Isii PEOCEEDINGS OF THE GEOLOGICAL SOCIETY, 



stones to t"he west of it, are truly synclironous groups. One 

 great result of this tripartite arrangement of the Permian group, 

 viz., lower and upper sandstones, with an intermediate limestone 

 or its fossiliferous equivalent, is that we are thus enabled to cor- 

 relate the British deposits of this age with the Permian forma- 

 tions of the Continent. 



It is further stated in this memoir, that the Upper Permian 

 consists of red sandstones with courses of red shales, all perfectly 

 conformable to the underlying Permian rocks, there being a 

 regular transition or passage into these from the Middle Permians. 

 Wherever they have been examined, whether in Westmoreland, 

 the east of Ctunberland, or in the north portion of St. Bees 

 Head on the west coast, they are not only perfectly conformable 

 to the Middle Permian strata on which they rest, but are in inti- 

 mate connexion with them. Whatever may be the angle of 

 inclination of the one is always that of the other ; and there is no 

 trace of erosion on the surface of the lower or supporting strata, 

 as might have been expected between rocks of Palaeozoic and 

 Mesozoic age. 



The authors then observe, that although there are certain shales 

 and sandstones in the neighboui-hood of Carlisle which are re- 

 ferred to the Trias, they have found no evidence in any portion 

 of Cumberland of the mode in which the lower members of this 

 Mesozoic group were associated with the upper portion of the 

 Palseozoic division. In conclusion, they add some remarks on the 

 comparison between the Permian beds in the county of Durham 

 and those of Westmoreland, and point out the great distinction 

 between the flora of the Permian strata and that of the Coal- 

 measures. Looking also at this great extension of the Permian 

 rocks in the north-west of England, they suggest the possibility 

 of productive Carboniferous deposits being obtained at some future 

 day by sinking through some of these overlying Permian sand- 

 stones. 



Avicula-contorta Bed. — The question of the true relations of 

 these Avicula-contorta beds, about which so much has been lately 

 Avritten, as to whether they strictly belong to the Triassic or 

 Liassic series, has been ably discussed by M. Eenevier of Lausanne, 

 in a paper read before the Societe Vaudoise des Sciences Natu- 

 relies*. Having carefully explored the fossiliferous beds near 

 Villeneuve, at the eastern end of the Lake of G-eneva, he ascer- 

 tained the existence of two distinct zones of fossils closely con- 

 nected together, biit yet characteristically distinct. The upper 

 zone corresponds with the true Infralias of Valogne, Hettange, the 

 Lyonnais, &c., and with the beds of Ammonites angulatus and 

 A. planorhis of Wiirtemberg. The lower zone is the true Avicula- 

 contorta zone of the Alps, parallel to the Bone-bed of England 

 and Wiirtemberg, and to which the name of Eha^tic beds has 

 been generally applied. They constitute an intermediate series 

 between the Liassic and Triassic formations ; and the great 

 ■'^ Quart. Joiu'n. Geol. Soc. a'oI. xx. part 2. p. 26. - 



