646 THE POPULAR SCIENCE MONTHLY. 



the fine lines of striation. The soft sandstones and highly-jointed 

 rocks are much less finely marked, and often show a broken and shat- 

 tered surface. 



Greenland. — To understand the appearance of Northern Europe 

 in the Ice period, we may consider the features presented by a similar 

 ice-covered country in modern times, and no country will better illus- 

 trate this phase of geological condition than Greenland. This island 

 is almost continental in its dimensions, containing not less than 750,000 

 square miles, and is all a bleak wilderness of ice and snow, save a little 

 strip extending to 74° north latitude along the western shore. 



The coasts are deeply indented with numerous bays and fiords or 

 firths, which, when traced inland, are almost invariably found to ter- 

 minate against glaciers. Thick ice frequently appears, too, crowning 

 the exposed sea-cliffs, from the edges of which it droops in thick, 

 tongue-like, and stalactitic projections, until its own weight forces it to 

 break away and topple down the precipices into the sea. The whole 

 interior seems to be buried beneath a great depth of snow and ice, 

 which loads up the valleys and wraps over the hills. The scene open- 

 ing to view in the interior is desolate in the extreme — nothing but one 

 dead, dreary expanse of white, so far as the eye can reach — no living 

 creature frequents this wilderness — neither bird, beast, nor insect. 

 The silence, deep as death, is broken only when the roaring storm 

 arises to sweep before it the pitiless, blinding snow. 



This represents perfectly the state of the northern part of our con- 

 tinent in the Ice age. We have a slight inkling of what it must have 

 been universally, from the heroic messages sent down in the winter 

 from the meteorological observatory stationed upon the summit of 

 Mount Washington. 



Some of the Greenland glaciers attain a vast size. Dr. Kane re- 

 ports the great Humboldt glacier (see Fig. 1) as sixty miles wide at its 

 termination. Its seaward face rises abruptly from the level of the 

 crater to a height of 300 feet, but it is not known how deep it may 

 extend under the sea. Another important ice-stream is the Glacier of 

 Eisblink, on the northwest part of the island. It projects seaward so 

 as to form a promontory thirteen miles in length. It comes from an 

 unknown distance in'the interior, and plunges deeply into the sea. 



Since ice is lighter than water, whenever a glacier enters the sea 

 the dense salt-water tends to buoy it up. The great tenacity of the 

 frozen mass enables it to resist the pressure for a time. By-and-by, 

 however, as the ice reaches deeper water, its cohesion is overcome, and 

 large segments are forced from its terminal part, and floated up from 

 the bed of the sea, to sail away as icebergs. The glacier evidently 

 crops under the water to considerable depths, or, so long as the force 

 of cohesion is able to resist the tendency of the salt-water to press it 

 upward. The annexed diagram will show how the ice pushes down 

 into the sea, carrying morainic materials at its base, which accumu- 



