g TRANSACTIONS OF WAGNER 



THE LIFE FEATURES OF THE COASTAL PLAIN AND THE PIEDMONT 



ture can scarcely be regarded as a controlling factor, although Merriam bases 

 his scheme of faunal zones on this as the main issue. It seems unHkely that 

 any such differences in temperature could exist on either side of this faunal 

 boundary as to affect vitally the reproductive functions of closely allied species 

 of birds or of reptiles. The Kentucky Warbler, for example, belongs in the 

 same genus (Oporornis) with the Mourning Warbler and the Connecticut 

 Warbler. All three are birds of very similar habits and life relations, and yet 

 the two latter breed entirely beyond the Hmits of the former species. The 

 same is true of the Golden- winged Warbler and the Blue- winged Yellow Warb- 

 ler, of the two species of Chickadee, and of the Acadian Flycatcher and its 

 near relations the Least and Alder Flycatchers. Nor is it conceivable that any 

 such differences in temperature, prevaiHng over the upland and lowland, exist 

 as to form a reproductive barrier. The "effective temperatures" adduced by 

 Merriam are averages made to fit the facts of distribution. The causes must 

 be looked for elsewhere. 



The most significant feature in the distribution of the Carolinian fauna in 

 the lower Delaware Valley is its relation to the Coastal Plain. As we have seen, 

 this Coastal Plain in southeast Pennsylvania and southern New Jersey is a 

 narrowing northward extension of a wide southern territory which is char- 

 acteristically austral in its forms of plants and animals. The relation between 

 a land and its life is unquestionably a relation established by geologic condi- 

 tions rather than by any direct climatic influence; it is in the nature of a his- 

 toric sequence dependent upon an ancient underlying cause — in this instance 

 the addition of a coastal continental margin of land which began some time 

 during the Tertiary. By a slow process of uplift land was added along the 

 eastern border of Old Appalachia, at first most likely as a fringe of bars and 

 beaches between which and the main land salt lagoons with their characteristic 

 vegetation of sedge forms appeared. Further uphft would gradually convert 

 lagoons into drier areas of sand and clay, and new lagoon conditions would form 

 to seaward. At a later period a considerable strip of this Tertiary uphft suf- 

 fered submergence, a state of affairs probably still going on as already noted. 

 At the southern end of Appalachia, this Atlantic Coastal Plain merges with 

 the great Gulf lowland — an uphft of the Mississippi embayment of early Ter- 

 tiary time which embraces the whole lower coastal of Texas and the Gulf States 

 to the present site of the Ohio confluence. The time involved in the gradual 

 emergence of this alluvial sand and clay, which represents the waste of an enor- 



