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Source area for Leschi erratic?

Reader Wes Gannaway, a paleontologist in Bellingham, suggests the source area for the bivalve-bearing Leschi erratic could be the rocks around Harrison Lake, BC. He has only seen the photos posted here of the fossils in the erratic, so this is remains a hypothesis only, but I think it is a reasonable one. I have started a separate page in the field trips portion of this website just for this erratic, and will add new info to it as we all learn more. That page is here.

Wes wrote:
“The gray siltstones are along the shore of Harrison Lake and contain
an assemblage of ammonites and clams including the Buchia crassicola, which
I believe are the dominant Buchia species at Fossil Creek in the Nooksack
Group. The formation borders on the Cretaceous/Jurassic boundary, age
equivalent to the Nooksack Group. The fossils are abundant in the Mysterious
Creek Formation. C.H. Crickmay wrote a paper in 1930 on the locality. His
paper names them Aucella sp. and Jeletzky named them Buchia, although
I don’t know enough about the species to identify which one is in the
boulder. Aucella is also found in the Jackass Mountain area. Someone with
the knowledge of the species should take a look at the fossils in the
boulder. I am just looking at the photo and using the general shape and rock
color to call it Buchia from Harrison Lake.”

Thanks for that, Wes. Here’s some more information: (ain’t the web wonderful?)
Here’s another blogger’s post about fossil hunting in the Mysterious Creek Formation. And this blog has photos of large Buchia fossils, including this one.


Further web investigation turns up this abstract of a 1983 UBC MSc done by Andrew Arthur on stratigraphy and fossils in the area. If you follow the above link to the thesis abstract, you’ll find a download file of the entire thesis as a pdf. In it are many photos and drawings of fossils, mostly ammonites, found in the Mysterious Creek and related formations.

As a source region for the Leschi erratic, the Harrison Lake area makes good sense. The Vashon ice flowed south right through there. Any paleontologists out there who want to take a crack at this problem?

6 Responses

  1. Buchia are abundant in the Spieden Formation on Spieden Island in the northern San Juans. I found a football sized piece of sandstone with ‘Buchia in Olympia while planting rhodies. The late VS Mallory identified them for me.

    • Is this forum still active? I live in Olympia and found a fossil with imprints that a contributor to The Fossil Forum thought might be Buchia sp.

    • Yes still active Theresa. You found the fossil in an outcrop in Olympia? That would be different. Dave Tucker

  2. I have large rock full of Buchia fossils which my late mom found under a fallen tree in Gig Harbor. It looks very similar to the above photo.
    Here is a photo of it: https://photos.app.goo.gl/3byjY1VKePsKhjw38

    • Jeff,
      Not likely. Gig HArbor sits atop thick glacial till that is far far younger than Buchia. The stone from under the tree is most likely another erratic. DT

  3. Jeff,
    I sent photos of the erratic I found in Olympia to the Burke Museum at the University of Washington. Perhaps you may wish to do the same with your erratic, but they will want a metric ruler in the photo for sizing.
    The Burke curator identified the imprints from my photos as Bucchia sp. The erratic in the photo you uploaded is about the same size as the erratic that I found. My neighbor recently found a much, much larger erratic laying on the ground under a tree. I know this is a geology forum, so apologies for the clutter on non-geology topic, but finding an erratic has motivated me and my neighbor and her kids to learn more about geology and paleontology and paleomagnetism and lateral displacements, etc etc etc.

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