Collection Data

Page Contents: Section | Significance | Background | Location & Dates | Taxonomic Contents | Documentation | Description of Collection | Collection Inventory | Collection Assets

Alderson: Santa Monica Mountains (Tuna Canyon Formation, Upper Cretaceous)

Section Responsible for Processing

Invertebrate Paleontology


This is a rare collection of Cretaceous invertebrates from the Santa Monica Mountains, Los Angeles County, California. Late Cretaceous rocks and fossils of the Santa Monica Mountains remain poorly known and this collection adds to the small collection available previously.


The specimens were collected by John M. Alderson during his paleontological research and geologic mapping over the past several decades. The collections have helped to elucidate the stratigraphy in a geologically complex area. A geologic map resulting from this research was published by the U. S. Geological Survey in 1994 and some mapping was incorporated into a geologic map of the Topanga 7.5' Quadrangle published by the Thomas W. Dibblee Foundation (1992).

Publications directly related to this collection include:

Groves, L. T., and Alderson, J. M. 2008. Earliest record of the genus Haliotis (Mollusca: Gastropoda) from the Late Cretaceous (Campanian) of Los Angeles County, California. The Veliger 50(1):24-26, figs. 1-4.

Shapiro, S. A., Alderson, J. M., and Fritsche, A. E. 2001. Depositional environment and age of Upper Cretaceous rocks in the Santa Monica Mountains, Los Angeles County, California. Geological Society of America, Abstracts with Programs.

Saul, L. R., and Alderson, J. M. 2001. Late Cretaceous molluscan faunas of the Santa Monica Mountains, Santa Ana Mountains, and Simi Hills, southern California: a comparison. Geological Society of America, Abstracts with Programs.

Yerkes, R. F., Campbell, R. H., and Alderson, J. M. 1994. Preliminary geologic map of the Topanga Quadrangle, southern California. U. S. Geological Survey Open File Report 94-266.

Alderson, J. M., and Saul, L. R. 1992. A probable occurrence of the ammonite genus Hoplitoplacenticeras Paulcke, 1907, on the Vizcaino Peninsula, Baja California Sur, Mexico. First Internationa Meeting on Geology of the Baja California Peninsula, Memorias, Universidad Autonoma de Baja California Sur, La Paz, Baja California Sur, Mexico, p. 97-99.

Alderson, J. M. 1988. New age assignments for the lower part of the Cretaceous Tuna Canyon Formation, Santa Monica Mountains, California. Geological Society of America, Abstracts with Programs.

Saul, L. R., and Alderson, J. M. 1981. Late Cretaceous Mollusca of the Simi Hills: an introduction in M. H. Link, R. L. Squires, & I. Colburn, eds., Simi Hills Cretaceous turbidites, southern California. Society of Economic Paleontologists & Mineralogists, Pacific Section, Fall 1981 Field Trip Volume and Guidebook. p. 29-41, 3 pl., 1 fig.

In addition, a number of papers published by various authors since about 1981 have used Cretaceous fossils collected by John Alderson in the Santa Monica Mountains. Included are articles that reported on the genera Yaadia, Gyrodes, Calva, Perissytis, Volutoderma, Lysis, Tessarolax, and Turritella.

Collection Location and Dates

Primarily from the central Santa Monica Mountains between Rustic Canyon and Tuna Canyon, Tuna Canyon Formation, Upper Cretaceous. Mapping and collecting began in 1975 and is ongoing.

Taxonomic Contents

Mollusks, including ammonites, bivalves, gastropods, and scaphopods.


Detailed locality data in the form of annotated topographic maps and field notes accompanies the material from each collecting locality.

Description of Collection

Approximately 10 cabinets of specimens in the main collections area at the Museum's Invertebrate Paleontology facility, South Grand Avenue.

Collection Inventory

Specimens are unpacked, housed in archival cardboard trays, and arranged by collecting locality. Detailed locality data accompanies the material from each collecting locality.

Collection Assets

No collection assets available.

Curatorial Status (Click to view)