Page:Popular Science Monthly Volume 79.djvu/427

This page has been proofread, but needs to be validated.
THE BERING RIVER COAL FIELD
423
Part of the Cunningham Claims. Taken from divide west of Kushtaka Glacier.
Overlooking First Berg Lake and Bering Glacier from the Green Claims.

of the formations are not well exposed, and hence the number of seams of coal is not well known. The evidence suggests more than a dozen seams, varying in thickness from 6 inches to more than 35 feet. The Tokun formation overlies the Kushtaka conformably and consists of about 2,500 feet, chiefly of sandy shales, but containing also, sandstone and a subordinate amount of limestone. All the evidence thus far found indicates that the Stillwater formation is marine, the Kushtaka, non-marine, and the Tokun marine.

The Structure of the Region

The structure of the rocks of the coal field is, in genera], monoclinal, the most prevalent strike being northeast: the dips are usually