Rockin the Rockies

Rockin the Rockies
Stowe Mtn

Friday, December 7, 2012

Fossils in the Pierre Shale of Colorado Springs

I'm not sure fossils have a place in a rock hounding blog, but I guess they are rocks after all.  Today was too nice to sit home (55F) and study, so I decided to try my hand at finding baculites (late Cretaceous) and anything else preserved in the Pierre shale see:(http://en.wikipedia.org/wiki/Pierre_Shale). As I recall from High School Latin class the word for stick is Baculum. My magister threatened me with a baculum or made me bring crustula the next day if I got the answer wrong in Latin class. Latin must be the origin of the naming convention for baculites as they are long slender stick-like fossils. I have found baculites in outcrops of shale along Fountain Creek before, and having not visiting this favorite site for over a year I decided to give it a try. I have a couple sites that I let erosion do the work and I just stop by once a year hoping to collect some fossils. The creek is usually quite low this time of year, so I can get access to spots that are otherwise difficult. The particular shale cliff I visited today faces west and north. The west side is dry and crumbly but the north side is moist and almost impossible to get anything out of the shale whole(shady and wet). As I approached the site I noticed someone had been busy tearing down the shale. A fellow fossil hunter left me a nice metal sign post to do some tearing down of my own. Care must be taken when peeling back the shale so as not to bury yourself.  This particular site had an overhang of about 15 feet, so I used some care so that I wouldn't become one of the resident fossils. Not all of the shale has fossils, but this particular spot seems quite fossiliferous. Despite others working the area, I soon found a prize in the shale wall about 9 feet off the ground. I used the metal sign post that someone else left and helped myself. I used to gather a few of these specimens every time I visited this site and then put one or two up for silent auction at our club meetings. When nice 75M year old specimens enclosed in their original nacre sold for less than $5 I decided I'd rather keep the fossils than let them go for that cheap. A friend of mine has gone to Baculite Mesa NE of Pueblo, but he has never found any baculites with the nacre shell still in place. In past years I've found Jeletzkytes here as well. Cleaning the baculites is always a dance between getting rid of the dirt to see the nacre and sutures for identification and preserving the nacre, as it is very crumbly. Here are my pictures of today's hunt.
Geese enjoying a warm December day



Baculite fresh out of the Pierre Shale, about 7 inches in length

Cleaned baculite with nacre
A Jeletzkyte encased in Pierre Shale
Not sure what this is, maybe a coral or worm burrow
Another Jeletzkyte, not sure of exact name
Shells and other oddities found in the Pierre Shale