Glaciers and Icebergs in Scotland. 131 



We need scarcely point out how correctly the effects of glacier 

 motion now described, apply to the marks of abrasion seen on 

 the rocks at Gare Loch, and how completely they account 

 for appearances which we are unable to explain by any other 

 means. The dressed surfaces seen in a Swiss glacier valley, 

 the rounded domes, the scratches, furrows, and grooves, re- 

 taining their parallelism to each other, and to the axes of the 

 valley, without the least regard to the natural declivities of 

 the surface — the stones thrown out by the ice, with one side 

 gmooth and striated — all have their exact counterparts at 

 Gare Loch. Let us pursue the comparison a little farther. 



Fragments of rock and gravel collect on the flanks of the 

 glacier in long lines resembling terraces, and are called late-^ 

 ral moraines. Other stones and gravel, mixed with clay, are 

 thrown out at its lower end, and extend across the valley like 

 a mound or bank with sloping sides. These, which are called 

 terminal moraines., are pushed before the glacier when it is 

 advancing, and left behind it when retiring. If, as sometimes 

 happens, a glacier continues to shrink for a period of years^ 

 a series of these transverse mounds are formed behind one 

 another ; and if it again expands, the inner ones, unless very 

 large, are pressed forward till the whole are united. In the 

 same way, a receding glacier will leave a series of lateral 

 moraines below one another on the flanking declivities ; and 

 if it recedes very gradually, and finally disappears, these may 

 be so close to one another, and so much alike, that, when 

 modified by atmospheric infl.uences for some thousand years, 

 they may lose the terraced form, and assume the appearance, 

 of an equable covering of alluvial matter. The absence of 

 terraces, therefore, does not necessarily imply the non-exist- 

 ence of moraines. It should be stated also, that where two 

 or three minor glaciers unite, the resulting compound gla- 

 cier has " medial" moraines, or trains of stones and gravel 

 on the middle as well as at the sides ; and when the ice dis- 

 appears, these are sometimes found, not in lines or ridges, 

 but irregularly difl'used over the surface of the valley. The 

 moraines transport immense masses of rock from the upper 

 extremities of valleys to the lower, frequently over a dis- 

 tance of many leagues, and which are therefore called 



