112 DYNAMICAL GEOLOGY. 



animation of this reveals the same structure precisely. 

 Here, then, was the place of a still earlier reef. 



Brief History of the Process. There was, there- 

 fore, a time when the north shore of the Everglades (d, 

 section, Fig. 61, B) was the southern shore of Florida. 

 At that time the place of the present southern coast was 

 occupied by a living reef. On this reef coral islands were 

 formed, which gradually coalesced into a continuous line 

 of land, the shoal water between it and the mainland was 

 filled up, and the whole added to the mainland ; the 

 southern coast being transferred to its present position, 

 and the shoal water, with its mangrove islands, changed 

 into the Everglades, with its hummocks. In the mean 

 time, however, i. e., while the present southern coast was 

 still a line of keys, another reef was formed in the place 

 of the present line of keys, and the former have therefore 

 died. This new reef in its turn was converted into a line 

 of keys, which will eventually coalesce into a continuous 

 line of land, the shoal water will be filled up, and form 

 another Everglade, with its hummocks, and the coast- 

 line be transferred to the present line of keys. But 

 already another line is formed, and the previous line is 

 dead ; already the process of key-formation has com- 

 menced. We can not doubt that eventually, but proba- 

 bly only after many thousands of years, the Peninsula of 

 Florida will extend even to the present living reef. Far- 

 ther than this it can not go, for the deep water of the 

 Gulf Stream is close at hand, and forms its impassable 

 boundary. 



Farther northward, the extent of the coral formation is 

 less known, but it has been found on the eastern coast as 

 far as St. Augustine. The middle and western part of 

 Florida, as far as the north shore of the Everglades, is 

 probably older. The line dd (Fig. 61, A], therefore, 

 probably marks out the area which has been added to 

 Florida by the agencies described. The area already 



