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The mission of the San Mateo County Historical Association is to inspire wonder and discovery
of the cultural and natural history of San Mateo County.

Object Record

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Catalog Number 2014.009.016
Description Cardium sp., cockle (clam) fossil dating from between 1.5 million years ago to .75 million years ago commonly found at low tide in littoral (sandy and muddy bottom) or sub-littoral (open bay, muddy marine) zones. Fossil specimen is comprised of two shells sandwiched together. Larger shell on top has distinct growth rings, with sediment filling the spaces between rings. Smaller shell on underside surface also has growth rings, but are not as pronounced. Dark brown sediment fills the space between the two and anchors them together. Both shells are in varied shades of brown and beige. Surrounding sediment also contains smaller shell fragments.
Object Name Shell, Animal
Collection 3D - Paleontology
Title Cardium sp.,Cockle (clam) Fossil, 1.5-.75 Ma
Date 1.5 - .75 Ma
Kingdom Animalia (Animals)
Phylum Mollusca (Molluscs)
Class Bivalvia (Bivalves)
Order Veneroida (bivalve order)
Family Cardiidae (Cockles)
Genus Cardium
Species sp.
Inscription Text none
Provenance Fossils taken from Merced Formation collected at Westborough Boulevard at Highway 280 in the late 1970s or early 1980s. (See Yancey 1978, Fig. 2: Artifacts taken from E Stratified Section/D-5929). Most specimens (especially clams) in this collection are not extinct and can still be found in the Bay Area.
Notes Retired Geologist Ken Lajoie identified on 4/24/2014.
Dimensions H-1.875 W-2.5 D-2 inches
Search Terms Fossils
Shellfish
Merced Formation
South San Francisco
Subjects Fossils
Shells
Shellfish
Marine biology