Dec., 1918] Are the Ten Thousand Smokes Real Volcanoes? 109 



FUMAROLES EMERGING FROM SANDSTONE STRATA. 



Finally, far down toward the end of the Valley, we found a 

 considerable area from which this tuff had been removed by 

 erosion. In the bluffs of tuff still standing along the edges of 

 this bare area, we found some sections where the whole length 

 of the throat of a burned out fumarole had been exposed. 



Photograph by J. W. Shipley 



A NEARER VIEW OF A LINE OF FUMAROLES. 



There is no surface indication of fracture. They probably spring from a deep- 

 seated fissure. 



These conduits ran clear down through the tuff to the bed rock 

 beneath. (See page 110). At another place, we found a deposit 

 on the surface of the bed rock which looked like that from an 

 old fumarole, having apparently been formed by continued 

 action of the fumarole after the erosion of the overlying tuff. 

 We were not, however, satisfied with such evidence of burned 

 out fumaroles, for there is always the possibility of misinterpret- 



