Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/201

Rh AND CIRQUES IN NORWAY AND GREENLAND. 103

eight between north-east and south-east, one looks to south-east, and not one to south. Similarly, around the Justedalsbneen, out of forty-one cirques, twenty-five look to north, four to west, eleven to east, one to south-east, none to south.

I do not, indeed, say that no cirques in Norway look to south ; but they are very rare on the south sides of the mountains as com- pared with the north. When a valley runs from east to west, cirques very often occur on the side which faces the north, while on the other there are none. Many examples of this might be found in districts of Norway where cirques abound.

In Greenland it is hard to say whether the cirques upon the whole are chiefly found upon the north sides of the mountains, for that country has been but little explored or mapped ; still, if we look at the configuration of the land on the south side of Umanak Fjord, we see from the mountain of Kelertinguak and to the north- east a row of cirques which, as far as observed, are not to be seen on the north side of the fjord. The configuration of most of the highest mountains in Norway is due to cirques ; for their summits are often only the highest point of the crest which surrounds a cirque. The same coufiguration is observed in the high mountains of Greenland. Glittretind may be taken as an example in Norway, Kelertinguak in Greenland.

How are these remarkable semicylindrica] recesses formed? In the papers of Mr. Bonney and Professor Gastaldi we find two theories advanced. Mr. Bonney thinks the Alpine cirques have been formed by streamlets pouring down along the cirques, and gives an example of six or seven streamlets having worked out a recess only a few yards broad, yet with the form of a typical cirque. Along the fjord- sides of Norway, where rivers precipitate themselves from the mountain-wall, recesses of a form resembling that of the cirques are very often seen ; but the large typical cirques are scarcely pro- duced in this manner ; for, putting aside the fact that the part of the crest surrounding the cirque and sloping to the latter is only some metres broad, so that it cannot feed even a very small stream, there is in many cirques, as above mentioned, a lake, which cannot be formed by these streams ; for neither still water nor the running water of streams can erode lakes, and those in the cirques are evi- dently formed in the same manner as the cirques themselves.

Professor Gastaldi does not doubt that the cirques were formerly occupied by glaciers, and that glaciers are able to scoop out deep beds in soft rocks in high Alpine regions. From the above obser- vations we can get a hint of the mode in which cirques are formed. We see, first, that on the whole they are not dependent upon the nature of the rocks ; for they are found in granite, gabbro, gneiss, metamorphic schist, quartzose slates — in limestone and gypsum in the Alps, in basalt as well as in the rocks of the Azoic formation in Greenland. It is needless to remark that the above excludes the idea of cirques being old craters.

We have already pointed out their connexion with glaciers past Q. J. G. S. No. 129. m