IMPERIAL INSTITUTE MONOGRAPHS ON MINERAL RESOURCES WITH SPECIAL REFERENCE TO THE BRITISH EMPIRE TIM PREPARED UNDER THE DIRECTION OF THE MINERAL RESOURCES COMMITTEE OF THE IMPERIAL INSTITUTE, WITH THE ASSISTANCE OF THE SCIENTIFIC AND TECHNICAL STAF^ /\ (0 COAL BY J. H. RONALDSON, M.I.M.E., M.Inst.M.M., F.G.S. WITH MAPS AND DIAGRAMS LONDON JOHN MURRAY, ALBEMARLE STREET, W. 1920 IMPERIAL INSTITUTE MONOGRAPHS ON MINERAL RESOURCES WITH SPECIAL REFERENCE TO THE BRITISH EMPIRE IMPERIAL INSTITUTE MONOGRAPHS ON MINERAL RESOURCES WITH SPECIAL REFERENCE TO THE BRITISH EMPIRE PREPARED UNDER THE DIRECTION OF THE MINERAL RESOURCES COMMITTEE OF THE IMPERIAL INSTITUTE, WITH THE ASSISTANCE OF THE SCIENTIFIC AND TECHNICAL STAFF COAL BY J. H. RONALDSON, M.I.M.E., M.Inst.M.M., F.G.S. WITH 12 MAPS AND 2 DIAGRAMS LONDON JOHN MURRAY, ALBEMARLE STREET, W. 1920 ALL RIGHTS RESERVED IMPERIAL INSTITUTE MINERAL SECTION THE Imperial Institute is a centre for the exhibition and investi- gation of minerals with a view to their commercial development and for the supply of information respecting the sources, composition and value of minerals of all kinds. The Imperial Institute is provided with research Labora- tories for the investigation, analysis and assay of minerals, and undertakes reports on the composition and value of minerals, for the information of Governments and producing companies and firms, in communication with the principal users in the United Kingdom and elsewhere in the Empire. Important minerals from within the Empire are exhibited in the respective Courts of the Public Exhibition Galleries, and also in the Mineral Reference Collections of the Institute. A special staff is engaged in the collection, critical revision and arrangement of all important information respecting sup- plies of minerals especially within the Empire, new methods of usage and other commercial developments. Articles on these and related subjects are periodically pub- lished in the Bulletin of the Imperial Institute, and monographs on special subjects are separately published under the direction of the Committee on Mineral Resources. ^48391 IMPERIAL INSTITUTE Advisory Committee on Mineral Resources The Right Hon. VISCOUNT HARCOURT, D.C.L., Chairman. *Admiral SIR EDMOND SLADE, K.C.I.E., K.C.V.O. (nominated by the Admiralty), Vice-Chairman. EDMUND G. DAVIS, Esq. *WYNDHAM R. DUNSTAN, Esq., C.M.G., LL.D., F.R.S., Director of the Imperial Institute. J. F. RONCA, Esq., M.B.E., A.R.C.S., Department of Industries and Manufactures (nominated by the Board of Trade). *Professor J. W. GREGORY, F.R.S., Professor of Geology, University of Glasgow, formerly Director of Geological Survey, Victoria, Australia. Sir ROBERT HADFIELD, Bart., F.R.S., Past-President, Iron and Steel Institute. Captain A. L. ELSWORTHY, Intelligence Department, War Office, (nominated by the War Office). W. W. MOYERS, Esq. (Messrs. H. A. Watson & Co.), Liverpool, R. ALLEN, Esq., M.A., B.Sc., Imperial Institute, Secretary. * Members of Editorial Sub-Committee. MINERAL SECTION Principal Members of Staff Superintendent R. ALLEN, M.A. (Cantab.), B.Sc. (Lond.), M.Inst.M.M. Assistant Superintendent S. J. JOHNSTONE, B.Sc. (Lond.), A.I.C. i Senior Assistants G. M. DAVIES, M.Sc. (Lond.), F.G.S. W. O. R. WYNN, A.I.C Assistants S. BANN. A. T. FAIRCLOTH. F. H. BELL. R. C. GROVES, M.Sc. (Birm.). H. BENNETT, B.Sc. (Lond.). E. HALSE, A.R.S.M., M.Inst.M.M vi . PREFACE THE Mineral Resources Committee of the Imperial Institute has arranged for the issue of this series of Monographs on Mineral Resources in amplification and extension of those which have appeared in the Bulletin of the Imperial Institute during the past fifteen years. The Monographs are prepared either by members of the Scientific and Technical Staff of the Imperial Institute, or by external contributors, to whom have been available the statistical and other special information relating to mineral resources collected and arranged at the Imperial Institute. The object of these Monographs is to give a general account of the occurrences and commercial utilisation of the more important minerals, particularly in the British Empire. No attempt has been made to give details of mining or metal- lurgical processes. HARCOURT, Chairman, Mineral Resources Committee. IMPERIAL INSTITUTE, LONDON, S.W.y, Sept. CONTENTS CHAPTER I PACK COAL: HISTORY, GROWTH AND OUTPUT OF THE COAL INDUSTRY I CHAPTER II BRITISH SOURCES OF COAL SUPPLY United Kingdom : England and Wales '. u Scotland ........ 29 Ireland ........ 35 Asia : British North Borneo ...... 39 Federated Malay States ..... 40 India 41 Africa : Nyasaland -, . 66 Rhodesia . 67 Union of South Africa . " . . . .68 Southern Nigeria. ...... 79 North America : Canada ........ 80 Newfoundland ....... 104 Australasia : Australia 105 New Zealand ....... 1/14 ADDENDA : Kenia ; Tanganyika Territory ; Somali- land ; Trinidad ; Jamaica ; Windward Islands ; British Guiana 158 APPENDIX 159 REFERENCES TO LITERATURE ON COAL . . .160 ix NOTE : Numerals in square brackets in the text refer to the Bibliography at the end. COAL CHAPTER I COAL : HISTORY, GROWTH AND OUTPUT OF THE COAL INDUSTRY HISTORICAL IT may be regarded as remarkable that the use of coal has only become general within the last few centuries, though the existence and the combustible character of coal must have been known in very early times. It is believed that it was used as a fuel by the Chinese long before the Christian era, and evidence of its use by the Romans, during their occupation of Britain, exists in the coal and ashes found among the ruins of many of their stations near the coal-fields [4/p. 5]. W. Warington Smyth states that " the first worked coal- field in Germany seems to have been Zwickau, in Saxony, dating from about the tenth century " [8 /p. 3]. Certain ecclesiastical records indicate that coal was being won prior to A.D. 1113 in the coalfield of Worm, which lies partly in the districts of Julich, Aschen and Limburg [i] [3] [7]. There is no clear evidence that elsewhere coal was mined to any extent till toward the end of the twelfth or the beginning of the thirteenth century. About this time Cistercian monks are said to have mined coal from the outcrops of seams in the high ground of a suburb of Liege, and R. L. Galloway [4] says, " Its discovery in Bel- gium, according to the legend as quoted by Schook in his 2 HISTORY, GROWTH AND OUTPUT OF COAL 7radatu$ de Turffis (Grorngae, 1658, p. 223), was made in 1189 by a pilgrim, who pointed it out to a smith." About the same time, according to Galloway [5], the monks of Holyrood Abbey received a grant of the tithe of the colliery of Carriden, near Blackness, west of Edinburgh, and the monks of Newbattle Abbey, near Dalkeith, received a grant of a colliery on the sea- shore at Preston, east of Edinburgh. Galloway further says that in England, soon after the granting of the Magna Charta (A.D. 1215), there is " evidence of a com- mencement having been made to work coal and to carry it from the north of London," that " before the close of the reign of Edward I (A.D. 1307) the mineral was being dug, though doubt- less only on a small scale, in most of the coal-fields of England, Wales and Scotland," and that at first it was " only used by humble artisans, such as smiths and limeburners." But at this time its use in London met with such opposition on account of the smoke that an enactment was passed forbidding its use under severe pains and penalties. However, in spite of this, and doubtless on account of the growing scarcity of wood, its use increased and was extended to domestic purposes. Gradually the demand for coal also arose in France, and, by the end of the sixteenth century, the export of coal to that country appears to have attained relative importance, 1 so much so, indeed, that the fear of exhausting the supply raised the question of prohibiting its export from England. No definite action, however, was taken, but in Scotland " an Act of Parliament was passed in 1563 prohibiting all persons from transporting coals out of the realm under penalty of confisca- tion of the ship and cargo." The introduction about this time of the process of making cast iron, for which purpose wood charcoal was used, followed by a great demand for large