Professor's experiment shewing that toads died when confined without air or food in closely glazed stone cells, no more disproves the repeatedly alleged discovery of live toads in coal, than it does their extraction from blocks of marble, of which latter fact, at least, there does not appear to be any reasonable doubt.*

In concluding this chapter, it may be interesting to mention that, at the beginning of 1833, some “Observations on Coal" were read before the Philosophical Society of Newcastle, by W. Hutton, Esq., from which it appeared that, on examining with the microscope one of those slices of coal in which Mr. Witham had discovered a distinct vegetable texture, the attention of the Author was excited by the remarkable appearance of several cells in that part of the coal where the texture of the original plant could not be distinguished. The coal of the Newcastle district is considered by the Author to be of three kinds: the first, which is the greatest in quantity and the best in quality, is the rich caking coal so generally esteemed; the second is cannel or parrot coal, or splent coal of the miners; and the third, the slate coal of Jameson, which consists of the two former, arranged in thin alternate layers, and has conse

*The occurrence of living toads embedded, or rather entombed, in cavities of the deep strata has been adduced as a striking objection to the igneous theory of Hutton, and of course, as an equally striking testimony in favour of the hypothesis of aqueous solution, which commonly bears the name of Werner. Mr. Murray, the chemist, has remarked, that the lethargy of the toad and lizard may continue without the extinction of life for ages; and both these animals have been found embedded in stone: "a toad," says this author, was found under the coal seam, in the ironstone over which it rested, in a coal mine at Auchincruive, in Ayrshire." Toads have often been buried in garden pots, and found alive after long intervals. Mr. Jesse mentions an instance of a toad so buried, which at the end of twenty years was taken up much increased in bulk.

CELLULAR TEXTURE IN COAL.

109

In these varieties of coal,

quently a slaty structure. more or less of the vegetable texture could always be discovered: thus affording the fullest evidence, if any such proof were wanting, of the vegetable origin of coal. Each of the three kinds of coal, besides the fine distinct reticulation of the original vegetable texture, exhibits other cells, filled with a light wineyellow coloured matter, apparently of a bituminous nature, and so volatile as to be entirely expelled by heat before any change is effected in the other constituents of the coal. The number and appearance of these cells vary with each variety of coal: in the finest portions, where the crystalline structure, as indicated by the rhomboidal form of its fragments, is most developed, the cells are completely obliterated : the texture being uniform and compact, and the whole arrangement indicating a more perfect union of the constituents, and a more entire destruction of the original texture of the plant. After describing these cells, and illustrating them by drawings, Mr. Hutton proceeds to speculate on their origin in the cannel coal: he considers it highly probable that they are derived from the reticular texture of the parent vegetable, rounded and confused by enormous pressure: moreover, that though the perfectly and imperfectly developed varities of coal generally occur in distinct strata, yet it is easy to find specimens which in the compass of a single square inch contain both varieties. From this fact, as also from similarity of position in the mine, the difference in the different varieties of coal are ascribed to original difference in the plants from which they were derived.*

* London and Edinburgh Phil. Mag., April, 1833.

CHAPTER VI.

THE COAL FORMATION.

Review of the arrangement of carboniferous strata, as forming coal fields, coal basins, and coal measures— Arrowsmith's map of the coal districts-Somersetshire coal field-South Gloucestershire or Bristol coal field-Forest of Dean-South Welsh coal field-Shropshire field-South Staffordshire and Warwickshire-North Staffordshire-North Wales -Lancashire coal field-Yorkshire, Nottinghamshire, and Derbyshire coal fields-Whitehaven coal field-Northumberland and Durham—Unexplored localities in England-Scotch coal fields-Ayrshire -Paisley-Lanarkshire-East Lothian-Culross -Irish coal fields-Districts of Leinster, Munster, Connaught, and Ulster-Description of a coal basin-Somersetshire and South Welsh basins— Mantle, and inverted basin shapes-Swilleys or small basins.

WE have already adverted to the geological position of the carboniferous group of strata (vide p. 36), where it will also be seen that the terms used at the head of the present chapter are applied to one of those five general classes or suits, into which the

ARRANGEMENT OF COAL STRATA.

11F

whole known series of mineral beds may be comprehensively resolved. The class of rocks here alluded. to, and to which, for distinction's sake, the name of nedial has been applied, range downward from the class terminating, as the case may be, with what rologists term the upper or newer red sandstone, conglomerate or magnesian limestone, and contain not only the great coal deposit, but likewise the older limestone, or as it is sometimes designated from the organic remains embedded in it-encrinal limestone, and the red sandstone, on which it reposes.* may be remarked that the immense and diversified series of strata upwards, from the old red sandstone, constitute the region of vegetable remains, and to a great extent of the metalliferous deposits also.

It

It is not, however, intended to mould the matter of the present Chapter into any systematic form, nor to make it the vehicle of any particular theory: the terms "Coal Formation," may, therefore, conveniently be used to designate :

I. Those generally insulated tracts of carboniferous strata, commonly known in this country under the appellation of "coal fields."

II. The scope and inclination of the strata, denominated from their flexures, and occasional spherical formation," coal basins ;" and

III. The succession and order of strat, as uis

* It is an interesting fact, as connected with geological enquiries, that these depositions are not always found conformable with the underlying masses, as to parallelism of their surfaces. In some situations, the newer red sandstone fills up the superior inequalities of the subjacent strata, as if the matter which afterwards consolidated into the stone above named had, in the first instance, flowed over the previously contorted mountain limestone and coal measures, no disturbing force having subsequently been exerted to prevent the tranquil settlement and aggregation of the conglomerate.

played in a vertical section, and called measures."

"coal

Of these three views of the coal formation, it may perhaps be remarked in addition, that the first is that which chiefly interests the topographer; the second the geologist; and, the third, the miner.

The map, engraved by Arrowsmith to accompany the Report of the Coal Trade, printed by order of the House of Commons, in 1830, shews in a striking if not very precise manner, the geological position as well as the commercial distribution of the coal of England and Wales. But it must be recollected that in computing from the coloured areas on this map, the entire space is often erroneously taken as underlaid with coal; for in most of the large fields, there are extensive tracts of barren or unascertained strata: this being the case, the districts afterwards described are rather given as those within which coal occurs, than as being entirely occupied by it. If, however, a person take an ordinary map of this portion of Great Britain, and draw a line from Weymouth, on the English Channel, to Jedburgh, on the Scottish Border, and then draw at right angles with that line, other lines, as follow:-1, on the west side, from St. Bride's Bay to Pontypool; 2, on the east, from Wolverhampton to Atherstone; 3, on the east, from Newcastle-under-Lyne to Cheadle; 4, on the west, from Chester to Mold; 5, on the east, from Huddersfield to Pontefract; 6, on the west, from Whitehaven to Appleby;-such lines will intersect nearly every portion of coal district in England and Wales. It may be further remarked that, if another line, parallel with the former be drawn, from Gosport on the south to Guisebrough on the north side of the