26 The Geology of Lochrutton. 



the deepest portion would lie near to the glacial drums on 

 the west side. Further up the Loch the old channel would 

 swing- more into the middle in order to meet the Auchen- 

 franco bend. North of this line of maximum depth the 

 slope under water of the eastern bank would lessen until the 

 outlet was reached. The lower western shore, on the other 

 hand, would be more or less precipitous until the first band 

 of rock was encountered near the village. The upper end 

 would from the Aery first contain a large proportion of 

 boulder clay washed in from the moraines around. The 

 original maximum depth might be approximated by 

 measuring the angle of inclination formed by the sloping 

 sides of the old Merkland valley. This would give the depth 

 of the apex ; and with an allowance for the fall of the river 

 from that point an indication of the depth of the channel 

 would be given. 



Old Chart. 



In 1880 a series of soundings of the Loch were taken. 

 The results thus obtained show that at that date the amount 

 of sedimentation resting on the old bottom was very great. 

 The whole of the upper end was considerably filled in. It 

 was four hundreds yards from the top of the Loch before 

 24 feet of water was found. This increased gradually 

 until j)2 feet was reached between Dution's Cairn and the 

 Lake dwelling. About fifty yards south of the Cairn the 

 greatest depth was found to be 52 feet 6 inches. Along 

 line No. 15, near the mouth of the Minnin Burn, there Mas 

 a 12 feet platform stretching out three hundred yards. From 

 that point there was a steep gi'adient. Eighty yards further 

 out the depth had fallen to 36 feet— 1 in 10. 



This deepest point was exactly midway between the 

 mouth of the Minnin Burn and the opposite shore. Sound- 

 ings not over 12 feet included the whole of the Loch north- 

 east of the islands, except a narrow strip running from the 

 Cairn towards the village. The chart shows very clearly 

 the trend of the old valley making for the north-west shore. 



Soundings were taken again in 1887 'dong the longitu- 

 dinal line No. I, and the transverse line No. 15, and doMn 



