778 
BULLETIN OF THE BUREAU OF FISHERIES. 
Channel as the normal seasonal sequence to the late June state of 1915, a type of 
circulation also suggested by a corresponding rise in bottom temperature on Browns 
Bank (p. 619). 
Much lower salinities, however, on the neighboring parts of Georges Bank at 
this same date 99 are equally clear evidence that no drift had taken place westward 
from the channel; nor have we ever found any indication of an overflow in that 
direction. 
It is probable that offshore water encroaches over the outer edge of Georges 
Bank to some extent during most summers, at deeper levels as well as at the surface 
(p. 771), an event made evident in 1914 by the very high salinity of the bottom water 
(34.9 per mille) on its southwest part on July 20 (fig. 142, station 10216). The 
effect of this highly saline water, however, was so closely confined to the southern 
side of the bank at the time, that a station on its northern part, only 42 miles away 
(station 10215) showed no evidence of it, the salinity not only being much lower 
(32.09 to 32.9 per mille) but the whole column much more nearly homogeneous 
Fig. 142. — Vertical distribution of salinity on the offshore banks in July, 1914. A, Browns Bank, 
July 24 (station 10228); B, northeast part of Georges Bank, July 24 (station 10226); C, eastern 
part of Georges Bank, July 23 (station 10223); and D, southwestern part of Georges Bank, July 
20 (station 10216 ) 
surface to bottom. Nor did any overflow from offshore take place farther east on 
Georges Bank in 1914 up to the last week of July (if it ever does), although water 
of 34 to 35 per mille then washed the bottom below the 100-meter contour all along 
the outer edge of the bank (stations 10217, 10219, 10221, and 10222). 
In summers when the seasonal cycle is more backward (1914 seems to have 
been rather a forward year in this respect) oceanic water may not encroach on the 
bottom on any part of Georges Bank before August and perhaps not then. In 1916, 
for example, two stations on the western and southwestern parts of the bank (10347 
and 10348) gave no evidence of any such event on July 23, the salinity being nearly 
uniform vertically at both, its value (32.4 to 32.6 per mille) no higher than the mean 
for the whole column on the northern parts of the bank at about that same date 
in 1914. 
Wide regional variations in salinity are to be expected over the broken bottom 
of Nantucket Shoals, depending on the strength and on the mixing effects of the tidal 
« Station 10223 and 10224, 32. 6 to 33. 03 per mille in 65 to 75 meters; fig. 142. 
