Granite Blocks from Ben Cruaehan. 363 



merly been unable to explain by what means the granite 

 blocks, supposed to have been derived from Ben Cruaehan, 

 had crossed the mountain group between Loch Fyne and Loch 

 Lomond, so as to gain access to the latter, and form a stream 

 extending to the Clyde and Glasgow. Since then, he had 

 discovered, in this very mountain group, a granitic tract, not 

 marked on the geological maps, in the immediate vicinity of 

 Loch Sloy, at a height from 1500 to 2000 feet, and agreeing 

 in mineral character with these travelled blocks, which may 

 therefore have descended Loch Long and Loch Lomond, with 

 the same facility that the granite blocks of Ben Cruaehan 

 have entered Loch Awe, and those of Loch Etive have 

 reached Oban and Kerrara. They are dispersed along the 

 sides of the valleys, to the height of 300 or 400 feet. Mr 

 Hopkins then referred to the possible causes of the disper- 

 sion of the granite blocks ; — if by ocean currents, then the 

 country must have been depressed nearly 2000 feet, as Wales 

 is believed to have been about the same period ; if transport- 

 ed by floating ice, independently of glaciers, then also the 

 country must have had a lower level: terrestrial glaciers 

 may also have been agents, if their existence was allowed. 

 The character of the blocks, — being at first large and angu- 

 lar, but becoming smaller and more rounded, — was opposed 

 to the supposition that floating ice or terrestrial glaciers 

 were the principal agents in their removal. If floating ice 

 had been the cause, then the sphere of dispersion would 

 probably, also, have been much greater. In Glen Wray he 

 had observed indications of what he had considered true mo- 

 raines. He was inclined to believe that more than one of 

 these causes had been in operation in the dispersion of these 

 blocks from their respective centres. 



On Fish Destroyed by Sulphuretted Hydrogen in the Bay of 

 Callao. By Dr J. L. Burtt, U.S.N. (Proc. Acad. Nat. 

 Sci. Philad., vi. 1.) 



One occurrence always excited much interest, whenever 

 there was an evolution of sulphohydric acid gas (a frequent 

 occurrence) from the bottom of the bay of Callao. The first 



