PIPER— FLORA OF THE STATE OF WASHINGTON. 21 



THE OLYMPIC MOUNTAINS. 



This is an almost circular group of mountains, Avhich occupies 

 much of Clallam, JeH'erson, INIason, and Chehalis counties. The 

 mountains are quite isolated. The_y consist of numerous peaks, vary- 

 ing in height from 1,800 to over 2,300 meters ((;,000 to 7,500 feet), 

 the highest being Mount Olympus, altitude '2S)'?,H uieters (8,131 feet). 

 Owing to their isolated position the drainage froui these mountains 

 is in all directions, but the largest streams flow into the Pacific Ocean. 

 Nearly all the streams head in small glaciers. 



These mountains are very difficult of exploration, and their geol- 

 ogy is l)ut little'known. The peaks consist, for the most part, at least, 

 of a laminated igneous rock which dips at a very steep angle, so that 

 the sunnnits of the ridges and peaks are often exceedingly narrow, 

 not rarely indeed being hollowed out beneath by the falling rock. 

 The age of these rocks is unknown. 



The streams have all worn very deep gorges along their courses 

 almost to the center of the mountains. This is due, perhaps, more 

 to the soft character of the rock than to the lapse of a great period of 

 time. This fact, however, renders it exceedingly difficult, and often 

 impossible, to pass from one dividing ridge to another. 



Owing to the circumstance of these mountains standing first in the 

 path of the moist Pacific Avinds the precipitation of rain and snow is 

 very great. In exceptional seasons some of the glaciers may ])e of 

 annual duration only. Such a glacier may disappear entirely by 

 the end of the summer, the snowfall of the succeeding Avinter being 

 sufficient to form it again. 



The (^lymi)ics are really a portion of the coast system of mountains, 

 isolated, owing to the fact that the portion of the system in south- 

 west Washington consists only of hills Avhich rise to little over 300 

 meters in height, through which the Chehalis Itiver forms a l)road 

 gap. The portion of the system to the northward is widely severed 

 by the Straits of Juan de Fuca. 



THE PUGET SOUND BASIN. 



This term is applied to the broad valley lying l)etween the coast 

 system of mountains and the Cascades. It has an average breadth 

 of about 80 kilometers (50 miles). Much of the central portion of the 

 basin near the head of Puget Sound is comparatively flat, and less 

 than 30 meters above sea level. Along the greater portion of the 

 Sound the shores rise abruptly, often in bluffs 30 meters high (PI. 

 Ill), thence sloping more or less gently into hills 90 to 200 meters 

 high or more. The basin proper may conveniently be limited for our 

 purpose by the 700-meter (2,300-foot) contour line. 



