Scallop imprint found on beach:
Scallop imprint found on beach:
Point Loma is part of the Point Loma Formation, near the coastline of San Diego. According to the second citation, “The massive, ungraded sandstones in the Point Loma Formation have sharp upper and lower contacts, thick lenses of mudstone clasts, and common load-deformation structures, suggesting deposition largely by grain-flow processes.”
The Upper Cretaceous strata in the Point Loma formation contain abundant trace fossils of the species Qphiomorpha and Thalassinoides, which suggest that the area was a shallow sea during the Cretaceous Period.
According to The Fossil Forum (Citation 1), “Towards San Diego, get off at the Tecolate Road/Sea World exit. Proceed west on Sea World Drive — past Sea World, it becomes Sunset Cliffs Blvd. Drive to the end of Sunset Cliffs and park in the lot for Sunset Cliffs Park. Look along the top of the sea cliff.”
Gary Kindel, “Fossil Collecting Sites in North America,” (Digital Rockhound’s Companion Site 2009) http://www.digitalrockhound.blogspot.com
Philip Kern et al, “Trace Fossils and Bathymetry of the Upper Cretaceous Point Loma Formation, San Diego, California,” (San Diego State U, Rice U 1974) http://gsabulletin.gsapubs.org/content/85/6/893.abstract
Geology: The fossiliferous layers are part of an unnamed Pleistocene formation. Once you park, walk down to the beach and look for the sedimentary rocks on the beach cliff. However, the geology of the area should be similar to the Monterey formation which contains both Gaviota Beach, and Jalama Beach.
Fossils: The layers of sandstone contain marine assemblages from the Pleistocene epoch.
Geology of the Area: Centerville Beach is part of the Rio Dell Formation, giving it very similar geological history to the Scotia Bluffs nearby. The sedimentary rocks were once a mud rich layer that was deposited on the edges of a shallow sea during the Pleistocene epoch. Look for layers of grey unconsolidated mud, which will be fossiliferous and have shell fossils protruding from the surface. Low tide is the best time to look for fossils on a beach.
Paleontology/ Fossils Found: Moon Snail, Giant Pacific Scallop, Clam, Pandora shell, Cockle, Snail, Channeled Dogwinkle, and other fossils can be easily found on the cliffside of the beach.
Leslie Scopes Anderson, “Unearthing Evidence of Creatures from Deep Time,” (Humboldt U 2011) www2.humboldt.edu
Ellin Beltz, “Fossil Localities – Humboldt Bay Area,” (Field Trips by Ellin Beltz 2008) http://www.ebeltz.net
Geology of the Area:
The cliffside of this beach contains shale from the Monterey Formation. The fossiliferous shale dates back to the Miocene epoch. There are talus slopes in many areas created by folded and slanted strata.
Be careful of falling shale from the cliffside. Although it poses a hazard, the fallen rocks are more convenient to split than extracting shale from the outcropping. Split fishes can be found near the bottoms of the formation. Additionally, petrified whale bone has been recovered on the beach.
As you can see in the figure above, three prominent outcroppings jut out from the Monterey formation, marked 1, 2, and 3 on figures B and C above. Figure A shows that Jalama Beach, to the left of Gaviota, is part of the Monterey Formation bearing marine Miocene fauna, and Oligocene rocks are found more inland.
Fossil fish and petrified whale bone are in the outcroppings.
Use this Stanford Study of Lompoc Fossil Fishes to identify your fish finds.
David Jordan, et.al, “Fossil Fishes of Diatom Beds of Lompoc, California,” (Stanford University, 1920)
Images: “Jalama Beach,” (The Nautiloid Network) www.nautiloid.net
Kathleen Surpless, et.al, “Evolution and stratigraphic architecture of marine slope gully complexes: Monterey Formation (Miocene), Gaviota Beach, California,” (Trinity University, March 27, 2007)
Geology of the Beach:
The yellow brown sandstones that contain the fossils are part of the Purisma formation. Collecting is best at low tide, when the outcroppings are most exposed.
Paleontology of the Fossils:
The fossils originate from the Pliocene epoch of the Neogene period. Bivalves, gastropods, sea urchins, crabs, marine mammal bones from whales and seals can be found. Shark teeth have also been recovered from the beach, but are rare.
An extensive photo gallery of the fossils common at Capitola Beach can be found here: http://nextcenturyimages.com/nature/capitolafossils2307/index.html
“CA Capitola,” (Paleontica Fossiel August 2012) <http://english.fossiel.net/sites/fossil_site.php?plaats=506>
Geological History of the Area:
The area of the Gaviota and El Capitan State Beaches contain a series of folds such as the Gaviota Offshore Fold trend which suggests the area is by the Eagle fault and has experienced pressure. Six hydrocarbon (oil) seeps have been found at the El Capitan- Gaviota shelf. During early Miocene time, calcareous plankton dominated this basin fill, but by the middle Miocene, the expansion of the East Antarctic ice sheet led to intense upwelling in eastern boundary current areas. The shelf from which the specimens were collected from is part of the Monterey formation and is riddled with a series of marine gullies. The beach-bordering segments are part of the El-Capitan-Gaviota Continental Shelf.