PHYSICAL CONDITIONS AND AGE INDICATED BV FLORA OF ALUM BLUFF FORMATION. 



43 



men treated in this way, some of which were 

 10 inches in diameter, survived the rough 

 handling on the river boat and the freight 

 transportation to Baltimore. 



Fossil, plants from Alum Bluff have been 

 mentioned by Langdon,' Foerste,- and Dall.^ 

 A few fragments of Sabalites were collected 

 by Dall, but no systematic collections were 

 made until I visited this outcrop in 1910 in 

 comjiany with E. H. Sellards, State geologist 

 of Florida. 



CHARACTER OF THE FLORA. 



The flora is limited to 13 described species, 

 although fragments of other species are present, 

 and I observed but did not succeed in collecting 

 a palmately veined Ficus, leaves of Gj'minda 

 or Xanthoxylum, and pods resembling those of 

 the existing Gleditsia aqiiatica Marsh. 



The determined species comprise a spot fun- 

 gus (Pestalozzites), a very abundant fan palm 

 (Sabalites), and 11 species of dicotyledons, in- 

 cluding an elm, breadfruit, buckthorn, cam- 

 phor, satinwood, ironwood, and persimmon. 

 There are 1 1 genera in 9 families and 8 orders. 

 These famihes are the elni (Uhnaceae), mulberry 

 (Moracese), pisonia (Nj^ctaginacese), senna 

 (Csesalpiniacese), i"ue (Rutaceie), buckthorn 

 (Rhamnace^), laurel (Laurace£e), sapodilla 

 (Sapotacese), and ebony (Ebenacese). The 

 families Lauraces? and Sapotaceis are each rep- 

 resented by two species; the remaining seven 

 families have each a single species. By far 

 the most abundant form is the palm, broken 

 stipes and detached rays of which are thickly 

 crowded in the sands in places. Four of the 

 plants are ordinarily considered strictly tropi- 

 cal — the breadfruit (Ai-tocarpus), brasiletto 

 (Cffisalpinia), Nectandra, and satinwood (Fa- 

 gara). The genera Pisonia and Cinnamomum 

 are commonly considered tropical, but Pisonia 

 reaches the keys of southern Florida in the ex- 

 isting flora and the camphor tree (Cinnamo- 

 mum) ranges northward to southern Japan and 

 to the rain forests of southwestern China, 

 while Cinnamomum camphora Linne is hardy 

 in cidtivation around Tallahassee, Fla., and is 



' Lansdon, D. W., Some Florida Miocene: Am. Jour. Sci.,3d ser.,vol. 

 38, p. 322, 1889; Geolog>- of the Coastal Plain of Alabama, p. 373, 1S94, 



2 Foerste, A. F., Studies on the Chipola Miocene of Bainbridge, Ga.. 

 and of Alum Blufl, Fla.: Am. Jour. Sci., 3d ser., vol. 46, pp. 244-254, 1893; 

 Fossil palmettos in Florida: Hot. Gaz., vol. 19, p. 37, 1894. 



' Dall, W. H., and Stanley-Brown, Joseph, Cenozoic geology along the 

 Apalachicola River: Geol. Soc. America Bull., vol. 5, pp. 147-170, 1894. 



not uncommon as an escape from cultivation 

 in woods and thickets throughout peninsular 

 Florida, being freely seeded by birds. In fact, 

 soU, humidity, and the length of the growing 

 season seem to govern the extension of the 

 tropical flora into the temperate zones to a 

 much greater extent than actual extreme -tem- 

 peratures, the existing floras of both south- 

 eastern Asia and southeastern North iVmerica 

 showing many parallel examples of such ex- 

 tensions. 



The Sabalites is represented in the existing 

 flora by the genus Sabal Adanson, which is now 

 confined to America. It consists of eight 

 coastal or stream-border shrubs and trees, five 

 of which are confined to the West Indies, 

 Mexico, and Venezuela; one is confined to 

 peninsular Florida, and two range northward 

 along the Atlantic coast to the Carolinas. 



The large mass of frayed and tangled rays 

 and stipes of Sabalites in a matrix of sandy 

 alluvium both at Raglan, Miss., and Alum 

 Blirff, Fla., suggest that at the time these de- 

 posits were laid down the shores were low and 

 were densely clothed with palmetto "swamps" 

 or brakes. 



The genus Ulmus, although it has tropical 

 aUies, is in the existing flora a strictly north- 

 temperate form having about 16 widely dis- 

 tributed species. 



The family Rhamnaceas is mostly tropical, 

 but several of the genera extend into the Tem- 

 perate Zone, and Rhamnus, in particular, is 

 mostly extratropical in the North Temperate 

 Zone. There are about 75 existing species, and 

 of the dozen North American forms several 

 range northward to Canada and British America 

 and only 1 ranges as far south as Florida. 



The genus Bumelia has about a score or 

 more of existing species, ranging from Brazil 

 northward through Central America and the 

 West Indies to the United States, where two 

 species are found as far north as Virginia and 

 Illinois. 



The genus Diosp}TOs belongs to a large 

 family that is mostly tropical in its distribution. 

 Of the more than 200 existing species our 

 common Diospyros i^irginiana Linne is found 

 as far north as southern New York aiid New 

 England. The genus is represented in south- 

 ern Europe, and there are several species in 

 eastern Asia. Moreover, of the 100 or more 



