only from the deposits which fell 

 at distances greater than 15 miles 

 from the mountain. If streams 

 of lava flowed out, they did not 

 come within sight of the coast. 

 The deposits which were studied 

 in detail vary in thickness from 

 55 inches at the head of Amalik 

 Bay, 15^ miles from the moun- 

 tain, to 31^ inches at the east end 

 of Afognak Island, 113 miles 

 from the volcano. 



Throughout this entire district, 

 at least three layers correspond- 

 ing to the three major outbreaks 

 can be observed. The bottom 

 layer is of relatively coarse gray 

 material ; the middle layer is 

 finer and is brown, and the upper 

 layer is the finest and is light 

 gray or almost white. Each layer 

 decreases in thickness with the 

 distance from the volcano, the 

 decrease being most marked in 

 the bottom and middle layers 

 (see pages 132 and 176). 



The bottom layer consists of 

 fragments of pumice mixed with 

 a small proportion of fragments 

 of crystals of feldspars and py- 

 roxenes and other dark minerals. 

 The pumice -is consolidated lava-, 

 froth, mostly white, and varies in 

 size from pieces i or 2 ounces in 

 weight and 2 or 3 inches in long- 

 est dimension, which fell 15 miles 

 from the volcano, to material of 

 the grain of fine sand, which fell 

 70 to 100 miles away. 



The middle or brown material 

 near the base of the mountain 

 consists of several layers, which 

 differ from the lower bed in con- 

 taining a smaller proportion of 

 crystalline material and in con- 

 taining a considerable amount of 

 yellowish and brownish pumice. 

 At distances of 70 to 80 miles 

 from the mountain this material 

 consists of two brown layers, the 

 lower one of sandy grain and the 

 upper of very fine dust. At dis- 

 tances of 90 to 100 miles from 

 the mountain only a single layer 

 could be recognized, and that was 

 composed of impalpable brown 

 dust. 



166 



