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them, could not have been excavated by glaciers. In the above- 
named paper he had brought forward reasons for maintaining 
that cirques were excavated by numerous rather small strearns, 
acting on rocks, suitably stratified, whose cormposition and ar- 
rangement admitted of considerable meteoric erosion, This 
cirque in Skye, a double one, viz. €-shaped, had its cliffs seamed. 
by the tracks of numerous streamlets, each with its little talus 
of débris resting on sloping glacier-worn rocks below. He held, 
therefore, that this cirque had been brought to its present state 
by the action of strearlets, fed by rains; and had to a large 
extent been pre-glacial, seeing that the floor was ice-worn, Its 
configuration forbade him to attribute it to a glacier, unless this 
agent could be invested with a power of eroding vertically. 
Mr O. Fisuer said the author had shewn the glacier erosion 
theory would not hold, but he thought that vertical cliffs must 
necessarily be formed by being attacked from the bottom, and 
that streams pouring down from above would have a tendency 
to produce a talus and so to mask rather than to form a cliff. 
He called attention to the action of the sea as evidenced in the 
Alps. 
Professor Mitter mentioned an instance shewing how slight 
the excavating power of water often was: at Bamberg, veins of 
quartz in a rock scarped some 800 years ago, and since then 
weathered, now protrude only from 4 to } an inch. 
Professor Liveine thought that streams could only cut away 
the bottom of a talus, when they were shot out by an overlying 
sheet of ice. 
Mr Bonney, in reply, thought it possible that in many cases 
there had been a pre-existing favourable configuration of the 
ground, but how that was produced there was now nothing left 
to tell. He said that streams in flood could move débris from 
slopes or taluses where they had deposited it when at their 
usual volume; that it was impossible to lay down a general rule 
as to either the rate of erosion at any place—(he had no faith 