cast-iron cannon, hastened the exhaustion of wood fuel in England and fostered the use of coal. It is, however, to the invention and perfecting of the modern steam engine, the conversion of coal into coke, and improvements in the metallurgy of iron, at a later date, that is chiefly due the phenomenal increase in the consumption of coal 1 France continues to be the chief importer of British coal, and in 1913 took i2f million tons [6]. HISTORY, GROWTH AND OUTPUT OF COAL 3 during the last century, an increase evidenced by the following figures [8/p. 9]. It is estimated that about the year 1800 in Great Britain about 10,000,000 tons of coal were raised in a year ; that in 1850 the production was 42,000,000 tons, that France was raising 4,433,000 tons, Prussia and Belgium smaller quantities, and Austria a little above 1,000,000 tons. A comparison of these figures with those on page 5, and the diagrams on pages 8 and 9, give a striking illustration of the rapid growth of coal-mining to its present enormous proportions, of the progressive character of the industry, and of the world-wide competition. CLASSIFICATION OF COALS The classification of coals adopted in The Coal Resources of the World, 1913, is as under : Anthracite. Class A x . Fuel ratio, 1 12 or over. Calorific value, 14,500 to 15,000 B.T.U. Carbon, 93 to 95 per cent. Volatile combustible matter, 3 to 5 per cent. Semi-anthracite. Class A 2 . Fuel ratio, 7 to 12. Calorific value, 15,000 to 15,000 B.T.U. Carbon, 90 to 93 per cent. Volatile, 7 to 12 per cent. Anthracitic and High-carbon Bituminous. Class BI. Fuel ratio, 4 to 7. ^Calorific value, 15,200 to 16,000 B.T.U. Carbon, 80 to 90 per cent. Volatile, 12 to 15 per cent. Does not readily coke. Bituminous. Class B 2 . Fuel ratio, 1-2 to 7. Calorific value, 14,000 to 16,000 B.T.U. Carbon, 75 to 90 per cent. Volatile, 12 to 26 per cent. Generally cokes. 1 The fuel ratio is obtained by dividing the percentage of fixed carbon by the percentage of volatile matter. 4 HISTORY, GROWTH AND OUTPUT OF COAL Low-carbon Bituminous. Class B 3 . Moisture content occasionally reaches 6 per cent. Volatile matter, up to 35 per cent. Fixed carbon -f $ volatile _ Hygroscopic moisture + volatile ~ Calorific value, 12,000 to 14,000 B.T.U. Carbon, 70 to 80 per cent. Makes porous, tender coke. Cannel. Class C. Yields 30 to 40 per cent, volatile matter on distillation. Calorific value, 12,000 to 16,000 B.T.U. Very porous coke. Lignitic or Sub-bituminous. Class D x . Generally contains over 6 per cent, of moisture. Moisture, freshly mined, up to 20 per cent. Fixed carbon -f~ volatile ~ Hygroscopic moisture -|- volatile ~ Calorific value, 10,000 to 13,000 B.T.U. Carbon, 60 to 75 per cent. Lignite. Class D 2 . Moisture in commercial output, over 20 per cent. Calorific value, 7,000 to 11,000 B.T.U. Carbon, 45 to 65 per cent. See also Appendix, p. 159. PRODUCTION, CONSUMPTION, EXPORTS, IMPORTS AND RESERVES OF COAL In order to realize the magnitude and resources of the coal industry, it will be useful, before referring in detail to the coal-fields of the British Empire, to include tables giving : The Annual Coal Production in Principal Countries [p. 5], The Consumption, Export and Import of Coal in Principal Countries [p. 6]. An Estimate of the Coal Reserves of the British Empire and of other Countries [p. 7]. An Estimate of the Coal Reserves of the World, in Con- tinents, with special reference to those of the British Empire [p. 10], The Diagram (pp. 8-9) show graphically the growth of the in- dustry in principal countries in 50 years. HISTORY, GROWTH AND OUTPUT OF COAL TABLE I Table of the Annual Coal Production of the Principal Countries of the World In million tons (metric tons of 2,204 Ib.) * 1895. 1905. 1913-* 1916. 1917.8 1918.8 1919." British Empire i Great Britain and Ireland 194-35 239-89 292-12 260-562 252-56 231-36 233'49 Australia 4-01 6-83 12-62 9.972 10-07 11-13 IO-70 Canada . 7-96 13-62 12-718 12-75 13*59 I2-38 India 2-65 7-92 16-07 I7-536 18-51 21-05 22- 1 1 New Zealand . 0-76 1-41 1-92 2-294 2-IO 2-07 South Africa . 1-40 3-22 7-99 9.081 7-07 9-40 9-85 Total . 206-36 267-23 344-34 312-16 305-06* 288-60 Other Countries i Austria-Hungary 27-25 40-72 53'68 d 46-099 Belgium China 20-41 21-84 22-84 9-27* 18-863 14-92 13-82 18-49 France . Germany 28-24 103-96 36-05 173-66 4 o-8 4d 21-473 158-89 28-90 167-36 24-14 160-51 22-34 210-30 Italy 0-25 0-31 o-37 1-306 1-72 2-00 Japan . 4-84 II-89 21-42 22-902 26-52 23-74 30-83 Mexico . m-, j 2-45 mr __, ._ - - Russia . 9-10 I7-I2 33-37 26-282 ._ _ . Spain . Sweden . United States Other Countries 1-77 0-20 177-59 i-75 3-20 o-33 35I-I2 4-55 4-02 0-36 517-20 14-66 5-495 0-41 535-479 113-64 5-68 0-44 591-11 195-34 7-l6 615-43 196-60 493*75 105-31 Grand Total (approx.) 581-72 928-02 1,341-0 f 1,263-0* i,339-o 1,332-0 1,170-0 * Figures for 1913 and 1916 are taken from official returns. Supplemented by figures from statistics of Iron and Steel Federation. b N.S. Wales only. c Statistical Abstract of U.S.A. d Including lignite. * Chinese Year Book (estimated for 1914). f Mineral Industry, 1918. * Figures for British Empire are from official returns, and for others from Mineral Industry, 1918. h Figures are official, or from U.S.G.S. estimate to Aug. 15, 1920. * Except where otherwise indicated, the metric ton of 2,204 Ib. is used in this monograph. HISTORY, GROWTH AND OUTPUT OF COAL TABLE II Pre-War Consumption, Export and Import of Coal in Principal Countries (1913) In million tons (metric) Consumptions. Exports. Imports. British Empire : Great Britain and Ireland 192-18 99*95 British Dominions . . 65-26 6-69 18-39 Total .... 257-44 106-64 18-39 Foreign ; * Austria-Hungary 59-66 7.72 13-7 * Belgium . . 26-72 4-98 8-86 * France .... 58-25 1-30 18-71 * Germany .... 254-59 34-57 10-54 *Italy .... II-OI 0-19 10-83 * Russia .... 41-00 O-IO 7-73 *Spain .... 6-71 O-OI 2-70 United States . 498-95 19-98 1-38 British Dominions (Analysis) : Australia .... 8-81 2-13 Canada .... 30-63 1.48 17-21 *India .... 15-94 o-77 0-64 *New Zealand . 2-18 O-2I 0-48 * South Africa 7.70 2-10 0-06 65-26 6-69 18-39 (Compiled from Official Returns of each country.) * Calculated, Production + import -export = consumption. HISTORY, GROWTH AND OUTPUT OF COAL CO ON O N VO >O M O\ covo O t^OO tx O vO 1O vS in in CO O > O n v> o\ao O O vo m t-s O oo tvoo O H in M vocoto>oOMtx tNvo rj- m o> O O cooo Q o o li'i 50 I en I N M" I I 1 VO ' CO ' ' 1 1 1 H M M I OS CO M CO N co 1 1 MOOCOM VOCO VO OMTf- iovo MCO TJ-^-N f^ OM-^- -^OO\co voco O^ votNOO ir> f^ OotO OOsO OOO O 1O NCO I1O >OOO~ O> M~ d" nTocT I COfNVO'vO^ I M* I 10 M CO M W ' 0\ VO ' -* O ONO OO O\ O^OO 1 1 * 1 "1^ 1 1 W Ok 1 1 f 1 K I' M CO tNOO OVO U 2 oo o\ o ooo o\ o * M fNOO * I II M 1O , ~ I I. I -I OUTPUTS OF COAL x > OF THE 500 THREE LARGEST f 1 1 PRODUCING COUNTRIES 1 1865-1916 450 1 1 Millions of Metric Tons 1 1 * 400 f 300 / / // N: -- 260 / // / v 200 // / ^"^ /' ' / ^^ / ^r ISO .^^ / X _ / / / X 7 50 ^^ 10 U * t U) O ! b 1 2 2 2 S 2 2 -United States Germany UniredKingdotn OF THE MINOR PRODUCING COUNTRIES 1865-1916 Millions of Metric Tons "Auslro- Hungary Russia France Japan Belgium India -Canada Australia Sou rh Africa Spain New Zealand Italy Sweden to HISTORY, GROWTH AND OUTPUT OF COAL TABLE IV Estimate of the Coal Reserves of the World, in Continents, with Special Reference to those of the British Empire In million tons (metric) Class A. Classes B. and C. Class D. Totals. British. Anthracite Coals, in- cluding some dry Coals. Bituminous Coals. Sub-bitumi- nous Coals, Brown Coals and Lignites. Oceania : Total . British . Asia: Total British Africa: Total British . America : Total . British . Europe : Total British . 659 659 407.637 11,662 11,662 22,542 2,158 54.346 H.357 I33,48i 133,236 760,098 76,399 45,123 45,033 2,271,080 283,661 693,162 178,176 36,270 35,138 111,851 2,6O2 1,054 74 2,811,906 948,450 36,682 170,410 1,279,586 57,839 5,105,528 784,190 169,033 79,ooi 56,769* 1,234,269 189,533 Total . 496,846 3,902,944 2,997.763 7.397.553 British . 