10 IN LOWER FLORIDA WILDS 



of the Everglades drains freely through this porous 

 rock, sometimes in wide prairie-like channels be- 

 tween the "islands" and sometimes it appears as 

 springs on the eastern side of the ridge. This 

 rocky ridge, which Dr. John K. Small has appro- 

 priately called "The Everglade Keys," is surely 

 a series of ancient sea beaches, formed one after 

 the other during the gradual elevation of this 

 area. This is indicated by the strata being greatly 

 cross bedded throughout a considerable part of 

 it. In places between these old beaches the 

 water must have been sheltered and quiet, as is 

 indicated by many fossil bivalve shells found 

 clinging together in a natural state. A northern 

 sandy part of this ancient shore line overlaps the 

 rocky ridge and was deposited at a later time. 

 This ridge was the great highway over which 

 plants and animals from the American tropics 

 migrated northward and those from the north 

 came southward. 



In all probability the Everglades (which we 

 shall personally inspect in another chapter) began 

 to develop at about this time. The upper part of 

 the chain of keys, doubtless in process of formation 

 before the time of this uplift, was then thrust up, 



