THE GLACIAL GEOLOGY OF NORTHUMBERLAND 113 



and constitutes the water-parting for many of the small 

 streams which make up the Chevington Burn. 



In the smaller valleys, the drift is often disposed either in 

 long ridges rudely parallel to the trend of the valley, or 

 forms a barrier across it. In the Harehope Burn both forms 

 exist, the upper longitudinally arranged and composed chiefly 

 of local material, the lower transversely disposed and remark- 

 ably porphyritic in character. Other examples of the former 

 kind are met with in the Eglingham Burn and the Barrow 

 Burn near Wilkwood ; of the latter type, good examples occur 

 in the Lisles Burn, the Wansbeck between Angerton and 

 Bolam, the Font at Roughlees, the Edingham Burn at Windy 

 Marsh, and the Spartley Burn near Coppath. Many of the 

 drift barriers are crescentic and morainic in appearance. 

 Both forms of ridging have given rise to lakes, some of which 

 still exist, e.g. Kimmer Lough in the valley of the Eglingham 

 Burn and Harehope Lough, the latter being partly artificial. 

 In other cases the lake has drained itself, but the lake-bottom 

 and the breached barrier remain as conspicuous features. 

 Perhaps the best example of this is on the Wansbeck about 

 Angerton and Middleton ; a small lake-bottom also occurs in 

 the Priestdene Burn above Chathill, the barrier being a low 

 drift ridge connecting two outstanding kaims. The lake- 

 conditions which have left their mark in the Till valley were 

 probably produced by a combination of ice- and drift- 

 damming. 



The small lakes or loughs in the open country, with the 

 exception of those near the Roman Wall, which appear to be 

 rock-basins, are clearly drift-dammed in most, if not all cases. 

 Many are now represented by bogs or mosses, and these are 

 frequent where the kaims abound. They nestle among the 

 massed kaims, especially on Langlee Moor, or are barred by 

 drift-ridges when these lie parallel to the contours. Many 

 examples of the latter class can be seen on the western sides 

 of the Bradford kaims. 



In conclusion, the author wishes to tender his best thanks 

 to Messrs. R. C. Burton and G. Weyman for their help in 

 examining many of the deposits described in this paper. 



