1906. No. 3. AMUNDSEN'S OCEANOGRAPHIC OBSERVATIONS IN 1901. 107 
temperatures is several degrees down to depths of many metres) whilst 
on the much longer way from Spitsbergen to the New Siberian Islands 
the water of the same current is cooled only 2°C. at the most. 
And again, the formation of the enormous masses of ice over the 
deep North Polar Basin disengages a great quantity of heat, compared 
with which the amount of heat consumed in melting ice during the short 
summer-months is indeed very small. The observations during the 
“Fram” Expedition also prove that the heat consumed by this melting 
(which is chiefly limited to the upper surface of the ice) is derived di- 
rectly from the sun and atmosphere, and not from the underlying sea- 
water (see above p. 80). This is also to a very great extent th 
case in the East Greenland Polar Current north of Denmark Strait (cf. 
above p. 79). 
Pettersson also believes that this layer, 200 metres thick, of Polar 
water, covering the North Polar Basin (which is diluted by an intermixture 
between the water from Siberian (and American) rivers and the water carried 
into this Sea by the Atlantic Current) can only be formed by the mel- 
ting of ice, and that therefore "the fresh water from the Siberian rivers 
is converted into ice by freezing before its admixture with the Atlantic 
water”. He says that *it is necessary to admit this, because the inter- 
mingling of two water-layers of different salinity in a deep sea is an 
extremely slow process” (/oc. cit. p. 321). Under these circumstances it 
is not clear how Pettersson thinks the layers of ordinary coast-water 
along the continental coasts can be formed without any formation or 
melting of ice. If he be correct, it is to be expected that during the 
summer the river water must float on the surface along the Siberian 
coast. But at only short distances outside the mouths of the Siberian 
rivers the surface water already has salinities of 10 and 20 %. Pettersson 
apparently believes that all ice in the North Polar Basin is formed in 
the shallow sea over the continental shelves near the coasts, and is 
afterwards melted during its drift across the deep North Polar Basin. 
If so, the thickest ice-floes met with during the drift of the “Fram” 
1 If the heat required for the melting of the ice were chiefly taken from the heat of the 
warm Atlantic undercurrent, as assumed by Pettersson, it would be unlikely that this 
melting would depend to any great extent on the season. For this undercurrent has 
always very nearly the same temperature, and there could not consequently be any 
great difference in the distribution of polar ice in summer and winter; whilst in seas 
like the Kara Sea, and the shallow Siberian Sea, there could hardly ever be any ice- 
melting because there is no warm undercurrent. But nevertheless there is actually å 
very great difference in the distribution of the ice between summer and winter as 
Pettersson himself points out. 
