408 Part IV. Chapter 2. 
according to my observations, are rag Pinus a Betula een Tsuga canadensis, Thuja 
occidentalis, Betula lutea, Acer rubrum, while somewhat back from the gorge together with the 
above mentioned trees, Pinus = Betula fein, Quercus SE Q. alba, Q. tinctoria 
beneath which occur Amelanchier canadensis, Hamamelis virginiana, Gaylussacia resinosa. The rock 
erevices show Campanula rotundifolia var. Langsdorfiana, Polypodium vulgare, Aralia racemosa, 
Rubus odoratus, Ribes rotundifolia and on the shelves, clumps of Rubus strigosus. 
Conclusion. The southward extension of the coniferous forest of which the 
Adirondack Mountains form a part is found following the plateau region in 
central, and southern New York and northern and western central Pennsyl- 
vania (west of the mountains) about as far south as the 40° of north latitude. 
The coniferous forest belt only extends into the southeastern quarter of Warren 
County Pennsylvania; the northern and western portions Iying beyond the 
Alleghany River show oak, chestnut, hickory ‘. Much the same association of 
species is found in this forest, as in the Adirondack mountain forests. Pinus 
Strobus is dominant here. Upon the best soils various hardwoods grew with 
it. For example at a place in Lycoming County, Pennsylvania near Otter Run 
an astonishingly large number of kinds of trees occurred on a fresh sandy loam 
in mixture with Pinus strobus?). 
pon an area of not more than twenty acres the m species were growing in natural 
forest: Liriodendron tulipifera, Tilia americana, Acer saccharum, Acer rubrum, Prunus pennsyl- 
vanica, Prunus BIN, Nyssa sylvatica, Fraxinus americana, Ulmus fulva, Tizians cinerea, Carya 
anarı, an and poreina (= Hicoria minima, ovata and glabra), Quercus alba, Q. Prinos, Q. rubra, 
tinctoria, Castanea dentata, Fagus americana, Ostrya virginiana, Carpinus caroliniana, Betula 
er Betula lutea, B. lenta, Populus tremuloides, P. grandidentata, Pinus resinosa, P. rigida, 
P. virginiana, Tsuga canadensis?). Pinus Strobus and hemlock are the prevailing trees mingled with 
Acer saccharım, beech and species of Betula, while the herbs are such as grow beneath the 
shade of the dominant forest trees most of which have been mentioned above. Although we 
have treated the Pocono plateau as part of the northern Appalachians, yet with some propriety 
its flora may be considered to be closely similar to that of the great coniferous of the St. Law- 
rence—Great Lake Region. 
2. Atlantic-Gulf Coastal Region. 
The plant formations, which together form the vegetation of the great At- 
lantic coastal plain, occupy soil of a comparatively recent geologic origin, when 
the coastal plain was raised permanently above sea level, for since the beginning 
of Cretaceous time, this country has passed through sererel vicissitudes of history, 
at times being dry land, as it is now, and at times sea bottom. So the shore 
of the sea has öscilläted slowly back and forth across this part of the Atlantic 
plain and gravels, sand and clays have been deposited. Three distinct physio- 
graphic areas are recognizable: the elevated plain, the coastal marshes and the 
1) The counties of Pennsylvania which together form the hemlock-white pine belt are 
Bradford, Tioga, Potter, McKean, Warren, Forest, Elk, Cameron, Jefferson, Clearfield, Indiana, 
Cambria, Somerset and parts of Armstrong, Clinton, Lycoming, Sullivan, while Centre, Susquehanna, 
Lackawanna, parts of Wayne and Monroe were noted for their hemlock woods. 
2) PincHoT, GIFFORD and GRAVES, HENRY $.: The White Pine 1896: 30—3I. 
EEE NETTE 
