28 



PROFESSOR P. F. KENDALL AND MR E. B. BAILEY 



been the corrom builder here, and as a consequence it has transferred its allegiance from 

 the southern to the northern drainage system. No valley can be more heartily 

 recommended to anyone desirous of studying corrom formation than this one, owing to 

 the number and beauty of the cones * which enter it rfrom either side. There seems 

 indeed to have been some little competition as to whether the Aikengall Burn or its 

 neighbour to the north should actually succeed in establishing the corrom of the valley ; 

 but once the former had settled this point in its favour, it made sure of its conquest by 

 attacking and partially demolishing the work of its rival. One is especially impressed, 



TTrm-rm 



C'-CORHOM W^PRE-GLAC/JL WATERSHED 

 Fig. 6. 



both here and in the case of the great Dry Burn valley (Thurston valley) further north, 

 with the probability that the main readjustments, which we can recognise to-day in the 

 glacial drainage system, were virtually completed almost as soon as the opportunity for 

 them arose through the continued retreat of the ice sheet. Thus, to judge from the 

 erosion effects, it would seem that the reversed drainage, initiated upon the corroms of 

 these two valleys, had formerly a much greater volume than at present, and one is led 

 to speculate regarding a time when the streams were apt to be swollen into mighty 

 torrents by the melting of the snows in the hill country. Although a corrom to be 

 permanent must be built of sand, gravel, or some such material, we must not neglect 

 the probability that the corroms of the glacial period may have largely resulted from 



* Pi. III. fig. l. 



