BIGELOW: COAST WATER EXPLORATION OF 1913. 165 



The bottom temperature was higher south than north of Delaware 

 Bay, and instead of being coldest over the mid-zone of the continental 

 shelf, decreased from the shore seaward, with increasing depth. 



Temperature profiles. The lines were planned to afford three com- 

 plete profiles across the continental shelf, one abreast of Montauk, 

 one off Barnegat, and one opposite the mouth of Chesapeake Bay 

 respectively, besides several incomplete ones in intermediate posi- 

 tions, and a complete profile from the deep basin of the Gulf of 

 Maine to the Gulf Stream via Georges and Nantucket Shoals. The 

 latter (Fig. 9) shows that there was a marked temperature contrast 

 between the waters on either side of the Shoals which form the 

 southern boundary of the basin of the Gulf. On the north, the deep 

 basin, below twenty-five fathoms, was filled with water of 42° or 

 colder, with a rapid rise in the upper twenty fathoms to the surface 

 temperature of 62°-63°. On the southern side, the coldest water was 

 about 47°, at sixty fathoms, while the surface temperature was some 

 6° warmer at the off shore end of the profile (Station 10061) than in 

 the Gulf (68°). Over the Shoals in the centre of the profile there 

 are local regions of complete vertical mixing by the tidal currents, 

 as for instance on the southwest side of George's Bank (Station 10059) 

 where the temperature was practically uniform from surface to bot- 

 tom (54.7°). On outer edge of the continental shelf the coldest water 

 (47.3°) was not on the bottom, but at fifty fathoms, with warmer 

 water (51.5°) below it. And as Gulf Stream water was to be expected 

 only a few miles further off shore, it is fair to assume that this water 

 colder than 50° indented the warmer ocean water like a tongue, as 

 represented by the curve for 50°. The fact that there was no water 

 on this line colder than 47° shows that the cold bottom water (45°) 

 west of Nantucket Shoals (Fig. 10) was not continuous with the still 

 colder water of the Gulf of Maine. 



The next profile (Fig. 11), running from the neighborhood of 

 New York to the 500 fathom curve in Lat. 39° 55', shows the cold 

 water on the shelf at 20^0 fathoms, indenting into the warmer water 

 over the slope. The temperature was much higher, depth for depth, 

 outside the edge of the shelf, than over the latter, as is shown by the 

 sharp seaward dip of all the curves. And at the shore end of the 

 profile the same was the case, the curves rising as the land is ap- 

 proached, with equal temperatures about five fathoms nearer the 

 surface at Station 10067 than at Station 10066. In the central part 

 of the profile (Station 10065 to 10066) there was little horizontal 

 change in temperature from east to west. 



