514 Kirk — Paleozoic Glaciation 



in 



mer. When fresh the conglomerate as a rule is massive 

 and exceedingly hard. 



The nature of the deposit is such as to suggest a till. 

 The heterogeneous character of the bowlders, both as 

 regards size and material, and the apparent lack of strat- 

 ification in the main, point to a true till rather than a 

 submarine bed of ice-transported glaciated material. 

 Such evidence as is at hand indicates that the Heceta area 

 was very near the shore line and might easily have been 

 land while the glacial material was being deposited. 



The question of interglacial periods in the Silurian of 

 the region can not at present be discussed with any 

 degree of certainty. The finer points of stratigraphic 

 succession are not known owing to the complex structural 

 relations, the poorly shown outcrops, and the apparent 

 lateral variation in character of sediments. I believe, 

 however, that there are several distinct bodies of tillite 

 separated by marine sediments. At the old Haida vil- 

 lage of Klinkwan on the southwest coast of Prince of 

 Wales Island and a few miles north of the west shore of 

 Klakas Inlet are what I take to be beds of tillite inter- 

 bedded with Silurian graptolite shales. The same con- 

 dition obtains on the east shore of Dall Island in the 

 neighborhood of View Cove. These tillites and shales 

 I believe come above the limestone series overlying the 

 tillite on Heceta Island. On Heceta Island itself, unless 

 there has been considerable repetition by faulting, which 

 does not seem probable, two or three distinct beds of 

 tillite are indicated. 



Permian Glacial Deposits. 



In Pybus Bay, Admiralty Island, and on the Screen 

 Islands off the west shore of Etolin Island are conglom- 

 erates strongly suggesting glacial material. In both 

 cases these overlie high Carboniferous beds which have 

 been correlated by Girty with the Gscshelian. Overlying 

 the conglomerates are Upper Triassic beds. Where seen 

 the conglomerates had not weathered down and it was not 

 possible to obtain loose bowlders which might show 

 scratches ; facetted bowlders occur in the conglomerate, 

 however. It will probably be found that this is a true 

 glacial deposit and to be correlated with the conglomerate 

 described by Cairnes near the Alaskan-Canadian boun- 

 dary. A conglomerate similar to that described above 



