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THE OOLITES OF THE CAVE DISTRICT. 



By ALFRED MARKER, B.A., F.G.S., 



Of St. yokns College and the Woodwardian Micsezwi, Cambridge. 



The strip of Oolitic rocks lying on the western side of the Yorkshire 

 Wolds is deserving of more notice from geologists than it has yet 

 received, forming, as it does, a connecting link between the dissimilar 

 areas of Lincolnshire and North-East Yorkshire. The whole district 

 indeed possesses considerable interest from its comprising a great 

 range of formations in a small compass. A traverse three miles in 

 length may be made from the Trias to the Chalk, embracing Lower, 

 Middle, and Upper Lias, Lower, Middle, and Upper Oolites, and 

 Neocomian. 



The Jurassic strata strike N.N.W. from the Humber in the 

 neighbourhood of Brough to near Market Weighton, a distance of 

 about ten miles. They dip easterly under the Chalk of the Wolds, at 

 the base of which occur a few feet of red and yellow, marly and 

 nodular Chalk, as at Speeton, Hunstanton, &c. The unconformity 

 below the Chalk is well marked in this district, for at Welton and 

 Brantingham dales that formation overlies clays probably of Neoco- 

 mian age (the equivalent of the Speeton Clay), while northward it 

 gradually creeps over older strata, until at Goodmanham, near Market 

 Weighton, the Red Chalk, with its characteristic fossils in abundance, 

 rests upon the Lower Lias. Westward the Middle and Lower Lias 

 form low^ escarpments overlooking the Triassic plain, as at North 

 Cliff, where a fine exposure shows beds with Lima gigantea, Modiola 

 minima^ &c., belonging to a lower horizon than any exposed on the 

 coast. The Liassic beds of this district have been fully described by 

 Messrs. Tate and Blake, but the Oolitic rocks seen between them 

 and the Wolds have received but little remark, not being noticed in 

 Mr. Hudleston's otherwise exhaustive papers on the 'Yorkshire 

 Oolites.' 



The strike of the beds is uniform, but owing to their low angle of 

 dip their outcrops are thrown into sharp bends to the East by the 

 little valleys at North Cave, Newbald, and Sancton. It is worthy of 

 note that each of these valleys is coincident with a line of faulting : 

 the faults are at right angles with the strike, and of inconsiderable 

 throw. 



The Lower Oolites are represented chiefly by 'roestones' or 

 impure Oolitic limestones with some beds of sand (as at Ellerker, &c.). 

 The Oolite is often flaggy, but sometimes thick-bedded and suitable 

 for building purposes : in some places it is hard enough to take a 

 polish. It is generally yellowish-brown in colour, owing to weathering, 



May 1885. 



