(AP and staff) - A conservancy group has successfully bid on a privately-held prehistoric American Indian Hopewell earthwork site in Ohio after the land was put up for auction.

Arc of Appalachia launched a fundraising campaign two weeks ago to save the earthworks outside of Chillicothe from possible development.  The group bid $650,000 for the nearly 90 acres of land after coming to the auction with $350,000 in secured pledges. 

The earthworks, known as the Junction Group, consist of a number of mounds, four full circles, three partial circles and two almost square enclosures - including Ohio’s only known quatrefoil, a four-leaf clover shaped enclosure.

The site, which is now mostly plowed down to ground level but whose subsurface features are very clear to sensors, was most likely used for ceremonies and as a gathering place.  

Arc of Appalachia succeeded with a similar campaign a few years ago to buy a hilltop earthwork near Bourneville.  

Ross County had more than two dozen Hopewell earthworks, but only five are now part of a national park, one is cooperatively managed, and only one has been reconstructed.

Experts use modern remote sensors to uncover far more about them without disturbing them, than excavations could.