40 TARR AND MARTIN CHANGES OF LEVEL IN YAKUTAT REGION 



canoes can not now go, where small islands and stacks Avere formerly 

 separated from the mainland by navigable water. 



AMOUNT OF LAND ADDED BY UPLIFT 



We have no quantitative statement to make regarding the amount of 

 land added by this uplift. It is, however, very slight, considering the 

 amount of uplift. The reason for this is that the shores of the fiord in 

 the regions of marked uplift are almost everywhere steep and the water 

 deep. Consequently the new shoreline is separated from the old by a steep 

 grade, sometimes vertical or even overhanging, and rarely less than 30 

 degrees, excepting on the beaches and deltas. On the deltas and larger 

 beaches the coast has migrated seaward sometimes more than a hundred 

 yards; but such a width of new land is distinctly exceptional. An 

 attempt was made at a rough calculation of the increase in size of Haenke 

 island, where the rock slope is fairly steep, where beaches form only a 

 small percentage of the shore, and where the uplift was marked (17 to 19 

 feet). This estimate is 25 or 30 feet of new land, on the average, around 

 its entire shore. 



Biological Evidences op Uplift 



barnacles 



In most parts of the fiord barnacles are abundant on the rocky shores 

 at present sealevel; but their dead remains are also abundant on the up- 

 lifted shoreline, and very often are more abundant there than in the 

 present tidal zone. Two species (Balanus cariosus, Darwin, and Bala n us 

 porcatus, Darwin*) cling to the rocks of the elevated shoreline (see 

 plate 17, figures 1 and 2). Naturally in places of considerable uplift the 

 animals have not grown to such size since the uplift as they had developed 

 before. Among the dead barnacles great forms an inch and a half in 

 diameter are not uncommon ; but among the living forms, where the uplift 

 was considerable, three-eighths of an inch was the maximum diameter. 

 In many of the barnacles the inner valves are still held together by the 

 organic tissue, though most commonly it is only the outside shell that 

 remains intact. 



These dead barnacles were found on all the uplifted rock coasts where 

 the formation is not too fissile to retain them, and their absence was 

 decidedly exceptional in regions where other evidence suggested uplift. 

 They stand out clearly on the dry rock surface, especially under over- 

 hanging cliffs, and are so readily visible from a boat that their presence 



* We are indebted to Dr W. H. Dall for the identification of marine animals collected 

 on the elevated shoreline. 



