THE RlDGWAY PAtlLf. 69 



the south, and making themselves apparent by their yellow colour, 

 by the paucity of vegetation growing upon them, and by beds of 

 samty ferruginous rock occurring amongst them. There seem to be 

 three principal beds of brown or yellow sand or sandy clay in the 

 sides of the cutting between the two tunnels, the rest of the 

 ground being occupied by stiff blue or brown clay, the distance 

 covered by the whole section being not more than 200 yards. 



Thus, starting from the Purbeck beds at the northern mouth of 

 the south tunnel, we find 



From 70 yards . . . Yellow sandy clay, forming a heavy 



soil, with willows and boggy 

 plants growing upon it. 

 70 120 ,, ... Blue clay, covered with grass and 



sedges. 



120 150 ... Yellow sand. Blue clay, covered 



with willows and brambles. Ked 

 and yellow sand, 

 150 170 ... Blue clay, with large nodular 



lumps, covered with grass. 

 170 X. tunnel ... Chalk. 



Of the three plans which illustrate this paper, two were drawn 

 by the Rev. Osmond Fisher for "Barnes' Guide to Dorchester," 

 before mentioned, whilst the coloured ground plan is copied from 

 the model which was constructed by Mr. Fisher, and is now in the 

 County Museum at Dorchester. This drawing was made for me by 

 Mr. Moule, the Curator of the Museum, to whom I owe my best 

 thanks. 



In conclusion it may be remarked that the solution offered by 

 the Rev. 0. Fisher to account for the curious position occupied by 

 the Oxford clay disclosed in these sections at the Ridgway tunnel 

 is not entirely unique. Thus Professor Ruskin, when writing on 

 the influences which have produced the present external forms of 

 the Stratified Alps of Savoy, says : " An important result of 

 denudation has been overlooked viz., when portions of a thick 

 bed have been removed, the weight of the remainder would squeeze 



