San Diego Formation
Encyclopedia
The San Diego Formation is a mostly sand
, with rock layer from a former bay of San Diego
of Late Pliocene
age.
Besides those of clams and other mollusks, quite a few bird
fossils (which are generally rare) have been found in this geological formation. Among them is a possible ancestor of Cassin's Auklet
(Ptychoramphus aleuticus) and the loon
s Gavia concinna and G. howardae. The former was quite likely a close relative or even ancestor of the large black-headed loons; the latter was perhaps a small relative of the large grey-headed loons.
Sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
, with rock layer from a former bay of San Diego
San Diego, California
San Diego is the eighth-largest city in the United States and second-largest city in California. The city is located on the coast of the Pacific Ocean in Southern California, immediately adjacent to the Mexican border. The birthplace of California, San Diego is known for its mild year-round...
of Late Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
age.
Besides those of clams and other mollusks, quite a few bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
fossils (which are generally rare) have been found in this geological formation. Among them is a possible ancestor of Cassin's Auklet
Cassin's Auklet
The Cassin’s Auklet is a small, chunky seabird that ranges widely in the North Pacific. It nests in small burrows and because of its presence on well studied islands in British Columbia and off California it is one of the better known auks...
(Ptychoramphus aleuticus) and the loon
Loon
The loons or divers are a group of aquatic birds found in many parts of North America and northern Eurasia...
s Gavia concinna and G. howardae. The former was quite likely a close relative or even ancestor of the large black-headed loons; the latter was perhaps a small relative of the large grey-headed loons.
External links
- "Clams of Champions" article from "San Diego Formation"
- San Diego County Water Authority - Water Management - Local Resources