166 DESCRIPTIVE GEOLOGY. 



exposures of the underlying Tertiary are found, sufficiently show the 

 continuity of their original deposition. Their beds may be traced along the 

 line of bluffs bordering the valley of Sage Creek on the south and west. 

 Here the upper member is a hard siliceous shale, more like an older rock, 

 under which are seen the white limy sandstones; the lower beds being 

 concealed beneath debris accumulations. 



