578 



APPENDIX. 



Section in Central Washington.' 



Names of Formations. 



Thickness 

 in Feet. 



Characteristics. 



Rhyolite 



«~ Unconformity — 

 Roslyn formation. 



100-800 



3500 ± 



Compact lava and tuff. 



Massive yellow sandstone with some shale. 

 Roslyn bed of coal in upper part, and other 

 less valuable beds at other horizons. 



Teanaway basalt. 

 -^•^ Unconformity^ 

 Swauk formation. 

 -^ Unconformity ^- 



Igneous and metamor- 

 phic rocks. 



300-4000 



3500-5000 



Lava-flows with interbedded tuffs; lava 

 black and dark gray, compact or vesicular, 

 sometimes weathering brown or red. 



Conglomerate schist and quartzose sandstone 

 and shale, of light and dark colors; cut by 

 numerous dikes of diabase. 



1 Smith, G. O., Mt. Stuart folio, U. S. Geol. Surv. The section given is for the northern part 

 of the Mt. Stuart quadrangle. In its southern part, Miocene, consisting of igneous rocks, Taneum 

 and esite and Yakima basalt below, and of the Ellensburg formation above, overlie the Eocene. 



