Carmel Church Day 4

There’s not a great deal to report today, as Tim and I spent most of our time removing overburden to widen the pit; I estimate that we moved a little over two tons of material today. We did uncover a few as-yet unidentified bones, and tried to find the distal end of the rib that we exposed on Tuesday (the long, curved bone above). We couldn’t find the end of the bone, however, because it’s hidden under a large rock (the round object in the center, below):

This actually illustrates an important point quite well about the relationship between the bonebed and the conglomerate. When we first began excavating at Carmel Church, we weren’t sure of the age of the conglomerate. It sits on top of Eocene Nanjemoy Formation, and the bonebed is in the Calvert Formation, so at first we only knew that the conglomerate was somewhere between 14 and 50 million years old. With further excavation, we began to notice relationships like the one shown above, in which large rocks from the conglomerate are sitting on top of fragile bones that have not been reworked. This shows that the conglomerate and the bonebed formed at the same time, and since we know the bonebed is about 14 million years (based on land mammals and diatoms), we know the age of the conglomerate as well.

This entry was posted in Carmel Church Geology, Carmel Church mysticetes, Carmel Church Quarry, Chesapeake Group and tagged . Bookmark the permalink.

2 Responses to Carmel Church Day 4

  1. Doug says:

    Two tons? Sounds like a lot of work. At Lake Manix, all the paleontologist had to do was poke the ground a few times with a knife (i just did a post about it). Of course, he was simply removing fragments, not whale bones!

  2. Alton Dooley says:

    Two tons sounds like a lot, until you realize that that’s only about a cubic meter of clay. A construction crew could have probably done it in well under 30 minutes, but I spend most of my time behind a desk! Of course, making sure we’re not destroying something slows us down too.

    The bonebed is about 7-8 meters below the original ground surface, but it’s been sloped off so we’re approaching it from the side. Even so, there’s a lot of overburden to remove, and the further we go into the hill the thicker the overburden. Last year, we used a backhoe to remove as much as we dared, but that still leaves us with 2-3 feet to remove by hand.

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