79 



by stripping the surface in prospecting, and it is possible 

 that the Cobalt series may be found to rest on a surface of a 

 different character from those at present known. 



A glacial origin was at one time suggested for certain 

 breccias or conglomerates in the Torridonian of the North- 

 western Highlands of Scotland. In the report on that 

 region, published a few years ago, this suggested theory of 

 origin has been discarded.* " From the nature of the rocks 

 it may be inferred that the conditions of deposit were prob- 

 ably those of a rapid accumulation in shallow water near a 

 shore line, subject to violent currents and the influx of flood 

 or stream-borne materials, with occasional intervals of 

 quiescence during which the finer sediments were laid 

 down. ... In one instance, on the north side of Loch 

 Maree, it has been observed that the blocks in the con- 

 glomerate have come from the hornblende-schist ridge of 

 Ben Lair, and may have travelled a distance of three 

 miles." 



That surfaces on rocks resembling closely those pro- 

 duced by glaciers can be formed by other means is shown by 

 the observations of Dr. E. O. Hovey.* In speaking of 

 the accumulation of volcanic material on the side of Mt. 

 Pelee, he says : "From time to time the coat of new material 

 became water-soaked from the heavy tropical rains and slid 

 down the mountain in more or less of a sheet avalanche. On 

 the collecting ground of the steep upper cone, planation and 

 grooving were not prominent, but on the middle ground of 

 the Morne Saint Martin, where the force ot the avalanches 

 spent itself, planation and grooving were pronounced. In 

 June, 1902, the striated surface of the old agglomerate, with 

 here and there a heap of unassorted ash upon it, suggested 

 closely the appearance of a regularly glaciated surface with 

 its overburden of till." 



Dr. Hovey says further : " Where the crevicing of the 

 rock-mass has been favorable, the impact of stones hurtling 

 down the stream bed has broken off chips from the bed 

 rock, producing a good imitation of the ' chatter ' marks 

 made by a glacier." 



*The Geological Structure of the North-West Highlands of Scotland , 

 pp. 23 and 273. Memoirs of the Geological Survey of Great Britain, 1907. 



*Striations, U-shaped vallej'S, and hanging valleys produced by other 

 than glacial action. Geol. Soc. Am., Vol. 20. 



