1340 Prof. Sedgwick on llie Classification of the Strata [May, 



order of the successive formations, though sometimes disguised 

 by contortions, or interrupted by dislocations, is so plainly seen 

 in many fine natural sections as not to remain in any doubt. If 

 we attempt to connect the formations in question with the con- 

 temporaneous deposits in the more southern parts of England, 

 the task, though encumbered with some difficulties, may soon be 

 reduced within ;v'ery narrow limits. For the deposits in the 

 north-eastern parls of Yorkshire are superior to the 7iexv red 

 sandstone, which runs in one continuous mass from the banks of 

 the Severn to the mouth of the Tees ; and they are inferior to 

 the chalk which terminates in the bold escarpment of Flambo- 

 vough Head. Do they then admit of any natural subdivision 

 which will enable us to compare them with the several forma- 

 tions, between the new red sandstone and the chalk, which have 

 been described with so many excellent details by Mr. Cony- 

 beare ? That there is some difficulty in answering this question 

 is obvious from the fact, that in the description of the district in 



auestion, our best geological authorities are at variance among 

 lemselves. 

 Mr. Smith identifies the alum-shale of the Yorkshire coast 

 with the Oxford clay ; and the coal formation of the moors and 

 the limestone ot the vale of Pickering, with the calcareous grit 

 and oolite of the coral- rag formation. Mr. Greenough refers the 

 alum-shale to the lias, the sandstone and coal fonnation of the 

 moors to the great oolite, and the limestone of the vale of Pick- 

 ering to the coral-rag. Mr. Conybeare is inclined to identify 

 the formation of the moors with the inferior oolite, and the 

 limestone of the vale of Pickering with the great oolite. A part 

 of these discrepancies has undoubtedly arisen from the anoma- 

 lous character of the strata in question ; for there is obviously 

 great risk of error in attempting to bring into the same class 

 distant deposits which are unconnected, and bear little resem- 

 blance to each other. Notwithstanding these difficulties, 1 am 

 disposed to think, that a careful examination of a very small 

 number of facts, in addition to those with which we are now 

 acquainted, would enable us to determine with certainty the 

 respective places in the series of English formations to which 

 the strata on the Yorkshire coast are to be referred. 



The whole country bordering on this part of the coast is natu- 

 rally divided into several distinct regions, each possessino- a 

 distinct geological structure. 1. The low region extending 

 from the southern extremity of Holderness to Bridlington. 



2. The chalk downs terminating in Flamborough Head. 



3. The low argillaceous region constituting the vale of Picker- 

 ing. 4. The broken mountainous tract extending from the vale 

 ofPickering to the end of Huntcliff. o. The low region stretch- 

 ing from the mouth of the Tees towards the central plains of 

 Yorkshire. 



