346 Prof. Sedgwick on the Classification of the Strata [May, 



By a comparison of the dip and direction of the several parts 

 of the formation just described it appears, that from Filey 

 Bridge to Malton, the beds of oolite form a kind of basin which 

 supports the argillaceous deposit described in the preceding 

 section. For many of the details connected with the natural 

 history of this formation, I must however refer the reader to the 

 " Geological Survey of the Yorkshire Coast," p. 61 — 69. The 

 out-lier of Scarborough Castle Hill, another owi-/?er, which forms 

 the crest of the hill north-east of Hackness, and a third out-lier 

 (not marked in Smith's geological map of Yorkshire) crowning 

 the hill inimediately west of Hackness, afford the best possible 

 opportunities for studying the characters of the oolitic forma- 

 tion and its relation to the inferior beds. The same remark may 

 be applied to the fine natural section of Filey Bridge, and to 

 various quarries in the course of the river Derwent where it cuts 

 its way through the oolite into the vale of Pickering. An 

 examination of these localities led me to conclude, without 

 hesitation, that the oolite of this part of Yorkshire was in every 

 respect identical with the middle oolite or coral-rag formation ; 

 an opinion which was confirmed by an examination of severai 

 quarries near Kirkby Moorside during the following year. As, 

 however, this conclusion is of importance, and has been dis- 

 puted, 1 think it expedient briefly to state the evidence on 

 which it is founded.* For this purpose, it will be necessary to 

 determine the true characters of the middle oolite formation in 

 those localities where it is best exhibited. 



Section of the Coral-rag Oolite exposed in the Cliffs near 



Weymouth. 



Near Weymouth there are many highly instructive sections, 

 exhibiting all the three formations of oolite, and the intervening 

 clays in their natural order ; and in the cliff extending from the 

 jetty to the ruined castle, the successive beds of the coral rag 

 formation (beginning with the lowest and ending with the 

 highest) are exposed in an unbroken natural section. The fol- 

 lowing details connected with this section are extracted from 

 memoranda made on the spot in the year 1820. 



No. 1. A system of beds near the jetty resting immediately 

 on the Oxford clay.f They are composed of a variety of calc* 

 grit, very harsh and meagre to the touch ; and many ofthem are 

 almost made up of irregular stems branching out and intersect- 

 ing each other in every direction. Heaps of dried branches of 

 wood mixed with blown sand, and then cemented into one mass, 



* It is, perhaps, unnecessary to inform the reader that Mr. Greenough, Professor 

 Buckland, and iMr. Smith, have all, in their published works, identified the Pickering 

 oolite with the coral rag formation. 



-f- The Oxford clay near Weymouth is highly characteristic, and contains an incredr* 

 ble number of the gryphxa dUatata, 



