PHYSICAL OCBANOGKAPHY OF THE GULF OF MAINE 583 



miles) and its demonstration that the latter is clearly a tonguelike intrusion from 

 oflFshore. The records are not suiEcient to outline exactly how far 7°-water then 

 penetrated the southeastern part of the gulf; but the temperatures at such of the 

 stations as lie in the course usually followed by the inflowing current (6.3° and 6.1° at 

 40 meters at stations 1028S and 10299) suggest that readings as high as 7° would 

 not have been found farther west in the basin than is outlined on the chart at any 

 time during June, 1915. Undoubtedly, however, wide fluctuations occur from year 

 to year in this respect. 



If the data for the two years 1915 and 1925 can justly be combined, as seems 

 allowable because the preceding winters were not unusually severe, sHghtly higher 

 temperatures are to be expected over the eastern and central parts of the basin 

 generally than either in the northeastern corner of the gulf (including the Bay of 

 Fundy), on the one hand (40-meter level about 4° to 5°), or off Massachusetts Bay, 

 on the other, where the Fish Hawk recorded 40-meter temperatures of 3.5° to 4.5° at 

 most of her mid June stations in 1925. A 50-meter reading of 5.18° in the southern 

 side of the basin as late as June 25, 1915 (station 10298), suggests that the 6° to 7° 

 water then takes the form of a pool, as it is shown in the chart, entirely surrounded 

 by slightly lower temperatures except for its connection with still warmer water out- 

 side the edge of the continent, via the Eastern Channel. A regional distribution of 

 temperature of this sort is interesting as evidence that the influence of the indraft 

 through the Eastern Channel may raise the 40-meter temperature of the central 

 parts of the gulf slightly higher in late June than the figure (4° to 5°) to which solar 

 warming, unassisted, would bring it by that date. 



At a depth of 100 meters (fig. 43) the isotherm for 5° shows a tendency on the 

 part of this indraft to follow the eastern slope of the basin and to eddy to the west- 

 ward around its northern side, but this drift seems not to have been active between 

 the dates covered by this cruise (June 10 to 26) because not as clearly outlined as in 

 March, 1920 (fig 13), but showing a gradation in temperature from 8° in the Eastern 

 Channel to 5 ° at the mouth of the Bay of Fundy. Had water been flowing actively 

 inward through the channel at the time, a uniformly high temperature (7° to 8°) 

 naturally would have resulted over a considerable area in the eastern side of the gulf. 

 A transition of the opposite sort along the Northern Channel, from 6 ° to 7 ° at its 

 western end to 2 ° to 3 ° at its eastern end, is evidence equally clear that no general 

 movement of the water was taking place through this trough, either westward into 

 the gulf or vice versa. 



Unfortunately, no data are available on the subsurface temperatures along the 

 seaward slope of Georges Bank for June, but our Shelburne profile for June 23, 1915 

 (fig. 41), showed the warmest (8°) bottom water separated from the edge of the bank 

 by a much cooler (about 4°) wedge at 100-120 meters, as seems always to be the case 

 to the eastward of the Eastern Channel. 



The temperature of the bottom water in the deeps of the gulf is always interest- 

 ing because of the light it throws on the inward pulses (p. 922). During the last half 

 of Jime, 1915, this was fractionally warmer than 6° in the eastern and south central 

 parts of the basin at depths greater than 175 to 185 meters (stations 10288 and 

 10298), underlying a cooler stratum (4° to 5°) at 50 to 150 meters; and although 

 no record was obtained of the bottom temperature in the western arm of the basin 



