JL HE following feries of foflils affords us a curious exam- ple of the gradations, which we often obferve between the different kinds of rock. Thefe gradations were either over- looked, or but vaguely underftood, until the time of Werner, who by the beautiful difcovery he made in thus tracing the fteps of nature, attracted the attention of mineralogifts. An e- minent mineralogift of our own country, has made great pro- grefs in this interefting enquiry, and it is to be hoped, he will foon gratify us with the refult of his labours. N? A R R A N. No. I. ^/row the great vein D, Colour. Brownifh. LuJIre. Little glancing, and greafy. 'Tranfparency. None. Frafture. Uneven, approaching the fplintery, Hardnefs. Gives a few fparks with fteel. Quartz, and a reddifh fubftance like garnet is difperfed through it. N II. PITCHSTONE pajffing to Homjlone. Colour. Light wax yellow, yellowifh green, weak reddifh brown. Lujlre. None. Tranfparency. None. Frafture. Even, fplintery, fometimes uneven. Hardnefs. Hardly touched by the knife. Smell. Gives a ftrong earthy fmell when breathed on. Fufibillty. At 55? was covered with a flight enamel 5 at 69? became )l8 A RR AN, t became white, {lightly foftened, and was then fomewhat po- rous. A fragment from a fix-fided' column foftened at 81, and at 1 1 8 a compact brown vitreous mafs was formed, which had interfpeffed white grains. By decompofition it acquires a white, and in fome varieties a brick-red colour. It has difperfed through it cryflallifed and amorphous quartz, chalcedony, a very few cryflals of white felfpar, calcareous fpar, and alfo minute dark leek-green-co- loured cryflals, probably pitchflone. N III. Foffil which appears pretty nearly of the nature of Horn/lone^ or rather verging a little to Quartz -from thejlratulum B. Colour. Pale blackifh brown ; or, dark grey, approaching to black. Lujlre. Very little glancing. Tranfparency. A very flight degree at the edges.. Fratfure. More or lefs fine fplintery, and very compact. Hardnefs. Gives fire plentifully with fleeL Pieces of quartz are difperfed through it, as in the former j and a few cryftals of felfpar now and then occur. A R R A N. 1 19 N IV. Foffil Jlill more nearly approaching to Quartz, which is intermixed with the green pitch/lone of the great vein D. This fpecies of rock differs little in colour from the prece- ding ; but has more luftre and tranfparency, and is a little harder. It acquires a white crufl by the action, of .the weather, It has alfo, interfperfed, cryflals of quartz. -OBSERVATIONS. Thefe different gradations are all to be obferved in the fame vein, and appear to graduate 0r pafs into each other. Thus, the firfl, or brownifh-coloured pitchflone, by its little luflre, feems verging to the fecond ; and, in reality, we often obferve, in'the^fame fpecimens, the one pafTmg into the other. The pitchftone-hornftone fubflance, N II. as its name implies, has partly the character of the pitchflone, and partly that of horn- ftone. The degree of fufibility intimates that it is fenfibly dif- ferent from the pitchflone, yet not fufficiently refractory for hornftone. Klaproth found a fubftance of this kind fufible ; and Mr. Kirwan mentions a greenifh-white hornftone, from -Lorraine, which, from its. being fufible, feems analagous to this. We I2O A R R A N. We are fometimes fo lucky as to find fpecimens where the iecond pafles into the third j and often we obferve the third pafling to the fourth. Thefe four kinds of rock, then, prefent to us a complete gradation from pitchftone to hornftone ; and we have a few fteps towards quartz. In other countries, we have accounts of nearly fimilar appearances ; and thefe I may fhortly men- tion, as they will add frefh intereft to the detail we have now given. Reufs informs us, that he obferved pitchftone pafling, by various ftages, to hornftone, at Garfeback, near Meiflen *. Efthner remarks, that the Saxon pitchftone pafles fometimes to hornftone "f. and Mr. Kirwan, in his Elements of Mineralogy, obferves that it pafles to hornftone. CLAY PORPHYRY, vuben pafmg to born/lone Tormorc. Colour. Greyifh. Lnjire* None, I'ran- * Sammlung Naturhiftorifcher Aufsatze, &c. von Franz. Ambros Reuls, 362. f Efthner, Mineralogie, JB. ii, 445. A R R A N. 121 franfpartncy. A little at the edges. FraSfure. Even, pafling to the fine fplintery. Hardnefs. Gives a few fparks with fleel. It contains, immerfed in the bails, cryflals of common, red felfpar, and white felfpar approaching adularia. The cryflals are of confiderable fize ; and this is one of the principal di- ftinclions between this fpecies and fome of thofe found in Glencloy. It decompofes, in the form of a brick-red cruft, fi- milar to fome of the flones which are intermediate between pitchflone and hornflone. In other fpecimens, the porphyry, as it comes in contacl: with the veins of bafalt, has a bafe coniiderably refembling it ; and at the columnar promontory of Drumodoon, the fpeci- mens often cannot be diflinguifhed from what is called trap- porphyry. A fubflance intermediate between fandjlone and wacken, having a tendency to the columnar form Farm of Drumoodon. Colour. Yellowifh, Lujlre. None, Tran- 122 A R R A N Tranfparency. None. It feels much like a fandftone. Frafturc. Even earthy, with the appearance of rounded con- cretions. Hardnefs. Gives a few fparks with fteel : but it contains con- fufed fragments of quartz, which may have been the caufe of this. Emits a flrong earthy fmell, when breathed upon *. Fttjibiltty. Melted at 79* OBSER- * Lampadius has difcovered that hornblende contains charcoal diffufed thro* it ; and Mr. Kirwan has down that fome fpecies of pitchftone contain it. It ia conjectured that it may exift in other foffils, and caufe the peculiar earthy fmell which we perceive by breathing upon them. OBSERVATIONS TO BE MADE, FOR THE FARTHER ELUCIDATION OF THE MINERALOGICAL HISTORT OF ARRAN. VEINS. I. JL O examine the bafalt, wacken, and pitchftone veins, (which occur in fo many parts of the ifland,) with a view to difcover if they be Jlratified. "We fhould defcribe accurately the difpofition of the ftratulse of fuch veins, as it will enable us to determine their relative antiquity : thus, according to Wer- ner, the parts nearefl the fides of a vein are the moft antient, thofe in the middle the moft modern, and the intermediate of a middle age. II. In the examination of veins, it will be of confe- quence to obferve how they crofs each other ; which, Mr. Werner 124 A R R A N. Werner remarks, will enable us to determine tlieir rela- tive antiquity : thus, if two veins crofs each other, the moil modern is that which croiTes the other ; and, of two veins, the one which interrupts or flops the other is the mofl antient. III. To examine carefully the country in the vicinity of veins, fo as to determine if there be any beds of a matter fi- milar to that which fills the veins. It follows, from Mr* Werner's theory, that we mould generally obferve fuch ap- pearances. IV. To examine if the fides of the veins be more or lefs hard; where in contacl with the granite, micaceous fhiftus, porphyry, fienite, or fandflone. V. To examine the bafalt, and other veins, with a view to obferve whether they contain petrifactions, or even wood unaltered j alfo, if they contain boulder flones. STRATA. A & X' A ft. 12? STRATA. VI. To determine the direction and inclination of all the flrata throughout the ifland ; fo as to know whether they have much the fame general arrangement, and if they are frequently fituated in a fimilar manner with the flrata at the mouth of Loch-Ranza. VII. To examine particularly the flrata of fienite ; fo as to difcover its connection with the granite, porphyry and mi-* caceous fhiflus. VIII. In examining the great glens, as Glen-Rofa, Sa* nicks, &c. it will be of confequence to examine very particu- larly as to the difpofition of the granite in flrata ; thus either to confirm or refute the obfervations on the flratification of the granite, IX. To difcover whether the porphyry, which is ob- ferved among the granite mountains, be difpofed in veins or flEata,. X. To 1 2(5 X. To endeavour to difcover the fituation of the horn- blende and paliopetre which is obferved in blocks at the en- trance of Glen-Rofa. XI. In traverfing the hills of micaceous fhiftus, to be care- ful in obferving if any rocks of trap formation occur in Jlrata. XII. To determine the pofition of the breccia, with regard to the other rocks, at the head of Glencloy; and alfo, to examine, more particularly, the extent and pofition of the brec- cia of South Glen-Sanicks. XIII. To examine very particularly the appearance of the granite, at its junction with the micaceous fhiftus and ardefia, in different parts of the ifland. In this invefligation it will be necefTary to obferve, i. If the ihiftus, where in immediate con- tact with the -granite, be not harder than it is at a diftance, 2. If veins of granite are to be obferved flretching from the granite, and traverfing the fhiftus. 3. If the granite veins have the fame grain with that of the granite of the neighbouring ^mountains. 4. If the granite and fhiftus be irregularly inter- mixed at their jun&ion, 5. If the granite and fhiftus ever alternate A R R A N alternate with each other. This Werner confiders as a rare ap- pearance. I have not obferved it in Arran. 