Naturalist David Brenzel has been even busier than usual at the mammoth dig site! They’ve formed an interesting and important theory about our mammoths and he shares it with us. I’ve included a couple of his photos here; all eight are available on our Facebook page.
I’m just back from the Oskaloosa mammoth site–my 5th trip in a month. With school back in session, teacher demand is high to visit the site with students and experience digging first hand. The Indian Hills Community College (Ottumwa) Science Club came September 21. Grinnell College brought their introductory geology class October 5. It was the Cornell College Archaeology Club October 12 with various teachers and naturalists sprinkled throughout. In-between, there’s been a parade of geologists trekking to the site to study the bones and test a new theory about how the mammoths ended up here.
It has been said get three UI geology professors in a room and ask their opinions and you’ll get four, so it’s remarkable Dr’s. Art Bettis, Frank Weirich and Holmes Semken, Jr. have come to consensus about the origin of the bones. The fossil bed has always been noteworthy for its depth of 2+ feet. The bones weren’t buried flat on the ground, some are standing almost straight up! We’ve long assumed they eroded from their primary deposit and were transported to the site in a flood, where they were dumped into a deep pool. But looking at the layers of sediment we exposed in the course of digging over the summer, the professors developed a new theory: that we have discovered a deep ancient spring that drew these elderly woolly mammoths to it to die. Like some professors coincidentally, their teeth were worn, they couldn’t chew very well and were hungry all the time, but at least they weren’t thirsty. So we’re no longer searching for a primary deposit–we’re in it! The new game plan: trace the shoreline of the pool around this ice age spring to find the missing bones. The landowner has multiple springs emerging from the same geological stratum for about 300 feet along his creek. They are all worth checking for fossils.
Last week we hosted a visit by Dr. Chris Widga, assistant curator of geology, Illinois State Museum, and expert on ice age megafauna. He confirmed we’ve discovered three individuals–all woolly mammoths, likely two old bulls and an aging female. That makes the site unique in the Midwest. It’s not unusual to find multiple mammoth remains in a gravel pit, but those bones have been transported a long distance and are far removed from their sites of origin. We know our mammoths lived right here and are buried with the evidence of a wider ice age community. There’s a treasure chest of ecological information here about mammoth times (e.g. seeds, wood, pollen) and years of digging and research fun ahead determining how these incredible beasts lived.