356 Professor Jameson’s Geognostical Description 
iron-ore ; an arrangement which proves that these minerals are 
of simultaneous formation 
4. Coal . — The coal which is black coal, occurs in beds 
seldom more than a few inches in thickness, and is generally 
contained in the bituminous shale or slate-clay, rarely in the 
sandstone. By the gradually increasing mixture of clayey mat- 
ter, it passes into bituminous shale. The accompanying bitu- 
minous shale and slate-clay contain impressions of ferns, a fact 
which has been adduced in support of the opinion which main- 
tains the vegetable origin of black coal. We are inclined to 
call in question the supposed vegetable origin of this kind of 
coal, and are rather disposed to consider it as an original che- 
mical formation, and that the occurrence of vegetable impres- 
sions in the adjacent rocks no more prove its vegetable origin, 
than the existence of fossil quadrupeds in the gypsum of Paris 
prove that rock to have been formed from the debris of ani- 
mals of the class mammalia ‘f*. 
5. Limesto7ie.— This rock, w^hich is of a grey colour, with 
a splintery or uneven and dull fracture surface, occurs in thin 
beds, along with sandstone, bituminous shale and slate-clay. 
6. Greenstone. ( WMnstone .) — -This rock has been quarried 
at Bell’s Mills, St Bernard’s Well, in Broughton, at the Cus- 
tom-HoUse, in Albany Street; and in Leith- Walk opposite An- 
tigua Street. At Bell’s Mills the greenstone is in the form of 
a bed from 10 to 20 feet thick, which runs from north-east to 
south-west, and dips to the west under an angle of 25°. It 
rests on bituminous shale and sandstone, and is covered by bitu- 
minous shale. It contains a large imbedded mass of coarse 
drawing-slate, which includes a singular cotemporaneous mass 
of greenstone. From the manner in which the rocks were cut 
at one time by the operations of the miners, I was at first led to 
believe, that there were two distinct beds of greenstone, sepa- 
rated from each other by the drawing-slate; but a careful study 
of the positions and connections of the different masses, after- 
wards convinced me that the two apparent beds were portions of 
* Dr Hutton maintains, that this ironstone has not been formed in the saipe 
manner as the surrounding slate and sandstone. 
-f- Vide Wernerian Memoirs ^ vol. ii. p. 1. 
