Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/927

 single break for upwards of twelve hundred miles 1 of latitude and an average of four hundred miles of longitude, or from Cape Farewell to the upper extremity of Smith's Sound, and from the west coast of Greenland to the east coast of the same country, a stretch of ice- covered country infinitely greater than ever was demanded hypothetically by Agassiz in support of his glacier-theory.

2. The Defluents of this inland ice-field. — Are there any ranges of mountains from the slopes of which this great interior ice descends ? As I have said, we are not in a position to decide ; but the probabilities are in favour of the negative. There are no iceberg " streams" on the east coast of Greenland ; and bergs are rare off that coast. If there were many icebergs, the field of floe-ice which skirts that coast, and which has prevented exploration except in very open seasons, would soon be broken up by the force with which the bergs, breaking off from the land, would smash through the ice-field and, acting as sails, help, by the aid of the winds, as elsewhere, to sweep it away. I am therefore of opinion that the great ice-field slopes from the east to the west coast of Greenland, and that any bergs which may be seen on that coast are from local glaciers or from some unimportant defluent of the great interior ice. Nor do I think a range of mountains at all necessary for the formation of this huge mer de glace; for this is an idea wholly derived from the Alpine and other mountain-ranges where the glacier system is a petty affair compared with that of Greenland. I look upon Greenland and its interior ice-field in the light of a broad-lipped shallow vessel, but with chinks in the lips here and; here, and the glacier, like viscous matter 2 in it. As more is poured in, the viscous matter will run over the edges, naturally taking the line of the chinks as its line of outflow. The broad lips of the vessel in my homely simile are the outlying islands or " outskirts ; " the viscous matter in the vessel the inland ice, the additional matter continually being poured in in the form of the enormous snow covering, which, winter after winter, for seven or eight months in the year, falls almost continuously on it; the chinks are the fjords or valleys down which the glaciers, representing the outflowing viscous matter, empty the surplus of the vessel. In other words, the ice flows out in glaciers, overflows the land in fact, down the valleys and fjords of Greenland, by force of the superincumbent weight of snow, just as does the grain on the floor of a barn (as admirably described by Mr. Jamieson) when another sackful is emptied on the top of the mound already on the floor. " The floor is flat, and therefore does not conduct the grain in any direction ; the outward motion is due to the pressure of the particles of grain on one another ; and, given a floor of infinite extension, and a pile of sufficient amount, the mass would move out-

1 Rink, Journ. R. G. S. l. c, says 800 miles ; but throughout his valuable work he only speaks of the Danish portion of Greenland, of which it professes solely to be a description. Jamieson and other writers seem to think that it is only North Greenland that is covered. All the country, north and south, is equally swathed in ice.

2 While, for the sake of illustration, speaking of ice as ' viscous matter,' I must not be understood as giving support to the 'viscous theory' of glacier motion.