50 Tlie American Geologist. juiy. i89i 
As to the beginning of tlie moiincl-lniikler period we will give 
a few facts. In -the last number of the Poimlar Science Monthly 
Mr. J. F. James has given us a diagram of the old ice dam and 
of the lake Ohio which was caused b}- the glacier which is sup- 
posed to have crossed the channel of the river here. Now there 
ma}' be a difference of opinion about this lake and the dam, and 
3'et there is a significance to the map. It is a map of the territory 
of the village mound builders^ the most interesting class of mound 
builders which we have. Of course this does not prove much in 
reference to their age, and yet the limits of their territory and of 
the so-called lake are the same. Here we place the i-eign of the 
mound builders. If the paleolithic people preceded the forma- 
tion of the lake, or were cotemporar}' with it, the neolithic cop- 
per-using mound builders were subsequent to it. If the Indians 
of the hunter class were subsequent to the appearance of the bot- 
tom lands while the Hood plains had become what the}' are, the 
village mound Iniilders preceded them by many j'ears. In this 
way we read dates into our Archaeological records. We have the 
limits marked li}' geological changes. 
The close of the mound building period. Dr. Thomas has investi- 
gated a mound in the Scioto valle}' which was swept by the floods. 
.This mound is near a series of earth works which are called 
the Baum works situated on the lower land in the vicinit}' of 
Chilicothe, Ohio. The argument is that as this mound was so 
near the village enclosure, and as it contained some peculiar 
chambers which resemble the rotundas of the Cherokees, the vil- 
lage mound l)uilders were Cherokees, a coraparativeh' modern 
people. This, however, is the verv point which we doubt. The 
evidence is that Ohio was overrun b}' a succession of races or 
tril)es and that the early race of sun-worshippers who Iniilt walled 
villages and graded ways and dance circles, and sacred enclosures 
for burials, never placed their mounds on the flood-plain, l)ut al- 
ways on the upper terraces ; but the Cherokees having been a 
later race would naturally place their works as did all late tribes 
on or near the flood-plains. 
Tlie growth of the flood-plain in this locality seems to have 
been at the expense of the terrace on which the majority of the 
village mound builders placed their enclosures, and so the de- 
struction of the terrace may l)e regarded as a measure of the time 
which has elapsed since the villages were deserted. We find the 
