We had a small crew today, as Laura is away for a few days while Christina and Ashley spent the day at a SAGE workshop. Sam, Chip, and I spent the day at the quarry and made a lot of progress.
One of the first bones we removed today was a rather large cervical vertebra (top). This was pressed up directly against one of the big rocks, and was completely shattered and somewhat deformed, to the point that we’ll probably never be able to completely repair it.
We’ve found several strange bones on this trip that I haven’t been able to identify as even coming from whales. Here’s today’s strange, unidentified bone installment:
Chip exposed more of a rib he found yesterday, and uncovered a possible second rib (marked in red, below):
We also made an important observation about the boulders. The image below is a closeup of a vertical section through the bottom of the Calvert (the scale bar is standing on end):
Here’s a marked-up version of the same image:
Large boulders are outlined in light blue, “normal” Calvert Formation in red, and Eocene Nanjemoy Formation in dark blue, while the black hashed area is obscured by debris.
One question we’ve had about the giant boulders is when exactly they were deposited on the sea floor. Several of the ones we’ve looked at so far are sitting directly on the Nanjemoy Formation (like the one on the left of the image above). That means it could have been deposited anytime between 50 million and 14 million years ago; not exactly a precision estimate! But in the photo above notice that the boulder in the middle is both overlain and underlain by Calvert Formation, suggesting that they were deposited at the same time around 14 million years ago. Over the next week we’ll be looking under additional boulders to try and verify this observation.