TRANSACTIONS OF WAGNER 

 1546 



TERTIARY FAUNA OF FLORIDA 



fresh-water lakes constantly existing since the Ocala islands were raised above 

 the sea ; such is the geological history of the Florida peninsula. Denudation 

 of the organic limestones by solution rather than erosion is the prominent 

 characteristic of the changes in the surface. Soft, crumbling under the finger- 

 nail, the rocks of the plateau, if lifted five or six thousand feet, as claimed by 

 Dr. Spencer, would have been furrowed by canons and swept bodily into the 

 sea. Indeed, to me the proposition is inconceivable as a fact and incompatible 

 with every geologic and paleontologic fact of south Florida which has come to 

 my knowledge. 



The development of the geological characteristics of the peninsula, the ap- 

 proximate mapping of its formations, are features of the work that has been 

 done during the studies for this Memoir. Another feature which has aroused 

 some comment has been the development of our knowledge of the marine strata 

 which in Florida and its vicinity correspond to the epoch which in Europe has 

 come to be called and recognized, after Beyrich, as the Oligocene. 



Lyell and Deshayes in dividing the Tertiary into periods used the per- 

 centage of living forms as a criterion, adopting the term Eocene for beds con- 

 taining three to four per cent, of species surviving to the present day, Miocene 

 for those containing from seventeen to twenty per cent., and Pliocene for those 

 of which forty to fifty per cent, survive. There are several objections to this 

 method of classification, considered as indicating contemporaneity for the 

 strata concerned ; the view of species taken by different persons is by no means 

 uniform; the conditions in one region may be more favorable for surviving 

 than in another region at the same time, and the method as stated takes no 

 account of changes of climate or earth movements on a large scale, to which 

 fluctuations in the rate of evolution of living beings must more or less directly 

 conform. However, in practice the omissions have been more or less effectively 

 supplied, and the European time column having been thus worked out, the 

 establishment of synchronism in the scale of other countries, necessarily an 

 approximation" only, will be none the less useful because to a certain extent 

 arbitrary. 



According to De Lapparent '■' European geologists are now pretty much 

 agreed in recognizing two great divisions of the Tertiary: i, the Eggene 

 system, divided into Eocene and Oligocene series, corresponding to a state of 

 things still very different both geographically and faunally from the present 

 epoch, and especially including all the nummulitic formations ; 2, the Neogene 



* Traite de Geologie, ed. iv., p. 1409, 1900. 



