Locality 19, Arroyo Purisima - Beal (1948) (Oligocene of Mexico)

Also known as Loc. 19

Where: Baja California Sur, Mexico (26.2° N, 112.3° W: paleocoordinates 24.9° N, 103.9° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: San Gregorio Formation, Chattian (28.1 - 23.0 Ma)

• The San Gregorio Formation lies unconformably below the upper Ysidro sandstone and appears to be no more than 400 ft thick. Because of its similarity to the Monterey Formation of California Darton (1921) tentatively correlated the beds and named them the "Monterey beds". Limited evidence points to an Oligocene age, although the formation is tentatively assigned an Oligocene to early Miocene age based on macrofossils and diatoms.

• bed-level stratigraphic resolution

Environment/lithology: marine; brown, argillaceous shale

• No paleoenvironmental data presented.
• Argillaceous diatomaceous shales, somehat chocolate in color and containing numerous fish scales as a characteristic feature.

Size class: macrofossils

Collection methods: quarrying,

• Collected by Darton (1921), studied and determined by J. Gardner. No known repository.

Primary reference: C. H. Beal. 1948. Reconnaissance of the geology and oil possibilities of Baja California, Mexico. Geological Society of America Memoir 31 [A. Miller/A. Hendy/A. Hendy]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 43805: authorized by Austin Hendy, entered by Austin Hendy on 26.08.2004, edited by Mark Uhen

Creative Commons license: CC BY (attribution)

Taxonomic list

• Representative.
Bivalvia
 Arcida - Arcidae
 Pectinida - Pectinoidae
"Pecten cf. crassicardo" = Lyropecten crassicardo
"Pecten cf. crassicardo" = Lyropecten crassicardo Conrad 1856 scallop
 Carditida - Crassatellidae
"Crassatellites (Crassinella) sp." = Crassinella
"Crassatellites (Crassinella) sp." = Crassinella Guppy 1874 clam
 Cardiida - Veneridae
Chione sp., "Pitarinae indet." = Callocardiinae2
Chione sp. von Mühlfield 1811 venus clam
"Pitarinae indet." = Callocardiinae2 Dall 1895 venus clam
 Cardiida - Tellinidae
Macoma sp. Leach 1819 tellin clam
 Cardiida - Cardiidae
Cardium sp. Linnaeus 1758 cockle
 Solenida - Solenidae
Solen sp. Linnaeus 1758 clam
 Protobranchia - Nuculanidae
"Leda sp." = Nuculana
"Leda sp." = Nuculana Link 1807 pointed nut clam
Gastropoda
 Neogastropoda - Buccinidae
Chrysodomus sp. Swainson 1840 true whelk
 Vermetoidea - Vermetidae
Vermetus sp. Daudin 1800 worm shell
 Sorbeoconcha - Turritellidae
Mammalia
 Mysticeti -
 Mysticeti - Eomysticetidae
Eomysticetidae indet.3 Sanders and Barnes 2002 whale
 Odontoceti -
Odontoceti indet.1 toothed whale
Echinoidea
 Clypeasteroida - Scutellidae
Scutella andersoni sand dollar