No. 385.] FORESTRY AND GEOLOGY. 3 
It was from this point of view that investigations were com- 
menced, and as they proceeded it became more and more appar- 
ent that not only were the two great classes of angiosperms 
and gymnosperms strongly identified with certain geologic 
formations, but also that the distribution of many species within 
each of the zones was capable of being similarly identified, and 
their limits more or less accurately defined. 
This line of investigation could, of course, be almost indefi- 
nitely extended, so as to include a much larger number of 
species, and if the entire flora of the state could be written up 
from the same standpoint, an exceedingly interesting contribu- 
tion would result. If, further than this, the investigation could 
be made to cover a natural geologic area, instead of an artificial 
political one, the value of the work would be correspondingly 
enhanced. 
The above-mentioned facts having been recognized by pre- 
liminary exploration, steps towards more detailed investigation 
were taken by traversing the state in a series of routes as nearly 
as possible at right angles to the trend of the geologic out- 
crops, thus crossing these in succession and noting whatever 
changes in the vegetation were apparent from place to place. 
In pursuing the investigations in this manner the following 
facts were ascertained: 
If an irregular line be drawn between Woodbridge and 
Trenton, and a similar one between Eatontown and Salem, the 
typical deciduous zone will be found to lie north of the former, 
and the typical coniferous zone south of the latter, while be- 
tween the two is an area about sixteen miles wide, which may 
be termed the “tension zone,” because it is there that the two 
floras meet and overlap, producing a constant state of strain or 
tension in the struggle for advantage.} 
Within the limits of the deciduous and coniferous zones the 
conditions are more or less uniform ; the typical or characteristic 
species in each have become firmly established in the environ- 
ment most favorable to their growth, or unfavorable for others, 
1 An excellent general discussion of floral tensions may be found in Mr. Con- 
way MacMillan’s Metaspermz of the Minnesota Valley, pp. 594-600, Refts. Geol. 
and Nat. Hist. Sur., Minn. Botanical Series I 892. 
