PHYSICAL OCEANOGRAPHY OF THE GULF OF MAINE 
837 
the case, for were Georges and Browns Banks subject to frequent overflows by the 
high temperatures of the so-called “Gulf Stream” sufficient in amount to dominate 
the column from surface to bottom, existence on the Banks would become impos- 
sible for cod, haddock, halibut, and, in fact, for the whole category of boreal fishes. 
Under exceptional conditions departures from the normal temperatures and 
salinities along the zone of contact of the banks and tropic waters may allow the 
latter to reach the Gulf of Maine as a surface drift if driven by southerly winds. 
An overflow of this sort was, in fact, reported by Capt. E. Kinney of the S. S. 
Prince Arthur, who observed unusually blue water with gulf weed and a tempera- 
ture of 20° C. (68° F.) in the center of the gulf, latitude 42° 43' N., longitude 69° 
13' W., on July 14, 1911, preceded for several days by a strong current toward the 
northwest in its western side (U. S. Hydrographic Office pilot chart for January, 
1913). However, no events of this sort have come under our observation, so they 
must be exceptional, for their effects on the salinity of the gulf and on its plankton 
would be unmistakable. 
It may be definitely asserted, therefore, that tropic water from outside the con- 
tinental edge seldom affects the temperature or salinity of the gulf except as one of 
the constituents of the water that flows in through the Eastern Channel. 
It is one of the most interesting oceanographic features of the Gulf of Maine 
that the latter is so little subject to tropic influences, either in the physical character 
of its waters or in its fauna or flora, when tropic water lies so close at hand. 
COASTAL WATER FROM THE WEST 
The possibility that the coastal water overflows around Cape Cod from the 
west in any considerable volume, and so into the Gulf of Maine, seems extremely 
remote. On the contrary, all the evidence of current-meter measurements, drift- 
bottle experiments, distribution of temperatures and salinities (see especially p. 974), 
and geographic distribution of the fauna (bottom as well as planktonic) points to 
just the reverse movement — i. e., out of the gulf in this side. The evidence that the 
dominant drift past Cape Cod, and so around or over Nantucket Shoals, is out of 
the Gulf of Maine, not into the latter, is conclusive. 
RIVER WATER 
In addition to the superficial ocean currents just discussed, which bring water 
to the Gulf of Maine, its tributary rivers discharge a volume of fresh water so large 
that it must be taken into consideration in any study of the salinity or circulation 
of the gulf. 
Unfortunately, the annual combined discharge of the several river systems can 
not yet be stated, much less the contribution made by the numerous minor streams 
that empty into the gulf, for most of the flow measurements made by the United 
States Geological Survey within recent years (see especially Porter, 1899; Pressey, 
1902; and Barrows, 1907 and 1907a) have been for localities far upstream. The 
published data for the Kennebec at Waterville, Me., and for the Merrimac at 
Lawrence, Mass., are perhaps the most instructive in the present connection. These 
8951—28 54 
