274 Eev. T. G. Bonney — Formation of Cirques. 
maintained. Of those which I described, some indeed look N. ; bnt 
tlie Greux de Ckamps and Fer ä Cheval have a N.W. aspect, tlie 
former perhaps rather W.N.W. ; the Cirque Am Ende der Welt looks 
S.W., and the two under the Kotkstock almost due S. I am, tkere- 
fore, disposed to regard the fact which he notices as quite indepen- 
dent of any general theory of the formation of cirques. 
He further points out that there is a connexion between the Posi- 
tion of cirques and the height of the snow-dine ; and that cirques 
and glaciers are commonly associated. Hence he concludes that the 
cirques were excavated by the glaciers, and describes the mode in 
which he conceives this to have been effected. There is, no doubt, 
some connexion between the level of the snow-line and of the bed of 
the cirque. In the Alps, however, the bed of the more important 
cirques is generally far below the former. (Professor Gastaldi’s 
Statement I think places the lower limit rather too high.) Most of 
those which I describe have their floors about 4500' to 6000' above 
the sea-level ; but I have also seen them much higher. The rela- 
tion, however, in no way militates against my view, because, when 
the walls of the cirque rise up beyond the snow-line, the conditions 
most favourable to stream erosion prevail, as a perennial supply of 
snow rests on the higher ledges and slopes ; in fact, I think it would 
be difficult for a large cirque to be formed, unless the streams were 
supplied by suow-beds. Again, as to the connexion between cirques 
and glaciers. Mr. Heiland says, “Where the mountains are higher 
and isolated glaciers are very numerous, cirques are also numerous ; 
and as isolated glaciers are kere capable of being formed and main- 
tained at an inconsiderable height ahove the sea, the cirques also 
occur at but slight elevations.” As I have just observed, proximity 
to the snow-line is uudoubtedly favourable to the formation of 
cirques, and I quite agr-ee that the above association is one of cause 
and effect, only that which Mr. Heiland deems cause I consider eflfect 
— no doubt a rather important difference. I believe that isolated 
glaciers abound where cirques abound, because a cirque with its 
sheltered recesses is peculiarly favourable to the formation of a 
glacier. This connexion seems to me no more to prove his case than 
the occurrence of a puddle in the sheltered corner of a quarry proves 
that the water excavated it. 
I proceed then to offer reasons wliy I consider Mr. Helland’s 
theory of the formation of cirques inadequate. It is tlius stated — 
“ As the temperature around the glaciers constan.tly varies about the 
freezing-point, the incessant freezing and thavving of the water in 
the cracks in the rock may split it, and the glacier may do the work 
of transportation for the fragments thusbroken loose. On examining 
the interior of an empty cirque, we observe that a bursting, not a 
scooping out of the rock has taken place.” If I understand kirn 
right ly, he regards the cirque as formed by a sort of process of per- 
petual “ tooth drawing,” — the bed or slope of the mountain beneath 
the glacier is cracked by changes of temperature, the fragments are 
caught by the superjacent ice, lifted up, perhaps wrenched out, and 
borne away. Now with regard to this theory, I must remark in 
