82 Geological Society of London. 
It is clear that these geological considerations must be duly weigh- 
ed by those who speculate on the probable future duration of British 
coal, according to the actual or any assumed rate of consumption. 
Mr. Murchison, in describing the Dudley and Wolverhampton 
coal-fields, informs us that he has not yet found any fossil remains 
of decidedly marine origin, like those observed by Mr. Prestwich in 
Coalbrook Dale. The shells seem to be all of fresh water genera, 
and the Megalichthys Hibberti, and other fish occuring at Dudley, 
of species identical with those of the coal measures of Edinburgh, 
may have inhabited fresh water. 
The same author has colored on an Ordnance map the superficial 
area of the Silurian rocks connected with the coal-fields above men- 
tioned, and has shown that the Lickey quartz rock between Broms- 
grove and Birmingham, of which the geological position has remain- 
ed hitherto uncertain, is in fact nothing more than altered Caradoc 
sandstone, a member of the lower Silurian group. The same ap- 
pears as a fossiliferous sandstone in one district, while in another, it 
passes into a pure quartz rock, a modification attributed to the prox- 
imity of underlying trap, for analogous changes have been seen at 
neighboring points where the absolute contact of the sandstone with 
the trap is visible. 
We are also indebted to Mr. Murchison for some interesting re- 
marks on the dislocations of the strata in the neighborhood of Dud- 
ley, and particularly for a description of some dome-shaped masses, 
from the center of which the beds have a quaquaversal dip. He 
speculates on the probable dependence of these phenomena upon 
the protrusion of volcanic matter from below, at points where it has 
been unable to find issue. It would, I think, have been more satis- 
factory, if, in confirmation of his theory, some natural section of one 
of these dome-shaped masses could be pointed out, where not only 
a nucleus of trap was apparent, but could be shown to have taken 
up its actual position in a soft or fluid state. Even if we should 
find in some instances a subjacent central mass of trap, porphyry or 
granite, not sending out veins or altering the strata, the folding of 
the beds round such a protuberance might admit of an explanation 
like that suggested by Dr. Fitton. He has supposed a set of yielding 
strata to be pressed upon by a subjacent hill or boss of 
hard rock, in which case the effect of upward pressure might resem- 
ble that seen, on a small scale, in the paper of a bound book, where 
a minute knob in one leaf has imparted onenees number 