6. If the mica- ceous fhiflus, where it covers the granite, can be obferved gradually changing its character, and at laft, where in junc- tion with the granite, not diflinguifhable from it : a fact which has been obferved in other countries, and demon- flrative of the granite and fhiftus being formed nearly at the fame time. BUTE. BUTE. CHAP. IX. Outline of the MINERALOGY of the I/land of Burs; with Obf cr- eations upon the Formation of the Bed of the CLYDE, and an Account of the Route from Burs to the I/land of JURA. A HIS ifland is about eighteen miles long ; and the broadeft part, extending from eaft to weft, is five miles. It is feven miles diftant from the ifland of Arran ; but is feparated from the diftridl of Cowal by a channel which is only about half a mile broad, and, in fome places, fixteen fathoms deep. To- wards the north end it rifes into hills of confiderable height ; but thefe are neither fumciently high nor extenfive to afford fcenes fo fublime as thofe which charadlerife the moun- tains of Arran. The fbuthern part of the ifland is, in general, (excepting at its mofl fouthern extremity,) low, well cultivated, and, in feveral places, beautifully ornamented with wood, par- ticularly U T E, I2 9 ticularly near to Mount-Stewart, the charming feat of the Marquis of Bute. Although this ifland be deftitute of fine mountainous fcenery ; yet, the extenfive cultivation, and the general appearance of buftle and life, form a ftriking contraft to the lone waftes of the ifland of Arran. Rothefay, the only town in the ifland, is pleafantly fituated upon the fhore of a confiderable bay of the fame name. It is principally fupported by the herring fimery, and a very confi- derable cotton manufactory. The ifland feems to be traverfed by three irregular vallies, which run from eaft to weft. One crofles the ifland at the town of Rothefay ; the fecond at Kaimes Caftle, in the north"; and the other at Cil-Chattan, in the fouthern part of the ifland. The mineralogy of this ifland, fo far as I examined it, does not appear to be particularly interefting : but a clofer invefti- gation may difcover many things which efcaped my notice ; as I examined it in very unfavourable weather, and, befides, had the misfortune to lofe the fpecimens I had collected. BUTE. The whole of the iiland to the north of Rothefay is compu- ted of primitive rock, which rifes into confiderable hills about Kaiines Caflle, the feat of Lord Bannatyne. This half of the ifland is pretty nearly fiirrounded by the neighbouring land of Cowal, fo that the fea can have little power over its fliores, which are indeed very low \ but the narrow channel, as I have already remarked, is very deep. The flrata, in general, are, micaceous fhiflus, ardefia, and fhiftofe talc j and they alter- nate, and pafs into each other. Sometimes we alfo obferve chlorite ; which is either maflive, or forms a fpecies of flate ; and not unoften I remarked quartz, more or lefs penetrated with the chlorite, forming a dark-green-coloured {tone, fimilar to that I found in Arran* In feveral places confiderable veins of quartz are feeji, traverfing the flrata in different directions ; and fometirnes they exhibit curious phenomena. I obferved upon the fea-fhore, about a mile and a half fouth of Kilmi- chael ferry, a vein of quartz which deferves to be particularly noticed. As it rifes from die fea, it is very narrow; but it ibon becomes wider, and then divides into feveral confidera- ble branches, which traverfe the flrata in different directions. One of thefe branches prefents an appearance fimilar to that obferved in Glenrofa, in the ifland of Arran, and defcribed at pages 38, 39. This branch, having traverfed the flrata for feveral feet, is interrupted by a mafs of micaceous fhiflus ; but it a- gain ., BUTE* gain appears at a little diflance, and {till in its former direction. MafTes of micaceous fhiftus are alfo to be obferved in the midfl of the quartz vein. The appearance of a mafs of mica- ceous (hiflus, which is a fufible flone when compared with quartz, in the midft of a quartz vein, muft be confidered as decifive againfl the theory of Dr. Hutton : for it is impoflible to fuppofe that it mould remain unaltered in a heat capable of melting quartz, or keeping it in a foft ftate. The bafaltic veins, which occur fo often in Arran, are alfo pretty common in this ifland, and are found from two to ten feet wide, traverfing the primitive flrata in various di- rections ; and I even noticed them upon the top of the high- eft hills. % Near to Lord Bannatyne's caftle there are feveral Hate quar- ries, which have been worked for fome time, and are ftill con- tinued. Thefe flates, however, are not fo much ufed as thofe from Eafdale, which are, even here, preferred for economical purpofes. In fome parts of Germany, as at Ruhla *, they em- ploy a compact micaceous fhiflus for the roofing of houfes ; R 2 and * Voight Mineral Reifert durch das Herzogth. Weimar. Th. 2. Se. 24. BUTE. and it is preferred to fame kinds of ardefia, from its great du- rability. Probably fome fpecies of micaceous fhiftus, equally ufeful with that ufed in Germany, may be found among the hills in the northern parts of the ifland. Mr. May, the cham- berlain of Bute, informed me, that trials had been made for lead in the northern parts of the ifland, but without fuccefs. This I reckon no fatisfadlory proof that lead is not to be found in the ifland ; as, in all probability, the perfons, employed to inake the trials, were but little verfed in the bufinefs. The north fide of Rothefay bay is entirely compofed of pri- mitive rock, fo is alfo the north lide of Scalpa bay, which is fituated upon the weft fide of the ifland, and nearly oppofite to Rothefay ; but the fouth fides of thefe bays are compofed of red argillaceous fandftone, and fandftone breccia. The junc- tion of thefe primary and fecondary ftrata, is therefore to be looked for in thefe bays. The country between Rothefay and Cil-Chattan bay ; which is the loweft, moft beautiful, and beft cultivated part of the ifland ; is compofed of ftrata of red argillaceous fandftone, and fandftone breccia, alternating with each other, and both are traverfed with bafaltic veins. Upon the fhores, on both fides of this part of the ifland, there are inland cliffs, fimilar to thofe near BUTE. near the north end of Arran, and in feveral places we remark- ed banks of coral and fea {hells *, confiderably above the high water mark. Thefe appearances, as well as thofe that occur in Arran, are proofs of the land gaining on the fea. From Cil-chattan bay, to the fouthern extremity of the ifland called Gurroch-head, the face of the country is much altered ; it now becomes nearly as high as in the north end, rifing into irregular hills with abrupt perpendicular crags, that are al- moft characleriftic of a bafaltic country. From the little op- portunity I had of obferving this part of the ifland, I can only fay in general that it is compofed of argillaceous fandftone,. ftratified with bafalt, and traverfed by bafaltic veins. The bafalt is fometimes columnar, and frequently contains much hornblende. I was told that lime had been found in this part of the ifland* GENERAL * Thefe banks are ufuallymade of the MUlepora polymorpha,. of which there are many curious varieties. BUTE. GENERAL OBSERVATIONS ON THE CLYDE. Having now finifhed the outline of the mineralogy of the iflands in the Clyde, I fhall make a few obfervations upon the mode which nature appears to have followed in the forma- tion of the bed of the river, the rocks and iflands. The appearance of iflands in any quarter of the globe, na- turally fuggefts to the mind, the idea of fome powerful agent which has coiivulfed and broken the folid land, and formed it into detached mafles. This opinion is not fanciful, for ap- pearances, in many countries, fhow us, that the greater num- ber of iflands have been formerly joined together, and mufl have coiifthuted part of the adjacent continent. Thus, if we examine the rocks upon the oppofite fides of the Clyde,, we fhall find a great fimilarity in their nature, i. At Campbel- town, which is only a few miles from the extremity of the ifthmus of Cantyre, we obferve a fmall portion of fecondary ftrata, which correfponds to that upon the oppofite coafl of Ayrfhire. 2. The rocks upon the north and fouth ends of the ifland of Arran correfpond exactly with the ftrata upon the north and fouth fides of the Clyde. 3. The north end of Bute is compofed of a fimilar rock with that of Cowal, and the BUTE, the fouthcrn extremity is compofed of the fame rock with the Cumbray iilands, and thefe are of the fame rock with that of the Largs, which is on the fouth bank of the river. Thefe fatfls would fecm to indicate, that the oppofite banks of the Clyde were at one time joined together, forming a very conflderabb extent of folid land. If this be admitted, (and there feems little doubt of its truth,) we muft now endeavour to difco- ver what means were employed to break down the land. Philofophers in their fpeculations on this fubjecl, have ge- nerally mentioned two agents, which they imagine have produced thefe ftriking and awful phenomena ; thefe are the waves of the ocean, and earthquakes. The firft opinion has been ftrenuoufly contended for by the late Dr. Hut- ton, who affirms, that all bays, peninfulas, iflands, &c. have been formed by the long continued action of the waves of the ocean. This fpeculation at firfl fight feems very plau- iible, but a more attentive confideration difcovers to us a very exaggerated account of a comparatively partial operation ; and this is indeed pretty evident from the following facts. The channel between Italy and Sicily, is nearly the fame to day, as in the time of the Romans. The ifthmus of Corinth has not been vifibly altered for upwards of 2000 years. Scylla, of which Homer has given a corre<5l defcription, is now nearly in the fame 136 BUTE, fame flate as when he wrote *. The ruins of Beritta, the favourite feat of Auguftus, are ftill to be obferved in their ori- ginal fituation, upon the bank of the fea, and fo fituated, as to be out of the reach of the waves f. Ancona built by the Syracufians, is ftill by the fea fhore -f. Here, then, we have inftances of the land refifting the powerful waves of the Medi- terranean for upwards of three thoufand years. Dr. Hutton who was aware of fome of thefe facts, remarks, that " Our land is wafted by the fea ; and there is alfo a na- " tural progrefs to be obferved, which naturally takes place '* on this occafion ; for the coaft is found varioufly indented, " that is to fay, more or lefs, according as the land is expofed " to this wafting and wearing operation of the fea, and accor- " ding as the wafted land is compofed of parts refifting, with " different degrees of power, the deftroying caufe. The land, " thus being worn and wafted away, forms here and there " peninfulas, which are the more durable portions of that " which had been deftroyed around ; and thefe remaining u portions are ftill connected with the mainland, of which " they at prefent form a part. " But * Spallanzani's travclls through Sicily, vol. 4. p. 172. J Maundrell's travells from Aleppo to Jerufalem in 1669, 8tc. t Maundrell, ibid. BUT*. 