CHAPTER XI 



THE GENERAL . CHARACTERS AND GEOLOGICAL STRUCTURE OF THE 



TURKS ISLANDS 1 



The Turks Islands, well known on account of the salt industry 

 that has been long established there, are situated on one of the level 

 summits of a great submarine mountain range rising up from depths 

 of 2000 fathoms and over. The long and narrow bank on which the 

 ten islands lie is about thirty-seven miles long, as limited by the 

 100-fathom line. The depth of water covering the bank does not 

 generally exceed ten or eleven fathoms, and is often only three or 

 four fathoms; and so rapid is the submarine slope that, if limited 

 by the fifteen-fathom line, the bank would possess much the same 

 dimensions. 



Geographically this group forms the south-eastern extreme of the 

 Bahamas. Botanically it belongs to the Bahamian region, and 

 geologically its structure is that of the same archipelago, the familiar 

 aeolian formation of the Bahamas here prevailing. The islands or 

 cays are low in elevation, none of them reaching 100 feet in height, 

 the highest (Eastern Cay) being ninety-six feet, whilst the lowest 

 (Long Cay and Penniston Cays) do not exceed thirty feet. They are 

 usually long and narrow, and vary in length from five and a half 

 miles in the case of Grand Turk to less than 200 yards in that of 

 Round Cay. 



The general characters of this small group are those of the numerous 

 islands of the great archipelago of the Bahamas, all of which rise 

 from banks that are covered by a few fathoms of water. These 

 banks are the flat summits of a lofty range of submarine mountains 

 which terminate abruptly near the surface. Rising from the ocean's 

 depths of 2000 fathoms and more at the eastern end, the banks are 

 separated at the western extremity from the Florida coasts by 

 depths of about 400 fathoms. The 100-fathom line surrounds the 

 islands and reefs of the Little Bahama Bank, and a similar line 

 includes those of the Great Bahama Bank, with intervening depths 

 of less than 300 fathoms, the isolation of the banks increasing as we 

 go east, depths of 1000 to 2000 fathoms dividing those from which 



1 This chapter was mainly written nearly four years ago, when the author was 

 only acquainted with the monograph of A. Agassiz on the Bahamas. Since it has 

 been in type he has enjoyed the privilege of communication with Dr. Vaughan, who 

 has recently investigated the western Bahamas. His conclusions are of great 

 importance; but the writer has been obliged to deal with them in Note 39 of the 

 Appendix. 



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