in the Drift of the Valley of the Avon. 



227 



since perished. Again, what more typical emblem of fragility 

 than an egg shell, still we find fragments of bird's eggs carefully 

 preserved even indicating the position in which they sank to the 

 bottom and rested for countless years, until brought to light by 

 the restless hand of science. 



Not only do the fossil remains bear witness of the manner in 

 which the clay was formed, but an examination of the mammalian 

 Fauna strongly corroborates the statement, that the climate of our 

 island then resembled that of the Arctic Regions of the present 

 day. Hence there is nothing strange or unaccountable in the pre- 

 sence of the Reindeer, Musk Ox, 1 Ringed Lemming, Marmot, the 

 Woolly-coated Mammoth and Rhinoceros, creatures all peculiarly 

 adapted for a cold climate. 



The fluviatile origin of these drift deposits and the idea of the 

 former existence of rivers of such magnitude, may appear to many 

 persons as at best, a mere speculation just within the limits of possi- 

 bility, but far too bold to admit of anything like definite proof. 

 Let us then briefly enquire how far facts accord with the proposed 

 explanation, and for the sake of convenience let us examine the 

 deposits situated between the two ranges of chalk hills, having 

 Harnham on the south, and the Devizes road on the north. 

 Between these two points the chalk valley is partially filled up with 

 various admixtures of gravel, sand, and clay ; the gravel is spread 

 over the central position ; sand and numerous small fragments of 

 rolled chalk predominate on the south, whilst the clay and brick- 

 earth is chiefly found on the north side, in some parts attaining 

 the thickness of nearly 30 feet ; an excellent section of this clay is 

 exposed in the pits worked by Mr. Harding and by Mr. Baker. 



At the present day streams flowing over soft soils (or even hard 

 rocks,) are constantly wearing away more or less, sand, mud, 

 and stones ; any cause which impedes the current, such as banks, 

 curves in the river, &c, favors the deposition of the mud, sand, 

 or those materials which are comparatively light. It is clear then 



1 The Musk Ox has not as yet been discovered at Fisherton, its presence as a 

 fossil in our Wiltshire drift, has however been elsewhere recorded by Mr. 

 Cunnington. Wilts. Mag : vol. iv. 



