J. EF. Hilgard—Basin of the Gulf of Mexico. 291 
slopes are reached. The 100 fathom curve represents very 
closely the general continental line; the massifs of the peninsu- 
as of Florida and Yucatan have more than twice their present 
apparent width. As previously stated, one-third of the whole 
area of the Gulf has a depth of less than 100 fathoms. 
2. Very steep slopes lead from this submerged plateau to an 
area of 55,000 square miles, as great as that of the State of 
Georgia, at the great depth of over 12,000 feet. There are three 
ranges on the Florida and Yucatan slopes extending in the 
aggregate to more than to 600 miles, along which the descent 
between 500 to 1,500 fathoms, or 6,000 feet, is within a breadth 
of from six to fifteen miles. No such steep slopes and corre- 
with the same feature, the strong indentation to the westward 
of the present mouths of the Mississippi, indicating the prob- 
able site of the original fracture between the two slopes of 
the Mississippi Valley deserves attention. 
4. In regard to the problem of general ocean circulation in 
*ennection with the Gulf Stream, the most important feature is 
4 greatest depth of 344 fathoms. From observations reported 
elsewhere in the Coast Survey Reports, the average north- 
Stream is largely reinforced by a general northerly current 
= the outside of the West Indian Islands. 
