martin.] PETROLEUM FIELDS. 135 
The Triassic rocks occur on Cape Kekurnoi at the eastern entrance 
to Cold Bay, and on some of the capes and islands to the northeast. 
They doubtless underlie the Jurassic throughout the Cold Bay region. 
The Enochkin formation occupies both shores of Cold Ba}^ except at 
the northeastern promontory (Cape Kekurnoi) and at the head of the 
bay. It also extends in a belt along the shore of Shelikof Strait from 
Cold Bay to Dry Bay and probably as far beyond as Portage Bay. 
The Naknek formation forms the shore of the head of Cold Bay and 
occupies the entire interior region as far west as Becharof Lake and as 
far north as Katmai. 
The post-Jurassic volcanic rocks occur in a discontinuous belt near 
the center of the peninsula. This belt includes several volcanoes which 
lave been active in comparatively recent time. The lavas are probably 
ill either andesite or basalt. 
STRUCTURE. 
The most striking structural features are an anticline witli a 
northeast-southwest axis extending from a point 3i miles above the 
mouth of Oil Creek to Kanata and a syncline extending from near the 
mouth of Oil Creek northeastward into Cold Bay. The northern end 
jf this s} T ncline is cut off lyy a fault which extends up the valley of 
Dry Creek. The anticline terminates by flattening out. 
The dip is quite uniformly northwestward on the north shore of 
yold Bay and on the north side of Dry Creek. Along the south- 
eastern side of Becharof Lake it is northwestward and westward. On 
the western shore of Cold Bay it is northwestward or horizontal. On 
Dry Bay it is southeastward. The dips seldom exceed 15°, except 
toward the mouth of the bay, and are low and regular over wide 
ireas. 
The region between Becharof Lake and the Becharof-Cold Bay 
divide has a uniform westward and northwestward dip. This dip is 
reversed again near the center of the peninsula, so that part of 
Becharof Lake lies in a syncline, while near its northwestern shore a 
sharp anticline is said to rise, which brings to the surface not only the 
entire sedimentary series, but also the mass of coarse crystalline rocks 
:hat form the core of the peninsula throughout most of its length. 
There is also a great anticline parallel to the southern coast that has 
its axis near the ends of the forelands. 
INDICATIONS OF PETROLEUM. 
SEEPAGES. 
There are several seepages at the north end of the anticline near 
the oil wells. In all of these the flow of petroleum is large and con- 
stant. One of them furnishes lubricating oil for use at the wells, 
here is also a considerable flow of gas at one of these seepages. 
