VII.
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.