June, 1915. 



KNOWLEDGE. 



169 



Thus, the Alaskan earthquake of 1899 must 

 be ranked among the greatest of all recorded 

 earthquakes. 



This great earthquake, however, was not the 

 earliest of the series. So far as known, the first 

 earthquake occurred on September 3rd, at .3.3 p.m. 

 local time (or September 4th, 0.22 a.m. Greenwich 

 mean time). It was strong enough to be recorded 

 in the seismological observatories of Europe and 

 other distant places. There is some uncertainty 

 as to the seat of this earthquake, but as the coast 

 is said to have been uplifted at Yakataga, one 

 hundred miles west of Yakutat, it is possible that 

 the central region was in the neighbourhood of 

 that place. During the next week about fifty 

 slight shocks were noticed near Yakutat Bay. 

 Then, on September 1 0th, came two great earth- 

 quakes, one about 8 a.m. local time, the other and 

 greatest of all at 12.22 p.m. local time (or 9.40 p.m. 

 Greenwich mean time). On the same day about 

 Mty slighter shocks were observed. Both of the 

 great shocks originated in and near Yakutat Bay, 

 but it is probable that the uplift of the coast 

 occurred with the later of the two, as the earlier 

 one was not accompanied by any sea-wave. Severe 

 shocks also occurred on September 15th, 17th, 

 23rd, 26th, and 29th, intercalated among a large 

 number of minor shakings, to which little attention 

 was naturally paid by the inhabitants of the dis- 

 trict. At the time of the earthquakes eight persons 

 were camped along the shores of Yakutat Bay, 

 at the places indicated in Figure 151 by asterisks, 

 near the foot of Variegated Glacier. They were all 

 within a few miles of the region in which the chief 

 uplift had occurred. The great shock is said to have 

 lasted two and a half to three minutes, and, while 

 it continued, the ground waved up and down like 

 the swells of the sea, only with much more energy, 

 and then opened in long fissures. A small lake 

 behind broke from its bed and swept over the 

 camp. Shortly afterwards a seismic sea-wave, about 

 twenty feet high, swept in from the bay and 

 completed the destruction of the camps. Many 

 dead fishes, probably killed by the sudden shock 

 which they would feel all over their bodies at once, 

 were thrown up on the shore, and these supported 

 the few observers until they were able to reach the 

 village of Yakutat, about thirty miles distant. 



Changes of Elevation. 

 In most recent earthquakes which have accom- 

 panied changes of elevation the district chiefly 

 affected has been an inland one. The changes 

 observed have therefore been relative only, for the 

 trigonometrical resur\"eys which have been carried 

 out have not sufficed to determine the actual 

 movements of the ground in a vertical direction. 

 But in Alaska most of the measurements are 

 referred to the sea-level, and are therefore absolute. 

 Moreover, the coast-line in this part of the country 

 is so deeply indented by Yakutat Bay that the 

 field of observation may be regarded as areal 



rather than Ihiear. In most parts of the bay the 

 shores have been uplifted, in some depressed, while 

 in others no movement whatever could be detected. 



Figure 151. 

 Map of Yakutat Baj- and the neighbouring country. 



The form of Yakutat Bay will be seen from the 

 map in Figure 151. On the west side the bay is 

 bordered by a low foreland of glacial gravels. On 

 the east side the northern half of the bay is straight 

 and precipitous and the land behind rises abruptly 

 to heights of three or four thousand feet. Towards 

 the north, Yakutat Bay merges into a narrow arm, 

 called Disenchantment Bay, which is a true fiord 

 bounded on both sides by steep mountains. At its 

 north end the inlet turns abruptly backwards and 

 is afterwards known as Russell Fiord, the shores of 

 which are at first straight and mountainous. The 

 entire length of the inlet from the ocean to the head 

 of Russell Fiord is about seventy miles. 



To the north of Yakutat Bay the country is 

 occupied by lofty mountain ranges, those of St. 

 Elias and Fairweather, in the former of which the 

 culminating peaks rise to heights of eighteen 

 thousand and nineteen thousand five hundred 

 feet. From these mountains extensive glaciers 

 descend towards the sea, some of which, such as 

 the Galiano, Atrevida, Hubbard, Nunatak, and 

 Hidden Glaciers, will be referred to afterwards. 



Evidences of Elevation and Subsidence. — At first 

 sight the most striking evidence of the upUfts is 

 the physiographic evidence. Before the uplift there 

 had been a prolonged interval of rest, during which 

 the sea had in various places cut back chffs, 

 planed vock-benches at their feet, and deposited 



