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Friday, September 7, 2012

Digging for Trilobites at Spence Gulch

Over Labor Day we had another trip to Bear Lake.  Since I've been on somewhat of a fossil kick lately, I dragged everyone up to Spence Gulch in Idaho.  Ok- dragged isn't quite realistic.  Everybody was interested and volunteered to come. We drove north from Garden City for about half an hour, turned off on the Lanark Road, then turned west again on Mill Farm Road.  When we got to Dutch Flat we turned north on Road 939.  A little way down the road we parked, then hiked down the drainage looking for a huge cutbank.  Bingo.
After a short hike, we found the huge outcropping of Spence Shale.  This shale bed contains a high concentration of fossils and was first identified here in Spence Gulch. 
The biggest challenge I found at Spence Gulch was the rock quality is very poor.  There are lots of fractures and getting out large pieces to split is tough to do.  It's a tough balance- it's easy to find and get to, it has fairly abundant and interesting fossils, but the rock quality isn't very good.  We dug, splitted, and looked for trilobites for probably about 2 hours and came home with some pretty cool looking ones.  I need to brush up on my trilobite identification- all I know is these ones have spiny bodies and look cool. 
Here's one of the trilobites we found.  The spiny body is really cool.
This one is a different species. 
We also found countless fossils like this one.  We wondered if they were leaves, or what.  It's a hyolith, an extinct mollusk with a cone-shaped shell.  They're pretty common at some sites like this one. 
Here's a few more pictures of some of the trilobites.  It was interesting how you could spend 10 minutes splitting a chunk of shale and not find any complete fossils, but then be working on extracting another piece and have a great looking one fall out of the rubble. 

Nearest City: Liberty, ID
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  1. Awesome! Love the spines. We'll keep a lookout for you at Causey tomorrow.

  2. We went to this site in August of 2013. People have been digging at the base of the big cliff and off to the North (right side as you face the cliff). The pits are now back far enough that the shale is less fractured and has better plates. We got a lot of great specimens. It was especially productive to go through the tailings left from previous diggers, as weathering for a year or two splits the shale gently and reveals a lot more specimens. Definitely worth a re-visit if you haven't been there in a while.
    Sincerely, the Carr Family - Greg and Gloria.