264 w. A. E. USSHER ON THE TRIASSIC 
quartzite, capped by a drift containing boulders and occasional 
pebbles of the same rock. Near St. Cyr, by the highroad from 
Valognes to Montebourg, I visited a quarry of violet, red, and grey 
Silurian quartzite, capped in part by drift. 
In the grits of St. Sauveur le Vicomte, Rauville le Place, Besne- 
ville and Etanclin, fossils of the May type have been recognized. 
At Besneville, Homalonotus, Orthis redux, Coelaster, Paleaster, 
and Avicula matutina; at St. Sauveur le Vicomte, Homalonotius 
and Orthis reduw; at Varenguebec, Cleidophorus; at Etanclin, 
Orthis redux *, These rocks bound the Trias south of Valognes. 
Traces of the same formation have been recognized in the com- 
mune of Moon +, on the southern borders of the Triassic area, near 
the lmits of Calvados and La Manche. 
I visited the quarries of May (south of Caen), on the west side of 
the village. ‘The quartzite varies in colour from reddish and pale 
greenish to white. Here and there vertical red markings in the 
grey quartzite show a perfect resemblance to many of the charac- 
teristic Budleigh pebbles. 
The beds dip towards north 30° east. Some of them are very 
thick, one being observed of from 7 to 8 feet. A sandy bomb about 
6 feet in diameter was noticed in one part of the quarry face. 
During a couple of hours’ search I procured some specimens of 
Orthis redux and thoracic plates of Trilobites. 
= 
Devonian. 
The lower part of the Devonian only is represented in La Manchet; 
its constituents occur in the following descending order :— 
1. Schists with thin beds of soft grit containing much mica, sometimes alter- 
nating with limestones. 
. Greyish or blackish limestones, with alternating blackish schists, often 
micaceous. 
3. Grits of various colours, especially greenish, alternating with schists of the 
same hues §. 
tho 
This triad grouping reminds one of the Devonian flanking the 
South-Devon ‘Trias as given by Mr. H. B. Woodward |/:—1. Thin 
band of shales on limestones; 2. Slates; 3. Red Sandstones: in 
descending order. 
The Lower Devonian grits of La Manche are not so pure as those 
of the Silurian formation. It happens, however, that some of these 
grits, through the effects of metamorphism, have acquired a very 
close texture, and thus present the appearance of quartzites. The 
Devonian area lies between Pieux and Valognes on the north, and 
Lessay and Le Plessis on the south ; it is bounded by the sea on the 
west, and by the Triassic districts on the east. Beyond these limits 
* Bonissent, op. cz. p. 200. 
+ P.209. <A band of Silurian is shown on Knipe’s map bounding the 
Secondary area from Moon to Campigny. P. 224. 
§ Pp. 226, 227. || Geol, Mag. for Oct. 1877, No. 160. 
