EXCAVATIONS AT DEWLISH. 219 



flints and ordinary chalk-flints. The trench cannot be 

 traced on the western slope of the valley, although it was 

 searched for carefully by Mr. Mansel Pleydell.* This fact 

 lends support to the view that the valley was already in 

 existence when the trench was cut, and if this were the case 

 it follows that most of the present configuration of the land 

 had also been produced at that time. The trench is 

 continuous down the eastern side and is cut in the chalk in 

 such a way that its base is roughly parallel to the surface slope. 



In the correspondence which was published in Nature 1914, 

 discussing the late Mr. Osmond Fisher's suggestion that 

 the trench had been dug as an elephant trap, Mr, MacTurk 

 called attention to the effect of cloud-bursts in the chalk 

 wolds of Yorkshire, where deep gullies or trench-like channels 

 were cut by the sudden torrential streams which rushed down 

 the sides of the dry valleys. 



Gullies similar to those mentioned by Mr. MacTurk had 

 previously been described by Mr. G. W. Lamplugh in the 

 letterpress explaining the British Association collection of 

 photographs. These gullies are at Langtoft, near Driffield, 

 Yorkshire, where torrential rains fell in July, 1892, and 

 started cascades pouring suddenly down the slopes of the 

 dale, ripping gullies through the chalk and shaken rock and 

 spreading a fan of detritus at the foot of the slope after the 

 manner of rainstorms in arid mountain lands ! The rock 

 at this locality is chalk, forming one of the streamless dales 

 characteristic of the Yorkshire Wolds, with steep sides and 

 floored with gravels of an old watercourse. 



The photograph represents a trench or gully closely com- 

 parable with the trench at Dewlish, and Mr. Lamplugh's 

 remarks as to the sudden and torrential rains, and 

 their likeness to those of arid mountain lands are instructive 

 in light of Mr. Reid's suggestion of the arid conditions in 

 which the trench was formed and the obvious influence of 

 " pluvial denudation " disclosed by the sections to be described. 



* Proceedings Dorset Field Club, X., 14. 