25,836 716,505 986,264 1,728,605 (Compiled from The Coal Resources of the World, 1913) [2]. * This figure does not include the sub-bituminous coal of the new coal-field of Udi-Okwaga in Southern Nigeria, with an area amounting to about 1,800 sq. miles, over which known outcrops occur. CHAPTER II BRITISH SOURCES OF COAL SUPPLY UNITED KINGDOM ENGLAND AND WALES South Wales [No. i on Map]. This coal-field stretches east and west from Pontypool to St. Bride's Bay. The principal portion, fifty-six miles long, occupies part of the counties of Monmouth, Glamorgan, Brecknock, and Carmarthen, and is connected beneath Carmarthen Bay with the small western portion in Pembrokeshire. The field covers 842 sq. miles, of which 33 miles only lie in Pembrokeshire (Strahan). 1 The structure of the main field is synclinal ; the coal-bearing measures outcrop all round the edges of the basin, except where covered by the waters of Swansea and Carmarthen Bays and by newer rocks for a short length at Llantrisant, and are bounded by the outcropping older rocks. The strata dip much more steeply on the southern than on the northern out- crop, while at each end of the basin the dip is slight. An anticlinal fold, roughly parallel with, and comparatively near, the southern edge of the basin, runs east and west from Risca through Swansea Bay, developing a trough to the north and one to the south, and raising the lower coal to an accessible position over a considerable area. In the west of Glamorgan and in the south-east of Carmarthen there are certain areas where the productive coal-measures lie at a greater depth than 4,000 ft. and are still unproved. The Coal-Measures vary in thickness from about 4,000 ft. to 12,000 ft. and occur in the following order : (i) Upper series, consisting largely of shales with several bituminous coal-seams. 1 E. Hull gives a superficial area of 906 sq. miles and H. S. Jones nearly 1,000 sq. miles. iz 12 BRITISH SOURCES OF COAL SUPPLY (2) Pennant series, mainly sandstone, with coal-seams only in the west. (3) Lower series, chiefly shales, with the greatest develop- ment of coal and, near the northern outcrops, beds of ironstone. Twelve seams, aggregating 42 ft. in thickness, occur in the east of the field, while in the south and west of Glamorgan the number increases to upwards of 40, with about 120 ft. of coal. In the eastern part of the Pembroke field, where the lower series only is present, 8 seams, with 21 ft. of coal, occur ; but in the west, where a part also of the Pennant series remains, there are 18 seams, with 33 ft. of coal. The coal ranges in character from bituminous house-coal, through the famous Welsh steam-coal to anthracite of remark- able purity. Anthracite occurs in the north-western districts of the main field, and attains its greatest purity near Kidwelly, while in Pembrokeshire the coal is almost wholly anthracite. A characteristic feature of this coal is the gradation that takes place from one class of coal to another, a gradation both vertical and lateral. Thus, in the anthracite area, each seam, in any one section, is in general, but not in every case, more anthracitic than the one above, and each becomes more anthra- citic as it approaches the northern and north-western margin of the field. It follows from this that in the same mine the upper seams may yield house-coal and the lower seams steam- coal ; or, if the upper seams yield steam-coal, the lower may yield anthracite. There is, therefore, no clear line of demarca- tion of the anthracite field. The cause of anthracitization, as regards the South Wales coal-fields, has long been a matter of surmise and speculation. The subject has of recent years been studied with great care by Aubrey Strahan and W. Pollard [15], who have endeavoured to prove that this anthracitic character of the coal is due to the original composition of the vegetable matter forming the coal, and not to extraneous influences, such as extraordinary static or dynamic pressure or regional heat, however caused. The comparison made of the various coals in this investigation appears to be based on chemical analysis alone, and the main argument relies on the remarkable freedom ENGLAND 13 of Welsh anthracite from ash impurity. If this were the determining factor, might it not be expected that the purer layers of coal in any seam would approach more nearly to ENGLAND & WALES 9 . . *P anthracite than those containing more ash ? The analysis given on page 73 of the Memoir cited shows, on the contrary, that the purer layers of coal, with 2-66 per cent, of ash, in the Three- Quarter Coal from Monmouthshire, are further removed from 14 BRITISH SOURCES OF COAL SUPPLY anthracite than are the dull layers with 6*44 per cent, of ash. The facts and arguments presented in this Memoir are instruc- tive and interesting, but the conclusion arrived at is not alto- gether satisfying. The relative proportions of the three main classes of coal were estimated by W. T. Lewis for the Royal Commission on Coal Supplies (1904), thus : Bituminous, 30-42 per cent. ; steam, 47-31 per cent ; anthracite, 22-27 P er cent. The output in 1880 amounted to 21,165,580 long tons and in 1913 to 56,830,072 tons. The coal reserves, as estimated by the Royal Commission of 1904, after deducting the coal pro- duced, were in 1913 : Million Tons. In seams of i ft. and over to a depth of 4,000 ft. . . 36,000 In seams of 2 ft. and over at depths between 4,000 and 6,000 ft. 1,500 Bristol and Somerset [No. 2 on Map]. This coal-field on its eastern edge stretches for 25 miles from Wickwar in the north to near Frome in the south, and occupies to the west of this line an area roughly triangular in shape. An east and west faulted anticlinal zone, which crosses the River Frome 2 miles north of Bristol, divides the field into the small northern basin lying chiefly in Gloucestershire, and the large southern basin lying chiefly in Somerset. Two small outlying basins have been proved to the north and south of the mouth of the Avon. The general structure of the field may be considered as the result of an east and west synclinal fold crossed by another running N.N.E. to S.S.W. The effect of the series of folds to which these belong, on the South Wales and Forest of Dean coal-fields, is briefly outlined by H. S. Jevons [n/p. 77) : Succession of Strata near Bristol. (After R. Etheridge as quoted by Hull) [10 /p. 68]. Feet. Trias (Keuper) (Upper series, with 22 coal-seams, of which 9 average 2 ft. in thickness and upwards 3,000 Central or Pennant Sandstone, etc., 5 coal seams ...... 1,725 Lower shales, 36 coal-seams . . 2,000 Millstone Grit . . Hard siliceous grits, etc. . . . 950 Carboniferous Limestone Well shown in the Avon gorge . . 2,338 ENGLAND 15 The Carboniferous Limestone attains a thickness of 3,000 ft. on the southern edge of the field in the Mendip Hills, but in a distance of only 30 miles to the west, in the Forest of Dean, it dwindles to less than 400 ft. Estimate of Coal Reserves (Hull, 1903) Area. Visible 45 Concealed by newer formations . . . .105 150 sq. miles. Greatest thickness of measures with coal . . . 9,000 ft. Seams of 2 ft. and over, 20 ; aggregate thickness . 71 Total quantity coal down to 9,000 ft., in million tons . 6,036 Quantity of coal down to 4,000 ft. in million tons . 4,151 Strahan's estimate of the coal reserves below 4,000 ft., in The Coal Resources of the World, is 4,266 million tons. Good house, rich gas, coking, manufacturing and steam coals are produced, and the annual output of some sixty collieries is about 1,300,000 tons. The anticlinal ridge of the Mendips forms the southern boundary of the field, and it is inferred that to the south of these hills a coal-field, concealed beneath the Lias and New Red Marl of the Brue valley, may stretch as far south as Cannington Park. Similarly, an extension eastward in the vicinity of Bath has been conjectured. Forest of Dean [No. 3 on Map]. This interesting coal-field lies in Gloucestershire, west of the Severn, and consists of an irregularly shaped basin, 34 sq. miles in extent, encircled by Millstone Grit (so-called) and Carboniferous Limestone out- cropping above the level of the enclosed Coal-Measures. The following is the sequence of formations in descending order : Coal-Measures, with 15 seams .... 2,765 ft. Unconformity Dry brook Sandstone, so-called Millstone Grit . . .455 ft. Carboniferous Limestone Main /SSafto^toS? 011 *! 80 ft Lower Limestone Shales . 