228 On the Recent Discovery of Flint Implements 



that we ought to be able to point out the direction of the current 

 of the ancient river, and also a sufficient obstacle to account for the 

 still water on the north bank. 



A single glance at the position of the hill ranges will show, 

 that a stream of water flowing down the valley of the Nadder 

 from Wilton, will wash the base of the chalk and meet with the 

 first impediment to its progress in the curve of the hill at East 

 Harnham : the check thus produced would be but slight as compared 

 to that it would experience by encountering a volume of water of 

 greater velocity coming from the valley of the Avon. Then again 

 the elevated wedge shaped ridge of chalk at Fisherton would act 

 much in ths same way as the central column of a double arched 

 bridge, behind which accumulates a small heap of mud and sand. 

 Here then is substantial proof of the causes which must have 

 produced still water, and its concomitant mud on the north side of 

 the valley, and a brisk current, with but little deposit, on the south 

 bank. 



In like manner a careful examination will show the probable cur- 

 rents and directions of the old representatives of the Avon, 

 Nadder, Wiley and Bourne, throughout the entire length of their 

 courses. 



As affording an excellent illustration of the eroding action of 

 water, attention is particularly directed to the manner in which the 

 curved outline of the chalk hills has been altered and worn away 

 precisely at those points which offered the most resistance to the 

 onward flow of a body of water, this is perhaps nowhere so well 

 shown as in the valley of the Avon between the villages of Stratford 

 and Amesbury, particularly at Durnford and Heale. Here it is 

 most marked and indicates that the stream flowed in one direction 

 only. 



Of the third class or low level gravels, I shall say nothing 

 further than that up to the present time no implements, and but 

 very few organic remains have been found in them near Salisbury, 

 although a large quantity of this gravel has been dug for road 

 purposes, and most careful search has been made both by myself 

 and other geologists. On the Continent and other parts of 



