THOMAS. ] MOUND CONTAINING VAULT. 31 
Without further discussion of this group, which, as before intimated, 
presents, so far as the mounds are concerned, some features which ap- 
pear to ally the latter to one class of burial mounds found in Wisconsin, 
we will now refer to some other works of this district explored by the 
Bureau assistants. 
On the land owned by Mr. Fish, in Iowa, near the Mississippi River, a 
short distance below where the Little Iowa joins it, is a group of mounds 
placed on the crest of a ridge running parallel with the former stream 
about one-fourth of a mile therefrom. There are in all about thirty of 
these mounds, circular in form, and varying from 20 to 40 feet in diameter. 
These are all burial mounds, but one singular feature observed is that 
those on the higher sandy ground, although about the same size and 
haviug cores of clay similar to those on the firm clay portion of the 
ridge, have a layer of sand, some two feet or more added to them, yet 
when opened the contents and mode of construction of the two classes 
were found to be the same, to wit, a layer of hard clay covering de- 
caying human bones, fragments of pottery, and rude stone implements. 
There were generally two or more skeletons in a mound, which were 
placed horizontally side by side on the natural surface of the ground. 
Upon the terrace below the group were found the remnants of a row 
of comparatively large burial mounds. A railroad line having been 
carried along here, the larger portion of these works were destroyed; 
still, enough remained to show that the height varied fiom 6 to 15 feet, 
that they were composed chiefly of sandy loam similar to that around 
them, and that each had a hard central core of clay mixed with ashes, 
usually covering but a single skeleton. The relics found in them when 
opened consisted chiefly of stone axes, arrow and spear heads, and a 
few copper celts. In one, which was 32 feet in diameter and 8 feet high 
and less injured than the others, was a circular vault, walled as repre- 
sented in Fig. 8. This was built of flat, unworked stones, laid up 
4, 
SOF er a- 

RLS > RIOR 
Fic. 8.—Section of mound showing stone vault (Iowa). 
without mortar, gradually lessening as it ascended, and covered at the 
top by a single flat stone. In it was a single skeleton in a squatting 
posture, with which was a small earthen vase of globular form. 
A singular fact was observed in a group near the town of Peru, 
Dubuque County. This group is situated on a dry, sandy bench or 