165 ft. Old Red Sandstone 8,000 ft. or more. i6 BRITISH SOURCES OF COAL SUPPLY T. F. Sibley [14] regards the so-called Millstone Grit as the upper strata of the Carboniferous Limestone and terms it Drybrook Sandstone. It is conformable with the under- lying strata, but unconformable with the overlying Coal- Measures. The general dip of the basin is from the margin toward the centre. On the east the prevailing dip of the Coal-Measures is much less than that of the steeply-inclined older rocks ; on the north and west the difference of inclination is slight. The coal is found in 15 seams over i foot thick, of which eight are 2 ft. and more in thickness and aggregate 24 ft. of coal. The actual reserve of coal is estimated at 200 million tons, in addition to which there is a problematical 100 million tons in the northern part of the field. Leicestershire [No. 4 on Map]. This coal-field lies to the south of the Trent valley with Ashby-de-la-Zouche as its centre. The " visible " portion occupies 30 sq. miles, and a " concealed/' but proved extension is estimated to occupy 55 sq. miles. On the western side of the field the strata rise and are overlaid un- conformably by the Trias. In the central part of the field 33 seams of i ft. and over aggregate 94 ft. ; in the southern extension 22 seams total 91 ft. The " actual " reserve of coal is estimated to be 2,480 million tons. Warwickshire [No. 5 on Map]. This coal-field is, with the exception of the Kent field, the nearest to London. It lies in the north of the county, and extends from near Tamworth in a south-east direction to Wyken, a distance of 15 miles. The visible Coal-Measures, at their north-western end, occur as a syncline 4 miles wide, bounded on the west, north and east by faults, which bring in the New Red Sandstone. Thence they trend S.S.E. as a narrow strip on the west side of Atherstone and Nuneaton, and are bounded on the east by an outcrop of older rocks, which are partly overspread by Trias. To the west they dip beneath and are concealed by the so-called Per- mian and the Trias strata, but are " proved " and " partly proved " over an area estimated by Lap worth and Sopwith to occupy 32 sq. miles. The " visible " field has an area of 24 sq. ENGLAND 17 miles, and contains 10 seams over i ft. thick, with an aggregate of 40 ft. Five of these seams are workable in the north. South- ward, the sandstones and shales intervening between the seams and amounting to 120 ft. thin out, and the seams unite to form a single seam 26 ft. thick at Wyken, as occurs in the " Ten- yard " coal of South Staffordshire. Serious faults are absent. The peculiarly persistent thin bed of SpirorUs limestone is found in the upper coal strata. The estimated " actual reserve " is about 1,445 million tons. South Staffordshire [No. 6 on Map]. The coal-bearing area of this district stretches from the Clent Hills northward to Brereton, near Rugely, a distance of 21 miles, and has an average width of 7! miles. The estimated area, including the unproved portion concealed by newer strata, is 150 sq. miles. The " visible " coal-field lies between two nearly parallel faults trending north and south, beyond which, as well as to the north and south, newer rocks occupy the surface. A ridge of Upper Silurian rocks, which formed the original margin of the basin, limits the field on the south. Coal in the hidden portions has been opened out at Sandwell in the east and in Cannock Chase in the north-west. There are on an average eleven coal-seams in the north, aggregating 67 ft. Nine of these seams, proceeding southward, unite to form the famous " Ten-yard," or " Thick Coal " seam, 30 ft. thick near Dudley and 24 ft. at Sandwell. In the southern district 6 seams, inclusive of the composite " Thick Coal," aggregate 65 ft. The coal in general is suitable for domestic, smelting and manufacturing use, but never has the character of true steam-coal. The great industrial development round Birmingham, Dudley and Wolverhampton owes its growth to the rich deposits of coal and iron in this field. North Staffordshire [No. 7 on Map]. The coal-seams of this basin lie within a roughly- shaped triangle, whose apex is to the north near Congleton Edge. The area is no sq. miles, a further 1 8 sq. miles being occupied by the outlying Cheadle area to the east. The Coal-Measures of the main field are bounded on the east by the Millstone Grit and on the north-west by the Red Rock Fault of Cheshire, which throws down Triassic rocks. To the south the Coal-Measures are overlaid by and may con- i8 BRITISH SOURCES OF COAL SUPPLY tinue beneath the newer formations as workable extensions (see Concealed Coal Fields, below). The structure of the field, broadly stated, is a trough, con- stantly widening southward, of which the western lip bends over an anticlinal fold, and dips in a narrow strip to the Red Rock Fault. The sequence of strata in this neighbourhood is as follows : Trias . . . Bunter, peeble beds. 'Keele group (so-called Permian), Red sandstone and marls. Carboniferous Newcastle, or Halsowen group, Sandstone formation. Etruria group, Red marls. Upper Coal-Measures . Lower Coal-Measures. In 30 coal-seams over 2 ft. thick found in this field there is 140 ft. of coal ; other seams, ranging from i to 2 ft. thick, bring the total thickness up to 150 ft. The Coal-Measures of the Cheadle field are bounded on the north by older rocks, but extend southward as a concealed field of unknown area beneath the Trias. Strahan states that 17 seams, aggregating 65 ft., occur, but are varied and often individually absent, one only persisting over the entire field. The estimated " Actual Reserve " of South and North Staffordshire, inclusive of Cheadle, to a depth of 4,000 ft., is about 7,150 million tons, and between 4,000 and 6,000 ft. 2,955 million tons. Shropshire and Worcestershire [No. 8 on Map]. These coun- ties include the coal-fields of Coalbrook Dale and the more or less unimportant coal-fields of the Forest of Wyre, the Clee Hills, Shrewsbury, Leebotwood and Dryton. Coalbrook Dale, situated in Shropshire between Wolver- hampton and Shrewsbury, is a small triangular coal-field stretching from south of Ironbridge northward to Newport, and has an area of 18 sq. miles. The coal-bearing measures have a general dip to the east ; they are bounded on the north-west by a great downthrow fault, on the south-west by Silurian rocks, and disappear to the east beneath newer rocks, formerly classified as Permian. From the investigations of M. W. T. Scott [13] and D. Jones [12] it would appear that denudation occurred during the coal ENGLAND 19 period, and that the Upper Coal-Measures, with the Spirorbis limestones, were laid down in the hollows of the denuded surface and, in parts, beyond the limits of the folded Lower Coal- Measures . The unconformability thus formed is known locally as the " Symon Fault " [9]. The field is much faulted. The Lightmoor fault, trending N.E.-S.W., bisects the field, and to the west of this fault the coal is practically exhausted. Six seams, aggregating 27 ft. of coal, have been worked. The coal-field beneath the Forest of Wyre extends from the northern end of the Abberley Hills to the west of Bridgnorth, and then continues northwards as a narrow belt by the banks of the Severn to Coalbrook Dale coal-field. The area of the field is almost equal to that of the Forest of Dean. The Coal-Measures lie on Old Red Sandstone, and are over- laid by the so-called Lower Permian rocks, which exhibit a breccia resembling the debris from glaciers. 1 This bed is now regarded as a delta fan and not glacial. Seams, correlated with those of Coalbrook Dale, aggregate from 7 to 15 ft. of coal. Some miles to the west of the Forest of Wyre small patches of coal, capped by a bed of basalt, are found on the summits of the Titterstone and Brown Clee Hills, in Leebotwood and Dryton. Shrewsbury coal-field occupies a crescent-shaped belt, 18 miles long and seldom more than a mile wide, from a point east of Shrewsbury to the Severn, near Alberbury. The Coal- Measures rest directly on Cambrian and Silurian rocks, and are overlaid by the so-called Permian rocks. The upper Coal-Measures here, as in Coalbrook Dale, the Forest of Wyre, Warwickshire and Lancashire, contain the persistent Spirorbis limestone, a bed seldom more than a foot thick. The three known coal-seams have a total thickness of 6 ft. The estimated coal reserve of Shropshire and Worcester- shire is 360 million tons. North Wales [No. 9 on Map]. The visible portion of this coal-field consists of two areas separated by the great Bala fault, an area of 47! sq. miles on the north-west lying in Flint- 1 See Glacier Boulder Beds in South Africa, India, and Australia. The Lower Coal-Measures of N.S. Wales occur between marine formations, both of which contain undoubted glacial boulders. 