POSTGLACIAL, &c. t DEPOSITS OF CONTINENT. 497 



glacial climate. The beds referred to consist of banks of shelly 

 sand and gravel, but in many places they are made up almost 

 exclusively of shells, and principally of those of the common 

 mussel. They were first noticed during the Swedish Expedition 

 of 1861 by Malmgren and Torell, who detected the mussel-beds 

 in Hinlopen Strait, on the north coast of Spitzbergen, and by 

 Blomstrand, who found them at Advent Bay, in Ice Sound ; and 

 this latter locality was minutely examined by Nordenskiold and 

 Malmgren in 1868. The beds run up to a height of 200 feet 

 above the sea, and in some places are overlaid by a thickness of 

 eight and twelve feet of peat. They have yielded nine species 

 of molluscs, of which two, Cy^rina islandica and Littorina litorea, 

 no longer live in the Spitzbergen seas. The former of these is 

 found living off the coast of Greenland, but the latter does not 

 now come so far north. The common mussel is also a native 

 of the Greenland waters, but it seems doubtful if it is at present 

 living in the seas of Spitzbergen. Agardh, indeed, found a few 

 adhering to some algae on the coast of the island, but it has 

 never again been met with by the Swedish naturalists, although 

 carefully sought for. Even although a few individuals should 

 still denizen these icy waters, yet the contrast between the 

 present rarity of the species and its former great abundance 

 is sufficiently striking. All the other shells met with in the 

 mussel-beds are common arctic species living in the neighbouring 

 seas. Associated with them are considerable quantities of algae 

 and other plants, amongst which Fucus canaliculatus is common, 

 although it no longer occurs so far north. Heer mentions also 

 the occurrence of Dryas integrifolia, Betula nana, and Salix 

 retusa, but I am assured by Mr. Nathorst, who has made a 

 special study of the arctic flora, and who himself has visited 

 Spitzbergen, that the plants referred to by Heer are a form of 

 Dryas octopetal-a and Salix joolaris. 



Of course there is not the slightest doubt that these deposits 

 are of postglacial age. The Spitzbergen fiords during the 

 Glacial Period were filled with glacier-ice, which covered all the 

 low grounds, and the postglacial beds repose upon ice-worn 



2 K 



