346 UTewberry — Geology along the Northern Pacific P. P. 



It has been ascended, however, several times, and its labyrinths 

 sufficiently explored to prove that it carries from eight to 

 twelve glaciers, some of which are many miles in length and 

 will bear comparison with those of the Alps. 



Every traveler who enters Puget's Sound region from the 

 south is sure to be struck by the turbid milky appearance of 

 the water of the Cowlitz Eiver along which the railroad runs 

 for miles. This character it shares with all streams that drain 

 glaciers, and which has caused the Swiss mountaineers to give 

 to the waters of such streams the name of Qletscher Milch. Its 

 turbidity is due to the sediment produced by the constant 

 grinding action of these enormous masses of moving ice set with 

 stones upon their beds, and attests the sometimes disputed 

 efficiency of glaciers as eroding agencies. The Puyallup, White 

 Eiver, and other streams, which come down from Mt. Tacoma, 

 are alike milky, and each shows that one or more glaciers are 

 continually grinding away at its head. On the contrary, the 

 streams which do not come from glaciers and are supplied by 

 rain only, and that filter through the decaying vegetation of 

 the dense forests, carry very little sediment and that chiefly 

 carbonaceous matter. These are clear but brown, and the con- 

 trast which the water of such streams presents to that of the 

 rivers which drain the glaciers is very striking and justifies 

 the names borne by two such of Black and White Rivers. 



It has been contended by some writers, as has been mentioned, 

 that the extension of glaciers in former times was due simply 

 to an increase in the amount of precipitated moisture, but it is 

 easy to see that the heavy rain-fall of Washington Territory 

 might be increased indefinitely with no considerable elongation 

 of the glaciers. But even with the rain-fall remaining as it is, 

 if a depression of temperature should take place carrying the 

 present conditions of winter through the year, the glaciers 

 would soon creep down into their old beds, fill all the valleys 

 of their draining streams and finally coalesce to form one grand 

 glacier which would flow out through the Strait of Fuca to 

 the ocean. 



Following the coast northward from Puget's Sound we find 

 the glaciers coming down lower and lower until in Alaska they 

 reach the sea level. No one can claim that this is because the 

 precipitation is greater there, since observations show that it is 

 not, but every candid man will acknowledge that it is because 

 at the north the temperature is lower. He must also accept 

 these facts as a demonstration that a prime factor in the produc- 

 tion of the phenomena of the Ice Period was a secular depression of 

 the temperature. 



