10 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 1 28 



angulation targets of the U. S. Coast and Geodetic Survey set in 

 1945 with reference to the beach line. 



The beach is of gravel, composed of approximately 90 percent chert 

 with an admixture of igneous and sedimentary pebbles of white, red, 

 and gray sandstone, granite, and basalt, with a very small percentage 

 of limestone, derived mainly from the Brooks Range. This gravel 

 extends out to an irregular line where the water is 10 to 20 feet deep 

 and is there replaced by a silty marine clay of extremely fine grain. 

 This clay is spoken of as blue mud and extends inland under the 

 tundra at a depth averaging 40 feet. It is so sticky that an hour or 

 more is required to wash it out of a dredge. Where erosion has re- 

 moved the clay from under the tundra, the dredge often brings up 

 chunks of tundra from 50 to 75 yards from shore. 



Beyond the blue-mud zone is the rubble zone, consisting of pebbles 

 ranging from one-eighth inch or less in diameter to boulders that may 

 weigh tons. This rubble is ice-borne and is rather spotty. Sometimes 

 the dredge brings up gravel, but at others it jumps and jerks, showing 

 the presence of large boulders. Rocks 20 pounds in weight are some- 

 times brought up. The composition of the rocks is approximately the 

 same as that of the beach gravel. As one goes farther from shore the 

 boulder-strewn bottom is replaced by finer gravel and shell beds, 

 mostly Hiatella {=Saxicava). Inland there are, in the coastal plain, 

 many old beach lines, showing that the area has been uplifted and 

 depressed in relation to the sea, and tundra is sometimes encountered 

 many feet under the surface. 



ICE 



Ice exerts a great influence on the shore and bottom fauna ofif Point 

 Barrow. N. A. Transehe (1928) places the ice of the Arctic Ocean 

 in three classes: Fast ice along shore, pack ice (more or less freely 

 moving ice), and the Arctic pack. The first is 5 percent of the whole, 

 the second about 25 percent, and the Arctic pack itself constitutes 70 

 percent of the Arctic Ocean ice. 



None of this ice is stable. Papanin (1939) showed that the Arctic 

 pack moved in the direction of the Atlantic off Greenland at the rate 

 of 1,000 miles in nine months. In this pack, leads open and close or 

 freeze over and are piled into new ridges. There is, therefore, no 

 indication that any part of the Arctic ice is very old. Most of the pack 

 flowing out past Greenland is probably not more than four years old, 

 and much of it only two or three. If, as seems to be indicated, there 

 is a gyral in the Beaufort Sea, it is possible that ice may last several 