20 BRITISH SOURCES OF COAL SUPPLY shire, and an area of 56 miles on the south lying in Denbighshire. Rocks older than the Coal-Measures bound the field on the west, while Triassic rocks conceal the continuation of the Coal- Measures to the north-east under Wirral and to the east in Cheshire. In the concealed portions of Denbighshire the pro- ductive measures are overlaid by the equivalents of the Etruria marl, the Newcastle series, the Keele series of Staffordshire, and finally by the Bunter beds. The coal-seams of these counties have a general correlation and only slight differences over the field. In Flintshire 12 to 14 seams have a total thickness of 58 ft. ; in the northern part of Denbighshire, 17 seams aggregate 61 ft., which in the south of the field dwindle down to 37 \ ft. in 16 seams of lower quality. The principal seams in Flintshire, in descending order, are the Four-Foot (Coal and Cannel), Hollin (Coal with Cannel), Brassy, Main (7' o"), and Lower Four-Foot (in some places Cannel). Those of Denbighshire are the Drowsalls, Powell, Two-yard, Brassy, and Main. A special feature of the Flint- shire field is the Cannel coal found at Leeswood, near Mold and other places, and celebrated for its high gas-producing quality. The total area of the coal-field in Flintshire, including the small area of Neston, is 87! sq. miles, with an estimated reserve of i, 080 million tons ; the area in Denbighshire is 91 sq. miles, with 1,450 million tons. Lancashire and Cheshire [No. 10 on Map]. The bulk of this coal-field lies in the south of Lancashire within an area of extremely irregular outline. It stretches in an east to west direction from Staleybridge to Bickerstaffe, a distance of 32 miles. Spurs due to faulting strike out to the north and the south from the main body, and a narrow strip to the south forms the Cheshire area. The visible coal-field, according to Strahan [2 /p. 206], covers 484 sq. miles, and the coal-bearing measures continue to the south beneath newer rocks over an area of 70 sq. miles. The Coal-Measures were originally continuous with those of the Yorkshire field, but are now separated from the latter by the denuded surface of the Pennine Chain. The structure of the field is complicated, but may be broadly described as a basin of which the northern and eastern edges rest on the Millstone ENGLAND 21 Grit, while the western margin is denned by a downthrow fault, running north and south through Bickerstaffe, and throwing down the New Red Sandstone. The southern segment is hidden beneath the Mersey Valley. Faults are numerous, and the measures are in general steeply inclined. The middle Coal-Measures contain the following coals (Strahan) : District. No. of seams. tof coa l. Northern ...... 15 46^ ft. South-eastern . . . . . .19 70 ,, South-western . . . . .21 75 Well-known seams among these are the Arley Mine, Wigan Cannel coal, Ravenhead, Rushey-park, and St. Helen's Main. Many collieries in this field have long operated at great depths, Pendleton colliery, near Manchester, for instance, being 3,483 ft. deep. The " actual " reserve of coal is estimated to be 5,600 million tons. " Probable " reserves in the Cheshire basin and " pos- sible " reserves around Chester, the Wirral, and Liverpool are referred to under Concealed Coal-Fields below. Yorkshire, Nottinghamshire and Derbyshire [No. u on Map]. This coal-field is the most extensive in England. It extends from Leeds to Nottingham, a distance of 60 miles, and is roughly defined on the west by a line drawn from Halifax to a point 4 miles east of Derby, on the east by an arbitrary line running east of Pontefract, Doncaster, Worksop, Mansfield, and Not- tingham, beyond which the measures are hidden beneath un- conformable Permian strata. The width is, therefore, still unknown, but assuming an arbitrary limit to the east, the area is estimated as follows : Visible coal-field ........ 808 sq. miles. Concealed but proved coal-field ..... 568 Concealed but partly proved in the Trent valley . . 760 Total . ... . 2,126 The Coal-Measures outcrop on the northern and western margins, and dip at a gentle angle beneath the Permian cover for an unknown distance to the east, in which direction the structure of the field is still undetermined. Mining develop- 22 BRITISH SOURCES OF COAL SUPPLY ments of an extensive kind have, however, been carried out in recent years within the concealed area to the east and south of Doncaster. Coal-seams occur as under : District No. of seams. Northern area ..... 15 52 ft. Central area . . . . . .18 40 Southern area . . . . .21 50 The chief seam is the Barnsley Bed, which is in places from 7 to 10 ft. thick, and has been worked from Barnsley to Not- tingham. Other well-known seams are the Parkgate or Deep Hard, the Flockton or Deep Soft, the Silkstone or Black Shale, and the Warren House. The output in 1913 reached nearly 75 million tons. The reserve of coal over the proved coal-field in seams i ft. and more in thickness was estimated by A. C. Briggs for the Royal Com- mission on Coal Supplies in 1904 as follows : West Yorkshire ...... 8,367,385,000 South Yorkshire ..... 10,770,620,000 Derbyshire and Nottinghamshire . . 7,360,725,000 Total in long tons .... 26,498,730,000 But the figures given by A. Strahan [2 /p. 611] in 1913 are : Reserve to 4,000 ft. . . . 40,254,216,000 metric tons. from 4,000 to 6,000 ft . 985,000,000 Cumberland [No. 12 on Map]. The visible coal-field in this county follows the coast-line from St. Bee's Head to Maryport, a distance of 16 miles, and has its greatest width of 6 miles at Workington. It then continues north-east as a strip, about 10 miles long, from near Maryport to a point south of Wigton. Outcrops of Millstone Grit and Carboniferous limestone bound it on the south-east and east, and faults cut it off on the south and north. Its limits westward beneath the sea are unknown, but at Whitehaven coal is being worked at a distance of 4 miles from the shore. Beyond the northern limits of the " visible " field a con- cealed coal-field of much greater area possibly exists east- ward and northward beneath the mantle of Permian measures ENGLAND 23 as far as Carlisle, and beneath the Solway Firth to the small visible coal-field of Canonbie in Dumfriesshire. In the northern part of the known field there are 10 seams, in the central part 20, and in the southern part n, aggregating, respectively, 28, 57, and 45 ft. of coal. Inclusive of undersea coal within 5 miles of the coast the estimated " actual reserve " is 2,180 million tons, of which 40 per cent, is in the land area. An additional " probable reserve " of 1,200 million tons is estimated to lie between 5 and 12 miles from the coast under the sea. Durham and Northumberland [No. 13 on Map]. This im- portant coal-field lies chiefly in the county of Durham. Its outline is triangular, with the apex to the north at the mouth of the River Coquet and the eastern side on the North Sea, beneath which the measures extend. Its length from north to south is over 50 miles, and its width ranges from 5 miles in the north to 30 miles in the south. Permian rocks overspread the Coal-Measures on the Durham coast and along the southern margin. The area, of the field is computed as follows : Coal-field exposed ..... 588 sq. miles. under Permian strata . . . 125 ,, ,, under the sea .... 