68 FRIDTJOF NANSEN. M.-N. Kl. 
earliest, Stations and Mohn's Stations 302 and 303. The isotherm of 
o° C. obviously forms a ring outside this region as indicated in the 
map. It must be closed in the unknown region to the north; for in the 
North Polar Basin, in the western part of the Fram’s route (Stats. 19— 
26)! there were found temperatures above zero at 200 metres; and the 
cold surface water was separated from the cold bottom-water by a layer 
of water 600 metres thick, with temperatures above zero. At Kolthoff’s 
Station I (Æ I) the temperature was 102° C. at 200 metres; and at 
Mohn’s Stat. 351 a temperature of o‘1° C. was observed at 183 metres 
(100 fathoms), but, as before mentioned, Mohn’s temperatures, are liable 
to be too low for intermediate warmer layers. Along the Greenland 
coast there is another region of water with temperatures below o° C. at 
200 metres; but this is water with low salinity, from the cold surface 
layer of the Polar Current, pressed down against the coast on the right 
hand side of the Polar Current (see Sections [V—VII). Round Jan Mayen 
there is similar cold surface water with low salinity at 200 metres, which 
has been pressed down round the island. Section VII (Pl. IX) shows 
clearly that there cannot be any communication between this cold water 
and the cold bottom-water of the same depth at Amundsen’s Stations 
to the north; for the cold surface-water at 200 metres near Jan Mayen 
(Ap. II and M. S. 29) is separated from the cold bottom-water by 
several hundred metres of warmer water (see Sect. VII). To the north 
of Iceland there are similar conditions; the polar current is there blocked 
by the land, and its cold surface waters are pressed down below 200 
metres, at some places. 
The salinity at 200 metres is fairly uniform in the greater part of 
the region, generally, between 3490 and 34°95 000. But it is very 
characteristic that the salinity is on the whole lowest near the centre of 
the cold region, and there is a small area where it is even 34°88 and 
34°89 %0. In this central region the cooling has consequently been 
sufficiently great during the winter to make this water, with a some- 
what lower salinity, so heavy that it can sink down from above. 
The map shows that at 200 metres, the densities increase towards 
the central part of the region, and approach 28:10, The isopycnal of 
28:10 forms a closed curve, whose area does not coincide with that of 
the isotherm of —1° C., but is somewhat to the west of it. The isopycnal 
of 28:00 passes outside the region on both sides, east and west. 
f F. Nansen, Oceanography of N. P. Basin, p. 306. 
