BIOLOGICAL STUDY OF CHESAPEAKE BAY WATERS 
279 
miles, varying from 5 to 20 nautical miles in width, and covering an area of approxi- 
mately 2,800 square miles. i 2 
Sounds, small bays, and many small inlets make the outline very irregular. 
Several moderate-sized rivers empty their waters into the bay. On the west shore, 
beginning at the head of the estuary, are the Susquehanna, Patapsco, Severn, Patux- 
ent, Potomac, Rappahannock, York, and James Rivers; on the eastern shore the Elk, 
Sassafras, Chester, Choptank, Nanticoke, and Pocomoke Rivers are the most impor- 
tant ones. The Susquehanna and Potomac, which are the largest, and the rest of the 
rivers of the western shore supply by far the greater bulk of the fresh water emptied 
into the bay. 
While Chesapeake Bay extends almost directly north and south, its mouth faces 
the east. Cape Charles and Cape Henry, which guard the entrance to the north and 
south, respectively, are about 10 nautical miles apart, a distance which is considerably 
less than the average width of the southern part of the bay. This narrowed condition, 
together with the occurrence of a tidal delta cut by channels running parallel with the 
current, have an effect on the velocity of the current through the mouth. 
Chesapeake Bay is rather shallow, and there is not a great deal of difference between 
the upper and lower parts of the bay. Thirty or forty feet is about the average for 
deep water. Here and there, especially along the eastern shore, there are very deep 
holes: 150 feet off Kent Island, 114 feet off Poplar Island, 118 feet off Tilghman Island, 
114 feet off Taylors Island, 156 feet off Barren Island, 134 feet off Hooper Island, 122 
feet off Point No Point, 139 feet off Smiths Point, and 150 feet off Cape Charles City. 
All of these are close to the eastern shore except the one off Smiths Point, which is 
near to the western shore, and those off Taylors Island and Point No Point which are 
in the middle of the bay. 
The deep holes along the eastern shore are connected with one another by regions 
of greater depth than the average of the bay, so that there is a natural deep channel 
hugging the eastern shore more or less closely and extending from the head of the 
bay to Point No Point, from which region it crosses over toward the western shore, 
becoming lost near Rappahannock Spit (Windmill Point). The deep water then 
continues nearer the eastern shore almost to Cape Charles. (See fig. 1 and Coast 
and Geodetic Survey charts, Nos. 77 and 78.) 
These deep holes are of special interest on account of their permanence, their 
comparatively rich and unusual invertebrate fauna, and their relation to fishing 
grounds. It is at the bottom of the deep-water channel that the most saline and 
densest water is found. Similar deep pools are known in England — for example, the 
Sloyne in the Mersey River, Lune Deeps in the Irish Sea, and Lynn Well in the Wash. 
Wheeler (1893) has pointed out that these deeps are permanent because equilibrium 
of erosion has been attained, and filling up is prevented by the action of the tides 
combined with the production of eddies. Most of the deep holes of the Chesapeake 
are located close to the same shore as the submerged “deeps” of the Susquehanna 
River, studied by Mathews (1917). 
Geologists have generally agreed that Chesapeake Bay, in part at least, is a 
submerged river (McGee, 1888, Lindenkohl, 1891) and that the deep-water channel 
under consideration is the old bed of the Susquehanna River before the subsidence 
of the coastal plain. Probably, then, the deep channel was established in geological 
i This area has been computed for this survey by the U. S. Coast and Geodetic Survey, and it includes, in addition to Chesa- 
peake Bay proper, Mobjack Bay, Pocomoke Sound, Tangier Sound, Kedges, Holland, and Hopper Straits, Fishing Bay, Honga 
Eiver, Eastern Bay, Herring Bay, and the entrance to the Choptank River. 
