ammonites
Spring Canyon (Eocene to of the United States)

Also known as SDSNH 4041, 4042; Upper Pomerado Conglomerate

Where: San Diego County, California (32.9° N, 117.0° W: paleocoordinates 32.0° N, 105.8° W)

• coordinate based on nearby landmark

• outcrop-level geographic resolution

When: Pomerado Conglomerate Formation, Duchesnean to Duchesnean (40.4 - 33.9 Ma)

• said to be late Duchesnean to early Chadronian

•"about 10 m above the base of the upper member" (Walsh 2010)

• bed-level stratigraphic resolution

Environment/lithology: terrestrial; gray, green, silty mudstone

• "Locality 4041 consists of a single large rip-up clast of purplish and greenish mudstone occurring within a pale gray cobble conglomerate... almost certaintly derived from an immediately underlying, laterally extensive bed of pale greenish gray siltstone and mudstone up to 1 m thick, from which Locality 4042 was collected" (Walsh 2010)

Size class: mesofossils

Collection methods: bulk, chemical, sieve

• SDSNH collection

•"Approximately 360 kg of matrix from [4041] and ~3800 kg of matrix from [4042] were screenwashed using 30-mesh screens (0.6 mm square openings)... concentrates were processed... using the heavy liquid tetrabromoethane"

Primary reference: S. L. Walsh and R. Q. Gutzler. 1999. A new Mio-Pliocene marine bone-bed from north-central Chile. Journal of Vertebrate Paleontology 19(3):82A-83A [J. Alroy/J. Alroy/M. Uhen] more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 17039: authorized by John Alroy, entered by John Alroy on 21.09.1999

Creative Commons license: CC BY-NC-ND (attribution-noncommercial-no derivatives)