94 Geology of Wiltshire. 
and sufficient identity or resemblance in the organic remains which 
they contain to justify geologists in adopting the chronological 
classification above given. 
As one example of this fact, I may mention the coal-bearing 
so valuable for the uses of man. It is well ascertained that 
strata 
the true coal in every quarter of the globe, with scarcely an excep- 
tion, belongs to one and the same age in the history of the earth. 
It is composed of almost identically the same fossil plants, is buried 
in the same beds of rolled pebbles, and stone and shale, or indura- 
ted mud; and overlies and is covered by strata containing the 
same kinds of fossil shells. 
It will have been observed in the Tabular view given above, that 
speaking generally of this our island of Great Britain, the oldest 
stratified rocks appear on the extreme west, and that as we proceed 
thence towards the east, we pass in succession over the newer rock 
formations. This is owing to the fact, that the high mountain 
ranges of the island lie to the west, where, at some early period, 
the expansion of subterranean masses of hypogene crystalline rock, 
portions of which shew themselves in the granite and trap rocks of 
Devon and Cornwall, of Anglesea, the Hebrides, and the Grampians, 
have tilted up the stratified rocks on the western side of the island 
to a higher level than they generally range at on the eastern side. 
It was thought the violence accompanying this process, no doubt, that 
the older western strata were broken, bent, and doubled up into 
folds, in the manner we see them, and also that the general ‘dip’ 
or slope of the strata is found to be from west to east, each successive 
formation terminating towards the west in a step-like escarpment 
or break, from under which the older beds crop out in the manner 
indicated in the section here given. 
Our County of Wiltshire lying about midway between the east 
and west of the island, we find it, as might be expected from what 
has been said, to be composed, for the most part, of the middle 
series, or secondary strata in the above Table. Its geological 
formation is, indeed, of a very simple character. It contains no 
older rocks than the upper beds of the Lias, nor any newer than 
the chalk, except a few patches of clay and gravel belonging to the 
