1881 .] 
135 
[Haynes. 
tomahawk of North America), merely by their shape and mode 
of fabrication. The term palaeolithic is primarily restricted in 
meaning to such objects as 1 have described, when met with under 
peculiar geological conditions ; that is to say, when found embed- 
ded in the gravels which have been deposited by certain rivers 
during the period known to the geologists as the quaternary or 
pleistocene period. At that time their volume of water was much 
greater than it now is, which was caused by the melting of the great 
ice-cap that once covered the northern portion of both continents, 
accompanied by a climate much more humid than we have at 
present. Such accumulations of gravel are often of very great 
thickness, and embedded in them, side by side with the stone im- 
plements above described, are found the fossil bones of extinct 
species of animals, such as the mammoth, the rhinoceros tichor- 
rhinus, and numerous others, or of animals like the reindeer, or the 
musk-sheep, which have since migrated to the colder regions of the 
north, or which are now restricted to the higher Alpine slopes. 
This leads us to the third question to be considered, viz , the 
localities and geological conditions, under which these New Jersey 
implements have been discovered. Though the objects themselves 
may present the right type, shape, and general appearance, we must 
look carefully at the conditions under which they have been discov- 
ered before we can pronounce judgment as to Avhether they are to 
be regarded as “ palaeolithic implements,” or not. Of course 
when found in gravel beds, accompanied by fossil animal bones, 
no such question can be raised. But since the pleistocene period 
these gravel beds have been subjected to a constant process of 
denudation and removal by the action of the rain and other nat- 
ural causes, with the result that in some localities they have either 
partially or entirely disappeared. The same causes that would 
sweep away the finer and lighter particles would not be power- 
ful enough to affect the heavy palaeolithic implements, which 
would accordingly be left behind. Consequently we sometimes 
find such implements upon the surface in localities where 
the pleistocene gravels are no longer to be seen. Such is the 
case, for example, in the Valley of the Nile, where there are now 
no longer pleistocene deposits, though these occur in the adjacent 
Desert of the Sahara. Yet in the bottoms of the dry ravines or 
