Southeastern Washington and Adjacent Idaho. n 



tion of the basalt is correspondingly of a smaller degree, the rock 

 often crops out upon the surface. Such rocky lands are known 

 locally as scab-lands. They often occupy what appear to be for- 

 mer river valleys, although they are now dry or contain only small 

 streams or small groups of lakes. These valleys may be of con- 

 siderable extent; the local names, "Eight-mile Flat," "Twelve- 

 mile Flat," etc., indicate their size. 



Owing to the porous nature of the basalt, as well as to sheets 

 of clay, sand, and gravel interspersed between the successive 

 layers, springs are numerous throughout the region. Oftentimes, 

 wells dug merely into the soil afford a good supply of water, 

 although they are usually drilled into the basalt (8). In other 

 cases, as at Pullman, an abundant supply of fine artesian water 

 is obtained from beds of sand and gravel between the layers of 

 basalt. 



Standing above the surrounding plateau are numerous isolated 

 buttes and several ranges of low mountains. These are the tops 

 of lofty mountains not overwhelmed by the flood of basalt. 

 Among the former, Steptoe Butte, a perfectly conical peak with 

 an altitude of 3,613 feet, is a landmark to be seen for miles. 

 Likewise, Kamiak Mountain, running from east to west for a 

 distance of over two miles, and reaching an altitude somewhat 

 greater than Steptoe Butte, is equally prominent. In some cases, 

 only a few acres of the tops of buried mountains show them- 

 selves above the basalt. Such a butte may be seen just west of 

 Bald Butte, the culmination of a ridge of quartzite running out 

 southwestward from Thatuna Hills. Tekoa Mountains, near 

 Tekoa, Washington, are a low, outlying ridge of the Bitterroot 

 system. They reach a height of 4,000 feet. Gold Hill, not far 

 from Potlatch, Idaho, is the highest point (about 4,500 feet) of 

 another group, while Cedar Mountain (4,950 feet), northwest of 

 the Clearwater River in Idaho, is the highest point of a consider- 

 able range known as Thatuna Hills. These buttes and mountains 

 are very old geologically as compared with the basalt, and are 

 well eroded and mostly forest-covered. Southeastward their 

 streams empty into the Clearwater River. Elsewhere they are 



1 1 



