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The mission of the San Mateo County Historical Association is to inspire wonder and discovery
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Object Record

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Catalog Number 2014.009.018
Description Cardium sp., cockle (clam) fossil, 1.5-.75 Ma 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 four cockle shells embedded in sediment. One appears to remain intact, with half of its body exposed and the other half embedded. The partial shell of a second animal surrounds it. Two other cockles are also attached, perpendicular to each other. Shells are different shades of white, with some reddish patches throughout, likely indicating the presence of iron oxide. Growth rings on exposed shells are easily visible.
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.
Cardium sp. (Common name: Cockle Shell) still thrives in the Bay Area.
Dimensions H-2 W-2.875 D-2.5 inches
Search Terms Fossils
Merced Formation
South San Francisco
Subjects Fossils
Marine biology