SCIENTIFIC RESULTS 195 



Mcteiistic leads along tlie shore line with which visitors to the Arctic 

 J! re familial-. The heat cansing the melting comes from the sun 

 above and not from warm ocean currents beneath.*' 



Observations also show that the upper '20 to 40 meters of the water 

 column in sub-Arctic seas at the end of summer is relatively warm 

 and fresh; actually it is heated thaw water. (Helland-Hansen- 

 Koefoed. 1900. Pl.'LXVI: and Smith lO-JG. [). 3.) This top film 

 rests on a shar})ly contrasting icy substratum whicli in reality is a 

 relic of the previous winter's chilling. The l)()un(h»ry suiface 

 spreads out more or less horizontally at 20 to 40 meters; the German 

 so-called sprungschicht, or discontinuity layer, represents the limit 

 to which the summer heat has been directly carried down by mixing 

 by the waves, etc. Proof that this icy underwater is reminiscent 

 of winter cooling and is not produced by the ice is shown during 

 summer by po.-^ition of the upper surface of the cold bottom layers, 

 it lying below the deepest draft of the ice, while the latter is 

 actually melting. 



Any ocean in vertical cross section i)resents no homogenous basin 

 content but is composed of a great number of horizontal layers, the 

 thinne><t and lightest floating on the top and the thickest and 

 heaviest resting on the bottom.'^* The most ])ronounced stratifica- 

 tion of the oceans in high latitudes is generally over the slopes of 

 the basin and near the shore where the density gradient above the 

 " sprungschicht '' in the upper 100 meters becomes aln'upt in suin- 

 mer. The stable arrangement of the water particles under such 

 conditions resist any force that may tend to cause a vertical ex- 

 change between two different layers, for which reason both the latent 

 heat of melting and the direct chilling effect of melting ice are pre- 

 vented from proceeding to any appreciable depth. The thaw water 

 both of land and of sea ice is mucli lighter than the upper 20 to 25 

 meters in which the ice floated before it thawed, therefore, the thaw 

 water remains to mix with surface layers. ^^ 



As ])roof that the effect of ice melting does not extend to any 

 appreciable depth in the ocean, the reader is referred to a series of 

 records of temperature ami .salinity obtained February 28, 1921, 

 within a few hours of each other at two stations on the Grand Bank, 

 respectively about 60 and about 120 miles southeast of Cape Race, 

 Newfoundland. (Smith 1922. p. 64). Conditions at these two sta- 

 tions normally differ little from each other but on the morning in 

 question there was open water at station 141 while station 142 lay 

 just within the edge of an ice field that extended northward as far 



*'■ Helland-Hansen-Koefoed (1909. PI. L-VI), by means of deep-sea thermometers seri- 

 ally spaced at various uoints in the east Greenland current, recorded the temperatures of 

 the pools of warm surface formed In summer araonsst the ice cakes and also the rate at 

 which the solar radiation penetrated downward from the surface. Malmjiren (1928, 

 p. 14). from the Maud, within the Arctic Ocean pack, observed the suni nielring the surface 

 ice. while on the underside of the cover new ice was making. The thaw water with a high 

 freezing point, it is claimed, runs down from the top of the ice cover, but freezes upon 

 encountering the sea water with its normal summer temperature of about —1.6° C In this 

 manner a considerable part of the top cover of the ice is transported as an increment to the 

 underside. 



^ Defant (1929, p. 13) has emphasized the stability of the layers in the water nrasses of 

 the oceans. 



8»Pettersson (1883. p. 252) was apijarently of the same opinion. He wrote. " that part 

 of the ice which melts in the Arctic Sea leaves the water in a condition little favorable for 

 immediate diffusion. The density of the ice water at the melting point being inferior to 

 that of salt water beneath the ice, the melting process will tend to produce a thin super- 

 ficial .stratum of fresh water." 



