BIGELOW: EXPLORATIONS OF THE COAST WATERS. 239 



that of Gulf Stream water, though the latter is encountered in full 

 purity close to the continental slope (p. 190), and that it does not 

 bring with it a tropical, or Gulf Stream plankton, but only the more 

 resistant warm-water forms, shows that it is not true Atlantic water, 

 but the mixed-water resulting from the conflict between the inner edge 

 of the Gulf Stream and the coast water, which takes place all along 

 the continental slope, from Nova Scotia to Chesapeake Bay (1915). 

 That this is the case is further supported by destiny, for mixed water, 

 being heavier (below the level of the southern rim of the Gulf), than 

 Gulf water (p. 202) would naturally flow into the basin of the Gulf 

 via the Eastern Channel, by the ordinary estuarine type of circulation, 

 and being equally heavier than Gulf Stream water at this critical level 

 (p. 202), bars the latter from reaching the Eastern Channel. This 

 influx, apparently at its height in late summer and early autumn, 

 has little effect on surface temperatures or salinities. But at, and 

 below 40 meters salinities reveal it very clearly as a tongue enter- 

 ing the Gulf through the Eastern Channel, crossing Brown's Bank 

 where it meets the south and west flowing Cabot Current, thence 

 following the eastern slope of the Gulf, to turn westward along the 

 coast of Maine, as already described (p. 96). As depth increases 

 it. more and more nearly approaches undiluted ocean water in its 

 characteristics. But the gradual decrease in its salinity from south- 

 east to northwest, even in the deepest parts of the Gulf where it 

 receives no accessions of Cabot Current water (p. 190), is evidence of 

 a constant mixture with the fresher w*ater of the Gulf. It is possible 

 that pure Gulf Stream w^ater may sporadically reach the Gulf across 

 the western end of Georges Bank, just as it approaches the land, 

 locally, and temporarily, west and south of Cape Cod (1915). But no 

 actual instances of this have yet been observed, nor do the densities 

 on the two sides, north and south, of Georges Bank, (p. 202), suggest 

 any tendency toward it, at least in summer. 



The third import source of the Gulf water is the influx from the 

 rivers which empty into it. And as I have already pointed out 

 (1914a, p. 96), this is so great in amount that it would of itself be 

 sufficient to raise the level of the Gulf about half a fathom per year, 

 were the latter an enclosed basin. Finally, the possibility of an up- 

 welling of water from the Atlantic abyss into the Gulf, must be 

 recognized, less because of any actual probability of it, than because 

 circulation of this sort has often been invoked to explain the low 

 temperature of our coast, as contrasted with Atlantic, water (1915). 



That abyssal water does not enter to any great extent into our 



