Geology and Natural History. 265 



II. Geology and Natural History. 



1. Florida State Geological Survey ; E. H. Sellards, Geolo- 

 gist. Second Annual Report, 1908-9. Pp. 296, 19 pis., 5 figs., 

 geologic and topographic map in pocket. — This includes the 

 following : 1. A Preliminary Report on the Geology of Florida ; 

 by George Charlton Matson and Frederick G. Clapp, pre- 

 pared in cooperation between the United States Geological Sur- 

 vey and the Florida State Geological Survey under the direction 

 of Thomas Waylant Vaughan. 2. Topography and Geology of 

 Southern Florida ; *'y Samuel Sanford. — Scattered papers and 

 reports dealing chiehy with the coast line have heretofore been 

 the basis of our knowledge of Florida geology. We now have, 

 however, a preliminary report on the geology of the whole state, 

 together with a topographic and geologic map. In view of pre- 

 vious opinions, the reader of this report will be interested to 

 learn that the geologic structure of Florida is diversified, not 

 simple ; and that corals, instead of being the chief agent in the 

 formation of the bed rock of the state, have really played a minor 

 role : have always been limited to the extreme southeastern part 

 of the peninsula. "There appears to be no reason to suppose 

 that reefs have existed on the west coast or north of the north 

 line of Palm Beach County on the east coast " (p. 40). 



Florida is a region of low plains and deeply dissected uplands. 

 The state as a whole has an elevation of less than 100 feet. The 

 topographic map shows an area in the southern part of the state 

 150 miles long by 100 miles in width, with an altitude of less 

 than 50 feet ; and one of the longest rivers in the state, the St. 

 Johns, is nowhere more than 30 feet above the tide. On the 

 other hand, detached areas along the Georgia-Alabama line reach 

 250 feet and " small areas may exceed 300 feet." The drainage 

 is consequent and superimposed, and includes excellent illustra- 

 tions of extended streams. The imperfectly drained areas con- 

 tain thousands of lakes occupying either solution cavities or 

 shallow basins due to unequal deposition of sands. Lakes of the 

 former type predominate in the more elevated portion of the 

 peninsula, and the rate of solution by ground water in this area 

 is found by Sellards to equal the annual removal of 400 tons per 

 square mile. The Everglades, 22.4 feet above tide, are found to 

 be almost completely surrounded by a rim of rock ; and are 

 believed by Mr. Sanford to be similar in origin to the Dismal 

 Swamp of Virginia. 



In structure Florida is " the southern extension of the coastal 

 plain, and its history, in general, has been the same." An uplift 

 similar to the Cincinnati arch has raised the lower Oligocene 

 more than 100 feet above the sea. 



The geological formations include Tertiary and Quaternary ; 

 the oldest rocks belong to the Oligocene Period, and include the 



Am. Jour. Sci.— Fourth Series, Vol. XXIX, No. 171.— March, 1910. 

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