|An artist’s depiction of the Monks Mound is found within the interpretive center at Cahokia Mounds State Park in Collinsville, Illinois.
Researchers say their new study of the soil in the mound, which began collapsing in 2005, shows that the presence of annual plant seeds and spores, as opposed to perennials, shows the mound was probably built within a few decades. The workers got the soil and sediments from a nearby borrow pit (an area where material like soil, gravel or sand has been dug up for use at another location). Archaeologists surmise that workers got soil from a nearby borrow pit and used it to build the mound. They did so without wheels or beasts of burden, carrying the soil by hand.
The team, led by Dr. Neal Lopinot of Missouri State University, took advantage of the collapse in 2005 and took samples from 22 exposed areas of the mound to study sediments from the floodplain used in constructing it. Apart from remains of perennial plants used for food, they found seeds and spores from wild annual plants that grow once and then die. They concluded from this that the borrow pits where the soil was taken were disturbed frequently.
|Monks Mound with reconstructed stairs in a 2007 photo; repairs done to the mound at Cahokia in 2005 shored up the mound and kept it from further collapse.
In 2005 experts did emergency, high-tech repairs to the mound to shore it up. The completed repairs have saved Monks Mound from further collapse. It took intelligence to build it to last over 1,000 years without modern technology.
Compiled by Dr. Neil Gale, Ph.D.