bordering the Northern Pacific Railroad. 343 



ocean when it stood at a lower level. "Whether the change in 

 the relative level of land and sea here remarked was part of a 

 general movement which produced the influx of the sea into 

 the fiords which fringe the northwest coast; and whether this 

 is not a part of a still grander movement that flooded the old 

 excavated valleys of the James River, the Potomac, the Schuyl- 

 kill, the Hudson, the St. Lawrence and the Saguenay and at the 

 same time filled the fiords of the northeastern coast, are ques- 

 tions which cannot now be fully answered but are *worth con- 

 sidering. 



It will be noticed that the general plan of the topography of 

 this part of the coast is altogether similar to that of California ; 

 namely, the great wall of the Cascades bordered on the east by 

 the Willamette and Cowlitz valleys, and the Coast Mountains 

 along the sea shore, are reproduced farther south by the Sierra 

 Nevada, the great California valley and the Coast Ranges. 

 And these features are not only physically similar, but geologi- 

 cally identical; the Cascades being the northern continuation 

 of the Sierra Nevada, the more modern Coast Mountains being 

 continuous, the great trough between them essentially one, but, 

 filled at its center by a mass of mountains. 



SURFACE GEOLOGY OF THE PUGET'S SOUND BASIN. 



The name Puget's Sound is made in popular use to cover all 

 the peculiar group of inlets and tideways which lie immediate- 

 ly east of Vancouver's Island, — Puget's Sound proper, Admi- 

 ralty Inlet, Hood's Canal, etc. These occupy the northern ex- 

 tension of the great Columbian valley, which, like its counter- 

 part in California, lies between the Coast ranges and the Cordil- 

 leras. Farther north still this depression is deflected toward 

 the northwest by a change in the trend of the Cascade Mountains 

 and the representatives of the coast ranges on Vancouver's 

 Island. 



In Washington Territory the Coast Mountains are higher 

 than in Oregon and have received the local name of the Olym- 

 pian range, of which the highest summit is called Mt. Olympus. 

 This range terminates somewhat abruptly but is apparently 

 continued in the mountains of Vancouver's Island. Through 

 the gap between these and the Olympian range a deep channel 

 is cut, now an arm of the sea, called the Strait of Juan de 

 Fuca. In former times, when this portion of the continent, 

 and probably the whole northwest coast, stood higher above the 

 sea, this Strait was the valley of a great river which drained 

 most of the western slope of the Cascades in Washington Terri- 

 tory, and had as branches the Skagit, Snoqualme, Dwamish, 

 Puyallup, Nisqually and various minor streams. During the 

 Ice period this hydrographic basin was filled with a great gla- 

 cier made up of contributions from all the surrounding moun- 



