354 



L. MARTIN ALASKAN EARTHQUAKES OF 1899 



Koyukuk River. — Near latitude Q)^° north and longitude 156° 15' 

 west, in the Koyukuk Kiver, a northern tributary of the Yukon, is Treat 

 Island, 670 miles northwest of Yakutat (figure 3). Near here Messrs. 

 F. C. Schrader, T. G. Gerdine, D. C. Witherspoon, and a U. S. Geological 

 Survey party encountered water waves at 2.22 p. m., September 3, in a 

 stretch of river otherwise as calm as a mill-pond. Two of these waves 

 were 1% to 2 feet high in midstream and rose a foot or more above nor- 

 mal river level upon the banks. They moved rapidly upstream, north- 

 northwest, washing back several hundred yards on very fiat shores and 

 leaving pools and patches of water, foam, froth, sticks, and vegetable 

 rubbish. Mr. Schrader photographed the receding waves and the debris-^* 

 A shock was felt by one of the party, Mr. Baker, on shore and by natives. 

 The water waves at this great distance from the earthquake origin may be 

 ascribed to amplification of weak earth movements in the unconsolidated 

 Pleistocene silts over which the Koyukuk Kiver meanders here.-^ 



In the Lisbon earthquake of 1T55 the waters of Loch Lomond, in Scot- 

 land, at a considerably greater distance than this, were affected by water 

 waves at the proper time. 



Lower YuTi'on Hirer. — At Eussian Mission, or Ikogmute (figure 3), 

 near the lower bend of the Yukon Eiver, 730 miles northwest of Yakutat 

 and over 300 miles from the place of observation by Mr. Schrader, a 

 Eussian priest. Father N". N. Amcan, felt this shock at 2 p. m. The date 

 was not recorded by him, but it seems certain that it was the September 

 3d rather than the September 10th shock which he observed, because of 

 the time of observation. It was a heavy shock and lasted long enough 

 for one to run out of doors. The similarity of the unconsolidated Pleis- 

 tocene silts at this point to those on the Koyukuk suggest the reason for 

 sensible disturbances at this great distance from Yakutat Bay. This is 

 the most remote point from the origin at which the earthquake shocks 

 were sensible except to delicate instruments. 



Resume of September 3d earth qualce. — This earthquake is known to 

 have been felt at over thirty places (figure 3), the more remote of them as 

 much as 730 miles from Yakutat Bay. The phenomena recorded include 

 trembling of the earth, water waves, avalanches, etcetera, difficulty in 

 standing up, and nausea. It is not definitely known where the origin 

 was, but it has hitherto been assumed that it was in Yakutat Bay. The 

 fact that there was probably faulting and uplift of the coast at Yakataga, 



28 Described in discussion at Geological Society of Washington, April 25, 1906, and in 

 subsequent correspondence. 



29 See plate Ix, opposite page 448, 21st Annual Report, TJ. S. Geological Survey, part 



ii. ip.po iroo. 



