4 FLORIDA REEFS. 



their steepest shore is turned towards the Gulf Stream, while their more 

 gradual slope inclines towards the mud flats which they encircle. 



This is a point which it is important to notice, as it will assist us in our 

 comparison between the keys and the shore bluffs of the main-land, as well 

 as with the outer reef and the reefs of other seas, in all of which we find 

 that the seaward shore is steeper than that turned towards the main-land, 

 or, in the case of circular reefs enclosing basins (atolls), than that which 

 borders the lagoon. 



The reef proper extends parallel to the main range of keys for a few 

 miles south or southeast of it, following the same curve, and never receding 

 many miles from it. The distance between the reef and the main range 

 of keys varies usually from six to two or three miles, the widest separation 

 being south of Key West and east of the Ragged Keys, where the space 

 is about seven miles. Between this reef, upon which a few small keys 

 rise at distant intervals, and the main range of keys already described, 

 there is a broad, navigable channel, extending the whole length of the 

 reef, from the Marquesas to Cape Florida, varying in depth from three to 

 six and seven fathoms, and, except off" Looe Key, where the passage is not 

 more than fourteen feet deep at low water, averaging from three to four 

 fathoms. 



Farther east the average depth is again the same as at Looe Key ; but it 

 becomes gradually more and more shoal towards the east, measuring usually 

 about two fathoms, or even less, to the east of Long Key and Key Largo, 

 but deepening again somewhat towards Cape Florida, where the reef con- 

 verges towards the main keys and the main-land. Protected by the outer 

 reef, this channel affords a very safe navigation to vessels of medium size, 

 and would allow a secure anchorage almost everywhere throughout the 

 whole length of the reef, were the numerous deep channels which intersect 

 the outer reef well known to navigators, and marked by a regular system of 

 signals. As it is, however, the reef seems to present an unbroken range 

 of most dangerous shoal grounds, upon which thousands of vessels, as well 

 as millions of property, have already been wrecked. These facts have 

 a stronger claim upon the attention of the government, since there are, 

 as already remarked, numerous passages across the reef which might enable 

 even the largest vessels to find shelter and safe anchorage behind this 

 threatening shallow barrier. 



The reef proper, as we have remarked above, runs almost parallel to the 



