266 Geology and Botany of Northern Pacific Railroad. 



There are but few localities in the Puget's Sound basin where 

 the rocky substratum rises so as to be visible above the water- 

 level. Along the northern and western margin of Vancouver's, 

 Sucia, Orcas and Whidby Islands, and at Chuckernuts and So- 

 home the rock appears, but at Tacoma, Steilacom, Seattle, Port 

 Madison, Port Townsend, and it may be said generally about the 

 Sound, the shores are steep bluffs, 100 to 150 feet in height, 

 composed of drift alone. From the cliffs at Port Richmond and 

 Tacoma, I took sub-angular scratched and ice- worn pebbles, as 

 characteristic and convincing as any to be found in the boulder 

 clay of the eastern States. 



The subsidence which caused the sea-water to flow into the 

 subaerial excavated valleys of Puget's Sound, filled also the chan- 

 nel of the Columbia to the Cascades, and the system of fiords 

 that fringe the northwest coast, of which these are representa- 

 tives. 



We have evidence, too, that the area occupied by the sea was at 

 one time much more extensive than now, for all the country im- 

 mediately about Puget's Sound is marked with a series of marine 

 terraces which Mr. Bailey Willis, who studied them when con- 

 nected with the Transcontinental Survey under Prof. Pumpelly, 

 tells me can be traced to a height of 1,600 feet above the present 

 ocean level. These terraces are conspicuous on the low divide 

 which separates the valley of the Cowlitz from the basin of Pu- 

 get's Sound ; and here, as over much of this region, the ground 

 is covered with pebbles and waterworn boulders, the product of 

 the long-continued dash of the shore waves on a slope composed 

 of drift materials. In the advance and recession of the shore- 

 line, the finer materials have been mostly washed away, and the 

 stony surface has little agricultural value. Fortunately it is 

 well adapted to the growth of trees : and the splendid forest 

 which covers it is perhaps an equivalent for all it has lost. The 

 facts here given show why the cultivation of the soil in Washing- 

 ton Territory is limited to the narrow belts of modern alluvium 

 along the streams, and indicate that the fisheries, coal-mining, 

 and lumber industry must be in the future, as they are now, 

 the most important sources of wealth. 