137 " But thole promontories and peninfulas are gradually de- " tached from the mainland, in thus forming iflands, which " are but little removed from the land. An example of this " we have in Anglefey, which is but one degree removed from " the ftate of being a promontory. Thefe iflands again, in " being fubdivided, are converted into barren rocks ; which " point out to us the courfe in which the loft or wafted land " upon the coaft had formerly exifted. " To be fatisfied of this, let us but look upon the weftern *' coaft of Scotland, from the iflands of St Kilda to Galloway, " on the one fide, and to Shetland on the other ; in this tradl, *' we have every teftimony for the truth of the doctrine that * c is confiftent with the nature of the fubjedl. The progref '" of things is too flow to admit of any evidence drawn imme- " diately from obfervation ; but every other proof is at hand ; " every appearance correfponds with the theory ; and of every " ftep in the progrefs, from a continent of high land, to the " point of a rock funk below the furface of the fea, abundant " examples may be found. We do not fee the beginning and " ending of any one ifland, or piece of country ; becaufe the " operation is only accomplifhed in the courfe of time, and the " experience of man is only in the prefent moment. But man * 4 has fcience and reafon, in order to underftand what has aU .S " ready 1^8 BUTE. " ready been from what appears ; and we have but to open " our eyes and fee all the ftages of the operation, although not " in one individual object. Now, where the nature of things " will not admit of having all and every flep of the progrefs " to be perceived in one object, an indefinite progreflion in " the various ftates of different objects, fhowiiig the feries or " gradation from a continent to a rock, muft form a proof in " which no deficiency will be found *" This is very probably a correct delineation of the mode which nature follows in altering the land, in fome few in- flances ; but it cannot be general, as it would give an age to the world quite inconfiflent with the Hebrew chronology; we muft therefore confider it as untenable. It may be reckoned tmphilofophical thus to fhelter ourfelves under the cover of what has been, by fome, conlidered a traditional tale; when facts and reafoning mould decide the truth of the argument. I am by no means of this opinion^ and however unfafhionable it may appear, I am firmly perfuaded, that any chain of reafon- ing, that does not coincide with that chronology, is falfe. As I have now proved the iiifufnciency of this theory, I might proceed to confider the other ; yet to prevent the fceptica}, from theufe of any undue argument, I will endeavour to mow, that allowing Dr. Hutton's obfervations to be correct, they wiH be *> Theory of the Earth, vol, id. p. 265* BUTE. be found quite infulHcient to explain the breaking of the land of the Clyde, &c. From the account I have already given of the nature of the ftrata upon both fides of the Clyde, it is evi- dent, that the ocean, in its fuppofed action, has broken down the hard primary ftrata, in preference to the fofter fecondary ftrata ; a fact which ftrongly indicates the agency of fome other power than the fea. Thus we find a confiderable por- tion of the primary ftrata carried away from the north end of / Arran, and Bute, while the fecondary and fofter ftrata at the oppofite ends of thefe inands, with the fandftone ifles the Cum- brays, (land in the middle of the Firth, defying the rage of the waves. Further, if we look at the map, we will find that all the arms of the fea which are connected with the Clyde, in place of being fituated in the fecondary ftrata, upon the fouth bank of the river, are only in the north fide traverfing a mountanious country which is entirely compofed of hard primitive rock. The great depth of thefe lochs or arms of the fea is very decifive againft Dr. Hutton's explanation. Loch Fyne, at its upper extremity, nearly oppofite to Inveraray, is about 60 fathoms deep : Loch Strevin, a fmall arm of the Clyde, almoft inclofed at its entrance by the ifland of Bute, is yet 38 fathoms deep : Loch Goyle, fituated further up the Clyde, is, at its upper extremity, where it is not a mile broad, about 37 fathoms deep : and Loch Long, near its head, is 28 S 2 fathoms t . BUTE tatlioms deep. Thefe lochs are far removed from any viol- ent aclion of the fea, or of currents ; fo that it is impoffible that they could have been formed as Dr. Hutton conjectures, allowing millions of ages for the purpofe. The other opinion which we have mentioned, viz. " that the land has been often fubmerged and broken by earthquakes," ieems to afford us a lefs improbable explanation of the prefent itate of the Clyde, than that advanced by Dr. Hutton. The fre- quent occurrence of earthquakes, in the different quarters of the globe, affords us numerous inflances of the fubmergence and breaking of the land : yet we are acquainted with none fo ex- tenfive as that of the Clyde. This, however, is of little impor- tance ; as .it is not improbable, that thefe cataftrophes were more frequent at a former period, than now. It would extend thefe obfervations to a great length, were I to enter into a de- tail of all the effects of earthquakes ; I mall therefore only fe- lecl: a few facls as illuftrative of the prefent opinion. In 1692, when the town of Port-Royal, in Jamaica, was deflroyed by a dreadful earthquake, vafl maffes of land were funk far be- neath the level of the fea, and mountains of confiderable ex- tent funk down, leaving In their place extenfive lakes. In 1693, the ifland of Forca difappeared, being fwallowed up by the ocean during a tremenduous earthquake. In 1678, there was B U T 2. was a great inundation in Gafcony, caufed by the finking of a part of the Pyrenees : the mountains having difplaced the waters, which exift in the cavities that are contained in the bowels of the earth. In the late moft awful earthquakes that have ravaged Peru, large mountains have been divided into two parts and feparated ; others funk down, when large and often bituminous lakes hare rifen in their place ; and laftly in the earthquakes that devaluated Calabria, there are inflances of mountains finking into the bowels of the earth *. Thefe facts entitle us to conclude, that at fome former pe- riod, this country was convulfed by great earthquakes, when the beds of the Clyde, and its numerous lochs were formed, by the fubmergence of the folid land : at the fame time Arran, Bute, &c. received their infular form, being part of the land that had efcaped the power of the earthquakes. Thefe iflands, as well as the lands on both fides of the river, have, no doubt, fince that period, experienced fome alteration from the long continued action of the weather and the waves of the ocean. Route * The earthquake that was felt in Canada, in 1663, overwhelmed a chain of mountains more than three hundred miles long. Clavigero r s hiftory of Mexico, p, 3Zi.- Kirwan's Geological EiTays, p. 500, I4'2 FROM BUTE TO }URA. Route from the IJland of BUTE to the I/land of J In travelling from the ifland of Bute to the Weftern Ifles, we have the choice of different tracks, as may be feen from the map. That which we purfued, although not the mofl conve- nient, was yet interefling, as it allowed us to glance at a confi- derable extent of highland country. Having examined Bute as much as circumflances would per- mit, we croffed the Kyles to a fmall houfe called the Kerry, fi- tuated in the diftrict of Cowal. In cromng, we perceived, at a diftance, feveral boats, filled with men drefTed in black, flowly rowing up the found. So unexpected an appearance did not fail to attract our attention ; and we were told that it was a fune- ral proceflion to a burying-place in the adjacent mountains of Cowal. Sxirely we could have hardly witnefTed a more flrik- ing fcene. Mortality is at all times awful ; but it was here prefented to us in a mofl impremve manner. The wild and lofty mountains riling from the fides of the channel ; the ak mofl perfect flillnefs of the water, which could be faintly heard dying away along the more ; the univerfal filence, not even diflurbed by the fcream of fea-fowl feemed as if nature was unwilling FROM BUTE TO JURA. unwilling to difturb the performance of the laft and melan- choly fervices to the dead. At the Kerry, the more is adorned with fweetly-rifing natu- ral wood ; fo that we left it with regret, to traverfe a country where grey, rugged mountains, and brown heaths, are the on- ly objects to which our attention could be directed. Having walked for about five miles through a dreary mountainous country, principally compofed of micaceous fhiftus, interfperr fed with chlorite, and traverfed with quartz veins ; we came to the next ferry-place, which is fituated upon the banks of Loch-Fyne, We crofTed from this to Eaft Tarbet, a diftance of about nine miles ; and obferved the mountains on both fides of the loch, all the way to Loch-Gilp Head ; having the fame general appearance, and being probably compofed of fimilar rocks with CowaL Eafl Tarbet is fituated upon the narrowefl part of the penin- fula of Cantyre ; for it is here only about two miles to the fea on the weft fide, which is called Weft Tarbet. There is a tole- rable road from the eaft to the weft fide ; which is of fome ufe, as this is not only the principal thorough-fare to the iflands of Ifla and Jura, but boats coming from the Weftern Iflands have their; cargoes unloaded here, and then are drawn acrofs the 144 FROM BUTE TO JURA. ifthmus, in preference to the circuitous and dangerous voyage by the Mull of Cantyre. It was once propofed to cut acrofs this narrow neck of land ; but the bad ground at WeftTarbet inclined the canal company rather to cut a canal from Crinan to Loch- Gilp Head, through a more confiderable track of ground, but reckoned more favourable for {hipping. The canal is now far advanced ; but it is very probable that its utility will by no means coincide with the fanguine expectations that have been raifed, by the company, and the country in general. The country, about Eaft Tarbet, is bleak and rugged. The hills rife to a confiderable height ; and are compofed of mica- ceous fhiftus in the lower part, but gneifs is to be obferved to- wards the fummit, and now and then indurated chlorite is found among the debris. Weft Tarbet prefents a more pleafing fcene, from the natural wood that grows there with confidera- ble exuberance. From Eaft Tarbet I now continued my journey towards the ifland of Jura, along the banks of Loch-Fyne, which is adorned with natural wood, giving a rich and picturefque effect to the high cliffs that rife above the road. The ftrata are, in general, micaceous fhiftus, in fome places alternating with confiderable of hornblende rock, and traverfed by bafaltic veins : and I was FROM BUTE TO JURA. 145 I was told that confiderable limeftone quarries were opened a- inong the neighbouring hills, and confequently muft be primi- tive limeftone. In many places we obferved perfons cutting down the wood, for the purpofe of making charcoal for the ufe of the iron forge near Oban. This is to be regretted ; for, in a morttime, the whole wood will be deftroyed, and the country deprived of one of its greatefl ornaments ; and merely for the fupply of the working of an iron furnace, that probably might be carried on equally well by a carefully-carbonized peat. Having walked for feveral miles along the bank of the loch, we now changed our courfe, and