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depositions of carbonaceous and 

 mineral matter. In some of the 

 larger coal-fields, the original form 

 of the lake cannot be traced, but 

 in the smaller ones it is distinctly 

 preserved. The stratum lying 

 over a bed of coal is called its roof, 

 and the stratum under it, the floor. 

 On the eastern side of England, 

 the coal strata generally dip to the 

 south-east point : on the western 

 side, the strata are more frequently 

 thrown into different and opposite 

 directions, by, what are termed, 

 faults and dykes. A fault is a 

 break or intersection of strata, by 

 which they are commonly either 

 suddenly raised or depressed, so 

 that in working a coal mine, the 

 miners come suddenly to its 

 apparent termination. A dyke is 

 a wall of mineral matter which, 

 from igneous or volcanic action, has 

 been forced upwards through the 

 strata, cutting them in a direction 

 nearly vertical. In these cases, 

 sometimes the coal is reduced to a 

 cinder for some distance on either 

 side of the wall or dyke. One of 

 the green-stone dykes of Ireland, 

 passing through a bed of coal, 

 has reduced it to a cinder for the 

 space of nine feet on each side. 

 Our ancient coal formation has not 

 been found in Italy, Spain, Sicily, 

 or in any of the more southern 

 countries in Europe. Coal is now 

 universally admitted to be of 

 vegetable origin, a question which 

 was long disputed. It is not 

 uncommon to find among the 

 cinders beneath our grates, traces 

 of fossil plants, whose cavities 

 having been filled with silt, at the 

 time of their deposition in the 

 vegetable mass, that gave origin to 

 the coal, have left the impression 

 of their forms upon clay and sand 

 enclosed within them, sharp as 

 those received by a cast from the 

 interior of a mould. Mr. Hutton 

 has recently discovered the most 



decisive and indisputable proof of 

 the vegetable origin even of the 

 most bituminous coal ; he has 

 ascertained that if any of the three 

 varieties of coal found near New- 

 castle be cut into very thin slices, 

 and submitted to the microscope, 

 more or less of vegetable structure 

 can be recognised. He says, " each 

 of these three kinds of coal, beside 

 the fine distinct reticulation of the 

 original vegetable texture, exhibits 

 other cells, which are filled with a 

 light wine-yellow-coloured matter, 

 apparently of a bituminous nature, 

 and which is so volatile as to be 

 entirely expelled by heat, before 

 any change is effected in the other 

 constituents of the coal." The 

 plants of the carboniferous group 

 are by no means confined to the 

 simplest forms of vegetation, as 

 to cryptogamic plants; but, on 

 the contrary, belong to all the 

 leading divisions of the vegetable 

 kingdom ; some of the more fully 

 developed forms, both of the di- 

 cotyledonous and monocotyledo- 

 nous class, having been already 

 discovered, in the first three or 

 four hundred species brought to 

 light. If violence had attended 

 the transport of the plants now 

 converted into coal, or discovered 

 fossil in the associated beds, the 

 appearance of those in the latter 

 would not be as we now find them ; 

 instead of appearing as if spread 

 out by the botanist for examination, 

 we should have had them crushed 

 and disfigured. Moreover, tran- 

 quillity seems requisite to explain 

 the condition of those vertical, or 

 nearly vertical, stems of plants 

 discovered in the coal measures of 

 different situations, where they 

 have been gradually enveloped by 

 different beds of sandstone or shale 

 through which they appear to 

 pierce. The alternations of lime- 

 stones containing marine remains, 

 and of sandstones, shales, and coal- 



