Flood-plain and the Mound Builders. — Feet. -15 
the flood-plain near Wyalusing, in "Wisconsin, and tliat neither of 
them were very ancient. This, however, cannot be said of the 
village enclosures of Ohio nor of the pyramids of the south, for 
these mounds seem to be now far bej'ond the reach of floods, and 
hence older. 
Still we have this significent fact that there are in the Daven- 
port Academy some elephant pipes and a tablet with some figures 
which resemble elephants. Davenport is near the mouth of the 
DesMoines, not very far from the great Meredosia slough and a 
little south of Muscatine lake. Now these are all surrounded and 
full of the late floods and can perhaps be called the last part, or 
the lowest part, of the flood-plain. No mounds are found on this 
low ground. But it is claimed that the mound from which the 
tablet was taken is on the low ground, which might be considered 
the river bench, only eight feet above high water. Now shall we 
take this as evidence? The members of the academy maintain 
that the elephant pipes are genuine. Shall we put the mounds 
on the river bench back so far as to allow the elephant or the 
mastodon to have been present, or shall we bring the mastodon 
up to the time when the river bench was eighf feet above the 
water and when the elephant eflSgy was frequentl}- submerged? 
Let us see where this will lead us in reference to the other mound 
builders and their antiquit}-. The hunter-tribes of which we are 
now speaking are the very last of the prehistoric mound builders; 
there were other tribes which preceded them by many years, per- 
haps by centuries. We grant the point about the mastodon for 
the sake of the argument. Then it makes the mound builder 
to precede the appearance of flood-plain and the disappearance of 
the mastodon. 
We now turn to the mounds of the flood-plains as compared with 
those on the bluffs. Here we quote from the geological report 
of Minnesota. Mr. Wm. Colvill says, ' ' The Assiniboines, the 
Omahas, the lowas and the Siouxs successively dwelt along the 
river in this county ( Goodhue ). All the mounds on the edge of 
the high bluffs are difl'erent from those of the terraces and those 
on the terraces different from those on the river-bench. All the 
mounds on the river-bench were said b}' the Sioux to belong to 
the Assiniboines. The dwellings were constructed by digging pits 
and placing posts or supports inside and covering the whole 
with brush and earth. In case of death within the dwelling 
