138 The Glacial Theory. 



ed by glaciers. Strath Earn is flanked irregularly with 

 ridges and terraces of gravel, the detritus of moraines and 

 adjacent hills are rounded and striated. Near Comrie, Dr„ 

 Buckland tested the value of the glacial theory by marking, 

 in anticipation on a map the localities, where there ought 

 to be evidences of glaciers having existed, if the theory 

 were well founded, and the results always coincided with 

 the anticipations. Full details of the circumstances are then 

 entered into by Dr. Buckland.* Similar remains of moraines 

 have been observed at Lock Earn, Callender, Edinburgh, in 

 Cumberland and Westmoreland, at Kendal and Lancaster, 

 and the line extends to Shap Fell. 



In a report to the Geological Society of France in 1840,f 

 M. Renoir states it to be his settled conviction, that glaciers 

 of much greater extent and force than any now existing, 

 formerly occupied the vallies of the Alps down to an actual 

 elevation of little more than four hundred feet ; and that in the 

 chain of the Vosges, the culminating or highest point of which 

 is little more than that of the mountains of Scotland, the 

 effects of glaciers are equally conspicuous and characteristic. 

 The pcrtished guttered surfaces have been observed in 

 situations too numerous to detail, while the vallies are bor- 

 dered by moraines, of which the following characters are 

 given : — 



We now know, from what has been pointed out by Messrs. Venetz, 

 Charpentier, and Agassiz,^ that the marks which, glaciers leave be- 

 hind them as they retire, are, \st, Terminal moraines, composed of 

 sand, gravel, pebble, and even at times a great number of boulders, 

 the whole more or less rolled, forming banks and curved lines 

 throughout the whole width of the valley, whose concavity is turned 

 upwards, higher towards the middle than at the extremities; of 

 a triangular form, and having the exterior face generally more in- 



* X Many of the memoirs illustrative of this subject have appeared in the previous numbers 

 of the Edinburgh New Philosophical Journal, 

 t Edinburgh New Philosophical Journal, January 1841, p. 280. 



