158 
THE GEOLOGIST. 
Wales, and adopted as the types of tlie Silurian system, and 
with those of Denbighshire and Merionethshire, to which his 
attention was directed by Mr. Bowman's papers on Langollen ; 
he points out the closest resemblance between the Silurian forma- 
tion in North Wales and in Westmoreland, while in mineral 
character they differ most materially from those of Siluria : never- 
theless the principal divisions of the Silurian system laid down 
by Mr. Murchison can be traced in each district by the evidence 
of the organic remains. 
''On the Stratified Rocks of Berwickshire and their Organic 
Remains J' By Mr. William Stevenson, of Dunse. 
1. In this memoir the author gives an account of the character- 
istic features, the order of succession, and the natm-e of the 
inorganic remains of the stratified rocks of Berwickshire. The 
lowest of these are greywacke and greywacke slate, forming an 
extensive system of arenaceous and argillaceous strata of various 
colours, gray predominating, found almost everywhere among 
the Lammermuirs, of which chain they constitute the fundamen- 
tal rock. In the rocks of this system no undoubted organic 
remains have been found, but some curious markings occur on 
the slabs, for which it is difficult to account without supposing 
the influence of organic agency. The greywacke presents the 
uniform appearance of a deep sea deposit, perhaps laid down 
upon the bottom of a wide spreading ocean of great profundity, 
and therefore removed from the disturbing action of wind and 
tide. The thickness of these strata, as displayed among the 
Lammermuirs, is very great, but the series is far from being 
complete, there being no appearance of the older strata on the 
one hand, and on the other their junction with the newer for- 
mation is always unconformable. The materials of which they 
are composed were probably derived from the disintegration 
of the granites and primary schists to the west-ward. 
2. The formation next in order is the upper di^dsion of the old 
red sandstone, the members of which rest unconformably upon 
