['K'KLIMIXARY CHAITKR. . 7 



thawing, also exerted a powerful influence in tearing loose 

 stones from the neighboring banks and piling them into 

 long heaps and gravel beds. In some of the lakes in Xorth- 

 western Iowa the frost power is producing wonderful phe- 

 nomena, giving rise to the popular error of walled lakes. 



Thus it will be seen that the tirst and greatest of the 

 drift forces was the glacier ; then the floating iceberg and 

 ice field produced their results, carrying the large boulders 

 from place to place, and dropping them over the ice cold 

 seas : and last, the wave and current forces of water, after 

 the ice had in part, or altogether melted, left the loose 

 clays, sands and subsoils, substantially as we find them now. 



Arctic travelers have made us somewhat familiar with 

 the desolations and savage beauty of the Xorth polar re- 

 gions home of the icebergs, land of the glaciers, and realm 

 of enduring frost. The phenomena there witnessed at the 

 present day are exactly similar to the ancient forces acting 

 over these prairies, as 1 have above attempted to describe 

 them, except in so far as they were modified by the leveler 

 nature of this country as compared with snow-bound, 

 ice-locked Greenland. 



The icebergs rise cathedral and sphinx-like from the 

 bosom of the fiords and inland sea-:, making an ice forest 

 in places over the watery wastes. They impinge upon each 

 other with the crash of parks of artillery, and float away oil 

 gulf streams and melt in warmer latitudes, strewing the 

 floor of the ocean with their adhering earth and stones. 

 The bla/e of the arctic summer sun lights them up into 

 brilliant colors. Peaks of flame, columns of emerald, sap- 

 phire and blue, move slowly over the green waters, and 

 the play of prismatic colors is indeed beautiful in all the 

 reflected and refracted changes of the bergs. Glaciers are 

 creeping slowly down from the neighboring mountains : 

 fed at their upper ends with perpetual snows : their lower 

 ends constantly breaking off in the waters, and sending 



