ROCKS OF NORMANDY. . 253 
In the railway-cutting at Pont-de-Six about 15 feet of whitish 
sandstone forms the base of the Trias upon the older rocks. M. 
Bonissent* mentions the occurrence of a limestone, sometimes frag- 
mentary, sometimes solid, at Pont-de-Six exhibiting very vivid and 
various tints, and regarded by him as identical with the limestone of 
Fosse Prémesnil. Consequently limestone or marlstone seems to 
occur in the Trias near its western margin, from Pont-a-la- Vieille 
to Pont-de-Six; and still further, if La Croix Morville (where a 
similar bed has been noticed) lies within Morville (an adjacent com- 
mune to Négreville on the south-east), or is a synonym for La Croix 
des Auneys of the same neighbourhood in the commune of Magne- 
ville. Southward from Valognes to Lieusaint, where an inlier of 
Silurian rock occurs, the Trias near its junction with the Infralias, 
judging from indications by the railway, appears to consist of marls 
and whitish sandstone, the latter probably uppermost. 
By the highroad from Valognes to Montebourg drifts conceal the 
subjacent rock. Between St. Cyr and Montebourg Silurian quartzite 
is exposed in a quarry by the highroad, forming the corner of a 
large inlier extending thence to Quinnéville on the eastcoast. Near 
its junction with the Silurian on the north of Montebourg the Trias 
appears to consist of marl. Near Montebourg, by the highroad to 
Carentan, yellowish-brown sandy soil with quartzite pebbles covers 
the surface, being probably to a great extent a redeposit of Triassic 
sands and gravels which may be concealed by it. 
Section LY. (fig. 4).—By the road from Montebourg to Le Ham 
Station, near the former, beds of coarse light brownish sand-rock dip 
to the north at a small angle. At Eroudeville a pit by the road shows 
8 feet of coarse yellowish-brown sand with small irregular quartzite 
pebbles exhibiting traces of bedding. A similar gravel, as I was in- 
formed, is worked near St. Cyr ; indications of it were noticed at about 
1100 yards to the south of Hroudeville: from this point to Le Ham 
Station no evidence is obtainable, owing to the covering of drift-soil. 
At Le Ham Station, however, red marl is exposed very near the 
Infraliassic junction. Proceeding along the railway from Le Ham 
toward Flottemanville, whitish sand-rock, apparently Triassic, is 
exposed in one or two places. [rom these observations I am in- 
clined to regard the Trias of Montebourg and Valognes as occurring 
in the following descending order :— 
1. Thin deposit of red marl under Infralias. 
2. Whitish sands passing into, or replaced by, pebble-gravels. 
3. Red marls, possibly alternating with, and resting on, sandstones. 
M. Bonissent, however, who had much more ample opportunities 
of studying the district, states} ‘“‘ that the grés bigarré rests on in- 
clined Silurian rocks at Montebourg, and disappears in other direc- 
tions beneath the Keuper and Lias.” He describes it as composed 
of yery fine and medium-grained métavites (an untranslatable term 
likewise applied to a variety of Cambrian rocks, p. 136; a species of 
sand or sandstone is meant) alternating with thin beds of whitish 
* Op. cit. pp. 267, 268. t P. 266. 
