36 Charles Maclarcn, Esq., on the Existence of 



very clearly that a glacier formerly'^occupied the bottom and 

 sides of the valley in which that loch lies. The more import- 

 ant of these phenomena are, first, scratches and groovings on 

 the rocks, exactly such as glaciers produce on the bottom 

 and sides of the valleys containing them, and which no other 

 natural agent is known to produce, unless it be the iceberg, 

 which, in many cases, is merely a detached portion of a glacier 

 set afloat ; second, large fragments of rocks scattered over the 

 surface, such as glaciers which have receded or disappeared 

 leave behind them ; third, a bank of gravel and clay crossing 

 the loch at its lower end, and resembling the terminal moraine 

 found at the foot of a glacier. The paper was afterwards 

 honoured with a place in the Edinburgh Philosophical Jour- 

 nal. My observations were made in the summer, and about 

 the same time Professor Forbes obtained evidence of the for- 

 mer existence of glaciers in the Isle of Skye. A second visit 

 to Gareloch, in July last, has afforded a variety of additional 

 facts which go to support the conclusion previously come to 

 —namely, that Scotland at an ancient epoch had an arctic cli- 

 mate similar probably to that of Greenland or Labrador* I 

 shall arrange my recent observations under a few heads. 



Lateral Moraines, 

 " Moraines" are accompaniments of glaciers, composed of 

 stony matter, and afford good evidence of their former exist- 

 ence after they have disappeared. They are of two kinds, 

 " lateral" and " terminal." A lateral moraine consists of 

 fragments of rock, gravel, and soil, which, loosened by rain 

 or frost from the elevated sides of the valley, roll down, and 

 collect on the flanks of the glacier, in long lines resembling 

 terraces. If cut through by a stream, 

 the profile or cross section presents 

 this appearance r k the surface of 

 the rock, m the moraine : As the gla- 

 cier bears a part of the debris along 

 with it, the moraine increases in size 

 towards the foot of the valley, and, like the glacier, it is not 

 horizontal in the longitudinal direction, but less or more in- 

 clined. This inclined position distinguishes moraines from 



