ROCKS OF NORMANDY. 947 
finding some rocks in Normandy identical in lithological characters, 
and accompanied by beds of Triassic age, I am led to infer that the 
Triassic strata of France and England were connected, and that 
the French Paleozoic rocks stretched far into the Channel from the 
Norman coast. 
Thirdly. As the Mendip area acted as a barrier between the mid- 
land and south-western counties until the Upper Keuper waters of 
both were united, there is no reason for supposing that a similar 
extension may not have caused the union of the Trias of England 
and France, even though a barrier existed in Normandy representing 
the extreme south-eastern margin of the English Trias. Points of 
analogy are furnished by the local variations of the attenuated sedi- 
ments in both areas, namely, in the Dolomitic Conglomerate of the 
Mendips and the small quartzite gravels of Normandy. 
Second Proposition. 
The second proposition brings me to the facts of this paper, 
namely, the actual nature of the Norman Trias and its environments. 
I shall only deal at length with the department of La Manche, as 
the major part of the Trias is contained within its limits, and as 
the same rocks in Calvados, directly subjacent to the Infralias, 
and dotted by its outliers, would furnish very little additional 
evidence. 
La Manche is divided into two distinct physical regions :—The 
Bocage, a plateau between Granville and Villedieu, from 490 to 650 
feet above the sea, formed of granitoid rocks, grits, and diverse schists, 
stretching to the north of the peninsula; and the Cotentin, only from 
80 to 100 feet above the sea, which includes the rich country between 
Valognes and Le Petit Vey, called “the Gulf of Cotentin,” where 
formations from the Coal-measures up to Recent beds are found resting 
on more ancient rocks whose summits may be seen here and there*. 
«The secondary area is bounded on the east by the sea, on the 
north by Cambrian and Devonian rocks, on the west by Devonian, 
Silurian, and (in one place) Carboniferous strata, and on the south 
by Cambrian rocks ;” “itis composed of Triassic, Liassic, Cretaceous, 
Tertiary, and Recent formations+,” to which we may add the Oolites 
of Calvados. In La Manche the Secondary area may be roughly 
estimated at 380 square miles; of this, however, a considerable 
portion consists of alluvial flats; and the Triassic rocks, where un- 
covered by the Infralias, are seldom visible, owing to the thickness 
and extent of the diluvium; the Triassic districts lie towards the 
north, west, and south of the Secondary area, and extend nearly 
as far as Bayeux in the department of Calvados. The '{rias is com- 
posed of quartzite eravels and conglomerates, sandstones, rock-sand, 
and marls. ‘The distribution of these components seems to have 
been much influenced by proximity to local and variable sources of 
The absence of any detailed section of the deposits from 
supply. | 
top to hase renders even the assignment of a general order of suc- 
* Bonissent, op. cit. p. 6. ‘t Lbid. p. 264. 
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