170 NEOZOIC TIME. [CHAP. X. 



of blue and black clays (150 feet). These were formed in 

 much deeper water, and include representatives of the 

 lowest Vectian beds, as well as the higher, many of the 

 fossils being similar to those found in the Atherfield Clay. 

 The Yorkshire succession, however, has much more re- 

 semblance to that of Hanover than to that of southern 

 England or France, and there can be little doubt but that 

 they were formed in a Germanic sea or gulf, which con- 

 stituted a separate marine province. 



Upper Cretaceous. The lowest stage of this series con- 

 sists of a variable group of clays, marls, sands, and sili- 

 ceous rocks which are known as the G-ault and Upper 

 G-reensand. It used to be thought that the argillaceous de- 

 posits were always older than the arenaceous, but it is pro- 

 bable that they are to a large extent replacive and coeval. 



As a matter of fact, in East Kent the formation consists 

 entirely of clay, more or less marly at the top, and including 

 a thin bed of dark glauconitic sand. To the westward 

 other beds of sand and siliceous stone come in, and in the 

 Isle of Wight it is lithologically divisible into three por- 

 tions, the lowest being blue clay (100 feet), the central 

 consisting of sandy micaceous marl (55 feet), and the upper 

 of yellow and grey sands, with layers of cherty stone (100 

 feet). Still further west the clays entirely disappear, being 

 probably overlapped by the higher beds, which consist of 

 grey and yellow sands, argillaceous below and glauconitic 

 near the top, with a total thickness of 150 to 130 feet. 

 These form the mass of the Blackdown Hills, and cap the 

 Trias of Haldon Hill south of Exeter. 



A similar group of beds doubtless swept northwards 

 across the centre of England, but only the eastern part re- 

 mains, all the western part between the Welsh hills and 

 the Cretaceous escarpment having been removed by the 

 erosion of subsequent periods ; we cannot, therefore, trace 

 the passage from G-ault to G-reensand across the Midland 



