28 July 2011
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 portraits of all three, concluding with the most interesting one (the deformed one):
Hope all is well with the geoblogosphere. I’m just back to the States after a fruitful sojourn in the Great White North, and I’m looking forward to getting caught up with things in the days to come.