Thk Geology of Lochiutton. 23 



this nioveiiK-nt. The lateral erosion is not only interest inj^, 

 hut is also of great significance. The original course of the 

 J.ade was along the face of a sloping rock surface now 

 occupied by the road. Although the banks were very much 

 higher on the left of the stream than the knolls of Shealing- 

 hill on the right, yet there has been a continuous movement 

 to the left. A section of the stream in front of Old Mill 

 Cottage shows lu)w the Lade has eroded the Moat boulder 

 ridges in its efforts to find a lower channel in the buried 

 valley. 



SliDIMKN r.\l I()\. 



This process has been continuous since the formation 

 of the Loch, and may l)c conveniently considered in two 

 distinct aspects : — 



J. The deposits now above water. 



2. Tlie accumulation of silt still under the present water 

 level, and burying the original floor of the Loch. 



These deposits are more extensive at the upper end, 

 and that portion may therefore be considered first. 



Following the plan of the old chart, we find that the 

 Merkland and the Carswadda Burns had each their own 

 outlet into the Loch previous to the em1)ankment. Around 

 the mouths of each feeder, and for a considerable distance 

 backward, there is a large expanse of Hat marsliy land com- 

 posed of black alluvium. The Hals are very extensive, 

 amounting to several acres. They show a gradual rise from 

 the lake outwards until the flowing contour of the glacial 

 deposits is reached. Around the Merkland feeder the 

 alluvium reaches nearly to Auchenfranco Farm. The line 

 of demarcation is very distinct. It shows not only the 

 relationship between the outer boulder cla\- and the younger 

 deposit of alluvium resting upon it, but also the different 

 character of the deposits. The demarcation line winds 

 sinuously round the lake head, and marks off the highest of 

 the alluvial fringe as the result of the earliest sedimentation. 

 It shows the point at which the water originally stood, and 

 is the same height as the top of the l.och banks at the 

 outlet. 



