854 
BULLETIN OF THE BUREAU OF FISHERIES 
The distribution of density must, in fact, strongly resist any force, such as 
offshore winds driving the surface water out to sea, which would tend to draw abyssal 
water upward over the continental slope abreast the Gulf of Maine; for in every 
case we have found a decidedly stable state of equilibrium prevailing there. In fact, 
most of our cross sections of the outer part of the continental shelf abreast the gulf 
and to the eastward show a general dynamic tendency of quite a different sort — 
namely, one leading to the development of a drift of the inner slope water toward 
the west (p. 847), while a counter drift of the outer slope water (or “inner edge of the 
Gulf Stream”) toward the east has often been recorded. 
In short, continued observation has not adduced any evidence that water from 
the ocean deeps ever wells far enough up the continental slope to reach the Eastern 
Channel, much less to overflow the offshore rim of the gulf. 
This conclusion does not imply that upwelling may not take place over the 
lower part of the continental slope from the Atlantic abyss. On the contrary, much 
evidence has accumulated to the effect that some such process is of wide occurrence 
along the lower part of the slope, below, say, the 500 to 1,000 meter level, westward 
and southward from Georges Bank. Perhaps the clearest evidence of this is afforded 
by a profile run from Chesapeake Bay to Bermuda by the Bache in January and 
February, 1914, when the uniform abyssal water (about 4° in temperature and 34.9 
to 35 per mille in salinity) was banked up against the slope to within 1,100 to 1,200 
meters (Bigelow, 1917a, ngs. 11 and 12). This also appears on a profile run by the 
Dana from Bermuda to Norfolk, Va.,in May, 1922 (Nielsen, 1925, fig. 4). But no direct 
evidence has yet come to hand that water from this deep source ever reaches the con- 
tinental shelf of eastern North America in volume sufficient to affect the temperature 
or salinity of the coast waters. 49 
In denying the occurrence of abyssal upwelling as a cause of low temperature 
in the Gulf of Maine, I do not refer to upwelling from shallow water along shore — 
a common event, which often exerts an immediate effect on the temperature and 
salinity of the surface water in the vicinity in spring and summer, as described in an 
earlier chapter (p. 550). 
RECAPITULATION 
The Gulf of Maine incloses a sector of the typical coastwise water of the north- 
western Atlantic, receiving its most important accessions periodically from the 
following sources: Slope water of high salinity (close to 35 per mille) and close to 6°-8° 
in temperature flows intermittently into the gulf as a bottom current, as it does 
also into the Gulf of St. Lawrence and into other smaller depressions on the conti- 
nental shelf. There is strong evidence that the slope water that reaches the Gulf 
of Maine has its source along the Nova Scotian slope to the eastward. The cold Nova 
Scotian current brings a large volume of water of low salinity into the gulf from 
the eastward, past Cape Sable, in spring, as a surface drift; but this current slackens 
or ceases altogether at other times of year. The gulf also receives a surface drift 
from the offing of Cape Sable, into the composition of which cold banks water from the 
east, slope water from the Scotian eddy, and tropic water all enter in proportions 
that can not yet be stated. 
18 For further discussion of this subject as it concerns the Gulf of Maine, see Bigelow, 1915, p. 255, and 1917, p. 239. 
