Piedmont Distriet. ; 461 
boundary is thus known industrially and geographically as the "fall line”. This 
boundary is one of the most strongly marked physiographic and cul- 
tural lines on the surface of the globe, so writes Professor W. J. MCGEE '). 
On the one hand lie the crystalline rocks, while on the other, there is a series 
of incoherent and undisturbed deposits of clay, sand and gravel, through which 
the waters move sluggishly in broad tidal estuaries, The pioneer settlers 
ascended the tidal channels to the falls of the rivers, where they found some- 
times within a mile, clear, fresh water, the game of the hills and woodlands 
‚and the fish and fowl af. the estuaries, as well, as abundant water power. 
Here are found such cities as Philadelphia, Baltimore, Washington, Richmond, 
Raleigh, Columbia, Macon, Montgomery in Alabam 
ere is also a marked delimitation of the Aoras of the coastal plain 
and the Piedmont Plateau. The forests of the former are mainly coniferous, 
of the latter, composed of broad-leafed trees with the corresponding under- 
growth of shrubby and herbaceous species. 
In New Jersey along the front of the Piedmont Plateau, which ends at the 
Hudson River, crossing the Delaware River at Trenton, where rapids occur, 
there is a transition belt where the coniferous forests of the coastal plain blend 
with the deciduous forests of the Piedmont Plateau, producing a constant state 
of strain, or tension. The elements in the deciduous flora are always ready 
to seize upon any advantage which will give them a foothold further south, 
while the elements in the coniferous flora are always ready for an advance in 
the opposite direction °). 
The Piedmont Plateau in New Jersey3) is Free: by the deciduous tree formation com- 
posed of Quercus Far Q. coccinea, (). alba, inctoria (= Q. Te Carya alba (= were 
ovata), Carya porcina (= Hicoria glabra), Eu tomentosa (= Hicoria alba), 
raxinus americana, e- agus americana, (= F. ferruginea), Castanea dentata (= C. americana), io: 
dendron tulipifera, Carpinus caroliniana, Platanus occidentalis, Acer rubrum, Cornus florida, with 
oecasional groups of Juniperus virginiana and Pinus strobus. Liquidambar styracifiua, Sassafras 
officinale and Populus tremuloides also occur in this forest, but are also abundant in the coni- 
ferous (southern) belt. — West Jersey from 'Trenton southward, west and southwest of the pine 
barrens, is characterized by a far greater variety of trees than the ee barrens. The most plentiful 
species, not found in the latter region, are Pinus inops (= P. SUR Juniperus virginiana, 
Geile air, Q. falcata (= Q. digitata), Q. bicolor (= Q. platanoides), Q. coceinea, Castanea 
dentata, Fagus americana, Betula nigra, Ulmus americana, Carya Tanne (= Hicoria alba), C, 
porcina (= H. glabra), C. amara (= H. minima), Carpinus caroliniana, Liriodendron tulipifera, Pla- 
tanus occidentalis, Diospyros virginiana, Cornus florida, Liquidambar styraciflua, Prunus serotina, 
Ilex opaca. 
A striking fact first emphasized by WITMER STONE is that the narrow Atlantic coast strip 
between the pine barrens and the salt ee has much the same flora as the lower Delaware 
Valley, though many of the trees are absent. The Piedmont Plateau is not typically developed, 
however, until the Delaware River is nd at Trenton, and southeastern Pennsylvania is entered, 
ı) Mc Ger, W. J.: The Lafayette Formation. Twelfth Annual Report U. S. Geological Survey 
1890—ı8gı1. Part I: 356—357. 
2) HoLLIcK, ARTHUR: The Relation between Forestry an Geology in New Jersey. American 
Naturalist XXXII: I—14; 109—116. 
3) HARSHBERGER, JOHN W.: The Vega of the Navesink Highlands Torreya Jan. 1910, 
