275 
Rev. T. G. Bonney — Formation of Cirques. 
limine that I cannot admit a necessary connexion between cirques 
and glaciers, because I see no possibility of drawing any hard and 
fast line between cirques, corries, and even the ordinary bowl-shaped 
heads of valleys so common in any country wbich bas been sub- 
jected to meteoric action. The small passes into the large, the slope 
steepens into the precipice ; but rain rills before they gather into a 
streamlet, streamlets before they gather into a river, all produce 
the same result ; viz. a bowl-like excavation in the mountain-side, 
which is drained by the one outlet valley. I have even seen cirques 
on clayey banks, in miniature, with walls that might almost be 
measured by inches. Connecting links may be found, through 
corrie and cwm, between the merest bowl-like hollow on some 
down of Chalk or Oolite or even some plateau of sandy clay, and 
the gründest cirque of the Alps or Pyrenees. The differences are 
due to the nature of the materials and to other local circumstances. 
Besides the above, the following objections seem to me to make 
Mr. Helland’s liypothesis untenable. 
1. The general smoothness of the rock in the bed of cirques and 
corries. Where I have seen the live rock in the bed of a cirque or 
corrie, it is usually smooth and iceworn. Were it formed as Mr. 
Heiland supposes, it should be always rough, — pitted with the 
sockets of the extracted rocky teeth, — because it is deepened, not by 
the wearing away of prominences, but by the fracture of fragments. 
The sharp-edged blocks of which he speaks, so far as I have seen 
them, are generally loose and strewn over the basin, i.e. they have 
either fallen directly from above or been dropped by the melting 
glacier. 
2. His theory fails satisfactorily to account for the tarns in certain 
cirques when they are true rock-basins. “ It does not seem likely 
that they were mainly scooped out like the great lakes, along the 
sides of which we see groovings and roches moutonnees one beside 
the other ; for in the little lakes one often sees sharp-edged blocks 
covering the bottom. When the glaciers of the cirques filled these 
small lakes so as to leave but little water, it seems probable that the 
water thus left would freeze in winter, so that the wliole tarn 
would be frozen to the bottom, and the rocks in that way broken 
loose. Whatever may be the manner in which these blocks are 
broken out, we see that, from their Situation and form, a bursting has 
taken place in these tarns, so that they are the last works of the 
glaciers in the cirques.” I quite agree with the final clause ; but 
think that the rest — that the existence of the tarn before its basin — 
is rather like “ seeing the roads before they were made.” These tarns 
are in fact among the basins which 1 readily concede to glacier 
action, because, if a small glacier forms in a previously existing 
corrie or cirque, the descent of the ice from the steep surrounding 
slopes on to the level floor will facilitate erosion; so this is just 
where I should expect to find — and commonly do find — a basin ; 
but I have seen true cirques without tarns. The floors also of these 
basins, as stated above, where visible, are smooth and iceworn. 
Further, as these basins appear to be sometimes of considerable 
