MAMMALIA. 
1 2 
A large number of the Adirondack lakes are heavily bordered 
with a dense frontage of arbor vitae (here called “white cedar”), 
which so overhangs the water that the lower limbs barely clear 
the surface. Around many of these lakes all the lower branches, 
up to a certain height, are dead, so that on viewing the shore 
one is struck with the strange appearance of a sharp cut line, about 
the height of a man’s head, extending partly, or entirely, around the 
lake. Above it the dense foliage presents an almost continuous and 
unbroken front, impenetrable to the eye, while below it not a green 
sprig can be seen, the dead limbs and branches remaining in the 
form of a broad belt. 
The cause of this phenomenon long remained a mystery, and many 
and amusing theories have been advanced for its explanation. It 
has been supposed that some unusual and unknown agency operated 
to produce a great overflow of these lakes, and that the present green 
line indicates the high-water mark of this unrecorded inundation, the 
branches below it having been killed by the water or ice. Were there 
no other reasons for disbelieving this hypothesis, its absurdity is de- 
monstrated by the fact that on many of the larger lakes the line is 
confined to one side. The only other theory, so far as I am aware, 
that is worthy of refutation, was advanced by no less distinguished a 
gentleman than Mr. Verplanck Colvin, Superintendent of the Adiron- 
dack Survey. Mr. Colvin’s theory is, that the snow which is blown 
off from the ice, on some of the larger lakes, and is sometimes piled 
in drifts in certain places along the borders, buries the lower limbs 
of the cedars; and he thinks that this snow “ in some unfavorable 
season, becoming compact and icy, had killed the enclosed evergreen 
foliage.”* * The fallacy of this view is proven, I think, by the follow- 
ing facts : ist, branches on the opposite or shore side of these very 
the leaves and stems of the “ bunch berry” or dwarf cornel ( Cornus Canadensis ), a small amount of 
wintergreen ( Gaultheria procumbent), and a few leaf-stems of the mountain ash ( Pyrus Americana) 
while throughout the mass were scattered numbers of beech-nuts with the shucks on. 
* Report of Adirondack Survey, 1SS0, p. 162. 
