550 



J. F. BLAKE ON THE TTPPEK 



representatives of the Osmington oolites. Like these same oolites 

 as seen at Weymouth and Osmington, they are in one place more 

 compact than in another. They are large -grain eel and more or less 

 rubbly at Trouvilie, especially towards the base, and in alternating 

 bands np to the top, where they are capped by a pisolite full of Nerincece, 

 forming a very characteristic horizon. At Auberville they are like- 

 wise very oolitic towards the base, and this is the only part of them 

 which is anywhere seen in the cliff; but as they have a dip towards the 

 S.E., the upper portion is exposed in stream- and road-sections near 

 Yillers, beneath the Cretaceous strata, and is seen to consist of a fine 

 massive oolite, perhaps as much as 20 feet in thickness, with scarcely 

 any fossils except Pecten qualicosta. The more pisolitic beds, however, 

 are crowded with fossils everywhere, the most abundant species being 

 EcJiinobrissus scutatus, Opis Phillipsii, and Cerithium muricatum. 

 Other fossils are Chemnitzia heddingtonensis, Pleuromya Voltzii, 

 Nerinwa elongata (or ? fasciata), Phasianella Buvignieri, and Lima 

 suhantiquata. Above this, at Hennecqville, are seen blackish oolitic 

 beds, of no great thickness, alternately hard and soft, with Trigonia 

 clavellata and Gervillia avicidoides, which may be paralleled with 

 the Trigonia-beds of Weymouth. The series above is variable, as 

 usual with the Coral Hag. At Hennecqville there are 18 feet of dark 

 unfossiliferous clay, rather sandy at the top, and rapidly changing in 

 character towards Trouvilie, where it is almost concealed. Hebert 

 mentions that at Yillers, in some locality which is now inaccessible 

 to observation, marls and limestones with Cidaris florigemma succeed 

 the oolites. Above this clay at Hennecqville the beds become oolitic 

 again through 12 feet, and very similar to those below*, most fer- 

 ruginous at the base, and cavitary towards the top by the decay of 

 fossils, the most abundant of which here are Opis corallina, and 

 Neri ncea fasciata? . There are also Cerithium muricatum., Littorina 

 muricata, and Isodonta Desliayesia. The capping of this mass for about 

 1 foot at Hennecqville is a ferruginous suboolitic limestone, full of 

 fossils, especially Cidaris florigemma and some corals — also Nerincea 

 imbricata, Opis eorallina, Cypricardia isocarclina, Pleuromya tellina, 

 Pecten vimineus, P. qualicosta, Lima proboscidea, Ezeogyra nana, &c. 

 This is the only representative of Coral Rag at this spot, where the 

 clay is thick ; but as we pass towards Trouvilie all that lies above 

 the Osmington Oolite rapidly changes its character and becomes more 

 calcareous. The last exposure towards the town shows massive lime- 

 stones with rubbly Cidaris-florigemma beds towards the top, through 

 an aggregate thickness quite as great as at Hennecqville (31 feet) ; 

 and in a large quarry in the town are seen beds which must be the 

 representatives of this portion, though very dissimilar. Here at the 

 top is a rubbly coral-reef mass, utterly irregular at its base, lying in 



* This clay and oolite are so similar to the clay and oolite below, that it is 

 possible one may be deceived by slips, and they may be actual repetitions. At 

 no place can the beds above the Lower Oolite be certainly determined ; but at 

 Trouvilie they actually lie at a considerable depth below the beds with Cidaris 

 florigemma, which latter are underlain by a more compact limestone. If there 

 be a slip, it is a very uniform one and parallel to the face of the cliff. 