136 ,, ,, Total 849 The general structure of the field is that of a trough, with the longer axis running north and south. The western margin rises towards and rests against the Pennine Chain, and the measures tend to rise in the north-east towards the floor of the sea, and in the south as a sub-outcrop beneath the overlying Permian rocks. Sixty seams have been identified, of which from 20 to 23, i ft. and more in thickness, are workable, and aggregate from 46 to 60 ft. of coal. The estimated " actual reserve " is 11,000 million tons, of which about 25 per cent, is under the sea. The output in 1913 was 56,352,264 statute tons. In the Carboniferous Limestone lying on the west of the Coal-Measures in Northumberland there are irregular occur- rences of a series of coal-seams which are the equivalent of the 3 24 BRITISH SOURCES OF COAL SUPPLY Lower Coal Series of Scotland. The seams number from 6 to 8, with an aggregate thickness of about 18 ft., and were esti- mated by Lindsay Wood to contain 158 million statute tons in the exposed portions. A further quantity of 2,455 million statute tons was estimated to underlie unproved areas, and is regarded as a " possible reserve." Some of these thin seams must, however, lie at great depth, and it is open to question whether all of this amount can be placed in the category of available coal. Kent [No. 14 on Map]. This concealed coal-field lies in the east of Kent, and is entirely covered by Cretaceous and Jurassic rocks, varying in thickness, roughly, from 800 to 1,400 ft. Geological deductions, indicated by De la Beche in 1846, and more fully elaborated by Godwin Austin in 1855, led to a belief in and finally to a search for this field. Boring on the site of the Channel Tunnel works proved the accuracy of these deductions by the discovery of coal in 1890. Subsequent boring has proved a coal-field of large extent, and the sinking of deep shafts and mining operations have demonstrated the value of the coal deposits, in spite of many difficulties, principally due to the presence of water-bearing ground in the Cretaceous rocks overlying the Coal-Measure. Similar, and at times even greater difficulties, it may be pointed out, have been encoun- tered and overcome in Belgium, the north-east of France, Westphalia, and some of the concealed parts of the coal-fields of England, with less technically perfect methods than are now available. The writer is greatly indebted to Professor William Galloway for having placed at his disposal much information regarding this field for the descriptions of its salient features, which is here largely made use of. The surface of the Coal-Measures dips southwards and south-westwards. Its average depth below sea-level in a line drawn from the South Foreland to Sandwich at a distance of about 2 miles from the coast is a little over 800 ft. Near Bishopsbourne it is 1,113, at Elham 1,323, and at Folkestone 1,374 ft. The thickness of the Coal-Measures in the Ripple borehole was 2,248 ft., and at Oxney, near St. Margaret's, ENGLAND 25 2,730 ft. were bored through without reaching bottom. These measures, according to the late E. A. N. Arber, represent a thick development of the Middle Coal-Measures, and of what are known as the Transition Measures, which lie between the Middle and Upper Coal- Measures proper, thus resembling, as in the fossil flora, the measures of the Pas de Calais coal-field. Nearly all the boreholes show that the seams of coal are more numerous and individually thicker towards the base of the measures than higher up, but for reasons not yet apparent no convincing correlation of the seams found in the various bore- holes has been established, except in the case of the seams found in Barfreston and Waldershare boreholes and Snow- down deep pit, and in that of the seam now being worked in Snowdown and Tilmanstone collieries, in a distance of about 4 miles. Kent coal-field lies in a roughly elliptical, but unsymmetrical trough in the older rocks. The major axis of the trough runs from a point slightly north of Chislet, through Dover, and continues for an unknown distance into the Channel. Starting from the most northern point of the major axis, the margin of the field curves round north-eastwards, gradually trending southwards, until it passes under the sea near Sandwich, and is thereafter supposed to turn more and more southward. From the same point on the axis the western curve of the ellipse turns westward, trending rapidly southward, and passes not far west of Bishopsbourne, Elham and Folkestone, where it disappears under the sea. The length of the coal-field from Chislet to Dover is 15 miles ; its width from Ebbsfleet to Elham is about 10 miles, and increases southward from that line. Its area under dry land is, according to Strahan, about 150 sq. miles, to which has to be added a submarine area of 56 sq. miles in an accessible strip parallel with the coast. The Ripple and Barfreston boreholes, 4^ miles apart, and practically on the same line from east to west as Tilmanstone and Snowdown collieries, may be taken as generally typical of the coal-field, and are as follow : BRITISH SOURCES OF COAL SUPPLY Ripple. Barfreston. Depth Thickness Depth Thickness Good Quality of coal in surface. Ft. of seams. Ft. In. surface. Ft. of seams. Ft. In. Coal. Ft. In. Barfreston bore. [n/p. 168]. 2,025 6 2 1,452 5 3 3 8* Soft, friable, coking 2,077 I II 1,850 2 9 p 2,185 6 10 1,914 2 6 p 2,410 4 o 2,197 4 ii 4 of Excel, domestic 2,637 i ii 2,762 6 9 6 9 Excel, steam 2,703 4 8 2,944 4 7 4 5 Steam and domestic 2,744 9 4 3,261 4 o 4 Medium steam 2,877 3 8 3,3i8 9 6 9 6 Navigation steam 2,992 i ii 3,328 3,170 Total Limestone 40 5 40 3 * Beresford seam. Moisture . Volatile matter Fixed carbon Ash f Snowdown Hard seam. Analyses of Coal Beresford. Hard. Seam at 2,944 ft. 1-39 0-87 0-83 30-31 26-98 20-87 62-87 68-10 75-75 5'43 4-05 2-55 100-00 100-00 The chemical constitution of the coal, as shown by these analyses, is excellent. Galloway says, " The seams found in Snowdown deep sinking below the Beresford are a little harder than the latter, but all of them partake more of the nature of the seams found in coal-fields between Kent and Rhenish- Westphalia, inclusive of the latter, than of those found in most of the coal-fields worked in other districts of this country. Some of the seams found in the deeper boreholes contain as little as 14 per cent, of volatile matter, and will, therefore, as far as their chemical constitution is concerned, rank as first-class steam-coals of the Welsh type. It remains to be seen whether their physical constitution will entitle them to be retained in that category." Tilmanstone and Snowdown collieries have produced coal since 1913 ; Chislet colliery is now producing a little coal, and it is understood that the sinking at Guilford colliery has now nearly reached the Coal-Measures. ENGLAND 27 Tilmanstone and Snowdown collieries have produced the following quantities from the Beresford seam : v Tilmanstone. Snowdown. Y mx> Tons. Tons. 1913 1914 1915 1916 1917 1918 40,054 27,946 82,310 55,823 41,546 103,126 103,040 118,109 135,350 I34, 8 9 129,002 109,087 531,302 54 8 > l8 The development of this coal-field has, considering its geographical advantages, been singularly slow. For one reason and another the necessary financial support has been difficult to obtain, but the potentialities of the field must gradually be recognized, and its resources utilized in many ways and directions. Strahan, following conservative lines, and allowing an aggregate thickness of only 10 ft. of coal over the field, arrives tentatively at a reserve of 2,000 million tons. H. S. Jones, with later information available and apparently on good grounds, trebles this quantity, and, in addition, indicates a " probable " reserve of 3,600 million tons of coal. Concealed Coal-Fields in England The wholly concealed coal-field of Kent has now been proved to a considerable extent by boring, and has entered the list of producing coal-fields. Its general characteristics have been already described. At Burford, in Oxfordshire, a bore-hole put down in 1875-7 reached Coal-Measures at 1,184 ft-, an d is said to have passed through some coal. More recently at Batsford, in Gloucester- shire, Coal-Measures were reached at 1,021 ft., and were found to rest upon Silurian rocks. Jurassic and Triassic rocks extend over the district, and the existence of productive Middle Coal- Measures is still undetermined. Extensions of known coal-fields to greater depths, either through the dip of the measures, or through downthrow faults, beneath a covering of more recent rocks, constitute the other 28 BRITISH SOURCES OF COAL SUPPLY