FLORIDA REEFS. 57 



united to the main-land by the complete filling up and consolidation of 

 the channel which once divided it from the extremity of the peninsula, as 

 a channel now separates the keys from the shore-bluffs, and the outer reef, 

 again, from the keys. These three concentric reefs, then, — the outer reef, 

 the keys, and the shore-bluffs, — if we measure the growth of the two latter 

 on the same low estimate by which I have calculated the rate of proo:ress of 

 the former, cannot have reached th-eir present condition in less than twenty 

 thousand years. Their growth must have been successive, since, as we have 

 seen, all corals need the fresh action of the open sea upon them, and if 

 either of the outer reefs had begun to grow before the completion of the 

 inner one, it would have effectually checked the growth of the latter. The 

 absence of an incipient reef outside of the outer reef shows these conclu- 

 sions to be well founded. The islands capping these three reefs do not ex- 

 ceed in height the level to which the fragments accumulated upon their 

 summits may have been thrown by the heaviest storms. The highest hills 

 of this part of Florida are not over ten or twelve feet above the level of the 

 sea, and yet the luxuriant vegetation with which they are covered gives 

 them an imposing appearance, recalling the islands of the Pacific. 



But this is not the end of the story. Travelling inland from the shore- 

 bluffs, we cross a low, flat expanse of land, the Indian hunting-ground, which 

 brings us to a row of elevations called the Hummocks. This hunting-ground, 

 or Everglade as it is also called, is an old channel, changed first to mud-flats 

 and then to dry land by the same kind of accumulation that is filling up 

 the present channels, and the row of hummocks is but an old coral reef 

 with the keys or islands of past days upon its summit. Seven such reefs 

 and channels of former times have already been traced between the shore- 

 bluffs and Lake Okee-cho-bee, adding some fifty thousand years to our pre- 

 vious estimate. Indeed, ujDon the lowest calculation, based upon the facts 

 thus far ascertained as to their growth, we cannot suppose that less than 

 seventy thousand years have elapsed since the coral reefs already known to 

 exist in Florida began to grow. 



When we remember that this is but a small portion of the peninsula, and 

 that, though we have no very accurate information as to the nature of its 

 interior, yet the facts already ascertained in the northern part of the State 

 formed, like its southern extremity, of coral growth, justify the inference 

 that the whole peninsula is formed of successive concentric reefs, we must 

 believe that hundreds of thousands of years have elapsed since its formation 



