16 The Geology of Lochrutton. 



but was actively discharging a river just previous to the 

 advent of the ice. The depth of the valley and the ex- 

 tremely hard nature of the rock bespeak a medium-sized 

 stream with great erosive power exercised during a long- 

 period of time. Such a stream could not be contained in a 

 small basin by evaporation alone, but would necessitate an 

 outlet broader and deeper than this valley. A comparison 

 with other pre-glacial river valleys proves that the great 

 amount of erosion required to excavate this deep valley 

 could only have been accomplished by a large stream ot 

 long standing and an uninterrupted fall to the sea. The only 

 spot in the whole district where such a large rock valley can 

 be found is situated underneath the Moat Farm. Along 

 both sides of this buried valley the old land surface of rock 

 dips rapidly towards a common centre. Behind the Barr 

 farmhouse the upper part of the western side of the valley 

 is just visible in scattered exposures piercing the turf. On 

 the eastern side, from the foot of the Loch to the water- 

 works, the dip of the Shealinghill rock surface is more pro- 

 nounced, and possibly the angle of inclination is greater. 

 The intervening portion has been filled in by accumulations 

 of morainic debris during the flow of the glacier along the 

 pre-existing valley. "- 



I have found other buried valleys in southern Scotland ; 

 some afford even less evidence than the above on which to 

 posit their pre-glacial origin, and yet it is held to be con- 

 clusive. In the case of Lochrutton a consideration of the 

 details that are available place the matter beyond contro- 

 versy. 



1. There are no rock exposures on the drums of the 

 Moat lands along the path of the buried valley, although 

 they are most conspicuous features on the other ridges of 

 the area. 



2. A close examination of the western shore of the Loch 

 reveals no trace of rock, but it is predominant on the eastern 

 flank and at the upper and lower ends. 



3. The lowest point available, i.e., the mouth of the 

 buried channel, stretching from the waterworks to the Barr, 

 has no rock in situ. 



