8 August 2012
Armored mud balls
Posted by Callan Bentley
At Devil’s Coulee in Alberta, there are dinosaur bones and Western Interior Seaway clamshell fossils — yawn.
What really got me excited, though, were the armored mud balls!
This phenomenon is as intuitive as it is bizarre. After a big rain, a glob of sticky, self-cohesive mud gets weathered out of the badlands. The globule goes tumbling down hill, where it encounters pebbles. The pebbles (and strands of grass, and grasshoppers, I suppose) stick to (and are partially mashed into) the exterior of the mud ball.
Eventually, it can attain a nice layer of exterior “armor” like an Ankylosaur. Here’s a different view (rotated a bit in perspective, and zoomed in) on that same armored mudball… Note the mudcracks!
A parting shot: two for one!
This was my first time seeing real live armored mud balls in the field. It was a thrill and a half!
Callan Bentley is Associate Professor of Geology at Piedmont Virginia Community College in Charlottesville, Virginia. He is a Fellow of the Geological Society of America. For his work on this blog, the National Association of Geoscience Teachers recognized him with the James Shea Award. He has also won the Outstanding Faculty Award from the State Council on Higher Education in Virginia, and the Biggs Award for Excellence in Geoscience Teaching from the Geoscience Education Division of the Geological Society of America. In previous years, Callan served as a contributing editor at EARTH magazine, President of the Geological Society of Washington and President the Geo2YC division of NAGT.
Crikey! Talk about ships passing in the night: I was working about 15 minutes away from Devil’s Coulee the entire month of June! My colleague and I visited the coulee on June 16. I don’t recall seeing any armoured mud balls; mind you, I wasn’t particularly looking for them, either! I was impressed enough by all the dino egg shell fragments all over the place.
We were there on the 9th. A week apart!