June, 1915. 



KNOWLEDGE. 



171 



preservation of the beaches, cliffs, benches, and 

 deltas in 1 905 ; the fact that in that year countless 

 barnacles and mussels were held together by 

 undecayed organic tissue ; the meagre numbers 

 and undeveloped forms of their successors in the 

 intertidal waters ; and the j'outh of the bushes 

 which have invaded the new shore-lines all point 

 to the conclusion that the uplift was accomplished a 

 few years before 1905. There is also other e\'idence 

 leading to the same result. The late Professor 

 L C. Russell visited Disenchantment Bay and 

 Russell Fiord in 1890 and 1891, and observed none 

 of the shore-lines which fourteen years later were 

 so clear. He landed with difticulty on Haenke 

 Island, where the beach has been raised nineteen 

 feet ; at the present time it is accessible in many 

 places. In 1895 the Canadian surveyors of the 

 Alaskan Boundary Commission took a number of 

 photographs in Yakutat Bay. One shows Cape 

 Enchantment as an island. In 1905 it was a 

 peninsula joined to the mainland by a bar that is 

 covered only by the highest tides. Three months 

 before the earthquake Dr. G. K. Gilbert landed 

 upon beaches which have since been raised fifteen 

 feet or more, and, though one of the chief authorities 

 on abandoned shore-Unes, saw no signs whatever 

 of the uplift. On the other hand, the Alaskan 

 natives definitely state that the uplifts occurred 

 with the earthquakes of September, 1899, and it is 

 important to notice that the questions put to them 

 did not suggest the answer. Thus, it would seem 

 almost certain that the changes of level took 

 place on September 10th, 1899, and chiefly, if 

 not entirely, with the second shock at noon, as 

 this was the only earthquake followed by seismic 

 sea-waves. 



The evidences of submergence are far less numer- 

 ous and less conspicuous than those of elevation, 

 but there can be no doubt that in small areas the 

 coast-line was depressed. In most of these trees 

 were killed by sand being piled up round their 

 bases, bj' waves washing awaj' their foundations, 

 or bv the submergence of their roots in salt water. 

 Figure 1 52 represents a portion of Khantaak Island, 

 in which spruce trees still standing erect have been 

 killed by submergence and by the partial burial of 

 the trees in beach sand. It is important to notice 

 that all the areas of submergence consist of un- 

 consolidated deposits. In some cases it is of 

 course possible that the submergence might be 

 due to a settling of the deposits during the shaking, 

 but the distribution of these areas of submergence, 

 as will be seen later, renders it probable that the 

 submergence was due to a real downward movement 

 of the crust. 



Again, there are large areas where little or no 

 change of level occurred, or where the uplift, if it 

 took place, was too small to be proved. In some 

 cases dead barnacles were seen on a stretch of 

 coast on which there were also living barnacles at 

 equal heights above the present sea-level. It is 

 possible that there may ha\"e been an nplilt of a 



foot or less, so that some barnacles were killed, while 

 others were kept alive by an occasional splash of 

 saltwater. On the map (see Figure 151) such areas 

 are considered as having undergone no movement, 

 unless there was conclusive proof of either elevation 

 or submergence. 



Amount of Elevation and Submergence. — We may 

 now turn to the measurements that were made of 

 the changes of level and their distribution along 

 the shores of Yakutat Bay and its branches. 



In the measurement of the uplift the most 

 serviceable evidence was that provided by the dead 

 barnacles. The vertical distance between the high- 

 est living barnacle and the highest dead barnacle 

 still attached to the rock was taken to measure the 

 uplift. In reality the uplift may in places have 

 been slightly greater, for the highest living barnacles 

 may have owed their preservation to occasional 

 splashes of salt water, while the highest dead 

 barnacles in 1899 may have lost their hold by 1905. 

 The effect of the double error may be to lessen the 

 actual uplift by from six to twelve inches. Four- 

 fifths of the estimates of uplift were made by 

 means of barnacles. The remainder depended on 

 the rise of mussels and other marine forms. On 

 the raised beaches measurements were made in a 

 few cases of the vertical distance between two 

 parallel lines of driftwood, but these as a rule 

 were checked by barnacle measurements in the 

 neighbourhood. 



In the case of subsidence the measurements 

 are probably less exact. They were generally 

 made on the \ertical distance between the base of 

 the lowest dead tree in place and that of the 

 highest tree or shrub which had been or was 

 being killed by the deposition of sand and gravel 

 aroimd it. 



From observations made along the coast in both 

 directions for a hundred miles or more from Yakutat 

 Bay it appears that, with two possible exceptions, 

 the changes of level were confined to Yakutat Bay 

 and its branches. The evidence, of course, is 

 practically confined to the neighbourhood of the 

 coast. With regard to the snow-covered mount- 

 ainous tract to the north we have, and can have, 

 no information whatever. 



ITie total length of the shores of Yakutat Bay 

 and its branches is about one hundred and fifty 

 miles. In 1905 more than a hundred good 

 measurements of the amount of uplift or depression 

 were made. These show that for about fifty miles 

 there was either no change or a verj' small change 

 of level. In Figure 151 these parts of the coast are 

 indicated by ciphers, measurements of elevation 

 are given in feet and inclies, while the depressed 

 portions of the coast-line are indicated h\ shading. 



A glance at this map will show how variable are 

 the changes of level both in direction and amount. 

 (i) There are considerable stretches of coast along 

 wliich changes of elevation are either negligible 

 or do not exist. Such are the west shore of 

 Yakutat Bay from a point opposite Port Latouche 



