ME. J. PRESTWICH ON SUBMARINE TEMPERATURES. 
637 
thermal conditions of those oceans with those of inland seas — the one so dependent on 
local climatal influences, and the other subject to influences so distant; for whereas it 
is the winter c#ld of the latitude which regulates the one, it is the cold of the polar 
winters which affects the other. Thus the temperature of from 54° to 55° F. at depths 
in the Mediterranean below the influence of the annual variations is that of the sub- 
winter months of that area, as that of 70° is for the Red Sea. But the most striking 
case is the sea of Okhotsk, where, in the parallel of Great Britain, but with a winter- 
cold under 20°, or possibly under 15° F., we have a nearly enclosed sea, of which the 
submarine temperature at 200 to 700 feet in the month of August is under 29° F., 
or nearly 2° below zero of Centigrade, the surface-temperature being 47° F. 
These questions have necessarily a very important bearing on many geological 
problems, especially those connected with climates and the distribution of species. 
For example, it is probable that the increased severity of the climate noticed within the 
historical period on the east coast of Greenland may arise from that elevation of the 
land which is shown, by the presence of raised beaches and marine remains at heights 
of from 50 to 300 feet or more on the north-western coast of Greenland 41 and amongst 
the islands of the Northern-American archipelago beyond Baffin Bay, to have taken 
place at a comparatively recent period ; for this, by lessening the width and depth of 
the many small straits opening into Baffin Bay, has thrown a larger volume of the 
polar waters into the other channels, as that between Greenland and Spitzbergen, and 
has thus had the effect of increasing and strengthening the ice-bearing current from 
the north which passes down the east coast of Greenland. The amelioration of climate 
towards the close of the Quaternary period may also have been locally greatly influenced 
by the elevation of the land and shallowing of the seas around Britain and Norway, 
by which any flow over this area of the deep polar currents has been diverted. 
The cognate questions also connected with the southward range of an Arctic fauna 
or the northward range of a tropical fauna, and, to compare the water with the land, 
the insular-like character of the fauna of inland seas (all so liable to changes with any 
alteration in the direction and volume of those deep and obscure f undercurrents to 
which we have been referring, or by their ingress into seas before closed), are of the 
highest importance in the consideration whether of the later or of the older geolo_ 
gical phenomena of the globe. They are, however, beyond the immediate range of 
this paper, which I submit as a starting-point for further research. 
To conclude, the observations recorded in these pages, after subjecting the readings 
to the necessary corrections, show : — 
1. — a. That a stratum of water at and under 35° F. extends beneath the Atlantic from 
the Arctic to the Antarctic seasj; and, as it traverses all the parallels of latitude 
* There is the same evidence of recent elevation on the coasts of Behring Strait. 
t Using the word in contradistinction to “ conspicuous ” surface-currents, such as the Gulf-stream, the 
effects of which are well known, and have so often been reasoned upon in connexion with geological phenomena. 
t This has now been more fully established by the recent expeditions of the ‘ Porcupine ’ and ‘ Challenger. 
4 q 2 
