28 The Geology of Lochrutton. 



by the Tail Burn cutting its way through the tumultuous 

 mass of moraine mounds, and finally falling over the famous 

 Grey Mare's Tail. 



Conclusions. 



The springs which flow from Tarannon greywackes 

 amidst such an extensive system of rock folding are very 

 deep-seated, and may therefore be depended upon for a 

 supply when slightly inclined porous strata wdll have failed. 



If the apex of a synclinal fold is tapped by an artesian 

 well there is every prospect of a considerable addition to 

 the present supply. 



The present stream in the Merkland valley is very much 

 smaller than the original river that cut the groove ; therefore 

 the Loch is not receiving its full share of water from that 

 area. The Minnin Burn also does not give a discharge pro- 

 portionate to the valley in which it lies. 



There is comparatively little drainage received from the 

 western side of the Loch, and yet the Barr Burns on the 

 north side of the drums were supplying water during the 

 excessive drought. Another method of augmenting a storage 

 supply against a dry summer would be to utilise again the 

 Merkland basin. The material excavated from the basin 

 might be used, if found suitable, for a dam. 



If the water had been drawn from the western side of 

 the Loch very little rock excavation would have been 

 required in laying the pipes or in sinking the filter beds. 



The futility of erecting an embankment at the lake top 

 across a deposit of mud fifty feet deep is apparent. The 

 continual disappearance of the material poured in at its 

 formation needs no further explanation. The sedimentation 

 of the upper portion of the Loch is excessive. The increase 

 of silt under water is serious. The transportation of sedi- 

 ment to the lower end since the erection of the embankment 

 shows the increased projective force of the united feeders in 

 their banked condition. 



Many other deductions can be drawn from the foregoing 

 data, which come exclusively within the province of the 

 engineer, and are outside the scope of geological investiga- 



