A 3556 - Arroyo de Gua (Pliocene of Mexico)

Also known as A 3556

Where: Baja California Sur, Mexico (26.0° N, 111.3° W: paleocoordinates 25.8° N, 110.0° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: San Marcos Formation, Early/Lower Pliocene (5.3 - 3.6 Ma)

• The oldest fossiliferous deposits exposed along Arroyo de Gua and Arroyo de Arce are correlatted with sediments on San Marcos Island as the fossils indicate early Pliocene. Along Arroyo de Arce the San Marcos Formation is a volcanic conglomerate containing interbedded sandstones and shell reefs. Fossils are more prevalent in the finer clastics whjich are common throughout the section implying the entire sequence is marine.

• bed-level stratigraphic resolution

Environment/lithology: offshore; poorly lithified sandstone and volcaniclastic conglomerate

• Generalized environmental limits of 20-60 m
• Volcanic conglomerate containing interbedded sandstones and shell reefs. Fossils are more prevalent in the finer clastics.

Size class: macrofossils

Reposited in the UCMP

• Material reposited in the UCMP collections.

Primary reference: J. W. Durham. 1950. 1940 E.W. Scripps cruise to the Gulf of California. Part II - Megascopic paleontology and marine stratigraphy. Geological Society of America Memoir 43(2) [A. Miller/A. Hendy/A. Hendy]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 44039: authorized by Austin Hendy, entered by Austin Hendy on 31.08.2004

Creative Commons license: CC BY (attribution)

Taxonomic list

• Exhaustive. Identified by J.W. Durham.
Bivalvia
 Pectinida - Pectinoidae
"Aequipecten abietis" = Argopecten abietis, Lyropecten modulatus
"Aequipecten abietis" = Argopecten abietis Jordan and Hertlein 1926 calico scallop
Lyropecten modulatus Hertlein 1925 scallop
 Ostreida - Pinnidae
Pinna latrania Hanna 1926 oyster
 Arcida - Arcidae
"Anadara (Anadara) formosa" = Anadara formosa
"Anadara (Anadara) formosa" = Anadara formosa Sowerby 1833 ark
 Lucinida - Lucinidae
Codakia ? distinguenda Tryon 1872 clam