vni THE ANTIQUITY OF MAN IN NORTH AMERICA 437 



The extensive shell heaps of the Aleutian islands have 

 been carefully examined and reported on by Mr. Dall, and are 

 found to exhibit some remarkable and probably unique pecu- 

 liarities. Complete sections were made across several of these, 

 and they were found to consist of a series of distinct layers, 

 each marked by some well-defined characteristics. In the 

 upper layers only are there any mammalian remains, and 

 these may be divided into three subdivisions. In the upper 

 bed there are found seals, walruses, etc., aquatic and land 

 birds, the arctic fox and dog, with well-made weapons and 

 implements, awls, whetstones, needles, and lamps. In the 

 next layer the dog and fox are absent, as are remains of 

 large whales ; and in the lower mammalian layer there are 

 seals and small cetacea only, but no birds or land animals, 

 and the weapons found are ruder. We then come to a con- 

 siderable layer in which there are no mammalian remains 

 whatever, but only fish-bones and molluscan shells, with rude 

 knives, lance heads, etc. Below this is a bottom deposit con- 

 sisting entirely of the shells of echini, and containing no 

 weapons, tools, or implements of any kind, except towards 

 the surface of the layer, where a few hammer stones are 

 found, round pebbles with an indentation on each side for 

 the finger and thumb. Echinus' eggs are now eaten raw by 

 the Aleuts, and it is the only eatable part of the animal. It 

 takes forty or fifty full-sized echini for a meal. Some of the 

 heaps cover five acres, and from a careful estimate founded 

 on experiments, and taking the probable numbers of a colony 

 which could have lived on such a spot, Mr. Dall calculates 

 that it would take about 2200 years to form such an accu- 

 mulation. A similar estimate applied to the upper layers 

 brings the time required for the accumulation of the entire 

 series to 3000 years, but that is on the supposition that they 

 were formed continuously. This, however, was evidently not 

 the case. Each layer indicates a change of inhabitants with 

 different habits and in a somewhat different phase of civilisa- 

 tion, and each such change may imply the lapse of a long 

 period, during which the site was abandoned and no accumu- 

 lation went on. These shell heaps may, therefore, carry us 

 back to a very remote antiquity. 



