Saturday, 23 January 2016
LINCOLN CREEK FORMATION: EOCENE-OLIGOCENE BORDER
It is a site I return to each year to see the erosion and what new specimens have worked their way to the surface.
The whitish strata consists of tuffaceous siltstone and sandstone with concretionary beds throughout. They are slightly older than originally thought, coming in around 37 million-years, straddling the Eocene-Oligocene border. Here a lovely crab, Pulalius vulgaris, sits in the sand. He would be in good company at the site amongst the more common scaphodpod shells and other wee gastropods.
The whitish aragonitic shells of scaphopods are conical and curved with a planispiral curve, looking a bit like an elephant's tusk, hence their common name. They prefer to live on soft substrates in subtidal zones so they are not as abundant or readily visible on our beaches as their gastropods and bivalves compatriots. Tusk shells and their fossil relatives, however, are found commonly in the sediments at Porter and other localities throughout the Pacific Northwest while crabs are found, but more rare.