Glaciers and Icebergs in Scotland. 137 



loch-head are : — 1. Ben Cruachen, 25 miles NNW. as the 

 crow flies ; 2. The Muir of Rannoch, 40 miles NNE ; 3. Ben 

 Achory, near Comrie, 40 miles NE. ; 4. Balahulish, in Appin, 

 45 miles NNW. ; 5. Ben Nevis, 50 miles N. by W. ; 6. Goat- 

 fell, in Arran, 25 miles SSW. 



It seems well established by observations made in Russia, 

 Northern Germany, Denmark, England, and North America, 

 that the motion of erratic blocks has been in a southerly, a 

 south-easterly, or a south-westerly direction ; or, to speak 

 more precisely, they came from some point between the W. 

 and NE. On these grounds, we may set aside the sixth 

 locality in Arran. But if the boulders came from any spot 

 in a northerly direction, say, for instance, from Ben Cruachen, 

 the nearest, how did they travel \ Supposing a mass of ice 

 to extend from Ben Cruachen to Loch Long, it would not 

 form a glacier, but a mer de glace. If the ice moved at all, 

 it would find its easiest issue westward, and by no possibi- 

 lity could it pass the mountain barrier M K I H E, and reach 

 Gare Loch. If we suppose the boulders to come from Bala- 

 hulish, Ben Nevis, Rannoch, or Ben Achory, we only increase 

 the difficulty. 



It is clear, then, that the granite blocks did not travel from 

 their native seats on glaciers. ,We must seek some other 

 agents to convey them, and these can be no other than ice- 

 bergs ; for it is idle to speak of currents of water in a case 

 like this. Icebergs are seen in the Atlantic in hundreds, 

 generally sailing southward, and some of them bearing gravel 

 and large fragments of rock. It is thus proved that they do 

 transport stones even for hundreds of miles ; and we find 

 travelled blocks in situations which it seems impossible they 

 could reach by any other mode of conveyance. I have pointed 

 out a boulder of mica-slate in Pentland Hills,* weighing 

 eight or ten tons, which must have come from a distance of 

 fifty miles at least. It lies on a pretty steep declivity 40 feet 

 from the bottom, and about 1000 feet above the sea ; and to 

 reach the place it must have passed over extensive tracts of 

 country from 500 to 800 feet lower than the spot on which 



* Sketch of the Geology of Fife and the Lothians, p. 220. 



