218 SMITH AND CURTIS — C AM ASIAN D : A VALLEY REMNANT 



tical exaggeration. Even the houses, and the roads which wind up to 

 this high valley, have been indicated on the model. 



Topography 



In its general form Camasland might be compared to a platter, bottom 

 side up, since it is a flat elliptical plain, lying within a comparatively 

 low rim, but high above the surrounding country. The level floor of 

 the basin, as can be seen in plate 20, is irregular in outline, and about 

 two miles long by one-half mile wide. The rim inclosing this plain rises 

 at one point 600 feet above the valley floor, but averages about 350 feet. 

 It stands, however, from 1,000 to 2,000 feet above the surrounding valleys. 

 A bold cliff extends with few breaks along the outer margin of this rim, 

 with steep talus slopes from the base of the escarpment to the streams in 

 the canyons below. 



The surrounding region is one of mature dissection, the valleys being 

 deep and the ridges cut to knife-edge divides, thus leaving no trace of 

 preexisting topography. The contrast, then, is marked between this 

 level valley of Camasland, with the gentle rise to the inclosing rim, and 

 the rugged country lying outside that rim. Thus Camasland is truly an 

 oasis among the rugged barren mountains. 



The valley floor, which presents an appearance of being perfectly level, 

 is, however, over 100 feet higher at the southern end than at the outlet, 

 this being a grade comparable with that of the floodplains of the larger 

 streams in the region. The outlet of Camasland is through a narrow cut 

 in the rim on the northwest side. Within this barrier, as may be seen 

 in the illustration of the model, only a tiny stream is visible, there being 

 at present a mere succession of shallow holes, or at best a small brook 

 struggling to reach the outlet. Beyond the rim Camas creek continues 

 down to Peshastin creek, its waters being materially augmented by a 

 tributary stream from the southwest. This tributary discharges a con- 

 siderably greater volume of water, but the difference in the valleys of 

 the trunk stream and of the tributary is both striking and suggestive. 

 The valley of the former is wider and its slopes are gentle, and pot-holes 

 are common along the stream channel, while the tributary flows in a 

 rugged, narrow, canyon-like valley. 



Geology 



forma tions 



Names and relations. — Three formations occur within the Camasland 

 area — sandstone, diabase, and alluvium. These are represented in the 