croffed through a long, dreary moor, and over hills, when we defcended to the plain at the head of Loch-Kilifled, The rocks are, all the way, of micaceous fhif- tus, which is, in many places, quite disintegrated, the loofe mica forming banks feveral feet thick. This mka, if free from iron, might be of confiderable value ; as we find Mr. Wedgewood ufing the fine white mica of Cornwall for the manufacture of porce- lain and his very .ufeful pyrometers J. It is therefore worthy the attention of the proprietors to examine the neighbouring country, where probably confiderable quarries of colourlefs T mica 4: Journal dcs Mines, No. 3. p. 119, 146 FROM BUTE TO JURA. mica might be found. At the head of Loch-Kilifled I obferved a confiderable ftratum of blue-coloured, granularly-foliated limeflone, ftratified with micaceous mifhis. The micaceous fhiftus is here- frequently mixed with felfpar, forming a fpecies of gneifs difficultly diflinguifhable from fandflone. After leaving this plain, we had a difficult afcent for a confi- derable way, but the tedioufnefs of the track was a little relieved by the natural wood through which We pafTed ; tliis, alfo, fooii difappeared, when brown mofTes, and grey, bleak hills, were again characteriftic of the country. Having walked for feveral miks through this dreary and defert fpot, we were fuddenly flopped upon the brow of a hill, from which we had a view of the grey, fteril mountains of the mainland, rifing into various rugged forms, and intermixed with lochs, thus preferring a wild and defolate feene. Soon afterwards, we came in fight of t&e rugged iftand of Jura, the ifland of Ifla, and, farther diflanr, the mountains of Mull. Thefe we viewed with much pleafure, as they were foon to be objects of our particular attention. We now dtefeendfed from the mountains to the fea-fhore ; where we obferved' an Id, gloomy, rainou& building, called Caflle Sweki, fituated in a wretched-looking country. Even the few inhabitants we faw, had fomething fo melancholy and deprefTed in their appearance ; their miferable huts were in fuch unifon with FROM BUTE TO JURA, 147 with the fcenery as to occafion in us an unufual lownefs of fpirits. We haflened, therefore, from this fpot, and crofTed a fmall ferry, and then walked about three miles to the more op- polite the ifland of Jura. The ilrata, all the way from Kilifled to this place, feem to be principally micaceous fhiflus, fre- quently pamng to talcaceous fhiftus. We here were fortunate in getting a boat, in which we pafTed to the ifland of Jura. We now examined a part of this ifland, and then crofled to Ifla, where we remained a few days ; and again returned to Jura, previous to our voyage to the Slate Iflands. As it would be irregular, and little fatisfadlory, to detail the obfervations in the exact order in which they were made, I prefer nril giving an account of Ifla, and then of Jura. T a ISLA 2SLA AND JURA. CHAP. X. Abftraft of the. Mineralogy of the I/lands ISLA and JURA, I SLA. JL HIS ifland is thirty-two miles long, and, in fome places, nearly as broad. It is the mofl foxithern of the JEbudse, or Hebrides ; and its name is traditionally derived from Ilia, the daughter of one of the kings of Lochlin, or Norway, who was buried in the parifh of Kildalton. Dr. Campbell, in his Politi- cal Survey of Great Britain, remarks that it is the Epidium In- fula of Ptolemy ; and he imagines (erroneoufly, however) that it is denominated Ifla, or The Ifle, as being the feat of govern- ment when the Weftern Iflcs were ruled by the princes of the liles. It It approaches fomewhat to a fquare fhape, and iu much in- terfected by the fea, in particular by two confiderable lochs, one on the weft fide, called Loch Graynard, the other upon the fouthern extremity, called Loch-in-daal. It is bounded upon the N. E, by the rugged and fteril iiland of Jura ; on the E. by the ifthmus of Cantyre ; towards the S. it is feparated only about 20 miles from Ireland ; but on the W. it is expofed to all the violence of the Atlantic Ocean* The cliffs around the coafls of the ifland are, in foine places, of confiderable height, particularly at Macarthur's Head, where they rife with great grandeur and magnificence. The mores are often covered with immenfe mafles which have fallen from the neighbouring cliffs ; but, in other quarters, the cliffs difap- pear, when we have fhores bounded by confiderable fundy beaches. Beds of cailloux roules, or boulder flones, are to be obferved upon the more, but placed a confiderable diftance above high-water mark ; and in the fpace of ground between the two lochs juft mentioned, there is an extenfive links, or down, where we find, under the thin covering of grafs, fand, boulder flones, and fhells. Thefe appearances, which are proofs of the retiring of the fea from the land, are to be feen in many parts of the Weftern Iflands. Thii I S L A. This ifland, when compared with many of the Hebrides, is low ; none of the hills being above 1 700 feet above the level of the fea. The low grounds are pretty flat, often well flickered ; and, through the exertions of the prefent proprietor, Walter Campbell, Efq, of Shawfield, improvements are carried on with fpirit : the mofs lands are daily rendered arable : thus beautify- ing the ifland, and rendering it the moil productive of the He- brides, its yearly rent being now about 10,000 1. * MINERALOGY. To render the few obfervations I have to make on the mineralogy of this ifland diftincl and fatisfactory, I will firft defcribe that fpecies of rock which forms the inte- rior, with its accompanying veins, and then trace the other ilrata around the coafls of the ifland. Mining Field. The interior, or middle part of the ifland, from its containing a great number of metallic veins, and be- ing the feat of all the workings, may be called the Mining Field. It * On the forfeiture of the Macdonalds, Ifla, Jura and the lands of Muck- rain were given to Campbell of Calder, upon condition that he would pay 500 1. of yearly feu- duty out of Ifla. Campbell, about fifty years ago, fold thefe lands to the Shawfield family for 12,000 1. which is now their yearly rent : a moft flrik- ing examp'e of what may be done by fpirited improvements. I S L A. '5* It is entirely compofed of blue-coloured limeftone, which is fuppofed to occupy about thirty-iix fquare miles ; extending in diftance (fo far as I could obferve) to the fea-fhore $ neither does it rife to any conliderable height, for other rocks generally take its place when it rifes to a few feet above the level of the fea. The limeftone ftrata dip towards the S. \V. Numerous fymp- toms of galena occur in this limeftone, and feveral veins have been worked with confiderable advantage. The principal feat of thefe workings feems to have been in the neighbourhood of Garthsnefs, which is fituated about the middle of the limeftone diftricl. At this place there are die remains of a lead vein, which runs S. E. and N. W. and dips towards the S. Betides the galena, there alfo occurred, in the working, rich copper pyrites ; and it is faid that, at one time, fpecimens of fulphu- rated manganefe had been difcovered. At Glafgow-beg there is another vein of galena, running E. S. E. and W..N. W. ; but it is traverfed by a baiakic vein, which runs nearly S. S. W. and N. N. E. At a little diftance fouthward from this, we obferve an opeacaft vein, which runs E, and W. and dips to the S. : it is alfo croffed by a bafaltic vein, as that at Glafgow-beg : the ba<ic vein is about nine feet tfide, and has thrown the lead vein about three feet from its original direction. There are many other mineral appearances beiides thefe now mentioned ; but.it would extend thefe notes to6 far to fpecify more of them. Many I ' 3 !> A. Many other bafaltic veins are alfo to be feen : fome traverfe the metallic veins ; others crofs each other : in fliort, a plan of this mining field would reprefent a limeilone diflrict divided into a number of angular and fquare fragments. The bafaltic veins are of various fizes, from one to twelve feet in width. Many of them run parallel to each other ; fome run in a crofs direction, marking, according to the manner in xvhich they interfect, their relative antiquity f ; and not unof- teii thefe veins fland up like artificial walls, owing to the limeftone being more eafily acted upon by the weather, and being confequently firft carried away. Befides the galena, confiderable quantities of copper pyrites have been found, but the quantity too fmall to be of any xonfe- queiice. Alfo, upon the fouth fide of the limeftone diftrict, near to LofTit hill, iron ore has been quarried ; but its fituation is not yet well afcertained ; and I am afraid, from the accounts I have heard, that it will be trifling. The workings in thefe veins have never afforded fluor ipar ; they produce only ba- rytes and calcareous fpar. Fluor fpar is a rare production in Scotland; ;~ Werner Neue Theorie von der Entstehung der Gangc. I S L A, '53 Scotland : I have only obferved it twice ; once in Shetland, as will be mentioned afterwards ; and in a vein among the gra- nite mountains of Aberdeenfhire. Before concluding this fhort defcription of the mining field, I mall mention two remarkable facts, which feem well authen- ticated. i. Silver. It is ^confidently affirmed that a lump of ca- pillary filver, weighing fixteen ounces, was found with the galena, in the vein at Garthsnefs. This is an iiiterefling fact ; and, ihould the veins be again opened, will prove a frefli incentive to carry on the working with fpirit, as it is not impro- bable that veins of filver may be found. We know that fcarcely three years have elapfed fince native -raver was difcovered in Great Britain, and it is of confequence to obferve, that it occur- red in a fituation fomewhat analogous to that in Ifla, the filver forming a firing, branching from the fide of a vein of galena ^, 2. >uickfilver. A quantity of this valuable metal was difcovered 'in a peat mofs fome years ago ; and Dr Rotheram informs me that it is now in the pofTefuon of Mr Campbell. Some flight fearch has U been f It was at Hurland, in Cornwall, where this filver was difcovered. 154 i s L A. been made to difcover its fituation, but without fuccefs. This muft not, however, be confidered as a proof that no veins exift ; for, to determine this, it will require a more regular mode of invefti- gation than has yet been purfued. Farther, the following fadls {how that limeftone rocks are not unfavourable to the produc- tion of quickfilver : i. It is found in globules, in white lime- ftone, at Marfala, in Sicily ; (Mineralogie Sic'dienne, par Borch, Turin 1780.) 