xlii. OSMINGXON MEETING. 



deposited. Later on in geological time a second series of disturbances took 

 place affecting the Cretaceous strata, much as the previous ones had done the 

 Oolitic. Mr. Hudleston (to whose writings I have been frequently indebted in 

 preparing these notes) considers that these very important movements, to which 

 the present structure of this part of the South of England is mainly due, 

 were initiated during the Miocene period. It is an interesting fact that 

 in many places the Cretaceous strata rest unconformably, as in the 

 present case, upon the rocks below them, showing the occurrence of great 

 general disturbances before their deposition. This is the case nearly all 

 over Europe, in Arabia, and probably also in India. If we were to walk 

 down the little stream which flows into the sea at Osmington Mills, we 

 should come successively, starting at Upton (which is situated one mile to the 

 N.N.E. of the Mills), to the following beds : Wealdeu, Purbeck, Portland, 

 Kimmeridge, Coral Bag, caused by the slicing off by denudation of an anticlinal 

 ridge in the neighbourhood of the Mills, and in parts we should find the remains 

 of some Cretaceous Beds resting on it. One of the most notable instances of this 

 action near Weymouth is that known as the Wey mouth Saddle, of which the 

 Forest marble, forming the central line of the anticline, stretches from Langton 

 Herring to Broadwey, the higher beds appearing successively on each side, but, 

 as I hope we may perhaps visit that interesting neighbourhood another year, I 

 will not dwell upon it. In the eastern cliffs of Ringstead Bay may be seen a fine 

 section, showing the series of Oolitic strata from the Portland Beds down to the 

 Coral Rag. Underneath Holworth House the blue Gault clay may be observed to 

 rest on the up -turned edges of the earlier formations, and no doubt the geologists 

 present will perceive many other interesting details. It is a curious fact that the 

 Portland screw (Ccrithium Fortlandiciini) , which is one of the most striking and 

 well-known fossils in the roach at Portland, is almost absent in the corresponding 

 bed here. The remains of saurians are frequent in most of the strata about here, and 

 I may mention that in the Dorset Museum are some teeth, vertebrae, and portions 

 of the head, and other bones of a gigantic Pllosaurm from the Kimmeridge 

 clay of Ringstead. The large paddle in the Museum is from the same formation 

 at Kimmeridge. \_PUosaurus had somewhat the same general character as the 

 Cimoliosaitrns, which some of those present may remember to have seen at my 

 house, but was much larger.] On the beach a little to the west of the Mills, where 

 I fear we shall hardly have time to go to-day, we find masses of Coral Rag, 

 detached from a neighbouring stratum, containing fossils, of which the most 

 conspicuous is Triyonia clavcUata, a beautiful double shell with rows of 

 protuberances, of which this specimen that I exhibit is rather a poor representa- 

 tive. There is a very fine block of them in the Dorset Museum, * and other species 

 of Trigoma abound in our local Oolitic rocks. We shall find similar bloeks 

 in our walk along the beach. There are also many other fossils, e.g., Chcnniitzia, 

 obtainable ; for instance, I once picked up a fine piece of coral nine inches 



A slab containing Trigonia clawllata is figured in "Proc." II., 19. 



