Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/936

 fjord. In concluding what I have got to say regarding the sub- glacial rivers, I cannot help remarking that the effect of this great ice-covering over Greenland must be to thoroughly denude any soft sedimentary strata which might have reclined on the underlying igneous rocks at the time when the whole country got so over- spread. Now we know that during the later Miocene epoch the country supported a luxuriant vegetation, as evinced by the remains which I and others have collected from these beds I was struck, when studying this subject in Greenland, with the fact (though I have no desire to push the theory too far) that the only places where I did not see former ice-action were the very localities where these Miocene beds repose. These localities are a very limited district on either side of the "Waygatz Strait, on Noursoak penin- sula, and Disco Island, neither of these localities having apparently been overlain at any time by the great inland ice. Koursoak penin- sula juts out from the land, and only nourishes small glaciers of its own ; and Disco Island is high land, possessing a miniature inland ice or mer de glace, with defluent glaciers of its own. If the great inland ice had ever ground over this tract, I hardly think it possible that the soft sandstone, shales, and coal-beds could have survived the effects of this ice-file for any length of time.

5. The Moraines. — Moraines are usually classified as lateral, median, terminal, and profonde 2, or under the glacier. Prom the simple character of the Greenland glacier, as described, it will be readily seen that the median moraine, formed by the junction of two lateral moraines, must be rare, while the terminal takes, ex- cept in rare instances, another form. Ordinary alpine glaciers, when grinding down between the two sides of a monntain-gorge, get accumulated on their sides rubbish, such as earth, rocks, &c, which fall either by being undermined by the glacier, by frost, or by land-slips, until two lateral moraines are formed. If the glacier anastomoses with a second, it is evident that two of the lateral moraines will unite in the common glacier into a median one. "When the glacier terminates, this moraine carried along with it, is deposited at its base, and forms the terminal moraine. Over the lower face of a glacier, according to the heat of the day, some ma- terial is always falling, a thimbleful of sand, it may be, trickling down in the stream of water ; or a mass of stone, gravel, and earth may thunder over the edge. If the glacier advances, it pushes this moraine in front of it, or, it is possible, may creep over it and carry it on as a moraine profonde. This moraine profonde consists of the boulders, gravel, &c, which the glacier, grinding along, has carried with it, and which, adhering to its lower surface, help to grind

1 Heer, in the 'Philosophical Transactions,' 1869, pp. 445-488. In this treatise of Prof. Heer I have printed a few notes on the geology of these Mio- cene beds ; but, owing to an accident, I did not see them in proof. Hence there are several errors. The title of the paper is also apt to mislead. These geolo- gical and 'other points I hope in due course to correct in a full account of the geology of the Waygatz Straits, with illustrative sections, sketches, &c. 2 The term moraine profonde was first used by Hogard in his ' Coup d'ceil sur le terrain erraticoie des Vosges ' (1851), p. 10.