While walking dry runs in the Waukon Junction in Allamakee County, Iowa, a few years ago, I found this oddball cobble mixed in with the usual local chert and dolostone on a hillside. Already knowing that isolated patches of glacial till existed in the area, I carried the out-of-place rock home with me. It turned out to be a chunk of BIF (Branded Iron Formation), a unique type of sedimentary rock that formed in the Precambrian Era of Earth's early history. BIF formed in long-vanished oceans about two billion years ago and is composed of thin, alternating bands of red jasper and gray hematite. Vast deposits exit in the Lake Superior region and are mined for their iron contact.

Ice Age glaciers carried this piece from Northern Minnesota and dropped it on the hillside when the ice melted. The scratches and grooves in the hard stone are a testament to the brutal forces of the ice and being crushed against other stones during its long-frozen journey.