GENERAL GEOLOGY 



33 



Both seemed as seen from the ship to be wholly vol- 

 canic, but pebbles of crystalline rocks like those found on 

 St. Lawrence Island, farther north, and on the Siberian 

 mainland were found on the beach of St. Matthew, where 

 they may possibly have been brought by the ice. 



We made landing on the northeastern side of St. Mat- 

 thew near the north end, and afterward coasted along the 



a. b 



FIG. 6. CLIFF-SECTION, NORTHEAST SIDE OF ST. MATTHEW ISLAND. 



whole length of the island. We found it, as reported by 

 Dr. Dawson, who touched at the southeast end and then 

 coasted along the shore as we did, to be made up of bald, 

 rounded hills, the residual portion of more extensive vol- 

 canic accumulations of some antiquity, but without modern 

 cinder cones (figs. 6 and 7). We landed at the prominent 

 point forming the southern border of the broad bay that 



FIG. 7. CLIFF-SECTION, ST. MATTHEW ISLAND. 

 Enlargement of a-b in fig. 6. 



sets into the middle of the island (fig. 8). Dr. Dawson 

 describes the same section as seen from his ship. 1 



As we coasted along the eastern shore of the island 

 there could be seen, extending for a long distance to the 

 south of the bluffs where we landed, a lower bed of dark 

 lava with a quite smooth upper surface. Above this lay 

 a very thick bed of a light-colored lava which seemed to 

 be the same as the light trachytic rock which made up the 



1 Geological Notes on Bering Sea, etc., Bull. Geol. Soc. Am., vol. v, p. 136. 

 1894. 



