THE RED BEDS OF COLORADO 207 



The presence of marine fossils in northern Colorado, up to within 

 roughly the last hundred feet of the Lykins series, would indicate 

 that the expresssion, "continuous land mass," is too sweeping. 

 Case's evidence, however, as to deltaic conditions in Colorado 

 accords with the writer's interpretation of the Lykins sediments. 



Conclusions. — It may now be proper to summarize briefly the 

 conclusions reached in this article. They are (i) that the Fountain 

 formation of Colorado is very largely an alluvial fan or braided- 

 river deposit; (2) that the Lyons formation of Colorado is chiefly 

 eolian under desert conditions; (3) that the Lykins formation is 

 chiefly an upper-delta deposit. 



