70 ALASKA. 



the exceptiou of the summits of a few ciutler-hills. The supply 

 of water is abundaut aud good. The only liviug stream of 

 water ou the Seal Islands is found on Saint George, a small 

 clear brook that empties into the Garden Cove ; but the area 

 covered by fresh-water lakes on this island is very much less 

 than that of Saint Paul. 



Weathered out or washed from the basalt aud i^ockets of 

 olivine on the islands are aggregates of augite, seen most 

 abundant on the summit slopes of Ahlucheyeh Hill, Saint 

 George. Specimens from the stratified bands of old, friable, 

 gray lavas, so conspicuous on the bluffs of the north shore of 

 this island, show the existence of hornblende and vitreous feld- 

 spar in considerable quantity, while on the south shore, near 

 the Garden Cove, is a large dike of a bluish and greenish-gray 

 Ijhonolitic rock, in which numerous small crystals of spinel are 

 found. A dike with well-defined walls of old, close-grained, 

 clay-colored lava is close by the village of Saint George, about 

 a quarter of a mile east Irom the lauding, in the face of breccia 

 bluffs that rise from the sea. It is the only example of its kind 

 on these islands. 



The foundations of the islands, all of them, are basalt, some 

 compact, grayish-white,#but most of them exceedingly porous 

 and ferruginous ; and upon this solid floor are many hills of 

 brown and red basaltic tufasf cinder-heaps, &c. "Polovina 

 Sopka," the second point in elevation on Saint Paul's, (550 feet,) 

 is almost entirely built up of red scorite and breccia. The 

 bluffs at the shore, "Polovina Point," show the hard basaltic 

 underpinning upon which the hill rests. The tufas ou both 

 islands decompose and weather into fertile soil, which the 

 severe climate renders useless. There is not a trace of a granitic 

 or gneissic rock found in situ. Several metamorphic bowlders 

 have been collected, which were dropped upou the beaches by 

 ice-Hoes, brought dowu by the strong northwesters from the 

 Asiatic coast. 



The black-brown tufa and breccia bluffs at the East Laud- 

 ing, Saint Paul's Island, rise abruptly from the sea there GO to 

 80 feet, with stratified horizontal bands of a light-gray calcare- 

 ous conglomerate or cement, in which are imbedded sundry 

 fossils characteristic of the Tertiary age, such as Cardium green- 

 landicum, decor<ifuni, Astartc pcctuncida., &c. This is the only 

 locality in the Prybilov Islands where any paleontological evi- 

 dence of their age can be found. 