2. Behind Guancavelica, in South America, the ardefia pafles into limeftone, which is rich Jin filver and mercu- ry; (Helm Tagebuch reifen durch Peru^ p. 431.) In the mine- ralogical colleclion at Paris there are fpecimens of limeftone, brought from the neighbourhood of Grenoble, which contain quickfilver *. Obfervations. The mineral treafures of this iiland, from their being iituated fo near the furface, muft have early attrac- ted the notice of the inhabitants ; particularly as the Norwe- gians, the former mailers of the ifland, were early celebrated as miners. We do not, however, find any mention of thefe mines, until the time of Boethius J, who wrote 300 years ago ; but * Journal des Mines de la Republique Francoife, No. I. p. 77. % Boethius Sector. Reg. Defcript, - I S L A. but even at that period they feem to have been of much conli- deration, for he remarks, " cum frumenti ferax, turn metallo- rum dives." Since that period they have paffed through many hands ; but do not appear, in any of them, to have been con- dueled with all the judgement necefTary for fo difficult and im- portant a bufinefs. It is a matter of much regret that thefe mi- neral appearances, as well as many others, equally interefling, in different parts of Scotland, have not been profecuted with more advantage. Many circumflances have contributed to this want ef fuccefs ; but, we apprehend, the principal one is to be found in the ignorance of the generality of miners, who are too often men of little education, and obftinately wedded to their own foolifh practices. Even in Cornwall, where the mining bufi- nefs mould be beft underftood, we obferve them often working in an expensive manner. In Scotland particularly, wanderers from other countries, not regularly bred in the principles and practice of mining, have often impofed upon landed proprie- tors, by holding out to them flattering profpects of great gain, and have thus thrown a temporary obflacle in the way of improvement. It is to be hoped that the increafing tafte for chemical and mineralogical fludies will enable proprietors to treat fuch pernicious pretenders with that contempt they fo juftly deferve. U 2 Having IJJ I S L A, Having defcribed the mining field, I ihall now proceed to mine the rocks around the mores of the liland ; and to do this with regularity, will begin at Portaskeg, a finall harbour iituated upon the found of Ifla. Here the cliffs are low, and compofed of compacl micaceous miftus ; which paffes either to Ardefia, or Gneifs ; and in all thefe gradations, are to be obferved, rounded or irregular fhaped pieces of granite. This granite, which is compofed of red-coloured felfpar, and white quartz, and fometimes iron pyrites, cannot be faid to be connected by a pafte in the manner of a breccia, as the gra- nitic mafTes and fhiftus pafs into each other, mowing that they have been formed at the fame time. Ferber *, who has ob- ferved limilar appearances in the mountains of Ruma, agrees with Pallas j~, in fuppofing that gneifs, micaceous fhiilus, and ardefia> are formed from the detritus of granite mountains ; and upon this theory, he explains the appearances we are now confidering. He conjectures, that the groifer particles of gra- nite, having undergone a little alteration, are agglutinated in the form of granite, and inclofed by an aggregation of the fmaller parts, which . become argillificd, forming the ardefia, This explanation is untenable, and unneceflary, when we con- fider * New Tranfa&ions of the Imperial Academy of Peterlburg, vol. n. / f Obferyations fur les Montagnes, 410. Peterfburgh, I S L A, fkler that after the greater part of the granite was precipitated, flill a fmall quantity might remain, which would be depofi- ted along with the ardefia, and form thin ftrata inclofed in it J, or irregular fhaped difperfed pieces, as in the cafe at Port- afkeg. From Portafkeg the coafl becomes gradually higher as we approach Macarthur's-head, and is formed for a confiderable way of rocks iimilar to thofe I have juft mentioned, which the fea has in fome places * hollowed out into considerable caves. As we approach nearer to this great head-land, the cliffs become much higher, and the micaceous fhiflus, &c. dif- appears ; a granulated quartz taking its place *. Immediately upon the more, I obferved a large bafaltic vein traverfing the granulated quartz, rifing up through it like an immenfe wall, and j Karften 3 Helvet. Mag. and Monnet 25 J. Phyfique, 85. * Mr Mills, in his account of fome ftrata in Ireland and Scotland, detailed in the Philosophical tranfa&ions of the Royal Society of London, for 1790, has given a defcription of Ifla. As it differs confiderably from the observations I am now to detail, it will be neceflary as I proceed, to contraft our obfervations ; fo that i future travellers, may be enabled to judge, who is in the right. Speaking of this part of the iflaud, he fays, '* that it is compofed of chert, which extends to Macarthur's-head, IjS I S L A. and extending along the more to a confiderable diftance ; in fome places forming a powerful barrier between the fea and a few cottages, which are built at the bottom of the cliffs. Having reached the head-land, I obferved the cliffs rifing to a great height, and compofed of ftrata of arenaceous quartz, ele- vated at an angle of 45 ; and the rocks being tinged of a red colour, give a very wild character to the fcene. This arena- ceous quartz extends to a confiderable diftance ; but is at length interrupted by a rock, which has much the appearance of a breccia, being compofed of varidufly fhaped pieces, (and fome of great fize) of the granulated quartz, connected by finaller particles of the fame quartz ; which has intermixed mica, and talc *. Frequently the whole has a red colour, which is owing cither to the decompofition of the mica, or fulphuret of iron, which is fornetimes difperfed through it. As we wandered a- long the fhore, I obferved this breccia interrupted by a vertical flratum of micaceous fhiftus : upon one fide of the flratum, is the breccia ; on the other, is the diftindl granulated quartz. I would recommend this appearance to the particular atten- tion * Dr Townfbn in his travels among the Carpathian Alps, obferved great ftra- ta of granulated quartz, (what he caLs primitive fandflonfci ^ing upon granite, and he obferved it in all the ftates From fine granulated quartz to that of breccia, as in the cafe with the rock of Ifla, Travels through Hungary, 4to. I S L A. 159 tion of future travellers, for I muft confefs, I was fo fatigued when I reached this fpot, that I could not give it that attention it undoubtedly deferves. The granulated quartz now forms cliffs along the fhore, until we come to a fmall bay, where flrata of micaceous fhiftus appear ; and here the hills rife to a confiderable height, being compofed of micaceous fhiftus upon the lower part, and towards the fummit, probably of gra- nulated quartz. We now crofTed over fome higher grounds until we reached Ben-vinkie, which is faid to be the higheft hill in the ifland, although it is not more than 1 700 feet a- bove the level of the fea. The lower region of this hill is compofed of micaceous fhiftus ; but as we go upwards, gra- nulated quartz makes its appearance ^ and upon the fouth- weft fide, which is very deep, a great vein of bafalt reaches very nearly to the fummit. The country becomes lower af- ter pafTmg this hill, and is pleafantly diverfified with fmall ir- regular hills, that are intermixed with natural wood. The cliffs upon the fhore are not very high, but are much broken by the a&ion of the fea, which has formed many detached rocks ; and thefe, having a grey colour, prefent a flriking pic- ture of fterility. Along with the micaceous fhiflus, we have now ftrata of ardefia, chlorite-flate, hornblende rock * ; and thefe * Thefe Mr Mill includes under the name of Hornftont . i6o i s i, A. o thefe continue to Loch-Kuneftle, a fmall harbour on the coaft. At this harbour, we obferved a low hill called Knock Kuneftlc, which is compofed of ardefia, chlorite-flate, &c. in its lower part ; but upon the fummit, decompofing greenftone makes its appearance. ! could not determine whether it forms a flratum or a vein ; but obferved, that when in a ftate of de- compofition, it affected the "compafs at the diflance of four feet. From this to Lugwillan, the coaft and country conti- nue rugged, and compofed of the fame rocks as thofe which extend from Macarthur's-head to Loch-Kuneflle. This little village, unluckily for the traveller, is extremely wretched ; pre- fenting a fad picture, if not of poverty, yet of dirtinefs and iloth. It would certainly be much for the advantage of the proprietors, as well as conducive to the comfort of the pea- fantry, if commodious houfes were built, and ftridl regulations with regard to cleanlinefs enjoined. I mention with pleafure, that Mr Campbell, has already in part begun this meritorious plan, and it is not to be doubted that he will foon feel the ad- vantages of it. After leaving Lugwillan, we met with a .fmall harbour named Leodamis, or Lowdinas bay, which affords fhelter to fmall veffels ; but like other harbours upon this coaft, it is dangerous from the number of funk rocks, which extend to a confiderable diftance. The rocks in this neighbourhood are com- pofed I S L A, l6l pofed of micaceous fhiflus, which by its decompofition forms a fine white fand, that covers the more ; and at the upper extre- mity of the harbour, I obferved feveral pieces of melanteria, or black chalk, which feemed to have been detached from ftrata that probably alternate with the micaceous fhiflus. We r now walked for ten miles, through a level country, to Loch- laggan, a finuofity upon the fide of Loch-in-daal. The rocks in this tract, are compofed of micaceous fhiflus, and the ge- neral appearance of the country, to the extremity of the ifland, where it is terminated by the lofty Mull of Kinhouth, announce a fimilarity of competition. From Loch-in-daal to the village of Bowmore, we pafTed thro' a level country, formed principally of micaceous fhiftus *, which appears, in fome places, to alter- nate with greenflone. This lafl mentioned foflil, as alfo wac- ken, have been obferved, in other countries, in a fimilar fitua- tion ; but bafalt, as Dr Mitchell informs me, is peculiar to the fiotzgeburge, or flratified mountains. We are, therefore, to confider the obfervations of the celebrated Charpentier f and X Faujas * Mr Mills remarks, that the whole extent to Kenhoath-head, and fooa to Bowmore, is hornftone. I J 4 Helvet, Mag. 445. 546. Jbid. 3. 