Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/196

158 158 AMUND HELLAND ON THE FJOEDS, LAKES,

the Justedalsbrroen (covering an area of about 870 square kilometres), and found it to be about 2,000,000 kilograms on a day in July. By taking account of the snow and rainfall of the above district I esti- mated that 180,000,000 kilograms of mud are carried away annually ; this quantity is equal to 6900 cubic metres of rock, or a cube whose side is 41 metres.

Extent and thickness of the Glaciers in Greenland and Norway daring the Glacial Epoch. — It is obvious that the glaciers once had a wide extension over the Outer Land of North Greenland, for roclies moutonnees, grooves, moraines, and perched blocks are seen in places far from existing glaciers. In the Outer Land of Greenland, as in Norway, the following glacial phenomena arc common : —

(1) Boulders are widely dispersed both on higher and lower levels in the two countries ; (2) The mountain-sides are grooved and polished as they now are along the glaciers in the ice-fjords ; (3) Roclies moutonnees are almost universal upon the Azoic rocks on the sides of the fjords and the islands ; (4) Moraines occur in places not now reached by glaciers ; (5) In both countries sea-banks lie before the deep fjords, representing the old moraines in front of the rock- basins of the fjord. To these we may add (as proved in the sequel) : — (6) Cirques, partly filled with glaciers, partly empty, and then covered with debris of a moraine ; (7) Lakes, fjords, and (partly) valleys, with correspondent features in both countries.

The boulders, grooves, and roclies moutonnees show the former ex- tent of the glaciers, and in some cases enable us to estimate their thickness. I will give some examples from North Greenland. On the south side of the mouth of the Jakobshavn Fjord deep grooves are conspicuous between the roclies moutonnees, which show that the glacier once filled the fjord to the mouth, was here of great thick- ness, and extended further out into Disko Bay.

Umanak Island, in the middle of the fjord of the same name, as already mentioned, rises to a height of 11G3 metres. The gneissic rocks on the side of this show groovings and are moutonnees every- where in the neighbourhood of the colony, and erratic blocks abound. Hence this fjord was also filled by an enormous glacier, from which perhaps the highest parts of the island protruded as Nunataks, In front of Umanak Fjord, near the sea, is an island called by the Danes Ubekjendt Eiland, and in front of the Waigat is the island called Hareoen. These I have not visited ; but Giesecke states in his diary* that on the former, which consists of basalt, he found boulders from the Azoic formation which he could not discover in the moun- tains. Hareoen consists of basalt, with shales and sandstones con- taining coal and fossil plants. According to M. Steenstrup it is 1800 feet high, and large erratics of gneiss are extremely abundant. These, as he informs me, occur up to the very summit of the island f. Hence Waigat Fjord was once filled with a glacier whose thickness (supposing the configuration to bo as at present) was at least equal

t "Om de kulforende Dannelser paa Oen Disko," Meddelelser fra den natur- historiske Forening, 1874.
 * Unprintccl, but preserved in the University Library at Copenhagen,