HARKER : OOLITES OF CAVE DISTRICT. 23 1 



several places along its line of outcrop ; only the white barren sands 

 are visible at Sancton Church, while the highest fossiliferous bed is 

 well exposed just south of South Cave. A fine section of the whole 

 was laid bare during the works for the Hull and Barnsley Railway 

 two years ago. The cuttings of this railway afforded exposures of most 

 of the Jurassic rocks of the neighbourhood : they are since mostly 

 grassed over, but a description by Messrs. W. Keeping and 

 Middlemiss was given in the 'Geological Magazine' for May 1883. 



The Kelloway Rock is probably the source of much of the sand 

 in the local drift : the red colour of the rock is due to an external 

 coating of ferruginous colouring matter on each grain ; the colour 

 was found to be completely bleached by dilute hydrochloric acid. 



The formation in question thins out to the north and west of 

 Sancton, apparently owing to an overlap, which thus obscures the 

 normal relation of the rock to the underlying strata ; but although no 

 equivalent of the 'Avicula-shales ' has been proved, the fact that the 

 base of the sands at Sancton, Newbald, and Drewton cutting 

 becomes argillaceous downwards is another point of similarity with 

 the Coast sections. 



The Kelloway Rock is abruptly overlain by a tenacious blue clay,, 

 of which about twelve feet were seen in the railway cutting, the top 

 not being shown. A few GryphcEa dilatata occur, and at the base 

 abundance of Belemnites owemi, with crystals of selenite and irony 

 concretions. This is the Oxford Clay, and the interesting feature 

 about it is its lithological resemblance to the corresponding strata at 

 St. Ives, &c., in contrast to the grey, sandy, crumbling shales which 

 represent the formation in North-East Yorkshire. 



There is no evidence of any members of the Corallian series 

 occurring in the Cave district, although pebbles of CoralHne Oolite, 

 with Che?jimtzia, &c., are found in the local drift about South Cave 

 and Brough. The Kimmeridge Clay occurs, but, like the Oxford and 

 Upper Lias Clays, it makes no show at the surface, and is difficult 

 to detect. There is no doubt, however, that some of the black 

 shaley clay underlying the Chalk of the Wolds is referable to the 

 Kimmeridge series, and Ostrea delioidea has been found near 

 Elloughton and Brantingham. The clay exposed in the railway 

 cutting at Weedley seems by its aspect and the Belemnites it yields 

 to belong to the Neocomian, a formation much more widely developed 

 on the west side of the Wolds than is generally recognised. The 

 impervious nature of the clay causes it to ' throw out ' the water 

 which soaks through the overlying chalk, so that the outcrop of the 

 Red Chalk is marked all round the outer edge of the Wolds by a 



May 1885. 



