Geological Society. 561 
schistose rocks of the North of Cornwall, and presented to the Society 
on the part of the Ordnance Geological Survey. ‘ 
Mr. De la Beche says that in the grauwacke of Western Somerset, 
Devon, and Cornwall natural divisions may be made, founded on 
marked characters. How far these divisions may coincide with those 
in Prof. Sedgwick’s Cambrian system he has no means at present of 
judging ; but he is of opinion that the whole of the district is older 
than the Silurian formations of Mr. Murchison. 
Some of the organic remains obtained at Dinas Cove, in Padstow 
Harbour, belong to a system of beds consisting of slates, sandstones, 
and conglomerates, which encircles the northern flank of Dartmoor, 
then makes a great curve south of Launceston, bends afterwards 
northward round the Rough Tor and Brown Willy granite, and lastly, 
again inclines southward, crossing the Padstow river to the seaon the 
western coast. In various parts of this line the system is fossiliferous, 
particularly where limestone occurs or calcareous matter abounds. 
The Tintagel slate, long since shown by Dr. Buckland and the Rev. 
John Conybeare to contain organic remains, belongs to this system. 
Part of the fossils which accompanied the letter were procured from 
Trevelga Island (Lower St. Columb Porth), and Towan Head near 
New Quay, from the same series of beds, which, in consequence of an 
east and west anticlinal line ranging by St. Eval, St. Issey, and St. 
Breocks Downs, is folded over to the south, and constitutes the 
schistose system of St. Columb Major, St. Columb Minor, New 
Quay, &c. 
The remainder of the fossils was obtained by Dr. Potts at the 
western entrance of Bodmin, and by Mr. De la Beche from the vi- 
cinity of Liskeard, on a prolongation of the same strata. 
Altered or metamorphic rocks, having frequently the appearance of 
gneiss, mica slate, hornblende rock, &c., occur in the neighbourhood 
of Tintagel and Camelford; and’Mr. De la Beche says, that a little care 
in tracing these rocks shows that they are altered portions of strata 
which possess the usual and varied characters of grauwacke. In con- 
clusion he observes, that there is every reason to believe that two 
movements have taken place of the land in Somerset, Devon, and Corn- 
wall, one to a height of 30 or 40 feet above the present sea-level, and 
another to an uncertain depth beneath it, since the vegetation of the 
land and the molluscous inhabitants of the neighbouring sea were the 
same as they now are. 
January 20.—A paper was read “ On the geological structure of 
Pembrokeshire, more particularly on the extension of the Silurian 
system of rocks into the coast cliffs of that county.” By Roderick 
Impey Murchison, Esq., V.P.G.S. 
This memoir was prefaced by an account of the origin of the terms 
Silurian and Cambrian Systems as applied to the older sedimentary 
deposits. Having occupied several years in establishing a fixed order 
of succession amid the strata of age anterior to the old red sandstone, 
and having finally named the formations in descending order, the 
Ludlow rock, Wenlock limestone, Caradoc sandstones, and Llandeilo 
flags, the author was urged by many leading geologists to propose a 
Third Series. Vol.8. No. 50. Supplement, June 1836. 3K 
