Wednesday, September 8, 2010

Herpetocetus skull #3, part 3 - Excavation, Day 2

The next day I returned to the locality, and with the help of my buddy Chris Pirrone, we finished undercutting the pedestal; due to the extreme cohesiveness of the sediment, we were able to undercut the pedestal by 3 inches on all sides - which is generally a rare opportunity; with many other fossiliferous units I've worked in, the side of the pedestal would collapse or calve off into the trench.
Within two hours of arriving, we were ready to begin the jacketing process. Above, you can see the top jacket.

Here's a view from the top of the cliff of the plaster jacket and the hole. You can definitely see that with the size of the hole, I was prepared for something sticking further into the cliff.
Soon after, we flipped the jacket over and I began removing excess rock from the base of the pedestal. After removing several inches, I used a jigsaw to cut off the plaster 'lip' that was left from the base of the pedestal.
Chris Pirrone, with the jacket.
And finally, myself with said jacket. I have more pictures of the completed jacket, but they would give away the location, which I'm not terribly keen on doing. All in all, this excavation totaled about 8 hours. By comparison, the well preserved Herpetocetus bramblei skull I collected nearby in 2007 took about 12 hours of excavation, and four hours of jacket transport. Thanks to the much more convenient location of this fossil, jacket removal and transport took a total of two and a half minutes; the tide was way out, so we were able to walk (comfortably) with the jacket to a conveniently placed set of stairs, and then up. The battle Chris and I waged in July 2007 to get the other Herpetocetus skull off the beach is quite a story, and one that I don't think I've detailed here previously.

Anyway, as I probably already mentioned, this specimen includes the first complete rostrum of
a Herpetocetus ever collected, and will feature prominently in my future studies of this enigmatic fossil mysticete.

3 comments:

Meredith said...

Very cool. Can't wait to see the prepared skull.

Robert Boessenecker said...

Hey Meredith! I'll be posting pictures of the skull under preparation soon. Although the anterior rostrum is damn beautiful, the posterior 'face' is chopped up by a bunch of parallel, en echelon fractures.

Meredith said...

Hmm. If I ever get around to flipping my whale skull to do the dorsal side maybe we can brainstorm on how to get the pieces back together. I have a feeling it will be similarly messed up.