626 



/ HARLEN BRETZ 



pointed loessial hills, surrounded by the scarred and channeled 

 basalt scablands, without seeing in them the result of a powerful 

 eroding agent which attacked them about their bases and most 

 effectively from the scabland's up-gradient direction. 



DETAILS OF A SCABLAND SURFACE 



All scablands are channeled to a greater or lesser extent. These 

 channels are eroded in basalt to depths varying from a few feet to 



Fig. 4. — Devils Canyon at mid-length, looking south. A double fall existed here 

 when the canyon was eroded. The island and the eastern part still remain. 



hundreds of feet. Commonly there are many shallow channels on 

 each tract. Most tracts also have a few deeper channels, of the 

 proportions of canyons' (Figs. 4 and 5). All channels in a tract 

 are intricately interlaced, resulting in a multitude of butte- 

 like hills, knobs, and ridges among them. Few channels have 



'Upper Grand Coulee (1,000 feet deep). Lower Moses Coulee (900 feet deep), 

 Devils Canyon, Franklin County (500 feet deep), and Palouse Canyon (500 feet deep) 

 are the most noteworthy examples. 



