130 BERRY— LOWER EOCENE FLORA OF [April 25, 



to a time which marks the first recorded appearance of angiosperms, 

 as that of the South Atlantic and Gulf states. Xo single part of 

 Ninth America contains so continuous a series of Tertiary deposits 

 carrying fossil plants. In this area are found abundant floras in the 

 lower and middle stages of the Eocene, a small flora in the Upper 

 Eocene, considerable floras in the Oligocene, some in the later Mio- 

 cene, and rather abundant fossil plants in the Pliocene, as well as 

 numerous Pleistocene deposits carrying fossil plants. The Rocky 

 Mountain region is rich in Eocene fossil plants and there are some 

 Miocene floras, but practically no Oligocene or Pliocene floras are 

 known. The Pacific coast region likewise furnishes Eocene and 

 Miocene fossil plants but none of Oligocene age. 



The fossil floras of the Coastal Plain are found in an area where 

 it is possible to attain to some measure of accuracy in predicating the 

 general character and course of ocean currents and w r inds and other 

 physical features of the environment. On the other hand the west- 

 ern floras just mentioned grew in areas where vulcanism was great at 

 times ; in areas of great orogenic activity, where changes in topog- 

 raphy were numerous and elevations of several thousands of feet are 

 recorded ; areas in which climatic conditions not only varied from 

 place to place, but passed through a large cycle of secular changes. 

 All these factors greatly complicate the floral history. 



The floras of the southern Coastal Plain are moreover checked for 

 the most part by very abundant marine fauna in intercalated beds, or 

 the plant-bearing beds which represent the coastal swamps and the 

 shallow water deposition of the old embayment merge laterally with the 

 contemporaneous limestones or marls which were forming in more 

 open waters along the coasts to the southward, so that there is a con- 

 siderable body of facts bearing on depth, character of the bottom, and 

 marine temperatures, with which to compare land temperatures. 

 These criteria have been admirably worked out for the Florida area 

 by Doctors Dall and Vaughan for the post-Eocene and their results 

 furnished a reliable datum plan for the deductions to be derived from 

 the study of the fossil floras of those times. 



With the exception of fragments of the petrified stems of coni- 

 fers, palms and dicotyledons the plant-remains are in the form of 

 impressions, mostly of foliage, but with a goodly representation 



