On the other hand the production of coals from morasses, as described in note XX. is evinced from the vegetable matters frequently found in them, and in the strata over them; as fern-leaves in nodules of iron-ore, and from the bog-shells or fresh water muscles sometimes found over them, of both which I have what I believe to be specimens; and is further proved from some parts of these beds being only in part transformed to coal; and the other part still retaining not only the form, but some of the properties of wood; specimens of which are not unfrequent in the cabinets of the curious, procured from Loch Neigh in Ireland, from Bovey near Exeter, and other places; and from a famous cavern called the Temple of the Devil, near the town of Altorf in Franconia, at the foot of a mountain covered with pine and savine, in which are found large coals resembling trees of ebony; which are so far mineralized as to be heavy and compact; and so to effloresce with pyrites in some parts as to crumble to pieces; yet from other parts white ashes are produced on calcination, from which fixed alcali is procured; which evinces their vegetable origin. (Dict. Raisonné, art. Charbon.) To these may be added another argument from the oil which is distilled from coals, and which is analogous to vegetable oil, and does not exist in any bodies truly mineral. Keir's Chemical Dictionary, art. Bitumen.
Whence it would appear, that though most collieries with their attendant strata of clay, sand-stone, and iron, were formed on the places where the vegetables grew, from which they had their origin; yet that other collections of vegetable matter were washed down from eminences by currents of waters into the beds of rivers, or the neighbouring seas, and were there accumulated at different periods of time, and underwent a great degree of heat from their fermentation, in the same manner as those beds of morass which had continued on the plains where they were produced. And that by this fermentation many of them had been raised from the ocean with sand and sea-shells over them; and others from the beds of rivers with accumulations of gravel upon them.
4. For the purpose of bringing this history of the products of morasses more distinctly to the eye of the reader, I shall here subjoin two or three accounts of sinking or boring for coals, out of above twenty which I have procured from various places, though the terms are not very intelligible, being the language of the overseers of coal-works.
1. Whitfield mine near the Pottery in Staffordshire. Soil 1 foot. brick-clay 3 feet. shale 4. metal which is hard brown and falls in the weather 42. coal 3. warrant clay 6. brown gritstone 36. coal 31/2. warrant clay 31/2. bass and metal 531/2. hardstone 4. shaly bass 11/2. coal 4. warrant clay, depth unknown. in all about 55 yards.
2. Coal-mine at Alfreton in Derbyshire. Soil and clay 7 feet. fragments of stone 9. bind 13. stone 6. bind 34. stone 5. bind 2. stone 2. bind 10. coal 11/2. bind 11/2. stone 37. bind 7. soft coal 3. bind 3. stone 20. bind 16. coal 71/2. in all about 61 yards.
3. A basset coal-mine at Woolarton in Nottinghamshire. Sand and gravel 6 feet. bind 21. stone 10. smut or effete coal 1. clunch 4. bind 21. stone 18. bind 18. stone-bind 15. soft coal 2. clunch and bind 21. coal 7. in all about 48 yards.
4. Coal-mine at West-Hallam in Nottinghamshire. Soil and clay 7 feet. bind 48. smut 11/2. clunch 4. bind 3. stone 2. bind 1. stone 1. bind 3. stone 1. bind 16. shale 2. bind 12. shale 3. clunch, stone, and a bed of cank 54. soft coal 4. clay and dun 1. soft coal 41/2. clunch and bind 21. coal 1. broad bind 26. hard coal 6. in all about 74 yards.
As these strata generally lie inclined, I suppose parallel with the limestone on which they rest, the upper edges of them all come out to day, which is termed bassetting; when the whole mass was ignited by its fermentation, it is probable that the inflammable part of some strata might thus more easily escape than of others in the form of vapour; as dews are known to slide between such strata in the production of springs; which accounts for some coal-beds being so much worse than others. See note XX.
From this account of the production of coals from morasses it would appear, that coal-beds are not to be expected beneath masses of lime- stone. Nevertheless I have been lately informed by my friend Mr. Michell of Thornhill, who I hope will soon favour the public with his geological investigations, that the beds of chalk are the uppermost of all the limestones; and that they rest on the granulated limestone, called ketton-stone; which I suppose is similar to that which covers the whole country from Leadenham to Sleaford, and from Sleaford to Lincoln; and that, thirdly, coal-delphs are frequently found beneath these two uppermost beds of limestone.
Now as the beds of chalk and of granulated limestone may have been formed by alluviation, on or beneath the shores of the sea, or in vallies of the land; it would seem, that some coal countries, which in the great commotions of the earth had been sunk beneath the water, were thus covered with alluvial limestone, as well as others with alluvial basaltes, or common gravel-beds. Very extensive plains which now consist of alluvial materials, were in the early times covered with water; which has since diminished as the solid parts of the earth have increased. For the solid parts of the earth consisting chiefly of animal and vegetable recrements must have originally been formed or produced from the water by animal and vegetable processes; and as the solid parts of the earth may be supposed to be thrice as heavy as water, it follows that thrice the quantity of water must have vanished compared with the quantity of earth thus produced. This may account for many immense beds of alluvial materials, as gravel, rounded sand granulated limestone, and chalk, covering such extensive plains as Lincoln-heath, having become dry without the supposition of their having been again elevated from the ocean. At the same time we acquire the knowledge of one of the uses or final causes of the organized world, not indeed very flattering to our vanity, that it converts water into earth, forming islands and continents by its recrements or exuviae.