26 
petroleum of pacific coast of Alaska. 
Lbull. 250. 
surmise, and the aid ordinarily derived from well records is not yet 
sufficient in this field to show conclusively the relation in depth 
between the occurrence of the oil and the structure and stratigraphy 
of the containing series. The structure of the field is complex, but 
if drillings are made after a careful consideration of all geologic 
details the existence of valuable oil areas may perhaps soon be proved 
and their definition safely suggested. 
CAPE YAKTAG PETROLEUM FIELD. 
Cape Yaktag is situated about 75 miles east of Controller Bay. 
The shore line is here straight, and there is no harbor which affords 
shelter for any kind of boat. (See fig. 1.) A strip of land from 5 to 
Geological section 
on Johnston Creek 
Cape Yaktag 
Fig. 1. — Sketch map of Cape Yaktag petroleum field. 
10 miles in width lies between the coast and Bering Glacier. The ice 
front is marked by a line of hills which are parallel to the coast 
and from which a steep slope descends to the sea. This slope is 
drained by many short parallel streams, some of which head in the 
ice. The Cape Yaktag oil field extends eastward for about 25 miles 
from the mouth of Yaktag Eiver, which is the easternmost of the 
longer streams reaching the ocean near Cape Yaktag (fig. 1). 
Geology. — The writer was not able to visit this region, so that the 
following observations are based upon the statements of others : The 
structure, it is said, is anticlinal, with the axis parallel to and very 
near the shore line. The dip on the southern flank of the fold is very 
steep, the rocks standing vertical along the beach. The dip on the 
northern side in much gentler, seldom exceeding 20°. This continues 
inland as far as the region has been explored. The rocks consist of 
shales with interbedded sandstone and limestone, the whole resem- 
bling very closely in lithologic character some of the rocks of the Con- 
troller Bay oil field. They here carry fossils which show them to be 
of Miocene age, A list of these fossils was published by Mr. J. E. 
Spurr." The structure of the region is very uniform, and no marked 
variations from the strike and dip recorded above were noticed. 
a Spurr, J. E., A reconnaissance in southwestern Alaska in 1898 : Twentieth Ann. 
Kept. U. S. Geol. Survey, pt. 7, 1000, p. '2CA. 
