138 G. M. DAWSON COASTS OF BERING SEA AND VICINITY. 



this island, probably near this place, and particularly notes the abun- 

 dance of jasper and chalcedony.^ 



Pinnacle island was so named by Cook in 1778. It is a narrow crest 

 of jagged rocks, apparently about a mile in length and lying north and 

 south. On some charts its height is given at 900 feet, and its higher 

 parts ma}^ reach this elevation, but as its form is very imperfectly shown 

 on the charts no accuracy can be attached to the height stated. It pre- 

 sents a series of vertical and sometimes overhanging cliffs to the sea on 

 both sides, gashed by transverse breaks into a series of narrow peaks and 

 pinnacles. In many places the sea washes the base of sheer cliffs which 

 often show low caves along the water line. Elsewhere rough narrow 

 beaches permit a landing to be made in calm weather. 



Myriads of birds find nesting places in the cliffs, Several polar bears 

 were also observed on the island, and on a low neighboring rock to the 

 southeast a considerable colony of sealions was noticed. 



Some hours were spent about the island under favorable circumstances 

 of weather on August 12, and the shore was closely followed all round 

 in the steam launch of H. M. S. Pheasant. 



The rocks are everywhere very similar to those of cape Upright, and 

 evidently belong throughout to the same old volcanic series.f Like 

 these, they are very much shattered and disturbed. Dark purplish and 

 greenish feldspathic rocks, which are often distinctly stratified or strati- 

 form and dip at various angles, are perhaps the most abundant. Some 

 beds of gray arkose material, like that of cape Upright, were also seen 

 here. These are now consolidated into, a hard rock, but occasionally 

 show very distinct stratification. Th6 granitic debris is here embedded 

 in a chloritic matrix. 



Saint Lawrence Island. 



Saint Lawrence island, the largest in Bering sea, is about 85 miles in 

 length, and is situated not far to the south of Bering strait. The western 

 end of this island was coasted from Southwest point to cape Chibukak. 

 Between Southwest point and cape Sanachno the shore is formed by 

 rugged cliffs several hundred feet in height, with some outlying rocks 

 and reefs. These cliffs are composed for the most part of a gray rock, 

 which from its massive appearance, as well as from the observations sub- 

 sequently made at cape Chibukak, is almost certainly granitic. This is 

 seen to be overlain, where higher ground approaches the shores, by hori- 



* An Account of a Geographical and Astronomical Expedition to the northern Parts of Russia. 

 London, 1802, p. 235. 



t The statement that Pinnacle island is a " volcanic chimney, still smoking " is incorrect. Bull. 

 U. S. Geol. Survey, no. 84, p. 258. 