known concealed coal-fields of England. These are in most cases being gradually approached or proved by deeper borings or sinkings. For the few details here given regarding them, we are indebted to the short but lucid descriptions to be found in The Coal Resources of the World, by Strahan. South Staffordshire. To the west of the known coal-field of South Staffordshire, towards Coalbrook Dale and north of a line drawn from Bridgenorth to Sedgley, Lapworth con- sidered there was a coal-field with a probable extent of 220 sq. miles. Exclusive of coal supposed to lie at a greater depth than 4,000 ft. or to be otherwise unavailable, he estimated a " prob- able reserve " of about 8,500 million tons. A " possible reserve " may also exist in ground to the south of the above area. On the eastern side of South Staffordshire, towards the Warwickshire coal-field, an area is estimated by Lapworth to cover 292 sq. miles, to have on an average 35 ft. of coal, and to contain a reserve of 10,000 million tons. But the covering of Triassic and other unproductive rocks is thick, and this large quantity of coal must for the present be regarded only as a " possible reserve." North Staffordshire. Lapworth has estimated that on the southern margin of the North Staffordshire coal-field, a sub-Triassic coal-field, extending from the north-western bound- ary fault of the known field, eastward almost to Uttoxeter, and as far south as Stone, has an area of about 96 sq. miles and a coal content of nearly 6,000 million tons. Only half, however, of this quantity is supposed to lie at a less depth than 4,000 ft. and to come within the category of " probable reserve." Cheshire Basin. In the country between the coal-fields of North Staffordshire, Denbighshire and Lancashire, coal prob- ably exists. But the depth is prohibitive except in parts towards the margins where there is a " probable reserve " of 30 million tons. To this is added 120 million tons, probably raised by faults to within 4,000 ft. or less of the surface along the eastern and north-eastern margins of the Cheshire basin. The " probable reserve " is thus 150 million tons. Chester, Wirral and Liverpool. A thick covering of Triassic ENGLAND 29 and probably barren Upper Carboniferous rocks is spread over 200 sq. miles of this district reasonably supposed to be coal- bearing. A thickness of 15 ft. of coal within this area would produce nearly 3,000 million tons, but it is prudent to regard this only as a " possible reserve." Deep boring at Heswall entered unproductive strata below the Bunter sandstone. Yorkshire, Derbyshire and Nottinghamshire. The Coal- Measures of this coal-field have a general dip to the east, and finally disappear beneath an increasing thickness of Permian, Triassic and Jurassic formations. The eastern limits of this extension are still unknown, but the aggregate thickness of coal would appear so far to be maintained. Strahan, from various considerations, reduces the estimate of 2,550 sq. miles given in 1905 as the area of the extension, to 760 sq. miles and the amount of " coal existing " from 46 million tons to a little under one- third of this figure. In this estimate the assumed thickness of coal is 20 ft. Vale of Eden and Solway Firth. On the northern side of the fault forming the boundary of the Cumberland coal-field to the north, there is an area of 40 sq. miles believed to be underlaid by coal at a workable depth. On the assumption of 21 ft. of coal, an estimate of about 814 million tons of coal is arrived at, and this is regarded as a " possible reserve." SCOTLAND The principal coal-fields of Scotland are found in the coun- ties of Midlothian, East Lothian, Fife, Linlithgow, Clackmannan, Lanark and Ayr. Broadly speaking, they lie in a belt stretch- ing for over 90 miles in a north-east to south-west direction from the coast of Fife to the Ayrshire coast. The average width is 25 miles. Small fields are also found, such as Lesma- hagow in the south of Lanarkshire, Sanquhar in Ayrshire, Campbelltown in the south of Argyllshire, and Canonbie in the south of Dumfriesshire. The last is possibly continuous, under the Solway Firth, with the concealed field in the north of Cumberland if it exists. Throughout England and Wales, except in part of North- umberland, the coal-seams occur only in the Coal-Measures, 30 BRITISH SOURCES OF COAL SUPPLY that is, in measures above the Millstone Grit. In Scotland, the principal seams occur in the same horizon, but profitable coals are also found beneath the Millstone Grit in the Carboni- SCOTLAND 10 10 SO ferous Limestone and, to a less extent, in the underlying Calciferous Sandstone. These lower coals are evidently due to the existence of swamp conditions favourable at times to growth of vegetation, at a period when the areas to the south SCOTLAND 31 were still covered by the sea. It naturally follows that the Carboniferous Limestone and Millstone Grit are more sparingly developed in the north than in the south. The coals of this lower series are generally thin, but are well developed around Lochgelly and Dunfermline in Fife. The following table is from Walcot Gibson's work, The Geology of Coal and Coal Mining [18] : Sequence of the Carboniferous System in Scotland (Red Sandstone ..... 600 ft. Coal-Measures -! Upper Coal Series .... 300 [Lower Coal Series . . . . 800 to 1,500 Millstone Grits : Roslin Sandstone or Moorstone Rock (almost barren of coals) . . . o to 700 ,, Upper Series of Lower Series of Limestone Calciferous Sandstone Series : Sandstone and Conglomerate Portions of the Scotch coal-fields have been subjected, at widely separated periods, to intrusions of igneous matter, which, as vertical dykes, add to the cost of mining, and, as sills following the beds, have destroyed large quantities of coal, particularly in Ayrshire, 2 Fife [17] and Linlithgowshire. Scotch coals are, as a rule, bituminous, and range in quality from good to medium steam, gas, house and coking coal. An- thracite also is found near igneous intrusions in the fields of Ayrshire, Lanarkshire and Fife. Cannel coal occurs in Mid- lothian, Lesmahagow and west and south of Glasgow. The Lothian Coal-Fields [No. i on Map]. These consist of the large, deep and, at the edges, steeply-inclined trough of Midlothian, and the smaller and flatter trough of East Lothian, partially separated from each other by the Carberry ridge. The major axis of the former passes from south to north by 1 " Edge coals " of Midlothian. 2 The writer has observed at Trabboch Colliery, Ayrshire, intensely hardened anthracitic coal in the centre of a 6-ft. seam untouched by igneous rock, and of which the upper and lower sections remained bituminous, an effect possibly due to the passage of hot gases evolved by igneous rock, 32 BRITISH SOURCES OF COAL SUPPLY Dalkeith and that of the latter by Tranent, the measures striking north beneath the Firth of Forth towards Fife, where they reappear. The Midlothian field includes the Coal-Measures and the Carboniferous Limestone or " edge coal " series, and has in the upper series 15 seams of coal aggregating 40 ft., and in the lower series, where best developed, 22 seams aggregating 65 ft. [2 /p. 621]. In the East Lothian field, on the other hand, the Carboniferous Limestone series only is represented, with 9 seams aggregating 31 ft. [io/p. 228]. Hull gives the total area of these fields as 95 sq. miles, but Strahan, at a later date, gives 128 J sq. miles, and an estimated actual reserve of about 3,140 million tons. Coal beneath the Firth of Forth [No. 2 on Map]. Coals of the upper and the lower series stretch as a north and south syn- clinal trough beneath the Forth, and occupy a probable area of 130 sq. miles. According to the figures of Gemmell, fur- nished to the Royal Commission on Coal Supplies, the upper series extends over 58 sq. miles and contains 20 seams aggregat- ing on the northern shore 65 ft., and on the southern shore 40 ft. The lower series, to a depth not exceeding 4,000 ft., may occupy 58 sq. miles, and as exposed has, on the northern shore, an average of 27 ft. of coal, and on the southern 44 ft. Beneath the 4,000 ft. level the lower series occupies an esti- mated area of 39 sq. miles. The coal contents are estimated as follow : Coal above 4,000 ft. . . . 