Spence Gulch Trilobite Trip

John has had trilobites on the brain recently. Seriously.

I realize that I never really wrote about our trilobite collecting trip to Spence Gulch, Idaho, so I thought I would fill you in. We did find the site. As I mentioned before, Spence Gulch is located in southeastern Idaho (see map below) near the town of Liberty, Idaho. We originally found out about the site from the Geo-Tools website. We knew the land is on National Forest Service property, so that was one good thing to find out, as far as invertebrate fossil collecting goes (you do not need a permit as long as you are collection common invertebrate fossils for non-commercial purposes only). Google earth showed us where we wanted to go (also see below), thanks to someone else marking the map. Once we found the right road to turn off of, it was reasonably easy to find.


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The Spence Shale (Lead Bell Shale Member of the Langston Formation) is exposed in a stream cutbank. While we were there the stream was dry. It is easy to see from an aerial photo but is not visible from the road. Once you see it though, you know you are there.
We collected for two days and did pretty well. All of the fossils we collected are now housed in the Museum of Western Colorado's paleontology collections. The trilobites we collected include:

• Peronopsis sp.
• Pagetia clytia
• Zacanthoides idahoensis
• Zacanthoides serratus
• Athabaskia bithus
• Oryctocare geikei
• Amecephalus idahoensis
  
• Achlysopsis sp.
  

The agnostoid trilobites Peronopsis and Pagetia dominated our finds (over 75% of what we found). The non-agnostoid Zacanthoides idahoensis (picture below right) was the most abundant, followed by Amecephalus idahoensis (picture above right))

Other fossils collected include:

• Brachiopods -
  Lingulella eucharis, Acrotreta sp., and Wimanella sp.
• Hyoliths - Hyolithes sp.
• Echinoderm - Gogia palmeri
  

Feel free to take a look at my pictures from that trip here.

















A big thanks to my husband who identified all of these bugs and did the bulk of the work!