68 
Discovery of Stone Implements in [January, 
glaciers and icebergs, and to separate the phenomena into 
the two classes to which they belong. When we do this we 
find, as I have endeavoured to show, that the land-ice came 
down from the north to a certain well-defined line in New 
Jersey and Pennsylvania, and that after it melted hack the 
country was submerged beneath a great expanse of water 
that covered the whole of the lower ground and reached far 
up the flanks of the hills, and that over this icebergs floated 
from the north, and dropped, as they melted, large stones 
brought from far distant ranges. This expanse of water 
was not limited to the area that the land-ice had covered, 
but extended far to the south of it into Virginia. After the 
land-ice retired, or whilst it was retiring, and before the 
country was submerged to such a depth as to permit the 
flotation of icebergs from the north, the upper pebble beds 
containing the stone implements were formed. Dr. Abbott 
has not only obtained his implements from beds that are 
clearly seen to have been spread out before the large blocks 
were scattered over the surface, but in one instance took 
one from the gravel below one of the large stones. From 
Mr. Wallace’s description his discoveries appear to have 
been made in gravels of the same age. 
West of the Appalachians the evidence all points to the 
same conclusion. We have in the Northern States, first, 
glaciated rock-surfaces and patches of till that witness the 
reign of land-ice ; then we have on its retirement a land- 
surface, with remains of vegetation (peat and forest beds) 
and of extindt mammals. Along with the latter at some 
places, at the same horizon in others, have been found the 
bones and implements of man, as I have described at the 
commencement of this paper. The next stage is marked by 
widespread beds of gravel or rolled drift, that indicate the 
rising of the water. The gravel is covered with brown clay 
containing great far-transported boulders, witnessing the 
submergence of nearly the whole country beneath the flood. 
This brown clay covers the land everywhere in the States 
of Illinois, Iowa, Kansas, and Nebraska, and I have traced 
it myself up to the flanks of the Rocky Mountains. It 
marks as surely the culmination of the great flood as the 
beds that follow it, the loess, mark its subsidence ; when the 
waters that had before covered the hills began to be confined 
to the valleys of the great rivers. From this time the 
mammoth, the megalonyx, the megatherium, the mylodon, 
the horse (until it was re-introduced from Europe), the 
gigantic beaver, and the lion were no more seen alive 
in North America, for their remains are not found in 
