— 3— 



Georgia is everywhere more or less hilly, but not moun- 

 tainous. A few isolated peaks, of which Stone Moun- 

 tain (see Bull. Torr. Bot. Club. vol. 28. plate 29) is the 

 best known and Kennesaw (1809 feet) the highest, rise 

 conspicuously above the general level. The Pine Moun- 

 tains in southwestern Middle Georgia (see Bull. Torr. 

 Bot. Club. 30: 292-294. 1903) are the southermost 

 mountains in the eastern United States, and some species 

 of ferns seem to reach their southern limits there. Middle 

 Georgia contains all the granite of the State, and some 

 gneiss, sandstone, etc.. but no calcareous rocks, as far as 

 known. The soil is largely a tenacious red clay, derived 

 from the decomposition of the underlying granitic rocks, 

 but in a few localities sand predominates. The ferns of 

 Middle Georgia are mostly such species as grow on bare 

 granite or in humus. 



The remaining three-fifths of the State, known as South 

 Georgia, is included in the coastal plain, which extends 

 in a broad belt along the coast from Long Island to 

 Mexico and up the Mississippi valley to southern Illi- 

 nois. The boundary between the Piedmont region and 

 the coastal plain is called the fall-line, because most of 

 the rivers which cross it have falls or rapids there. This 

 line is one of the most important natural boundaries on 

 the continent, and in going ten miles across it we can 

 often find more difference in the flora than in going sev- 

 eral hundred miles parallel to it. 



The. geological formations of the coastal plain are 

 Cretaceous. Tertiary, and Quaternary, each with several 

 subdivisions. In general the oldest formations crop out 

 farthest inland and at the highest altitude. The inland 

 edge of the Tertiary in Georgia is about 700 feet above 

 sea-level, but the Cretaceous region adjoining is some- 

 what lower, because its rocks are softer. 



The rocks of the coastal plain are principally limestones 

 of various degrees of purity and hardness (or rather im- 

 purity and softness), with some flint, and a conglomerate 

 known as Altamaha Grit, which underlies all the middle 

 third of South Georgia, but has not been traced beyond 



