954 W. A. E, USSHER ON THE TRIASSIC 
and greenish clay. In the upper part the rock sometimes passes 
into a quartzose puddingstone. Its structure is often massive in the 
lower beds, sometimes becoming shaly toward the surface. The 
sandstones (métaaites) are slightly micaceous, of a dirty white colour, 
very rarely exhibiting rose-coloured or bluish tints. No traces of 
animal remains were obtained ; but fragments of petrified trees were 
found lying horizontally in the middle of the sandstones (métaziées) 
in the commune of Hroudeville near Montebourg; they measured 
from about 6 to 10 metres* in length by 20 centimetres to 6 deci- 
metres t in diameter: the species were indeterminable. 
If these beds are really Bunter, a very great unconformity, elimi- 
nating not only the Muschelkalk (calcaire coquilliere) or its equi- 
valent, but also the whole of the lower and much of the upper 
Keuper series, could alone account for its occurrence. I think, how- 
ever, that the correlation can be successfully disputed upon the fol- 
lowing grounds :— 
First. The thinness of the Trias at Montebourg, ‘as the distance 
from the Infraliassic margin on the south to bare Silurian rocks on 
the north does not exceed 3 kilometres (3300 yards). 
Secondly. The similarity of the deposits to those already described 
in the neighbourhood of Yalognes, and hereafter to be noticed in the 
environs of Carentan. 
Thirdly. The impossibility of drawing hard lithological boundaries 
in a district where the constitution of the beds is so variable from 
local derivation, as M, Bonissent’s observations prove the Keuper de- 
posits to be. 
Fourthly. The absence of all mention of unconformability in M. 
Bonissent’s account. 
Fifthly. The excessive improbability of the existence of uncon- 
formity in the attenuated Triassic rocks of Normandy, and the 
absence of any circumstances favourable to its occurrence in the 
neighbourhood of Montebourg. 
At Mont Busnon in St. Cyr branches of trees were discovered 
in diluvium covering “ New Red Sandstone (Keuper)’f. It is a 
curious coincidence that arboreal remains should occur in the same 
district both in diluvium and Trias. I did not visit the Triassic 
districts on the west of the railway between Négreville and Ca- 
rentan. The fragmentary nature of the exposures of the Trias of 
that neighbourhood may be gleaned from the following. 
Between Urville and Orglandes, at Cauquigny, Picauville, and from 
Cretteville to Baupte, the Trias is covered by Infralias§. At Gour- 
besville, Orglandes, Hauteville, Biniville, and Reigneyille Cretaceou 
deposits occur, and rest directly on Paleeozoic rocks at Néhou, Golle- 
ville, La Bonneville, and Crosyille ||. Eocene beds are spread over 
the communes of Gourbesville, Hauteville, St. Colombe, Néhou, 
Reigneyille, Crosville, and La Bonneville: Lower Miocene is repre- 
sented at Rauville-la-Place, and Upper Miocene in the communes of 
* Roughly speaking, from 20 to 33 feet. 
+ Roughly speaking, from 8 inches to 2 feet. 
t Bonissent, op. cit. pp. 393, 394, § Lb. p. 275. || 20. p. 810, &e, 
