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!

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