 Hopewell trading networks were quite extensive, with obsidian from the Yellowstone area, copper from Lake Superior, and shells from the Gulf Coast.The Toolesboro Mound Group in Louisa County, Iowa included a large octagonal earthen enclosure that covered several acres; earthworks of this style are reminiscent of the monumental construction seen in Chillicothe and Newark, Ohio.It also has a group of seven burial mounds on a bluff overlooking the Iowa River near where it joins the Mississippi River.