Trilobite pygidium mold.
Trilobitten, member of thefossilforum.com says, “Isotelus iowensis pygidium “mold” from the Maquoketa formation, probably Elgin member. Lots of time the carapace is weathered away leaving behind the inflated mold.” However, Trilobiteruss says more… This is the link to the discussion.
Caleb Scheer, our reigning Paleontologist, just weighed in, “The roadcut above the quarry is in the Maquoketa Formation (Elgin member as Trilobitten said). That site in particular contains a lot of Isotelus and Ectenaspis trilobite parts that both exhibit terrace lines (the “crinckles”).”
The Hunt
I was driving around Cherry Grove looking for those quarried iron pits I have been told about (DNR stocks them for fishing) and after not finding them decided to stop and take a look at the 3 road cuts above Rifle Hill Quarry on Cty. 14. These are maybe a couple miles past the Mystery Cave entrance turnoff on #5. After the Cave has a fossil interpretive event, they take people here to hunt and trilos have been found. 🙂
Highly fossilized. LOTS of brachs and bivalves, some cephs, some crinoid sign. Occasional bryozoans and trilos found are almost invariably Isotelus.
Cut #1 going east:
Cut #1 going east–both sides of road.
Cut # 2 on the south side of the road:
On the south side of road just before you start going into the valley.
The rock with trilo bits and pieces in it and a ceph:
Trilo rock and a ceph.
Look for the small tree, that is where I found it. 🙂
The spot–note small tree.
I was just doing a quick walk of the cut and not going through shale or turning rocks. So this was pretty cool!
I then went on to the main cut just above the quarry:
At least a quarter of a mile of excellent hunting!
This is a peak into the quarry from the road. If you get this far, you missed the road cuts. 🙂
Roadside peak into Rifle Hill Quarry.
Happy Hunting!
