76 
The lower shales consist of alternations of clays, sandstones, 
shales, and dark blue bands of compact Limestone. We have, 
at least, one clear evidence of land surface in the beds which 
contain “ Grass-like Weeds,” as Mr. Stropparr calls them.* 
This is the first appearance of plants in the Carboniferous 
rocks, but though it indicates land or close proximity to it, the 
surface was sinking so as to admit of the formation of Lime- 
stone, with its abundant life. From this life some writers draw 
conclusions as to the climate which prevailed during the whole 
of the Carboniferous epoch. 
Where a Fauna is found associated with actual Coal Strata, 
considerable enlightenment is to be gathered as to the climate 
in which the vegetation flourished, but where none is found, as in 
in the case of the Bristol Coal measures, it appears to me very 
speculative to refer back to the Mountain Limestone for informa- 
tion. We must remember that a vast period of time elapsed 
between the beginning and the close of the Coal measures proper, 
and this lapse of time extended over the deposition of the Mill- 
stone grit, which in the Bristol district is upwards of 1000 ft. 
thick. 
By referring to the Section of the Coalfield, the characteristic 
Fossils of the Limestone are seen on the left hand side, and 
from them we may conclude that the climate was tropical. 
We must not neglect to notice that some of the Limestone 
beds yield bitumen, but it is not certain that it is of vegetable 
origin, for it may also be ascribed to the decomposition of 
animal substance. 
At the close of the Mountain Limestone a similar condition 
prevailed in many respects as with the Lower Shales. There 
was more alternation of beds, some indicating deep water, others 
close proximity to land and actual land surfaces, on which 
plants grew, but still the conditions were not such as to allow 
of the formation of Coal; a vast time had yet to elapse before 
that store of wealth was accumulated in the South-west of 
England. 
* Proceedings of the Bristol Naturalists’ Society, page 318, Vol. 1875-6. 
