16 HILLS AND VALES. CHAP. 



reference to causes now in action ; and a similar case occurs near 

 Oxford, between Wytham Hill and Cumnor Hurst. 



In all these cases the existing hollow is the work of denudation. 

 The Evenlode drainage may at one time have been like that of the 

 Churn, Windrush, or Coin, enclosed within an oolitic boundary, 

 now wasted away, or marked by only some solitary insular or 

 peninsular hills. Another example is in the Cherwell, whose head 

 waters are gathered among detached hills of oolite once connected 

 into an area as broad as the Cotswold Hills, but probably at no time 

 so elevated as they are. 



The course of a valley on these oolitic hills may be sketched freely 

 as beginning upon an undulated surface with several dry branches ; 

 then plunging among boldly swelling hills, often richly wooded 

 on their slopes, and forming portions of ornamental ground ; lastly, 

 the valley opens widely amidst extensive gravel deposits, which 

 it has brought down into the greater hollow of the Thames. 



Diagram VI. r. Khsetic or Westbury beds. I 1 . Lower lias limestones. 



l li . Lower lias shales. l ui . Middle lias or marlstone. l iv . Upper lias shale. 



l v . Liassic sands. i. Inferior oolite. f. Fuller's-earth rock. go. Great 



oolite. f m. Forest marble, and cb. Cornbrash. 



In the Cotswold ranges, and further to the north about Edgehill, 

 though a few steep banks occur along the valleys there are hardly 

 any considerable precipices, even among the woody banks of the 

 Churn and the Coin ; no waterfalls are known, nor as yet has any 

 ossiferous cave been discovered, even in the thick oolitic rocks. 

 Perhaps none must be expected ; for quarries are opened in almost 

 every part of this stony district, and where the stone is thickest, 

 and caverns might be most likely to occur, the excavations are very 

 extensive as at Painswick, Leckhampton, and Bourton-on-the-Hill, 

 and about Naunton and Burford, 



