94 ■ THE GLACIAL PHENOMENA OF THE COUNTRY 



quite dry (the Newbiggin Burn rises at its foot), and differs in 

 fact from the other slacks only in the northern slope of its 

 thalweg. 



It should be mentioned that careful examination of the 

 country in the area treated of has failed to disclose any more 

 valleys similar to those just described, though it is possible 

 that others are yet to be found. Two doubtful cases there 

 are, namely, on the Shafthoe Crags and near Wideopen, but 

 as the evidence is incomplete, it has been thought better not 

 to include them in this account. 



The phenomenon of these forsaken water-courses is by no 

 means restricted to this part of Northumberland ; they occur, 

 for example, near Alnmouth, and on Alnwick Moor, but they 

 attain their greatest development in and around the Cheviot 

 Hills. It is there they were noticed twenty years ago by 

 Clough,* and later by Gunn and Clough,| who refer to them 

 in the following words : — 



" At many places we meet with dry steep-sided little valleys 

 or denes crossing over watersheds. There is nothing to 

 suggest that they are along lines of weakness or outcrops of 

 soft beds, and it has been suggested that they may have been 

 formed by streams from glaciers." And again : " Ev,ery here 

 and there we are surprised by finding dry denes — deep-sided 

 valleys — crossing watersheds. They may possibly, in some 

 cases, coincide with the outcrop of veins or other soft beds, 

 but no such coincidences have been proved. Is it possible 

 that they were caused by glacial streams?" 



The careful examination of over twenty of these dry denes 

 has convinced me that they differ in no essentials from those 

 occurring in the country between the Tyne and the Wansbeck ; 

 they are generally deeper and longer in accordance with the 

 bigger features of the country, and their courses are often 

 complicated by branching, loop-Hke channels, the effect of 



* Mem. of Geo]. Survey, " Tlie Geology of the Cheviot Hills," p. 48 (1888). 



■'(■ Mem. of Geol. Survey, "The Geology of Part of Northumberland, including 

 the Country between Wooler and Coldstream," p. 4 (1895). 



