218 Part II. Chapter 3. 
the ridges. These tongues are the seaward extension of mixed forests of 
loblolly pine and hardwoods. A change to long leaf pine land takes place, 
where the Neocene formation meets the sands of the Eocene. The loblolly 
pine Pinus taeda, covers the sandy ridges of the Neocene formation, while 
the swampy flats grow a jungle of hardwood with some loblolly, climbing 
vines and palmetto thickets. The alluvial valleys are filled with hardwood trees. 
The longleaf pine area in Texas is shaped like a broad wedge thrust in 
between the loblolly pine at the south and the shortleaf at the north, and 
extends southwestward to the Trinity River, where the overlapping areas of 
loblolly and shortleaf form its western boundary’‘). It always grows on dry 
sands from necessity rather than preference for it finds refuge from the com- 
petition, which is generally too much for it on moister and better soils. 
The shortleaf pine Pinus mitis (= P. echinata) and post oak forests occupy 
the Tertiary plain, a region of sand beds and underlying clays, the remnant 
of an ancient plain worn away by erosion, in which the streams have esta- 
blished wide drainage bottoms. It is on these uplands that the shortleaf pine 
and oak prevail. In Texas, as in the South. Atlantic States, the live oak 
Quercus virginiana (= Q. virens) occurs on the coast plain, where westward 
toward the Neuces, it yields to the increasing aridity of climate, becoming a 
more stunted open growth spreading over the grass prairie, which become 
converted into woodland. | 
Northward extension of Areas. One fact is noteworthy in the study of 
the coastal plain flora and that is the tendency to a northward migration of 
plants. That tendency is clearly illustrated in the northward extension of the 
pine barren flora on Staten Island and Long Island. The soil of the 
islands is generally sandy, but is occasionally more firm, where the strata of 
clay approach and form the surface. The geologic formations to the south 
and southeast of a line drawn from a point below Long Branch to another 
near the head of Delaware Bay are Tertiary, while those to the north of it 
are Cretaceous. The Tertiary soils extend southward along the Atlantic Ocean 
to Florida and are occupied by a pine barren flora. On Staten Island, Creta- 
ceous strata are exposed in its extreme southern portion. They doubtless 
extend over the entire southern and eastern sections, but are mostly covered 
by a layer of material of variable thickness derived from the glacial drift. On 
Long Island, the great terminal moraine occupied the position marked by a 
range of hills extending throughout its whole length at an average distance 
of ten miles from the Atlantic. South of these hills sandy plains prevail, the 
material composing them having been formed partly from the modified drift 
of the hills, partly from the underlying Cretaceous strata. Those species 
detected on the Cretaceous soils of Staten Island, south of the moraine, and, 
therefore, not on the drift, are thirty four in number. 
1) Bray, WE: LG 
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