Geological Society. 569 
Shrewsbury. Mr.'Murchison has collected evidence of their diffusion 
over a wide area in Shropshire, tracing them at intervals from Maring- 
ton Green, N.W. of Shrewsbury, by the Wrekin and Wellington, to 
the high grounds between Bridgnorth and Wolverhampton, at least 
60 miles inland, and at heights varying from 300 to 600 feet. He has 
also been enabled to add several species to those mentioned in any 
former list. These shells having been examined by good conchologists 
(including Dr. Beck, of Copenhagen,) prove to be identical with spe- 
cies now inhabiting adjacent seas, viz. Buccinum reticulatum, B. un- 
datum, Dentalium entalis (Linn.), Littorina littorea, Tellina soldula ? 
Venus , Astarte ——, Cardium tuberculatum, C. edule, Cyprina 
islandica, Turritella ungulina (Beck), (Turbo ungulinus, Linn.,) Donax 
or Mactra. 
It was a prevalent belief that large boulders were usually lodged 
upon the surface of the gravel and sand; but cuts which have been 
made through mounds of these materials at Norton, near Shrewsbury, 
have proved that the larger blocks occur at considerable depths 
below the surface mixed up with shells, sand, gravel, and clay. This 
is the locality described by Mr. Trimmer* as indicating the exist- 
ence of dry land anterior to the deposit of the shells and gravel, by 
the occurrence of a peat bog, which he supposed to have been formed 
out of the remains of a submerged forest ; the stumps of the trees of 
which were said to be still rooted in their parent soil, and standing in 
their growing posture. Having examined the spot (accompanied by 
Dr. Du Gard), Mr. Murchison has obtained clear proofs that the sup- 
posed trees were stakes with sharpened points which had been driven 
down into a patch of subjacent clay; the other remains consisting of 
a plank and smaller stakes which had been laid horizontally. This 
woodwork formed the support of the old road, which in making the new 
one had been cut down beneath the ancient foundations. The 
patch of clay into which the piles were driven, lying in a depression 
between two hillocks of gravel, must have given rise to a wet and 
boggy spot, which having been rendered passable by piling and dam- 
ming, the dry materials of the contiguous hillocks were doubtless 
shovelled in to complete the road, thus giving rise to the deceptive 
appearances of marine drift overlying the supposed forest. 
Though the collocation of the boulders, sand, gravel, loam, clay, and 
shells is in parts very irregular, yet the materials are sometimes finely 
laminated: the whole, it is presumed, may have been thus brought 
together at the bottom of a sea, as the mass is not unlike many raised 
sea-beaches, with one of which, at the mouth of Carlingford Bay, Ire- 
land, recently visited by Professor Sedgwick and himself, the author 
compares it. 
From the evidences afforded by these recent shells it is inferred, that 
the tracts covered by them must have lain under the sea during the 
modern period; whilst from the continuation of the granitic drift 
from the high grounds east of Bridgnorth into the Vale of Worcester, 
Mr. Murchison conceives that the sea must at the same time have 
covered the Valley of the Severn from Bridgnorth to the Bristol 
* Proceedings of the Geological Society, Vol. II. p, 200. 
