182 PROCEEDINGS OF THE GEOLOGICAL SOCIETT. [Jan. 11, 



way. Some of these mounds (especially those near the Corbie Loch) 

 are certainly of a moraine-like character ; but in general they con- 

 sist of pebbly shingle and small gravel, like what mere watery action 

 would produce ; and this is the character of those large mounds near 

 the coast, which I have already mentioned. 



Fig. 6. — Section at Belhelvie. 



Sea. 



1 



1. Boulder-earth (inserted on the authoritj^ of Dr. Fleming). 



2. Fine laminated clay and sand, containing remains of Arctic shells. 



3. Gravel. 



The moraine -character is much more strikingly displayed in the 

 heaps of boulders and rough stony debris which cover the hills of 

 '^ig^ — a set of low eminences running out to the coast immediately 

 to the south of Aberdeen, and reaching an elevation of from 200 to 

 300 feet above the sea. These mounds of rough stony rubbish may 

 be well seen beside a small lake called the Loch of Loirston, a little 

 westward of the first railway-station to the south of Aberdeen, 

 called the Cove. A good section of them is exposed at the mud- 

 cliflt' facing the Bay of Nigg, where they are seen to rest directly 

 upon the hard grey boulder-earth. The position and general cha- 

 racter of these piles of stony rubbish at Nigg and Loirston would be 

 explained by supposing them to be the moraine of a glacier filling 

 the valley of the Dee ; and I do not see how else they can be ac- 

 coimted for. 



The foregoing observations will serve to show that these gravel- 

 beds form a subject of much interest and difficulty, and one that 

 wiU require a great deal of careful study before we can understand 

 it thoroughly. Cases may have occurred of glacier-lakes bursting 

 among the mountains, and sending a sudden deluge down the val- 

 leys, as sometimes occurs in the Alps and Himalaya at the present 

 day. The letting off of the Glen Eoy lakes, for example (if they were 

 of this nature, as I believe them to have been), might have produced 

 a considerable effect. The lowering of the water from the highest 

 to the middle line, and from that to the lowest, would set free a 

 large body of water into the valley of the Spey, while the final exit 

 of the contents both of Loch Roy and Loch Gluoy would have been 

 by the Caledonian Canal valley. Query, had this anything to do 

 with the gravel-beds near Inverness, or with those in Strathspey ? 



In whatever way we are to account for the valley-gravel, it can 

 be shown to be posterior to the laminated marine clay containing 

 Arctic shells, both by the tests of superposition and of included frag- 

 ments. It therefore represents a decided change of conditions fol- 