236. Charpentier, 8x, 187. I 162 I S L A. I>aujas St. Fond f, who aflert that bafalt flrata occur in pri- mitive mountains, as indicating only greenftone or wacken. The village of Bowmore, which is the principal one in the ifland, is pleasantly fituated upon the banks of the loch., and is the centre of all the bufmefs in the country. From this to Kiliru the roads lead through a flat country, part of which feems to have been gained from the fea. Near Kiliru rs the feat of Mr. Campbell, which is pleafantly fituated at the laead of the loch, but is much expofed, from the want of plant- ing. From Kiliru to the point of Runs, the ifland is in gene- ral low, excepting about the Runs, where it rifes into hills, of which Bentarvil is the higheft. Being difappointed in examin- ing that part of the ifland, we crofled from Kiliru to Kilchomam The country, in this direction, is low, interfperfed with fmali lochs, and in fome places well cultivated ; and micaceous fhiflus, traverfed with quartz veins, is the only rock that oc- curs. Near to Kilchoman, I obferved an old, ruinous, gloomy building, which was once the feat of the turbulent Macdonald, prince of the Ifles, but is now peacefully inhabited by the mi- nifler of the parifli. From Kilchoman to the fea-coaft, the country is low ; and the rocks, which extend along the fhore, continue to form low, broken cliffs of micaceous fhiflus, alter- nating f Faujas fur le Trap, p, 86. I S L A. 163 ternating with fand banks, until we come to Saneg-more. Here the cliffs rife to a confiderable height : and, being much expofed to the ocean, are broken into many fantaftic forms, pre- fenting a grand and romantic piece of fcenery. Knowing, from Mr. Pennant *, that there was a fine cave in thefe cliffs, we wifhed to examine it. Accordingly, having procured guides, through the goodnefs of Mr. Campbell of Sanicks, we de- Icended a fteep precipice to its entrance, when we found our- felves furrounded by lofty, rugged precipices, which towered far above us. The grandeur of the fcene was much heightened by the turbulence of the fea, which came rolling in flowly, but with .awful rnajefly, darning among the rocks, with a noife that refounded on all fides like the difcharge of artillery. Hav- ing entered the cave, we found it pretty extenfive, but damp and black, owing to the water falling from above. At a little urge) and fiotz rocks (flotzgeburge). Near to Mr Campbell's houfe, I obferved the ardeiia covered by grauwacken, and both apparently traverfed with the fame bafalt vein j which leads us to fuppofe that they were formed at the fame time ; and, in fupport of this, I may mention, that German mineralogifts have obferved thefe rocks to alternate *. Upon the fide of the B b ifland * Eijimerling, Band. 3. 105, i 94 E A S D A t Ev iiland oppofite to Eafdale, we have an appearance of flotz ilra- ta. Immediately upon the fhore, I obferved red -coloured argillaceous fandflone, flratified with fandflone breccia and bafalt, and' the whole traverfed with bafaltic veins. There are alfb quarries of ardefia tegularis in fome parts of the ifland. But the principal attention of the proprietors is turned to the ifland of Eafdale, where the (late has hitherto been found in great quantity. 1-AS-D ALE. THIS ifland is about half a mile long, and of the fame breadtK^ and is celebrated for its having afforded the befl and greateft quantity of ardefia tegularis, of any part, of equal extent, in Great Britain. A very connderable portion of the ifland is compofed of ardefia tegularis, and this is traverfed by bafalt veins. The ardefia, where in contact with the bafalt^ is ufelefs, being fhivery, and breaking into fmall pieces, unfit for the making of flates : it is alfo equally bad, where veins of quartz r limeflone occur. The E A S D A L Ev 1-95 The iiland is now cut very low, excepting a fmall portion at the fouth end ; and levels hav been made out to the fea, to carry off the rain water. As the greater part of the ifland is now upon a level with the fea, it is plain that the raifing of Hates muft be abandoned, or continue to be worked at a con- fiderable expence by means of machinery ; which would pro- bably be a bad plan, when we confider the extent and excel- lence of the rival quarries at Ballyhulim J. The mofl judici- ous arrangement would certainly be, to open more extenfive quarries in the neighbouring iftes of Luing and Seil, where, in all probability, after the ground is properly cleared, good flates may be foundo The ardefia in this ifland was firft quarried about one hun- dred years ago ; but was for a long time of little importance, as fandftone flag and tiles were generally ufed for roofing houfes. As the ufe of flates became more prevalent, the quarries were enlarged ; and the prefent managers having obtained a very fa- vourable leafe, thefe quarries have been wrought to fo great an extent, that 5,000,000 flates are annually fhipped from this ifland. The number of workmen is at prefent about 300 ; and B b 2 they J The quarries at Ballyhulifti employ about 200 men ; and the flates r.;* font to Leith, Clyde, England, Ireland, and America. 196 o B A N. they are divided into quarriers and day labourers. The quar- riers are paid annually at a certain rate for every thoufand flates : from lod. to ijd. I believe, as their work has been at- tended with more or lefs difficulty. The day labourers are employed at the company's expence in opening new quarries, and have from lod. to is. a day. O B A N. AS the weather continued very pleafant, we preferred going to Oban by fea, in place of the circuitous rout by land. Having procured a boat, we left Seil, with a fine breeze ; our voyage was agreeable, with fcenery often ftriking ; on one hand, was the lofty coaft of Mull, extending from Loch Bay to Crogan, all apparently bafaltic 5 on the other, the mainland rifing into fmall hills, alfo with a bafaltic afpect. Having patted the ifle of Kerrera, which lies acrofs the bay of Oban ; in a fhort time afterwards, we landed at the village. The bay of Oban is of a femicircular form ; is from 12 to 14 fathom , with good anchoring ground, and will contain 500 fail of O B A N. 197 of merchant mips. The village is pleafantly fituated at the upper part of the bay, a flation excelleiitly adapted for the fifhing. The decline of this branch of trade, has indeed been unfavourable to the rife of Oban ; but it is, notwithftanding, the mofl confiderable village on this part of the coaft, con- taining about 586 inhabitants. It is to the exertions of the two brothers, the MefTrs. Stevenfons, who fettled here in 1 778, that Oban is chiefly indebted for its prefent flourifhing con- dition. As we were anxious to proceed on our journey through the iflaiids, well knowing the variable flate of the weather in thefe highland countries ; we took but a glance of the rocks in the neighbourhood of Oban. The flrata immediate] y upon the fhore, on both fides of the town, are formed of dark blue co- loured argillaceous fhiftus ; immediately above this, I obferved in fome places bafalt, or bafalt porphyry. As we approach Dunolly caftle, which forms the extreme point of land upon one fide of the bay, vafl rocks of breccia appear ; and thefe continue all the way to Dunftaffnage caftle *. Both thefe caf- tles * At Boregonium, which is a few miles from Dunflaffnage, there are, accor- ding to Dr. Garnet, undoubted volcanic appearances, Dr Walker informs me ? that the pumice, which Dr. Garnet mentions, is the fcoriae from the iron fur-, naces, which were worked at that place by our anceflors, O B A Nv ties arc built upon rocks of breccia, which is compofed of va- rioufly fhaped pieces of granite, micaceous fhiftus, and fand- ftone, connected by an arenaceous breccia. Upon different parts of the coaft, and in the interior of the country, this breccia feems to lye upon a red coloured argillaceous fandftone. From Oban, the country becomes gradually higher as we approach the great mountain of Cruachan ; and the ftrata alfo change. If we walk by the Inveraray road, we obferve wacken, and fometimes bafalt covering the fandftone ; and in many places great rounded mafTes of granite, which formerly conftituted part of the breccia, are to be feen fcattered about. Thefe fandftone and bafalt ftrata, probably continue until ardefia and micaceous fliiftus, which form the lower region of Cruachan, make their appearance ; and this is fucceeded by the granite, which rifes through it, and continues to the top of the mountain *. Mr. St. Fond has given us a chapter upon the lithology of Oban, in his travels through Scotland ; but he has here, as ufual, intermixed his theoretical fpeculations with the defcrip- tions of th ftrata. He denominates the blue argillaceous fhiftus * I owe this information, with regard t-o Cruachan, te my friend Mr. Cad- dell. VOYAGE TO MULL* 199 4-hiftus of Oban, a limeftone ; this, he fays, is an aquatic pro- duction ; but the bafalt, he imagines to have been fuperindu- ced in a melted ftate under water, which prevented the lime- {lone from being altered ; and further, he defcribes the breccia as a volcanic matter, which has been thrown up in a fimilar mariner with thofe volcanic erruptions " in which water heat- " ed to the higheft degree of ebullition, enters into concourfe " with fire, and the different elaflic emanations generated by " fubterraneous combuftion." I muft confefs my inability to comprehend this explanation ; at any rate, it is now ufe- lefs to attempt fupporting this part of the volcanic theory, as it has been demonftrably refuted by Mr Kirwan, in his paper on bafalt, VOYAGE ro MULL. HAVING arranged every thing for the continuance of our journey, we fet fail for the ifland of Mull, which is about 15 miles from Oban. In our way, pafTed near to the ifle of Ker- rera, of which Faujas gives the following account. " A part " of this ifland is volcanic $ on the. coaft fronting Mull, there " are 2JOO VOYAGE TO MULL. " are collections of compact lavas in mafTes, and in large cur- " rents. This bafaltic lava appears fometimes in the form of " prifms, which are not very regular ; at leait in the places I " had an opportunity of examining. I alfo found fome rocks " of micaceous fhiftus of a whitifh colour, and others which " were greenim, with a porous texture. Thefe fhiftus, or * gneifs, are compofed of quartz, fteatites, and fmall fcales of " mica. " Near the rock of micaceous fhiftus, there is found com- " mon flate of a deep grey colour, approaching to black ; the " beds of which are almoft even with the ground ; quar- " ries might eafily be opened here with great advantage to " the country. They would even become an object of com- " merce. Among the flate, there are found fome brilliant " pyrites, the cryftallizations of which are cubical J." We next paffed the ifland of Lifmore, which is about nine miles long, but very