Here is a trio of concentrically-zoned chert nodules in Mississippian Castle Reef Dolostone, exposed at Sun River Canyon, Montana, just downstream from the roadside outcrop of the French Thrust: If you look closely at the lowermost of the three chert nodules, you’ll see it’s been split and offset by a small fault. Here are close-up … Read more
Happy Saturday morning, everyone. I’m on my way down to the National Mall for fellow Tribesman Jon Stewart’s “Restoring Sanity” rally, but I thought I would just quickly post a little geological treat for Mountain Beltway readers. These are pisolites (basically like a big oolite, but without the biological component that would qualify them as … Read more
This was brought in last week by a student… It’s a broken concretion that she found in Des Moines County, Iowa, many years ago. She also had a slab of limestone with crinoid columnal fossils, and a broken geode from the same locality. I think this concretion is a thing of beauty, like a fossilized … Read more