

V 



214 FAUNAL DIVISIONS OF EASTERN NORTH AMERICA. 



III. The Coastal Plain Fauna. 



The area occupied by this fauna is the Austral Zone of Merriam and later 

 writers. It has been divided into an Upper and a Lower Austral on the basis 

 of a difference in the aggregate of temperatures throughout the period of repro- 

 ductive activity. In the eastern portion of the country the Upper Austral is 



synonymous with the Carolinian Fauna, while the Lower Austral is the Austro- 

 riparian Fauna or Region of earlier authors. 



Geologically and topographically the area embraced in the Lower Austral 

 (and extending into the Upper Austral on the eastern seaboard) corresponds to 

 the Coastal Plain, a more or less flat country of Tertiary and Quaternary deposits 

 the latest addition to the southeastern portion of the continent. The Coastal 

 Plain is marked on its inland Atlantic border, where these deposits rest against 

 the older crystalline rocks, by a well-defined, though low, rise of land known as 

 the " fall-line." It includes the widening southward expanse of slightly sloping 

 plain from Southern New Jersey and Long Island (with narrow strips as far 

 north as Cape Cod) that lies between the ocean and the Appalachian Piedmont. 

 It is in reality the exposed portion of the continental shelf. Southward it 

 extends to the low Gulf shores (Austroriparian) and passes around the southern 

 foot of the Appalachians into the broad alluvial bottomlands of the Lower 

 Mississippi and Ohio drainage basin. On the western side of the Appalachians 

 the characteristic northern portion of the fauna (the Carolinian Fauna) has 

 spread northward beyond the limits of the Coastal Plain proper to the Lower 

 Lake Region as a result of the low relief of the land and the warm and moist 

 summer influence of the Gulf of Mexico. ■ 



This Coastal Plain fauna presents three well-defined types incident to the 

 diversity of soil and vegetation in different parts of the area— (a) the Alluvial 

 Forest Type, (6) tU Marshland Type, and (c) the Pine Barren Type. 



(a) The Alluvial Forest Type.— A large portion of this Coastal Plain is a 

 natural broad-leaf forest region, especially in the interior where it is covered by 

 grand forests, of great diversity of species, over the wide alluvial bottomlands and 

 lower hill slopes. Throughout these forests the magnolias and their allies are con- 

 spicuous, and among other characteristic species are the sweet gum (Liquidambar) , 

 the buckeyes (jEscuIus), the persimmon (Diospyros), a great variety of oaks 

 (Quercus), and many more quite as notable trees. Toward the south this forest 

 extends over the Piedmont, mingling on the lower mountain slopes with the 

 more northern deciduous forms of the Atlantic forest. On the Atlantic coast to 

 the north this type of forest extends up the bottomlands of numerous river 

 valleys as the Susquehanna, Delaware, Hudson, and Connecticut. Its distri- 

 bution appears to be largely a matter of rich alluvial soils, although the climatic 

 factors of heat and moisture undoubtedly exert a controlling influence in the 

 northward range of certain forms of its vegetation. This coastal plain forest 



from the geographical point of view, a part of the general deciduous Atlantic 

 forest of the eastern region. Its characteristic forms, however, and its soil 