narrow : it is according to Williams, com- pofed entirely of limeflone, .traverfed with bafaltic veins. Dr. Mitchell fuppofes that the limeflone belongs to the tranfition rocks. , $ Travels through Scotland, &c. VOYAGE TO MULL* 201 rocks (uebergangsgeburge). From the greater part of the ifl- and being formed of limeftone, at the fame time well fhelter- ed, it is rendered one of the mod productive fpots in the Highlands. After a fhort voyage, we came clofe in with the coafl of Mull, but on account of the tide, we were obliged to pull along the more for fome miles, which gave me an oppor- tunity of examining the more-, until we landed on the coafl: below Achinacraig. . G c MULL. MULL, CHAP. XIII. Outline of the MINERALOGY of the I/land of MULL. i A HIS ifland is about 22 miles long, and 16 miles broad. It is reckoned by fome writers to be the Maleos of Ptolemy * j and Cambden is of opinion, that it is the Mille of Pliny J. On the north, it is bounded by Ardnamurchan ; on the eafl, by the rugged flerile looking mountains of Morven, and the ifle of Lifmore ; to the fouth, are the ifles Jura, Scarba, and Slate ifles ; and on the weft ? I-kolmkill, Staffa, Coll, and Tiree. The coafl of this ifland is much diverlified in its appearance ; in many places we obferve a great extent of fleep and bold rocky * Campbell's Political Survey, vol. I. p. 599. t Britannia, p. 848, ft fj t L. 203 rocky ihore's, forming tremendous precipices ; particularly upon the fourth flrore rieatf Loch Buy. Often the fhores are low, but ftill rocky and dangerous ; fekloin is there any fandy beach, the coafl being generally covered by the immenfe maf- fes that have fallen from the neighbouring cliffs. It is low, however, towards the S. W. extremity which is called the parifh of Rofs. The ifland is very mountainous, and fome of the mountains rife to a confiderable height ; particularly Ben-More, which is reckoned the Jiigheft in the ifland. It is much interfecled upon the weft fide, where there are two confiderable lochs or arms of the fta, called Loch Skriddan, and the other Loch- na-gaul, Acnriacraig, where we landed from Oban } is fituated at a little diftance from the fea fhore, with fbme confiderable flats near it ; and thefe being cultivated, and in fome places wooded, enliven the fcene confiderably. The rocks are in general bafalt and wacken, which are in many places traverfed with bafaltic veins. The occurence of veins of bafalt croflmg a fimilar rock, feems to be very rare ; as I am well informed, that foreign mineralogifls, have never ob- ferved fuch appearances. Mr Faujas St. Fond, in defcribing C c a this 2O4 MULL. this part of the ifland, feems to have been much flruck with one of thefe veins, which he compares to a circus ; and has given a long detail of the way in which it may have been formed. This was all very unnecefTary, as this vein does not differ from many others to be obferved in the ifland ; and the idea which Mr St. Fond raifes of its magnificence, is far flretched it is trifling when compared with the grand ap- pearances upon the coafls of Ida and Jura. As we advance towards Loch Speleve, the cliffs upon the more do not increafe much in height ; but there are land cliffs behind them con- fiderably higher. The rocks are almoft entirely of bafalt and wacken, all the way to the loch, as alfo the hills in the neigh- bourhood. About half a mile from Achnacraig, I obferved a ftratum of blue coloured limeftone, covered with calcareous fandftone ; but thefe flrata are vifible only for about 80 feet, when they are loft under the bafalt. This limeftone contains in it belemnites, and is therefore to be reckoned with the tranfition rocks ; and is what Mr Kirwan confiders as the moil ancient of the fecondary ftrata *. As there is a good road, along the ftiore of the ifland, from Achnacraig to Tobermory, we preferred it to coafting by fea. Having * Geological EfTays, p. .226. MULL, 205 Having left Achnacraig, we parTed, for about a mile, through little wooded glens, which are extremely pleafant, particularly in a country where wood is truly a rarity. The ftrata ftill continued bafaltic, excepting at one place where I obferved a flratum of blue-coloured limeflone cropping thro' the foil. As we journeyed along the fhore at the bottom of the high hills which bound it, I judged it necefTary to examine fome of them to their fummits ; that I might obtain more diftincl in- formation of their nature, and have an opportunity of furvey- ing the neighbouring country. The day being fine, we began to afcend a high hill, about two miles from Achnacraig. The afcent was very fteep, until we reached an extenfive plain feve- ral hundred feet above the level of the fea. The ftrata, to this height, were bafalt and greenftone, and both frequently tra- verfed with bafaltic veins. The greenftone, even at a con.fi- xierable diftance, has a fingular fcorified-like afpecl, from the- felfpar having decayed, and the remaining hornblende, ref ena- bling a dark green, or bla*-cki(li cellular mafs, not unlike the fco- ria of an iron furnace. The plain was covered, to its whole ex- tent, with loofe ftones of an iron-brown colour. Hardly a trace of vegetation could be feen ; and the deep filence of this defert was disturbed only by the rufhmg of the cold piercing wind acrofs the mountain. The loofe mafTes of rock jufl mentioned, I found to be of breccia, which is compofed of va- rioufly 206 M U L L. rioufly fhaped mafTes of quartz, earthy felipar, hornilofle, and granite, connected by a bafalt or wacken ? bails J. It is proba- bly of the nature of bafalt tuff; which, according to German mineralogifls, is a rock with a bafalt or wacken bafis, having, immerfed, fragments of other rocks, as granite, quartz, &c. We now walked towards the fummit of the mountain, which we reached, after having paffed over a fucceflion of fmaller plains, or platforms, feparated from each other by fteep bafakic craigs. The fummit is compofed entirely of bafalt, which con- tains much hornblende ; and this rock has the property of re- verfing the compafs at a considerable diftanee, and even in de- tached pieces. From this elevated ntuation we had a fine view of the ifland, Towards Tobermory the mountains appear to- become gradually lower ; but, upon the weft fide, a tremen- dous groupe of varioufly-fhaped mountains appears before us, and among them Ben-more rifes with much dignity. The glens, which we obferved run from the mountain, are of great depth, very fteep, and apparently compofed of ftrata of ba- falt and greenftone. Thefe ftrata, however, run in a direction contrary to that of the vallies, which intimate that the land has t I am oMiged to marie this doubtful, as I unlodbily loft the fpecimens, which would have enabled rae r to determine the nature of the MULL. 207 has funk down, as we have already explained in our fpecula- tions upon the formation of the bed of the Clyde. We now de~ fcended from the mountain, but by a different route from that which we followed in afcending ; and although it was fatiguing and difficult, it afforded us an opportunity of obferv- ing the bafalt and greenftone alternating with each other, and elevated nearly to an angle of 45. We now continued our journey along the Tobermory road, with hills upon one hand, but in a fhort time the land on the other became low, ftretching out towards the found of Mull, to a point on which is fituated Duart Caftle. The hills, as alfo the hills near the more, are ftill bafaltic ; but we were informed that there is, at the caftle, a great ftratum of limeftone, which affords cornua ammonis and {hells. As we approached Achna- crofh, we obferved, upon the more, ftrata of argillaceous fand- ftone, with interfperfed bituminous and coaly matter, as is ufually the cafe with fandftone in coal countries ; and, at a lit- tle diftance, a rock, which feems to be analogous to greenftone, of which a particular defcription is , given in the following chapter. From this to Arros die mores are low, but the hills rife to a confiderable height j and both are formed of bafalt, greenftone, and and wacken, which I fomctimes obferved traverfed with bafal- tic veins. The bafalt, but more particularly the wacken, con- tains zeolite, which is either compact, fibrous, or cryftallized. I regretted extremely that I had not an opportunity of examin- ing this part of the country more particularly, as there can be ao doubt but that it would afford much curious information with regard to the rocks of trap formation. I have however to offer as an apology, (if fuch a thing is becoming,) that, in travelling over all that track of country, we were envelopped in thick clouds and pouring rain ; fo that the few obfervations as to the nature of the hills, were made by examining the de- bris in the ravines, or were now and then amfled by the par- tial difperfion of the clouds. I may now alfo remark, that, in travelling thefe countries with a view to the particular ex- amination of their mineralogy, it will be abfolutely necefTary for the traveller to carry along with him a tent, and other con- veniences, fo that he may encamp among the mountains, and examine them leifurely, and with that fcrupulous accuracy which the importance of the fubject requires. At Arros there is a fmall colonade of bafalt, upon which there are ftill the remains of an old caftle, once inhabited by Macdonald prince of the Ifles. In the bed of the river of Arros, (a fmall flream of water which comes from the neighbouring bafaltic f.1 U L L, 209 bafaltic hills,) I obferved numerous blocks of granite, fimilar to v thofe upon the hill near Achnacraig. Thefe blocks feem to be derived from a bafalt tuff fimilar to that obferved near Achna- craig ; and it is probable that fuch a rock may be difcovered in the neighbouring hills. It will be an object worthy the atten- tion of future travellers, to afcertain, whether this bafalt tuff-? merely covers the bafalt, as has been obferved by Reufs in the mountains of Bohemia, or alternates, as is the cafe with the bafalt tuff in the ifle of Canna, and in other parts of Scotland. It matters not in which of thefe fituations it be found : it is flill to be confidered as a fecondary rock, and, like thefe, te have been deposited from an aqueous fluid. Probably fome may think that thefe maffes have been feparated from the de~ compofing bafalt itfelf, as it fometimes contains pieces of gra^ nite. This, however, is an appearance fo rarely to be obferved in this ifland, that I can hardly imagine the granite blocks to 'be derived from that fource. 