Tag Archives: book cliffs

Dinosaur in a Cliff II

After two weeks of sawing and jackhammering, the team has cleared the sandstone ledge from above the quarry face.  This is always the moment when the real excitement begins… what’s actually buried here?  Something amazing?  Just a few ribs or frags?  Our first exposed elements consist of a limb bone and several ribs.  The best parts are the patches of skin impressions scattered here and there among the bones.

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NCSU graduate student Tyler Bridges collects skin impression samples for analysis. Several ribs are exposed in the foreground.

Exposed skin impressions were one of the reasons we went after the specimen, despite the cliff.  Where there’s skin, there’s usually good preservation, and good preservation means there’s likely to be good scientific data.  Much remains to be learned about skin preservation in the fossil record, which is a line of research being pursued by several NCSU graduate students.  From a taxonomists perspective, the dinosaurs of this age and region are important.  Most of them no doubt represent new species.

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As the summer excavations draw to a close, we hope to learn more about which bones were recovered.  The fruits of this summer will be prepared in the CNCC lab over the coming year.  We’ll keep you posted on the research.  In the meantime, the team is happy to be done with the jackhammer until next time!

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Dinosaur in a Cliff

Removing the bones of long dead animals from their rocky tombs is never an easy task, but sometimes the magnitude of what we’re doing really hits home.  On May 24th we met up with our friends and colleagues at Colorado Northern Community College (CNCC) to excavate a rather difficult site: a duck bill dinosaur buried in the middle of a 20 foot channel sandstone in the Upper Cretaceous Mesa Verde Group.  We teamed up with CNCC to lend them a helping hand since they had a summer field course they wanted to run at this site and in order for the students to actually dig up bone, we had to first plow through a 10 foot ledge of sandstone overburden.

The white plaster caps mark the level where the dinosaur bones are buried.  First job, clear all the sandstone on top!
The white plaster caps mark the level where the dinosaur bones are buried. First job, clear all the sandstone on top!

Typically removing overburden only requires hand tools (picks and shovels).  Sometimes we speed things up with a jackhammer, especially when the surrounding matrix gets too hard to pick through.  With sandstone, there aren’t many options, power tools are the only real way to go.  In this case, we used a jackhammer to plow through the ledge about 1-2 feet per day.

Even with a jackhammer, it was SLOW going.
Even with a jackhammer, it was SLOW going.

The other useful technique, especially when we get closer to the bone bearing layer, is using a rock saw to cut blocks and chiseling or picking them out.  This reduces the vibration on the bone as we get closer.

The quarry face is dropping.
The quarry face is dropping.
Cut block and chisel method, working well just above the bone layer.
Cut block and chisel method, working well just above the bone layer.
The team and the quarry back wall at the end of week 1.
The team and the quarry back wall at the end of week 1.

At the end of week 1, we’re still only half way there!

River Crossing

Driving down from the top of the cliffs on the last day in the western canyon we were greeted by a a reminder… we were far from the first people to explore this rugged terrain.  Just on the other side of the river crossing, we spotted a series of pictographs, painted images left on the rock cliffs by the native americans who inhabited this area.  I couldn’t help but wonder from the artwork if this same spot has been the place to cross the river for hundreds, and perhaps thousands of years.

Three people and three canoes (below)… feel like crossing a river?

Stormy Mountain

This afternoon we were hit by a massive thunderstorm. I was happily scampering about on the edge of a road cut when Bucky came pealing down the road shouting that the sky was falling (literally) and we better get off the mountain. We loaded the gear, I jumped on the back and we took off. Within seconds the skies opened and we were pelted with sheets of rain, high winds, and 10 minutes later… pea sized hail. unbelievable. Bucky did a stellar job, especially because we were loaded up with three people now that we are short one ATV. I took a backseat on this one, being the lightest to sit over the axle. This worked out well because I was able to take an awesome video of the lunatic ride down the mountain in the storm.

I will upload the video later but here are some photos.

The hail.

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Made it across the river.

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The scariest part–the hill that where our crewmember flipped his ATV last week. The hill is made of Mancos Shale, a rock that was deposited when a shallow seaway covered this area around 90 million years ago. When this stuff gets wet, it can be very slick.

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This is one of the reasons we were racing down the mountain, to get across this hill before it became impassable. In the end we all made it ok. This morning we head back up the mountain to put plaster caps on the bones we found. Collecting them will have to wait until next year!

Paydirt

This morning we spent three hours pulling the lost ATV up the cliff. The good news is, it was still drivable and we were able to get it back to camp, sort of in one piece. The handle bars and the frame are bent up so this one is out of commission.

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Nonetheless, one rider down, we trudged on. We stopped to prospect a basin with spectacular views.

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After several hours of prospecting we finally hit paucity–an area of the basin with ancient river channels and overbank deposits. Inside of these sediments we found lots of bone: turtle, dinosaur, and crocodile. The bone was a rare and beatific shade of peach on the outside and black on the inside. Here’s a shot of a pelvic bone from a plant eating dinosaur sticking out from beneath a sandstone.

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Jack and Jill

We were into some pretty heavy riding today. One of our crew lost control of his ATV and rolled it down a very large hill and into the river. He was pinned under for at least one roll, but the good news is that he escaped with minor injuries–mostly bruising–no breaks. Tomorrow we have to figure out how to salvage the ATV (if possible). Stay tuned.