Sunday, April 12, 2020

Clallam Formation and Vertipecten fucanus (Dall, 1900)

I had a bit of a hike on a closed logging road to access a steep slope. The road cut into the slope has a few small scale slumps exposing the underlying sandstone of the Clallam Formation.


The Clallam Formation is on north coast of the Olympic Peninsula along the shore of the Strait of Juan de Fuca from Slip Point on the east end of Clallam Bay to Pillar Point. The sandstone dominated formation forms a slight outward bulge of the coast line with steep bedrock cliffs down to a bedrock platform shoreline. I did not have the opportunity to get out along the shore. The cliffs and tidal platform were an early attraction for geologists and in particular paleontologists because the abundant well preserved fossils in the formation. William Healey Dall (https://en.wikipedia.org/wiki/William_Healey_Dall) spent time on this coast and described many of the mollusk fossils.

While I was not able to visit the shore, I did get to examine the rock on the road cuts and slumps I passed, and I readily found fossils.



Finding the well preserved fossil, I turned to Addicott, 1976 to see if I could identify the find. Addicott notes that Vertipecten fucanus (Dall, 1900) is the most characteristic mollusk in assemblages from the Clallam Formation. Given that I observed this fossil in most of the outcrops I looked at, I can back that up.

For non paleontologists, you could simply call these big scallops. Once upon a time I taught a paleontology lab class. I was always just a day ahead of the students and since then much of what I learned leaked out of my head. However, I have always had an appreciation for the detailed work of paleontologists and Addicott's detailed report help me understand the formation I was exploring.    

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