39 



ward and tumbled over the south bank of the hollow, squeezing 

 down at the same time underneath it portions of the Neocomiau 

 Sands which then covered the surface of the Kimmeridge Clay. 

 Mr Bonney has sufficiently described the pit in his Gam- 

 hridgeshire Geology, and I will only mention that the section 

 has been further cut back since the time when his description 

 was written, so as to expose the Kimmeridge Clay as well as 

 the Boulder Clay on each side of the great Boulder. 



[Mr Skertchly in his "Geology of the Fenland" has given a 

 detailed description of Roslyn Hole, with a plan and illustrations ; 

 the limits of the long Boulder are here indicated and its several 

 relations to the Neocomian Sands, the Boulder Clay and the 

 Kimmeridge Clay, are shown. The fault theory is examined and 

 dismissed : " I am confident," he says, " that such faults do not 

 exist, or they would be traceable across the country by inter- 

 fering with the strike of the Neocomian Sands."" 



After describing the positions of the beds in the several 

 parts of the pit, he states that the great Boulder of Gault and 

 Chalk does not extend into what he calls the lower pit, but that 

 a narrow band of Boulder Clay reaches down to the river. "In 

 thus working round the pit it is seen that everywhere Boulder 

 Clay is interposed between the great Boulder and the undis- 

 turbed Kimeridge Clay ; that the Boulder Clay is always 

 found below the great boulder whenever its base can be seen ; 

 that the limits of the. Boulder lie within the pits, so that it is 

 bedded in Boulder Clay ; and lastly that the Boulder Clay fills 

 a small valley in the Kimeridge Clay." He speaks of a similar 

 old valley filled with Boulder Clay as intersected by the highway 

 a mile east of Witchford. Again, " Large masses of chalk are 

 not peculiar to Roslyn Hole, for one occurs in the Boulder Clay 

 in Witcham Fields five miles west of Ely, but is of minor 

 importance,"] 



From Roslyn Hill the Boulder Clay stretches northward 

 and westward, capping the high ground by Little Street, Chetis- 

 ham and High-flyers Hall. 



