120 G. M. DAWSON — COASTS OF BERING SEA AND VICINITY. 



lower ridges and hills owe their present forms entirely to such action 

 The peripheral parts of the island have during the same period been 

 much reduced and cut back by the sea. 



The cliffs along the south shore and those about the middle of the 

 north shore display bedding, which in the planes of section appears nearly 

 horizontal. The individual beds are for the most part thick, and some 

 of them show a pronounced basaltic structure. 



Unalaska Island. — Respecting the island of Unalaska little can be added 

 to the notes lately brought together by Dr DalL* A good view was ob- 

 tained of that part of the north coast between Makushin and Captain's 

 bays, behind which rises Makushin volcano, the highest mountain (5,474 

 feet) on the island. The upper parts of this mountain and the high 

 ridges about it were deeply covered with snow in August, and small, 

 irregular glacier masses, more or less crevassed, were observed here and 

 there. 



Makushin is not a t5^pical volcanic cone, but an irregular, lumpy 

 mountain mass with some rather bold spurs and crests even about its 

 upper parts, which seem to evidence considerable waste by denudation 

 since the latest important eruptions. A cloud of white steam still, how- 

 ever, hangs about its summit. The natural processes of waste have not 

 acted sufficiently long upon this island to produce rounded forms or 

 light slopes. The hills are generally sharp edged, peaked and bold, but 

 often covered with herbage nearly to their tops. 



The shore-cliffs, from abreast of Makushin to Captain's harbor, show 

 horizontal or slightly inclined bedding, which is rather too fine and uni- 

 form to be explained as that of superposed lava flows. The beds ex- 

 posed probabl}^ consist of scoria or volcanic ash deposited under water- 

 Dall notes the occurrence of marine Miocene deposits in Makushin bay.f 



The slopes and hills about Captain's harbor were all closely scanned 

 for evidence of old beachlines, but none were seen. There appears to 

 have been no notable upward movement of this land since the denuda- 

 tion which produced its present form took place. The little flat about 

 the village of Unalaska is composed of gravel covered with black soil, 

 and is about twenty feet above high-water mark. Its occurrence might 

 almost be explained as a beach deposit at the present storm level, but it 

 more probably indicates a very slight rise of the land. 



Atka Island. — A call was made at Nazan bay, on the east side of Atka 

 island. This island, with others near it which were more or less imper- 

 fectly seen, appears to be practically entirely composed of volcanic rocks. 

 Some interesting notes on Atka are given by Dall in the publication 



* Op. eit., p. 242. 



t Op. eit., p. 243. In addition to tlie volcanic rocks of various kinds, Dall mentions tlie occur- 

 rence of granite or syenite [gabbro ?] in the interior of this island. Op. cit., pp. 233, 242. 



