140 NEOZOIC TIME. [CHAP. IX. 



no other bed containing the marine fossils of the Great 

 Oolite except the Cornbrash. Thus, out of a total thick- 

 ness of about 650 feet, no less than 550 are estuarine beds 

 a fact which proves the Yorkshire basin to have been in 

 close proximity to land of a continental character, and to 

 have received the deposits of a large river, the mouth of 

 which lay apparently to the north-east of the Yorkshire 

 coast. 



Of the western extension of the Middle Jurassic strata 

 we have absolutely no evidence beyond the fact that all the 

 marine limestones thicken in that direction a fact which 

 may be held to prove that their present outcrops are far 

 removed from their original western limits ; and since the 

 series seems to have overlapped the Lias in other direc- 

 tions, we may assume that it did also to the west. Eegard- 

 ing their eastern extension, important evidence has recently 

 been obtained from a boring at Eichmond, in which sandy 

 clays and limestones with Great Oolite fossils (87 feet 

 thick) were found below the Cretaceous strata, and resting 

 directly on red (Devonian ?) rocks. At Meux's brewery in 

 London similar beds occurred in the same position, the 

 rocks below being undoubtedly Devonian. It is clear, 

 therefore, that between Oxford and Eichmond the Great 

 Oolite overlaps the Inferior Oolite and the whole of the 

 Liassic series, so as to lie directly on the surface of the old 

 rocks which formed the eastern land of the period. 



These Oolites have not been proved to exist beneath any of 

 the south-eastern counties, but as they have a wide distri- 

 bution over northern and central France, there can be little 

 doubt that they are continuous beneath the Channel and 

 the southern part of England. 



The northern extension of this series is proved by thick 

 deposits along the western coasts of Scotland, where the 

 succession of marine and estuarine beds is very instructive. 

 In Skye and Eaasay the Inferior Oolite is represented by 



