NO, 9 MARINE INVERTEBRATES, ALASKA — MacGINITIE I3 



could often jump from shore onto a floe. Pack ice is a loose aggre- 

 gation of floes of all shapes and sizes often forming streaks of varying 

 width with open leads between. However, these leads are never free 

 from small pieces of ice, and the boat coxswain must be continually- 

 alert to avoid collisions. Among the writer's most pleasant memories 

 are days in the summer of 1948, cruising about among the ice floes 

 looking for leads of suflicient extent to allow dredging. Those days 

 were made all the more enjoyable by the companionship of the two 

 Eskimo boatmen Max Adams and Olaf Avenosook. 



In the summer of 1949 the ice went out during the night of July 19, 

 was in sight the following day, and then never came near shore again 

 that summer. No ice floes of any kind were visible until July 29, when 

 a few small floes grounded ashore and remained for a day or two. 

 After that no ice at all was seen. At different times aviators reported 

 the pack ice at distances 60 to 140 miles offshore. Since the big 

 ice did not come in during the fall, no large pressure ridge formed. By 

 inquiry from elderly Eskimos who had lived at Point Barrow all 

 their lives, it was ascertained that this phenomenon has happened 

 perhaps five times in the past 50 years, or on an average of perhaps 

 once in 10 years. 



Icebergs are formed by the breaking off of high pieces of glaciers 

 extending into the sea. The nearest glaciers to Point Barrow are to 

 the east in the Canadian Archipelago and in Greenland. In the sum- 

 mer of 1948 a large iceberg (pi. 7, figs, i, 2) grounded off Point Bar- 

 row, It was at least 25 feet high and was stratified, looking like no 

 other ice ordinarily seen at Point Barrow, It had fairly straight sides 

 and was grounded in about 200 feet of water. The dimensions were 

 about 70 by 100 feet and the top was fairly flat. This berg was viewed 

 from a PBY by Commander Paton of the U. S. Coast and Geodetic 

 Survey, Dr, Dobrin of the Naval Ordnance Laboratory, the two 

 pilots, a newspaper correspondent, and the writer. The pilot flew 

 alongside the iceberg and said his altimeter showed it to be 25 to 30 

 feet high. 



During the following winter two of these large icebergs grounded 

 about 25 miles northeast of Point Barrow base. Because of the strong 

 prevailing northeast current flowing past the Point and meeting the 

 northwest current out of the Beaufort Sea, the water is shallow for 

 miles northeast of Point Barrow, which accounts for the bergs' 

 grounding so far from shore. These icebergs undoubtedly came out 

 of the Beaufort Sea with the northwest current mentioned above. If 

 this supposition is true, it brings up problems of great interest. How 



