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, altitude 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 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 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 lttle 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 (PI. 
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 700-meter (2,300-foot) contour line. 
