_Age._ Shell-heaps have become intimately associated with the question
of the age of the human race, a question which has passed out of the
domain of the written, into that of geological history. It can only be
satisfactorily answered by following the method of the geologist, when
he attempts to determine the period when a given animal existed in
former geological times, viz., by a careful comparison of the remains
of such animal with those of existing species, and by an accurate study
of the geological and other physical conditions under which they are
found. In Denmark, such methods applied to the _Kjœkkenmœddings_, or
refuse-heaps, have yielded results of great importance to archæology,
and have shown that some of these heaps at least, as in Seeland along
the Isefjord, date back to a period when their geological surroundings
were somewhat different from what they now are, when the shores were
less raised above the sea, and the oysters, of the shells of which the
heaps are made up, had not yet retreated to where the fresher waters of
the Baltic, at the present time, mingle with those of the ocean in the
Kategatt.
The shell-heaps we have here described yield nothing which indicates
as high an antiquity as those of the old world. The materials of them
present some variety in the degree of decomposition which has resulted
from time and exposure, the lower layers being much more disintegrated
and friable, the shells in fact falling to pieces, while those of the
upper ones generally preserve their original firmness. That there was
a difference in time in which these layers were deposited, is further
indicated by the fact, that, in two of the heaps, a stratum of earth is
interposed between the earlier and later deposits, as if the locality
had been abandoned as a camping place, and then after a prolonged
absence of the natives had been reoccupied. Each heap, too, is covered
with a deposit of earth and vegetable mould, of variable thickness, and
in some cases, as at Frenchman’s Bay, supporting a growth of forest
trees, though these were nowhere of such size as to indicate that they
had lived a century. Mr. Morse has called attention to the abundance
of _Helices_, or land snails, which were exhumed at Crouch’s Cove,
and to the fact that these require a hard-wood growth for subsistence,
while at present the island, on which this cove is situated, is covered
with spruces. It is also noticeable that there has been in all the
localities, except at Salisbury, a disintegration of the shores, the
sea undermining and destroying the deposits. There can be no doubt that
these were once much more extensive than now, and that the water has
worked its way into their places. Lastly, these deposits contain the
remains of animals, as of the elk, not known at present to exist to the
eastward of the Alleghany Mountains; of the wild turkey, now virtually
extinct in New England; and of the great auk, which, unless it still
live on some of the small islands to the north of Newfoundland, has
receded almost, if not quite, to the arctic regions.
All these circumstances are certainly signs of the lapse of time.
Nevertheless, in the absence of any positive data as to how long a
period is necessary for the accumulation of vegetable mould, or for the
washing of earth from the slopes above on to the heaps below, or for
the rate of decomposition of shells in a given time, or of the rate
of the denudations of the shores; and in view, too, of the fact that
the animals represented in the heaps, but now no longer met with in
the regions of them, have all disappeared within the historic period
of this continent, it will be readily admitted that proof of great age
or “high antiquity” is not found in any or all the circumstances which
have been mentioned above.
On the other hand, it may be safely said that there is nothing in the
condition of these heaps which is inconsistent with the hypothesis that
they were begun many centuries ago. The examinations at Crouch’s Cove,
Eagle Hill, and Cotuit Port were sufficiently extended to enable us
to obtain a fair representation of the objects they contain; but in
no case was there found, nor have we been able to learn, that there
had been previously found a single article which could be regarded
as having been made by, or derived from the white man, nor did we
obtain any evidence that these particular heaps had been materially
added to since the European has occupied these shores. Had intercourse
with Europeans been once fairly established, it were a reasonable
presumption that we should have found at least a glass bead, a fragment
of earthenware, or an instrument of some sort indicative of the fact,
especially when we bear in mind that it would be in just such places,
where the savages collected around their fires and seething-pots to
cook and eat, that such objects might be expected to be broken or lost.
Finally, if the statements of Williamson on the authority of Johnson be
correct, viz., that “a heavy growth of trees was found on them” (the
deposits of clam-shells near Mount Desert) “by the first settlers,” we
have something like satisfactory evidence that their age could not have
been less than between three or four centuries.