4,252,000,000 metric tons. Coal below 4,000 ft. . . . 1,334,000,000 ,, ,, Fife and Clackmannan [No. 3 on Map]. As already men- tioned, the Fife field is linked beneath the Firth of Forth with the Lothian fields, and at its western end is, with the Clack- mannan field, continuous beneath the River Forth and its estuary with those of Lanark and Linlithgow. The area of coal-bearing measures in Fife, inclusive of a strip in Kinross, is 148 sq. miles, and that in Clackmannan, inclusive of a small area in Perthshire, is 41 sq. miles. In Fife, 20 seams over i ft. in thickness occur in the upper coal series and aggregate 65 ft., while in Clackmannan the number of seams decreases to SCOTLAND 33 17 and the thickness to 50 ft. The lower series in Fife con- tains 3gJ ft. of coal and locally, around Lochgelly, a consider- ably greater thickness, but in Clackmannan the aggregate decreases to 23 ft. The " actual reserve " of coal is about 6,180 million tons, and in Fife and Kinross the " probable reserve " between 4,000 and 6,000 ft. is 351 million. Linlithgowshire [No. 4 on Map]. The coal-bearing area of this county is 61 sq. miles. The Coal-Measures contain 4 seams aggregating 9 to 10 ft., and the Carboniferous Limestone 4 to 6 seams, with I2j ft. of coal, which, however, split up and thin out westward. The famous Boghead mineral occurred in the west of this district. The estimated coal reserve is 680 million tons. Stirling and Dumbarton [No. 5 on Map]. Coal extends over 193 sq. miles of these counties, but in Dumbartonshire is found only in the lower series. Where developed, the Coal-Measures have 34 ft. of coal in 13 seams and the Limestone from 17 to 25! ft. of coal in from 10 to 15 seams respectively. The coal reserve is 1,920 million tons. Lanarkshire [No. 6 on Map]. In this great industrial county coal is found over an area of 275 sq. miles. James S. Dixon [16] has stated that the Coal-Measures, which occur over a large area, contain in the Hamilton district 7 seams with an aggregate thickness of 27 ft., and, below these, 4 seams with 9 to 10 ft. of coal, while the Limestone series over an area of 235 sq. miles may average 6 ft. of coal in thin seams, which thicken eastward in Linlithgowshire between Bathgate and Wilsontown. In the detached portion of the field to the south around Douglas, 5 seams, aggregating 27! ft. of coal, are found in a small area of the Coal-Measures, while the Limestone series, which underlies part of the field, contains 50 ft. of coal on the south-western margin and 37 ft. to the north. The blackband ironstone of the lower series, discovered by Mushet early in the nineteenth century, has contributed largely in the past to the prosperity of this county. The coal reserve is estimated at 3,000 million tons. Renfrewshire [No. 7 on Map]. The area of this coal-field is 73 sq. miles, but the coal reserves only amount to 135 million 34 BRITISH SOURCES OF COAL SUPPLY tons, contained in 7 seams, aggregating i6| ft., in the Carboni- ferous Limestone. Ayrshire [No. 8 on Map]. Igneous rocks, occurring as erratic lateral intrusions, have destroyed large quantities of valuable coal, particularly in the southern half of the field, and in con- sequence an estimate of reserves is difficult. J. S. Dixon, in 1904, estimated the available coal as 1,082 million tons, while A. Strahan's estimate of the actual reserve in 1913 was 1,337 million tons distributed over 330 sq. miles. The Coal-Measures in the northern part of the field contain from 12 to 14 seams with 28 ft. of coal, and round the south- eastern, southern and south-western margin, from 7 to n seams with from 26^ to 30 ft. of coal. In the Carboniferous Limestone around Muirkirk, from 10 to 13 seams aggregate from 36 to 54 ft., but in the southern part of Ayrshire the series is poorly developed, and it is estimated that the seams over half the field become so thin and so affected by igneous rock as to be valueless. The blackband ironstone of the lower series occurs at Dairy in the north. A narrow patch of the Limestone series, some 5 miles long, lying in the Girvan valley, has 6 seams, with a total thickness of 27 ft. of coal. Dumfriesshire [No. 9 on Map]. Sanquhar Coal Basin. This detached area of Coal-Measures extends for 5 miles, with a width of 3 miles in the Nith valley beside the village of Kirk- connel, and contains 8 seams with 23 J ft. of coal. The Lime- stone series is absent. At Canonbie, 7 seams, each over 3 ft. thick, and aggregating over 40 ft., have been worked, but never wholly proved at one point. Two groups of seams are assigned to the Coal-Measures, and one to the Limestone series. These coal-bearing measures are overlaid to the south by the barren red sandstones and shales of the Carboniferous system, on which, in turn, Triassic sandstone lies unconformably. It is possible that this field may be the northern limit of the concealed coal-field in the north of Cumberland and the assumed part beneath the Solway Firth. The coal-bearing area of this county is estimated at 26 Jsq. miles and the coal reserve, inclusive of the small amount in Argyll, apparently at 667 million tons. Argyll [No. 10 on Map]. At Campbelltown, on the west coast SCOTLAND 35 of Kintyre, 2 sq. miles on land and half a square mile under the sea are occupied by Carboniferous Limestone, in which 8 seams aggregate 45 ft. of coal. Mining has been carried on here for many years on a moderate scale. Sutherland [No. n on Map]. At Brora on the Dornoch Firth coal of Jurassic age occurs and is probably nearly contemporaneous with the carbonaceous strata of Whitby in Yorkshire [19]. The coal, first worked here in 1598, is of com- paratively little value. The estimated quantity is I million tons. IRELAND There is evidence that the Carboniferous system extended over the greater part of Ireland, and that the productive Coal- Measures occupied a large area. But denudation in Permian times spared little of the latter, and remnants only of this wealth of fuel exist in small and isolated coal-fields. The coals in the northern half of Ireland are in general bituminous ; those in the southern half are semi-bituminous or anthracitic. They are found in seams which, excepting some in the Antrim and Tyrone basins, are extremely thin. G. A. J. Cole and E. St. J. Lyburn [2/p. 629] estimated the " actual coal reserve " of Ireland to be 180 million tons, and the " probable reserve " to be no million tons. Of the " actual reserve," 153 million tons lies in the Leinster coal-field. These resources, though comparatively small and mostly occurring in thin seams, might be more fully utilized were greater local enthusiasm applied to their continued development. Bally castle [20]. This field [No. i on Map] lies on the north coast of Antrim, and, though now practically abandoned, is of considerable geological interest. The coal-bearing strata are correlated with the Lower Coal and Ironstone series of Scotland, and are in the belt of north-east and south-west folding, which affected the Scottish coal-fields. The section of strata on Ballycastle Bay includes the upper, or Splint seam, 3 ft. thick ; the middle, or Hawksnest seam, 3 ft. thick ; and the lower, or Main seam, 4 ft. thick ; while on Murlogh Bay, to the east of Fair Head, similar strata, with seams from 2j to 5 ft. thick, are repeated over a small area. A 36 BRITISH SOURCES OF COAL SUPPLY few hundred tons only were mined in 1917. The area of the field is 4^ sq. miles, and if an average thickness of 3 ft. be assumed, the " probable reserve " of coal is 13 million tons. Tyrone [No. 2 on Map]. At Dungannon, in the southern portion of this coal-field, Lower Coal-Measures outcrop, and they are assumed to underlie an area of 8 sq. miles. Within this area, in the northern part of the field, Middle Coal-Measures, IRELAND 37 which are found outcropping at Coal Island, are assumed to occupy an unworked area of ij sq. miles [21]. The coal-seams occur in descending order as follow l : Ft In . Upper Coal 2 2 impure Annagher coal 9 O soft quality Bone coal . 3 O Shining seam 2 IO Middle Coal- Brackaville coal 5 o good quality Measures < (Coal Island) Gortnaskea coal 6 o fcannel 2 ft. \ coal 4 ft. Baltiboy coal 3 o sulphurous Derry coal . 4 6 good quality Yard coal . 3 o good quality