HYDROGRAPHY OF THE MARINE WATERS 



25 



MOUNT 0E5ERT ROCK -H 



PORTLAND 

 BOSTON 

 POLLUCK RIP 

 NANTUCKET 



BRENTON REEF 

 FIRE ISLAND 



-S 

 -S 

 -S 

 -S 



-5 

 -S 



FIVE-FATHOM BANK -S 

 WINTER QUARTER -S 



CHESAPEAKE 



-S 



DIAMOND SHOAL -S 



CAPE LOOKOUT 5H0ALS-S 



FRYING PAN SHOALS -S 



RATTLESNAKE SHOAL- S 



ST. JOHNS RIVER 



FOWEY ROCKS 

 SOMBRERO KEY 

 DRY TORTUGAS 



Fig. 8. Average annual surface temperature cycle in shallow water (averaging about 8 

 fathoms) according to records for 1Q28-30. The annual course of an isotherm may be read from 

 left to right. On the left are the lightship "S" and lighthouse "H" stations, from which the 

 records were taken. On the right are coastWise distances in hundreds of miles. Modified from 

 Parr (1933)- 



throughout the year close to the shoreline along the Atlantic Coast. In the 

 warmer months, as can be seen by reading from the bottom to the top of the 

 graph over the month of August for example, rather uniform temperatures 

 prevail from southern Florida to Cape Hatteras (Diamond Shoal). North of 

 Hatteras there is a moderate gradient of decreasing temperatures but no 

 temperature discontinuity or barrier short of the cold area around Nantucket 

 and south of Cape Cod. Later in the fall a temperature discontinuity appears 

 in the form of warm water in the Hatteras region (read Figure 8 for the 

 month of February for example) and this remains till spring. This is ob- 

 viously due to the Gulf Stream System, which is within a few miles of the 



