252 F. C. SCHRADER — GEOLOGICAL SECTION IN NORTHERN ALASKA 



flats and bars at the coast. Inland, these abandoned flats are probably 

 underlain, in part at least, by the lower beds of the Colville series; but 

 where their edges form the banks of the river at 10 to 20 miles from the 

 coast they seem to be composed of dark muck and ground ice for a 

 depth of 10 or 15 feet below the surface. 



