128 HARSHBERGER: PHYTO-GEOGRAPHIC SKETCH 
The angiosperms form about seventy species, which include three 
of Magnolia, four of Lériodendron, three or four of Satz, three of 
Celastrophyllum, one of Celastrus, four or five of Avalia, two of 
Sassafras, one of Cinnamomum, one of Hedera (with leaves that 
are apparently identical with those described by Heer as belonging 
to Andromeda), Cissites, Cornus, Diospyros, Eucalyptus, Ficus, Mex, 
Juglans, Laurus, Menispermites, Myrica, Myrsine, Prunus, Rham- 
nus and others.* 
A statement of the above facts is proof that during the Ter- 
tiary period and up to its close a dense forest existed in north tem- 
perate and arctic latitudes. The northern portion of this forest and 
the tenderer species unable to withstand the nipping frosts were 
exterminated with the advance of the glaciers. South of the great 
terminal moraine, which reaches as far south as the Ohio river, 
but separated from it by a zone tenanted by arctic-alpine plants 
and other boreal species now found on mountain-tops and in the 
Hudsonian and Arctic belts of North America, the original Ter- 
tiary forest, minus such genera as Eucalyptus, Ficus, Cinnamemum, 
etc., persisted, reaching its greatest denseness in the region drained 
by the Tennessee river and its tributaries. One tongue of this 
forest of less denseness probably reached in a northeastward direc- 
tion, as far north as a line following the windings of the west branch 
of the Susquehanna river to the Blue Ridge, thence along the 
Blue Ridge to the Schuylkill river, thence across to the southeast 
side of Great Valley and following the hills on the south side of 
Great Valley to the Delaware river. 
Arbitrarily considered, all of the territory above this line and 
between it and the terminal moraine was a country influenced by 
the glacial cold. All of the country south of it, protected by the 
Allegheny mountains, the Blue Ridge and other ranges of hills to 
the eastward of the Schuylkill river, was covered by a forest com- 
posed in the main of those species of trees, not destroyed by the 
glacial cold, that had existed in this region, and also in the far north 
prior to the advent of the last glacial epoch. Comparing the 
northern remnant of the magnificent Tertiary forest with the south- 
ern remnant of this forest in the region drained by the Tennessee 
* Knowlton, F. H. A catalogue of the Cretaceous and ‘tas plants of North 
America. Bull. U. S. Geol. Surv. No. 152. 1898. 
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