SCIENTIFIC RESULTS 41 



tlie bathyiiietiical iVatures of the :-helvos are iiiii)()itaiit factors in the 

 track of this stream of jKick ice. Baffin Bay, a shallow elon<i-ated . 

 basin covering 650 miles of latitude, connected with the Arctic Ocean 

 by the narrow openinoj between Greenland and Ellesmere Land, and 

 in a less direct way thron<rh the maze of Arctic sounds to the west- 

 ward, is one of the chief reservoirs of the ice. Davis Strait is the 

 bottle neck tbroufrh which a o-jvat ])roi)()rti()n of the ])ack emerges 

 into the Xorth Atlantic. Another i)robable source is the reirion of 

 Hudson Strait and Fox CMiannel. 'I'be Labrador current is the 

 irreat ajrency of transportation southward alono; Labrador, past 

 Xewfoundland, and over the Grand Bank. It is the low temperature 

 I of the water over the continental shelf from Baffin Land to the 

 iGrand l^auk. ai)proximatelv 150,000 s(|uare miles, the surface layers 

 lof which, are cliilled to 0° C. {'S2° F.) or lower, that permit \he 

 isoutbward drift of the i)ack. Fhe extent of these fri<):id shelf waters 

 land of those of Baffin J^ay furnishes a clew to the aii;<.n-e<T:ate annual 

 loutput of sea ice. If two-thirds of the total 4()T.0(»() s(|uare miles of 

 Ithe ice area is normally covered to a depth of 6 feet, the eastern 

 IXorth American pack consists of approximately 450 to 475 cubic 

 Iniiles of ice yearly. (See fig. 121. p. 200.) 



I The several tributary sounds located on the western side of Baffin 

 jBay and Davis Strait contril)ute relatively great (piantities of pack 

 Ito the eastern Xorth American ice stream. During the colder 

 imonths these oj)enings su])i5ly -' ice to the southward moving 

 imasses. l)ut in summer their discliarges create areas of o})en water. 

 (These chamiels from north to south are as follows: Smith Sound, 

 Jones Sound. Lancaster Sound. Hudson Strait, and Strait of Belle 

 Isle. The sounds of Baffin Bay contribute the greatest quantities of 

 ice, wdiile the straits to the south are responsible for the greatest 

 iunoimt of dissipation and Avastage. Summermeltingisusually viewed 

 las a phenomenon spreading from south to north. Hut in case of the 

 iXorth American i)ack. account must be taken of the disrui)tive infiu- 

 'ences along its western flank. Thus the discharge from Hudson 

 Strait very much hastens the dismemberment of the pack in tliat 

 'offing. The Marion expedition in 1!)2<S had an excellent o])i)ortunity 

 jto survey the i-esults of these disintegrations. As early as June 11 the 

 fiodthaah expedition arrived and found the Avaters open off Hudson 

 Strait and the ice lying quite far back both to the north and to the 

 Uuth. Sometime shortly prior to the (lodtliaah's visit, the strong 

 Ku-rents pouring in and out of the strait had api)arently severed 

 die ice stream and isolated the large Labrador field. On August 18, 

 {ibout two months later, the Maiioii ex])editi<)n found the offing of 

 he strait still clear; and tlie Labrador field had disappeared by that 

 ime, though the southern edge of the Baffin Land pack remained 

 ibout the same as it had been a month earliei'. 



In 192s the pack around Cape Dier, Baffin Land, consisting of 

 18,000 square miles of ice, never penetrated farther south than Cum- 

 perland Gulf after June, showing that the rate of its southward 

 idvance Avas offset by the rate of melting in the sun-heated waters 

 lischarged through Hudson Strait. The isolated Labrador field of 



1 "Meckins (1906, pp. 22-31 and appended map) after consulting the accounts of the 

 larious early explorations of the American Archipelago has constructed a map showing 

 he prevailing circulation. Mecking shows that practically all of the currents flow, and 

 nerefore the ice masses move, from west to east ; that is. from the polar regions into 

 iaffln Bay and Davis Strait. 



