PIPER FLORA OF THE STATE OF WASHINGTON. 21 



THE OLYMPIC MOUNTAINS. 



This is an almost circular group of mountains, which occupies 

 much of Clallam, Jefferson, Mason, and Chehalis counties. The 

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

 ing in height from 1,800 to over 2,300 meters (6,000 to 7,500 feet), 

 the highest being Mount Olympus, ialtitude 2,638 meters (8,131 feet). 

 Owing to their isolated position the drainage from 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 but 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 summits 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 fhan 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 winds the precipitation of rain and snow is 

 very great. In exceptional seasons some of the glaciers may be of 

 annual duration only. Such a glacier may disappear entirely by 

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

 sufficient to form it again. 



The Olympics 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 which rise to little over 300 

 meters in height, through which the Chehalis River forms a broad 

 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 between 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 (PL 

 III), 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 TOO-meter (2,300-foot) contour line. 



