They were made from earth, like dirt and maybe some brush. It depends whether the mound was more burials or buildings (ceremonial ones).
The earth
I think they built mounds for religious purposes and as cemetaries for the dead .
The Mound Builders built mounds of earth and stone
They built mounds so they could worship their god's and burials. Also for other religious purposes.
the building of mounds
They used the mounds as graves and for important ceremonies.
They are earthen mounds.
all over Ohio
The Indian Mound Builders built mounds for elite residential purposes, burials and religious and other ceremonials. The mounds were usually flat-topped pyramids or platform mounds.
They moved dirt! P.S. you guys are idiots
They built mounds out of dirt from the grass lands and they put in valuable stuff to them and traded with other tribes.
The purpose of mound builders was to build religious ceremonial places. The Mayans created.
building mounds such as the serpent mound
I think they built mounds for religious purposes and as cemetaries for the dead .
The Mound Builders built mounds of earth and stone
They built mounds so they could worship their god's and burials. Also for other religious purposes.
Building mounds.
the building of mounds