ANTICLINAL MOUNTAIN RIDGES 171 



into the basalt plateau it is monoclinal in part, but there it is 

 hardly a distinct ridge, becoming such only as it assumes an 

 anticlinal structure. In the vicinity of Yakima river, where the 

 descriptions quoted above apply, this anticlinal structure is pro- 

 nounced, and on the edge of Selah gap the anticline is seen to 

 be flat-crested with steep sides. For two miles west of Yakima 

 river the south side of the fold — erroneously termed the east 

 side in the last quotation — is cut away by Naches river, while 

 similar cliffs have been produced east of Selah gap on both sides 

 of the ridge by meanders of Yakima river. That these steep 

 escarpments in no wise indicate faulting seems evident by the 

 presence of efificient agents in these rivers at the base of the 

 cliffs, but is demonstrated by the presence of a remnant of the 

 southern limb of the fold south of Naches river. Here the 

 Ellensburg sandstone occurs with a steep dip to the south, just 

 where this portion of the anticline should be found, while east of 

 Selah gap, immediately beyond Yakima river, the fold is also 

 perfectly preserved. The presence of the Wenas basalt inter- 

 bedded with the sandstone makes it possible to work out the 

 structure with considerable certainty. As regards the "cross- 

 break running north and south," this appears to be explained as 

 a slight sag or fold, the anticline pitching differently on the two 

 sides of Selah gap. In brief, then, the assumption that this 

 ridge is due in any degree "to the tilting of a block of the 

 earth's crust capped with basalt along lines of fracture" seems 

 unwarranted by observed facts. The anticlinal structure is 

 plainly exhibited, and in this respect the ridge is no "exception 

 to other similar uplifts in the same region." 



The ridge next to be treated is Cleman mountain, an uplift 

 which, like those described above, crosses the Yakima, but is 

 most prominent ten to fifteen miles farther west. This has been 

 described as follows : '^ 



The Naches, for a score of miles at least above the mouth of Tiaton 

 creek, flows through a deep canyon, bounded on the east by the precipitous 

 face of a long, uplifted mountain mass having the topographic form of a great 

 fault scarp, in which the inclination of the strata is northeastward. The 



^ Bull. No. 108, p. 65. 



