Aside from being one of our great naturalists at the Nature Center, David Brenzel is also an paleontologist and digger of mammoth bones. We were fascinated by his adventures last season and he tells us of the first dig of 2013. It continues to amaze me the things he digs up!
I’m just back from Oskaloosa and our first dig of 2013. A break in the weather allowed us to get the excavator in last week to expand the pit and we didn’t waste any time bringing in a crew to resume digging Saturday. The first outing of a new year is always more about repairing winter damage than finding new bones, and such was the case this time. We expended a lot more effort rebuilding our amphitheater-style stairs in and out of the pit than looking for bone. We did, however, uncover about a dozen new large fragments under the tusk we found last November, and confirmed from a deep test pit that the bone-bearing layer extends at least another foot deeper. The bones aren’t laying flat on a single horizon, demonstrating we are still in the plunge pool where these things were dumped en masse 5,000-odd years ago. Dr. Frank Weirich of the UI Department of Geoscience and College of Engineering will return later this month to resume the search for the primary deposit with his state-of-the-art ground penetrating radar and Dr. Art Bettis, also from UI Geoscience, with his drilling rig.
The really exciting find Saturday was a layer of twigs and branches exposed by spring floods, contemporaneous with the bones and spruce log that we extracted last year. The log was radiocarbon dated to 14,000 B.C. A date on the mammoth itself is expected any day now. (Dating wood is easy; bones are another matter and one has to practice patience waiting in line for a bloke in New Zealand to get to your sample.) It’s not a date we’re after though this time, or more wood, but seeds and leaves. UI Geoscience Professor Emeritus Dick Baker is analyzing our plant macrofossils. He found spruce, larch and fir needles in the last (spruce log) sample and wants more sediment to get a better picture of this ancient ecosystem. Woolly mammoths aren’t supposed to be living in this kind of landscape–this is mastodon and giant sloth country. Woollies are thought to have migrated north with the tree line to find their favored forage of grasses and sedges. But here they are, in a boreal forest. Obviously these guys didn’t read the textbooks. The world has plenty of woolly mammoth bones but undisturbed sites with an entire ancient ecosystem preserved with the bones that can tell us how these beasts lived are as rare. There’s nothing else like it in Iowa. Other scientists can try to learn how and why mammoths died, we want to know how they lived and how these surprisingly modern-looking ecosystems functioned with 8-ton pachyderms tromping about.
To those Nature Center members who came out and helped dig last summer and discovered the second mammoth–yes, we’re going to schedule another outing for members this season. Give us a few weeks to get more of the schedule locked down. We’ll announce a date soon.
See…another great reason to be a member of the Nature Center!