310 BERRY— TERTIARY FLORAS OF THE [April 2., 



Extensive marine faunas indicate even more torrid conditions 

 than in the preceding epoch, uniformly distributed over this whole 

 area. 



Middle Oligocene. 



The Middle Oligocene deposits are those of shallow tropical 

 waters with a bottom temperature of at least 39° C. (70° F.), marine 

 toward the east with true reef corals in Georgia, but becoming 

 brackish or fresh toward the west, by reason of their shallowness 

 and the increased volume of fresh water from the Oligocene Missis- 

 sippi and Tennessee rivers and other streams. The flora is scanty 

 but includes tropical swamp types, the fern genus Acrostichum being 

 the most abundant form collected. 



The accompanying sketch map (Fig. 3) shows in a generalized 

 way the relation of land and water in the Middle and Upper Oligo- 

 cene. It is to be noted that the great Mississippi Gulf had been 

 reduced to a very wide and shallow reentrant. 



Upper Oligocene. 



Toward the close of the Oligocene a widespread emergence of 

 the land was inaugurated accompanied by a slight lowering of tem- 

 peratures. The floras are not abundant but are represented in 

 western Florida and central Mississippi. They contain very abund- 

 ant remains of several species of Sahal-Wka palms; the large leaves 

 of a species of ArtocarpHS or breadfruit; leaves of figs; of the Cin- 

 namomum or camphor tree; representatives of the genera Acacia, 

 Btimelia, Diospyros, Pisoma, Cyiniiida. Clcditsia, Nectandra, 

 Sapotacitcs, Rhanimis. Uluuis, etc. — the latter being the only genus 

 which is a strictly temperate type in the modern flora, although most 

 of the genera enumerated have representatives in the warmer parts 

 of the temperate zone at the present time. 



Miocene. 



A long interval followed the close of the Oligocene, during which 

 the coast line of southeastern North America was considerably sea- 

 ward from its present position, in consequence of which deposits 



