ROCKS OF NORMANDY. 251 
a cavernous millstone.” From this it appears that the Lestre marl- 
stone underlies the sand-rock and gravel previously noticed. 
Speaking of the Intralias of Valoenes and Yvetot, M. Bonissent 
says*, “The last bed, called ‘ marlicre’ by the quarrymen, is com- 
posed of greyish limestone feebly cellular, unfossiliferous, and of 
crystalline texture.” I quote this, as it appears from the descrip- 
tion to present much analogy to the rock just described at Lestre. 
Section II. (fig. 2).—Returning to Valognes and following the 
highroad thence to Pont-a-la-Vieille (in the direction of Cherbourg), 
the Trias crops out from beneath the Infralias at about 1100 yards 
from Valognes. The scanty surface-evidence seemed to indicate marls 
under the brown diluyial soil, but so feebly that it may be only a bed in 
or on sandstone. Approaching Pont-a-la- Vieille, the base of the Trias 
resting on Devonian schists appears to consist of whitish sands. M. 
Bonissent mentions 7 the occurrence of white (pelygénique) calcareous 
sandstones resting on compact, violet, reddish, greyish, and yellowish 
limestone at Pont-a-la-Vieille, Fosse Prémesnil, and Croix Morville ; 
the latter localities Iwas unable to find. This.shows, however, that 
in the north of the area marlstones were not unfrequently amongst 
the earliest Triassic sediments deposited, probably owing to the local 
development of Paleozoic limestones. 
Proceeding from Valognes westward to the viaduct of Pont-de-Six, 
north of Négreville, hard whitish calcareous sandstones are shown in 
a pit near the railway-station. M. Bonissent says that fine-grained 
very solid calcareous sandstones mottled with various tints are shown 
at Valognes. As Infralias is extensively quarried near Valognes 
Station, the beds immediately underlying it would appear to be are- 
naceous, possibly separated from it by a thin stratum of mar]: on 
the whole, howeyer, I am inclined to regard the lithological varie- 
ties of the Trias of the Valognes district as interchangeable. 
Section III. (fig. 3).—By the road to Pont-de-Six, at about a mile and 
a quarter from its junction with the Infralias of Valognes, the Trias 
consists of gravel and sand exposed in an extensive, though shallow, 
pit on the south side of the road. Subjoined (fig. 4) is a section of 
one part of the pit where it is 44 feet in depth. In other parts of 
the pit the gravel is faise-bedded, containing incipient bedding- 
courses of sand or pebbles; it appears to rest on sand, and in parts 
to be replaced by it. Taking all parts of the pit together, about 
15 feet of gravel and sand are exposed. ‘The character of the whole 
forcibly reminded me of sections of the Devon pebble-beds near 
Aylesbeare, Tallaton, and Kentisbere, where the larger pebbles are 
absent, the irregular association of sand, incipient indications of 
bedding, occasional false-bedding, and in many cases similar light 
tints being common to both; but the analogy ceases here, as the 
Devon beds occupy a much lower horizon than those of Normandy. 
Although very unsatisfactory, the evidence obtained in proceeding 
from the gravel-pits towards Pont-de-Six leads me to regard the 
subjacent rock as marl upon which traces of gravel, Triassic or deri- 
vative, seem to rest in one or two places. 
* Op. cit. p. 276. t+ P. 267, 1 P. 267, 
