THE BAHAMA ISLANDS. 215 
thirds of the whole Bahama area. Nassau, the principal sea- 
port of the group, is situated on the island of New Provi- 
dence, at the northwest angle of the second turn in the S. 
The Bahama group continues eastward, in a number of 
coral islands, to Turk’s Island, in longitude 71°-W.; but topo- 
graphically and geologically it extends two degrees farther 
west in a line of atolls and reefs to Navidad Island. The 
small map to the right on Plate XI. contains Turk’s Island 
and the reef islands east of it. Turk’s Island is situated near 
the southeast angle of Caicos Island. 
The western portion of the Bahamas is built up on the 
broad submarine plateau, five hundred to six hundred fathoms 
under water, that extends parallel with the continental coast- 
line from off North Carolina southward. The plateau in this . 
southern part has a breadth from east to west of about two 
hundred miles. More to the eastward along the Bahamas 
the water deepens, and at the same time the reef becomes 
narrower; and from the east end of the S stretches a line 
of independent coral islands, some of which are typical 
atolls. 
The peculiar form of the “ Great Bahama Bank” is partly 
due to the coalescence of separate islands with the main west- 
ern portion through coral growths. It probably secured thus 
the addition of Long Island Bank, Eleuthera Bank, and Cat 
Island; and almost certainly the last of the three, Cat Island, 
whose connection with the part next west is made by a nar- 
row submerged reef, fifty to seventy-five feet under water, the 
northern side of which pitches off at an angle of about forty- 
five degrees to a depth of fifty-five hundred feet. 
The S-like form is dependent also on the intrusion into 
the area of two deep and broad tongues of the ocean, one 
going in from the northward, commencing with two thou- 
