Mr. Lyeli on the Faluns of the Loire. 51 



fossils. Among the shells are numerous fragments of the large 

 Terebratula variabilis. The corals and some of the Testacea are com- 

 mon to the Faluns of Touraine, but none of the distinguishing fossils 

 of the latter have been discovered in the Carentan deposits. 



Sainteny. — In sinking a well at this place, more than sixty feet of 

 a white calcareous aggregate of comminuted shells were passed 

 through. At Longueville, one and a half mile from Sainteny, is a 

 soft calcareous stone, consisting of innumerable casts of fragments 

 of shells, among which Mr. Lyell detected the Pecten striatiis of the 

 Suffolk crag ; and a similar rock occurs at the farms of Blehou and 

 RafFanville, several miles distant. The fossils obtained at these lo- 

 calities could not be satisfactorily determined, but Mr. Lyell is of 

 opinion that they agree with those which are found near St. George 

 de Bohon, except that he observed no fragments of the Terebratula 

 variabilis. As far as they can be identified, they consist of Suffolk 

 crag species, and they do not appear to possess a character interme- 

 diate between the Suffolk fauna and that of the Faluns. 



Mr. Lyell saw no recurrence of this crag further south, and the 

 most northern point at which he noticed a deposit of the age of the 

 Faluns of Touraine was near Dinan, sixty geographical miles to the 

 south-east of Sainteny, the intermediate country consisting of ancient 

 strata and crystalline rocks. 



Faluns. 

 Dinan. — AL Desnoyers does not describe the Falun near Dinan, 

 although he alludes to it. The neighbourhood of Dinan is en- 

 tirely composed of granitic rocks ; but at the village of Evran, situated 

 near a stream which flows into the Ranee, seven miles south of Dinan, 

 is a small tertiary deposit, consisting of ten or twelve feet of white 

 coralline and shelly sand, overlaid by a bed of stiff, reddish-brown 

 clay, of verj' variable thickness. The great irregularities presented 

 at the junction of the two strata, and the occasional projection of 

 continuous layers of the sand into the clay, Mr. Lyell explains by 

 supposing that the former at the time of its denudation, and pre- 

 viously to the deposition of the clay, possessed a certain amount 

 of hardness, which allowed of its being undermined. At the bottom 

 of the sand occur large oysters, different from the common Touraine 

 species 0. virginica ; and in the same quarries Mr. Lyell found many 

 corals, fragments of Echinodermata, sharks' teeth, ribs of the Laman- 

 tin, vertebrae of a Delphinus, and a tooth of a Mastodon. Some 

 of the bones were buried in a solid semi-crystalline limestone, in 

 which casts of sheDs are common. The formation occasionally 

 assumes a concretionary or travertine structure : at Le Quiou it 

 is micaceous, and splits into flags ; and at the village of Pas de 

 Hac some pinnacles of soft, white, calcareous aggregate present 

 in the lower part fine examples of cross -stratification. At St. 

 Juvat the variety of building-stone called La juuge, and com- 

 posed of comminuted organic remains, resembles the deposit near 

 Sainteny, but the occurrence of casts of cones and large Cypraese 

 convinced Mr. Lycjl that it must be assigned to the Faluns. It 

 E 2 



