Ill Theory of the Origin of Coal, 



been rendered fashionable, of the origin of coal by subsidence 

 of vegetable matter in situ^ must be considered established as 

 of general application. I, however, adhere to the cautionary 

 remarks which I ventured to make last j^ear, and will now 

 endeavour to impress upon your minds the inapplicability of 

 such a theory, however true under limitations, to large por- 

 tions of the carboniferous strata in different parts of the 

 world. 



Since our last Anniversary statements have appeared in our 

 own country, both supporting and impugning the probable 

 truth of the theory. The last meeting of the British Associa- 

 tion being held at Manchester, geologists were there assem- 

 bled in the centre of a tract appealed to with great reason 

 by the supporters of this theory as containing many proofs of 

 its truth ; for, in the immediate vicinity of that town there 

 occur, as you all know, the beautiful examples of vertical 

 stems of large trees apparently in their original position, 

 which were formerly described before this Society. After 

 giving an elaborate and satisfactory account of the great Lan- 

 cashire coal-field, shewing that its lowest members, formed on 

 the flanks of the Penine chain, and subordinate to the mill- 

 stone grit, contain marine shells analogous to those of the 

 Mountain Limestone series, and stating that they are sur- 

 mounted by a middle and an upper group, the former consti- 

 tuting the richest coal-field, Mr Binney describes in great de- 

 tail the composition and contents of all the numerous roofs 

 and floors, as well as also of the coal-seams, which are includ- 

 ed between them. He shews also that the roofs vary in their 

 nature at diff*erent places, even over the same seam, and con- 

 tain the remains of many vegetables, sometimes, as near Man- 

 chester, in vertical positions, Sigillarice being in such cases 

 a most abundant plant ; other roofs of black shale in the 

 lower field are loaded with Pectens, Goniatites, Posidonia, and 

 fishes. The coal-floors, on the contrary, present a much 

 greater uniformity of structure, fire-clay similar to the under- 

 clay of Mr Logan being most abundant ; though it is admit- 

 ted, that a difl'erent or siliceous clay also frequently occurs, 

 and that two instances are known v/liere tlie coal rests at once 

 on coarse quartzose sandstone. Seeing, that with one excep- 

 tipn, all the floors throughout an estimated thickness of near 



