THE TORTUGAS AND FLORIDA REEFS. 133 



EXPLANATION OF THE PLATES. 



PLATE L 



Sketch map of the Tortugas, showing the position of the reefs on the southeast extremity of the great Florida Plateau, 

 and the commencement of the New Tortugas Reef to the westward of the Loggerhead Key. Reduced from Coast Survey 

 charts. 



PLATE II. 



Colored map showing the distribution of the principal types of reef-builders, as well as the distribution of coral sand 

 and ooze. The hydrography of this map is taken from Coast Survey Chart No. 471' ; the original of this plate was 

 colored on the spot. 



PLATE IIL 



Sections across the Tortugas, prepared from Coast Survey Chart No. 471', along the lines marked 1-1' to 10-10' on 

 Plate IL 6 fms. = J". 



PLATE IV. 



Sections across the Tortugas, prepared from Coast Survey Chart No. 471', along the lines marked A-A' to E-E' on 

 Plate II. 6 fms. = 4". 



PLATE V. 



Sketch map of the Marquesas. An atoll to the westward of Key West along the continuation of the line of keys, 

 with section along the line A S, prepared from Coast Survey Chart No. 470. Vertical scale, J" = 1 fm. 



Sketch map of the gi-eat atoll of Alacran Reef, on the Yucatan Bank, with a section prepared from the Hydrographic 

 Office Chart No. 403. Vertical scale, i" = 5 fms. 



PLATE VI. 



Sketch map of the southern extremity of Florida, to show the lines along which the sections Cape Romano-(?', S-G, 

 T-S, .1/-Cape Sable, .U-F of Plate VII., and tlic lines Mainland to 1, 2, 3, 4, 5, 6, 7, 8, 9-9 to 13-13, as well as the line 

 along the course of the reef of Plate VIII., have been taken. Prepared from Coast Survey charts. 



PLATE VII. 



Sketch map of Florida, showing the lines along which the sections of this plate have been prepared. See also 

 Plate VI. for some of the lines extending partially across the reef. Constructed from Coast Survey charts. 



PLATE VIIL 



Longitudinal section along the course of the reef from off the Quicksands to off Cape Florida. Cross-sections of the 

 reef along the lines 1-13 of the sketch map of Plate VI. Constructed from Coast Survey charts. 



PLATE IX. 

 Coral sand beach south of the Navj' Depot, Key West. 



PLATE X. 

 Mangrove Islands in the distance, seen from the mangrove beach north of the slaughter-honse. Key West. 



PLATE XL 



Lagoon formed by promontories and low islands covered with mangroves, on the northeast shore of Key West, near 

 the slaughter-house. 



PLATE XII. 



Coral-rock beach north of Fort Taylor, exposed to the action of the waves of the channel between the outer reef and 

 Key West. 



