Day #35 Deskcrop: Fossiliferous Packstone

After a string of igneous rocks it’s time to mix things up a bit and go sedimentary on you for a change. Today’s featured deskcrop is a fossiliferous limestone that I collected at the base of the Mississippian Muleshoe Mound in the Sacramento Mountains near Alamagordo, New Mexico during a spring break field trip led by University of Wisconsin carbonate sedimentologists Lloyd Pray and Toni Simo during my first year as a grad student at UW-Madison. I’m invoking the Dunham classification scheme to label this a “fossiliferous packstone” but I’d be glad to be corrected if any of my more sedimetarily inclined colleagues sees fit to do so. I can tell you that the most prominent fossils in this sample are the cyllindrical crinoid stems that appear throughout the muddy matrix of this rock.

Fossiliferous Packstone

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