140 BULLETIN OF THE 



mouutaiuous character. ludeed, it is at first sight difficult to find the 

 analoo'ues of these ureat anticlinal-like folds in the existing structures 

 of the land. They can hardly be classed with any of our known table 

 lands, for the reason that such elevations are in all cases more or less 

 associated with definite mountain folding. The only similar structure 

 which is known to me is that exhibited in the " Cincinnati anticlinal," 

 that well known- ridge extending from near Columbus, Ohio, to Xorthern 

 Alabama. This elevation in length and breadth may be compared to 

 that of Florida, though it never had more than one half the height of 

 the Floridian peninsula. 



In endeavoring to account for the Florida ridge, we must bear in 

 mind the processes of deposition which have evidently occurred in this 

 region. The geological histoiy of the sedimentation is about as follows. 

 To the west of Florida, in the Gulf of Mexico, we have a region which 

 from a remote time has been the seat of extensive accumulation of sedi- 

 ments. The Mexican Gulf in a more or less perfectly definite form is 

 one of the oldest topographic features of this continent. It is, as is 

 easily seen, the remainder of the continental trough which from an 

 early time has received a great share of detritus from the Appalachian 

 and Cordilleran fields. It has thei-efore been a region tending to sub- 

 sidence, through the well known influence of the weight produced by 

 sedimentary deposits on the surface of the earth. This subsidence has 

 naturally been attended by phenomena of counter-thrust elevation, the 

 characters of which I think are found in the curious uplifts of Yuca- 

 tan and Florida, which serve in part to bound this region of downward 

 movement. Besides the sediment contributed to the region of the 

 Mexican Gulf from the continental portions of North America, there has 

 been a considerable increase of such deposits from the island of Cuba. 

 This island, which probably came above the level of the sea in the 

 Mesozoic period, has evidentlv furnished a very large share of waste to 

 the neighboring sea-floors, as is shown by the extensive erosion indi- 

 cated in its highlands. A considerable portion of this detritus has 

 doubtless been accumulated in the region now occupied h\ the Straits 

 of Florida, and by the deep water between the Bahama Islands and the 

 greater land masses of Cuba and Hayti. I am disposed to consider the 

 extensive recent elevation on which rest the coral islands of the Baha- 

 mas as possibly due to the down-bearing of the crust caused by these 

 sediments. 



The Caribbean Sea has likewise long been a seat of extensive sedimen- 

 tation. A number of great rivers draining from old mountain districts 



