Plate 21 



View of mouth of Darkroom cave and adjacent wall from a photograph taken from the 

 lake edge on October 23, 1909. At a in the left upper portion we may see horizontal 

 slickensides. The fault plane, on which the cave was cut, shows a slight downthrow on 

 the right. The wall at the right shows for the greater part a surf ace produced by differential 

 solution. 