'ProfefTor St. Fond has fpeculated upon this fubjedl, as he obfer- ved fimilar appearances in different parts of the ifland. For the in- . formation of my readers, I will extract the following paffage from Jiis Travels. " Thefe lumps of granite (fays he) may have been ** ejected from granite quarries, which perhaps exifled at great D d " depths 2 IO MULL* " depths under thefe ancient volcanoes, by the cxplofions which " took place at that epoch, when extenfive corabuftions waited " thefe countries, and formed groups of iflands, which ieem " to have the fame origin. " It is, betides, within the verge of pombility, that thofe " parts of the mountains where they are now found were not, " at that period, elevated fummits, but rather formed part of " the bottom of the fea, and that thefe granite blocks w r ere " rolled from a diftance by the currents. It is poflible that " circumftances of fubterraneous explolion, equally terrible *' with thofe which formed the ifle of Santorini in the Archi- " pelago, or Montenove in Italy, may have raifed up the bot- " torn of the fea into volcanic peaks ; or, if it fhould appear " more plaufible to fome, we may refer to a period when " mountains ftill higher were covered by the fea : a fadl, which " cannot be doubted, fince marine bodies are found in great " abundance in beds of limeftone, or clay, fituated on the Alps " or Appenines, at a height three or four times greater." At Arros, we changed our route ; and in place of going on to Tobermory, we took our courfe acrofs the ifland to Luggan Ulva. The road, which is but indifferent, leads us among Mis of no considerable height, to the plain of Knock, litu- ated MULL, 2U ated at the head of Loch-na-gaul. The hills are compofed of ftrata, of bafalt, and wacken ; which are fometimes traverfed with bafaltic veins. The loch, which is of conliderable ex- tent, is bounded upon one fide by the mountain of Ben-more, with other neighbouring hills, that extend towards the fea more, forming lofty crags, not unlike thofe of Salifbury Hill near Edinburgh ; on the oppofite fide, are the hills that bound the road which leads towards Luggan Ulva. Ben-more, which is the highefl mountain in the ifland, is of confiderable mag- nitude ; and Mr St. Fond remarks that it has much the ap- pearance of the famous volcanic mountain Vesuvius. We did not afcend this mountain, fo that I cannot give any ac- count of the rocks of which it is compofed ; but I have had the opportunity of examining fpecimens brought from it by Mr. Caddel. It would feem from thefe, that it does not differ from the other parts of the ifland which I have already defcribed, being compofed of bafalt and greeiiflone ; even to its very fummit. This agrees pretty nearly with the obfervations of Mr. St. Fond, who tells us, that it is compofed of lava ; that is bafalt. We purfued our journey along the oppofite fide of the loch, which led us to Luggan Ulva ; I found little variety of rock ; the bafalt and wacken flrata traverfed with bafaltic veins, flill continu- D d 2 ing fI2 MULL. ing. The wacken, however, affords many beautiful fpeci- cimens of zeolite, and alfo a rarer foflil, the prehnite. Nearly oppofite to Luggan Ulva, lies the iinall iiland of Ul- va, which is evidently compofed of the fame rocks ; and far- ther diflant, is the ifle of Geometra, which is alfo bafaltic. As foon as the weather, which had been for fome time tern- peftuous, became moderate, we crofTed at die mouth of Loch- na-gaul, and landed immediately under the high cliffs, which we had feen from the head of the loch. We now walked a- long a confiderable extent of fhore, which is bounded by lofty crags, compofed of bafalt and wacken flrata, and both tra- verfed by bafaltic veins, which run in very different direc- tions. Immediately upon the fhore, I obferved flrata of argil- laceous fandftone, and fandflone breccia ; and we were told, that both coal and lead had been difcovered in feveral places in the neighbourhood. About 200 feet above the level of the fea, on the tract which takes us acrofs the mountains to Loch Skriddan, our attention was arrefled by the appearance of a curious fpecies of breccia. It is compofed of fragments of quartz, micaceous fhiflus, compact limeflone containing flint, and the whole cemented by an arenaceous bafis ; fometimes it has a calcareous bafis, when it has a yellow colour, owing to MULL, to a decomposition of the limeflone. Below the breccia we obferved a compact micaceous fhiftus. In going higher up, we had a more diftin- torn of coal. 3. If fandilone and limeftone alternate, and be accompanied with bituminous male, it is reckoned favourable for coal. 4. Sometimes where fandflone and bafalt alternate, coal has been found. 5. Mr Kirwan remarks that there is great probability of finding coal in the neighbourhood of mountains of argillace- ous porphyry f . 6. Although coal has never been obferved alternating with primary ftrata, yet it has fometimes been found in their im- mediate vicinity ; and coal has even been obferved lying on granite. I believe, however, that fuch coal flrata are gene- rally trifling. Having f Geological Eflays, p, 347. ON COAL, 239 Having, from an accurate inveftigation, difcovered fucli ftrata as render the prefence of coal probable ; we mufl next endeavour to difcover its actual exiflence. To do this, we mufl examine the beds and banks of rivulets, where, if fmall pieces of coal appear, we may be pretty certain that coal flrata exift near at hand. Ditches are to be examined ; for, in form- ing them, it is often necefTary to cut thro' the thin covering of gravel and fand which conceals the crop from our view. We fometimes obferve a footy-like matter fpread on the ground : this is formed from the decompolition of coal, and is therefore a good fymptom of its vicinity. Not unfrequently we obferve mafTes of coal, or bituminous wood, immerfed in the breccia which is obferved in coal countries : but this is often a falla- cious appearance ; for, upon cutting thro' the breccia, we find that the fubjacent rocks contain no coal ; fo that the pieces of coal or wood, which the breccia contains, are to be confidered as merely accidental. After having obferved any of the above-mentioned appear- ances ; our next endeavour is to obferve the crop, or the out- burfl, of the ftrata. This is a matter of much difficulty ; and requires particular attention to the difpofition of the fragments of coal, &c. If they be found upon the banks or bed of a ri- vulet, 340 ON COAL* vulet, we muft fearch from one extremity of the ravine to the other, to difcover the crop of the ftratum. If the foot-like matter is obferved, it will be necefTary to remark whether it lies upon a declivity or a plain ; as inattention to thefe circum- ilances has often been the caufe of great difappointment and expence to the coal-miner in overfhooting the ftratum, that is, cutting beyond its real fituation. Upon a declivity, we know that the decomposing and loofe matter of a crop will naturally fpread downwards, in proportion to the fleepnefs of the ground. On this account, wherever appearances of coal occur upon a declivity, we mufl trace the debris upwards ; when we mall find it increafe in depth towards the crop, and the coal is lefs and lefs decompofed as we approach nearer to it. On the other hand, where the footy matter occurs upon a plain, we always find it thicker, and far lefs fpread, than upon a decli- vity ; and, what is of confequence, it often fpreads in a direc- tion contrary to the rife of the ftrata. If we are fo lucky as to obferve the crop, we now endeavour to detecl: the ftratum ; which we do, either by digging towards its dip, or by follow- ing the fragments of coal until we have the ftratum fairly under our eye. It ON COAL. 241 / It often happens, however, that a country may be, in ge- neral, very favourable for coal, yet no pieces of coal or footy matter are to be obferved, owing to the coal flrata lying deep : in fuch cafes a good deal of difcernment is necefTary to deter- mine the particular places where the trials are to be made. As it would be very expenfive, in fuch cafes, to dig down until we mould meet with the coal, the common practice is to bore the ground j by which, at a fmall expence, we can know the magnitude and nature of the flrata, to a great depth. In fearching for coal, by boring, our firft object is, to deter- mine the point to which the flrata rife ; as it is this which en- ables us to determine at what place we mall begin to bore. The plan, at the end of this chapter, will fufficiently explain the mode of proceeding in this operation. Suppofe A B C D to reprefent a tract of country which is fufpected to contain coal, and where the rife of the flrata is towards A. We there make the firfl perforation, which will pafs thro' the flrata 4, 3, 2, i, to the depth of ten or twelve fathoms. If no coal occurs among thefe flrata, it is better to make a new perfora- tion, than to fink deeper. We therefore proceed onwards to B, where we fufpedl that the flratum 5 is ten or twelve fathoms deep. We here bore through the flrata, 8, 7, 6, to 5 ; H h and, Q K O A L. :md, as no coal occurs,, we do. not bore deeper, but proceed to ;he point C, where we make a perforation through the ftrata n, 10, 9, to 8. By being ftill unfuccefsful, we proceed on- wards to D, where the ftratum 1 1 will be about ten or twelve fathoms deep, and here we find coal at 12. By this practice,, it is plain that that no ftratum of coal can efcape notice, as the laft perforation always reaches down to the ftratum which was neareft to the furface in the former bore. Having difcovered the breadth of the flratum, either by dig- ging, when it is near the furface, or by boring, when it is co- vered by a great load of other ftrata ; our next concern is, to de- termine whether it be of fufficient importance to be w r orked. If it is not more than 15 inches in breadth, even altho' pretty near the furface, it is not worth working ; but if it be two feet, or two feet and a half wide, and of good quality, it can he worked in moft fituations with advantage. . * The quality of the coal is afcertained from the following circumftances : i. Its general appearance : whether it be more or lefs mixed with ftoney matter j or if there be laminae of bituminous fliale or ON COAL* 243 ndftone, dividing it into ftratuta ; or i it contains much pyrites or fulphuret of iron. 2. To theie may be added the teft of chemical analyfis, by which we afcertain the proportion-of carbon, bitumena nd aihes. /Htt/wt/ / //'/ OF VOLUMF RETURN EARTH SCIENCES LIBRARY TO -^ 642-2997 LOAN PERIOD 1 1 MONTH 2 3 4 5 6 ALL BOOKS MAY BE RECALLED AFTER 7 DAYS Books needed for class reserve are subject to immediate recall DUE AS STAMPED BELOW FORM NO. DD8 UNIVERSITY OF CALIFORNIA, BERKELEY BERKELEY, CA 94720 U.C. BERKELEY LIBRARIES CD3M71377S