Mojave National Preserve Paleontological Resource Inventory

Sofia Andeskie, Emily Johnson, Justin Tweet, Vincent L. Santucci, Debra Hughson

Introduction and Objectives

Mojave National Preserve (MOJA) of the National Park Service (NPS) is located in the Mojave Desert of southern California. MOJA hosts an extensive geologic record, with units ranging in age from the Paleoproterozoic (2.5 to 1.7 billion years ago) to the Quaternary (present day). The preserve’s topography is dominated by numerous mountain ranges hosting widespread geological exposures divided by expansive valleys, dunes, cinder cones, and a low-elevation ephemeral salt lake.

The fossils preserved within MOJA span from the Proterozoic Eon (uncertain maximum age of fossiliferous rocks, but at least approximately 550 million years ago) to the Holocene Epoch (beginning 11,700 years ago). Abundant and diverse marine fossils are preserved in units dated from the late Proterozoic through most of the Cambrian, as well as from the Devonian through the early Permian. More recent volcanic tuff and unconsolidated sedimentary deposits in valleys preserve Cenozoic flora and fauna. Some geological units are fossil-bearing, both within the preserve and in adjacent lands outside the boundaries of the preserve.

To better understand and protect these fossil resources, NPS staff have produced the Mojave National Preserve Paleontological Resource Inventory (Johnson et al. 2023). From October 2021 to January 2022, a field inventory was conducted to determine the scope and distribution (both temporal and geospatial) of paleontological resources at MOJA. A total of thirteen localities were documented and field-checked throughout the preserve. These localities resulted from field checks of previously reported fossil sites, as well as new discoveries based on literature searches and information provided by MOJA staff. Below we highlight some of the most intriguing fossil localities identified within the park, and new observations discovered as part of stratigraphic sections for the resource inventory project.

Early Paleozoic Assemblage of MOJA

John Hazzard was the first geologist to devote significant attention to the study of paleontology within MOJA. Throughout the 1930s and 1940s, Hazzard and collaborators identified Paleozoic assemblages within the Kelso and Providence Mountains (Hazzard 1933, 1954; Hazzard and Mason 1936; Thompson and Hazzard 1940, 1946). The Cambrian (early Paleozoic) strata present in the preserve include, from oldest to youngest, the Wood Canyon Formation, Zabriskie Quartzite, Latham Shale, and Chambless Limestone. As part of this paleontological inventory, MOJA Physical Scientist Sofia Andeskie and a Scientist-in-Parks intern, Emily Johnson, completed a detailed stratigraphic section of the Proterozoic to Cambrian rocks in the Kelso Mountains.

The middle member of the Wood Canyon Formation is composed of yellow to orangish-brown sandstone with faint cross-bedding. No fossils were observed. The middle member has a sharp contact with the overlying upper member of the Wood Canyon Formation. The upper member of the Wood Canyon Formation is approximately 20 m (66 ft) thick and composed of interbedded mudstone and sandstone. The Wood Canyon Formation is paleontologically notable because it spans the Proterozoic–Cambrian boundary, preserving fossils from the early radiation of animals with hard parts. Observed fossils in the upper member include vertical burrows ~1 cm (0.4 in) in diameter and ~2 cm (0.8 in) long. Other publications have noted horizontal burrows, soda-straw burrows called Skolithos, frond-like Swartpuntia sp., sponges, and trilobites (Stewart 1970; Bahde et al. 1997; Hagadorn and Fedo 2000).

The Cambrian Zabriskie Quartzite is 20 m (66 ft) thick and composed of white to yellow sandstone. The sandstone beds are well-sorted and composed of fine-grained sand. No fossils were observed, but other publications have reported Skolithos (Dunne 1972; Bahde et al. 1997; Fedo and Cooper 2001; Bedford 2003).The Cambrian Latham Shale is composed of a dark gray, brown, and greenish gray mudstone. Among the fossils found in MOJA are cyanobacteria, a possible cnidarian (“jellyfish”; Sphenothallus?), brachiopods (“lamp shells”), hyoliths (conical shelled animal), an undescribed armored worm, radiodont arthropods similar to Anomalocaris, trilobites, eocrinoids (early relatives of the crinoids, “sea lilies”), and invertebrate traces (Waggoner and Hagadorn 2005). Olenellid trilobites are found in fissile, dark gray shale slabs (Figure 1). Mount (1976, 1980) included photographs of specimens from the Latham Shale of MOJA, including part of an Anomalocaris-like radiodont (Figure 2) and the unnamed worm.

The Cambrian Chambless Limestone is a hard, ridge-forming, light to dark gray limestone. Massive sections of lighter gray limestone contain an abundance of ~2–4 cm (0.8–1.6 in) dark gray “algal” nodules, which have been strained by tectonic stresses. Other studies have observed brachiopods, hyoliths, snails, trilobites, and eocrinoids (Hazzard 1954).

This stratigraphic section is significant because MOJA has some of the most unusual Cambrian fossils in the NPS. Unusual fossils include the only radiodont, the only armored worm, and the only example of a late-surviving Ediacaran organism (Swartpuntia) known from the NPS. Additionally, MOJA has one of the three NPS records of eocrinoids and one of only two records of the enigmatic Sphenothallus. Geologically, MOJA preserves one of the few stratigraphic sections spanning the Proterozoic–Cambrian boundary in the NPS. This inventory report helps highlight these important natural resources and provides information to park staff to help protect these geologic units.

Figure 1. Head section of olenellid trilobite in a Latham Shale slab.

NPS photo by Justin Tweet.

Figure 2. Appendage fragment of an Anomalocaris-like radiodont.

UCMP photo by Dave Strauss.

Monte Cristo Formation

The Monte Cristo Formation is early to middle Mississippian in age and is a fossiliferous limestone formation composed of four to five members. The formations are dominantly light and dark gray limestone beds, with rare sandstone, quartzite, and dolomite units. These rocks were deposited in a shallow marine setting. The Monte Cristo Limestone is fossiliferous in a number of places within and just outside of MOJA. The assemblage includes corals, sponges, bryozoans (“moss animals"), brachiopods, bivalves, ammonoids, nautiloids, snails, trilobites, ostracodes (“seed shrimp”), crinoids (“sea lilies”), and possibly echinoids (“sea urchins”; Figures 3 and 4; Hazzard 1954; Hewett 1956).

Figure 3. Sponges in crinoidal limestone, Providence Mountains.

NPS photo by Emily Johnson.

Figure 4. Coral in the Monte Cristo Formation of the Providence Mountains.

NPS photo of Sofia Andeskie.

Miocene Fossils

Hobby rock and fossil collectors found the first reported vertebrate fossils in the Hackberry Wash area in the 1960s. Workers from the San Bernardino County Museum worked the Hackberry Wash and Wild Horse Mesa areas in MOJA during the 1970s and 1980s. They defined two local faunas: the Wild Horse Mesa local fauna, from between the Peach Springs Tuff and Wild Horse Mesa Tuff, and the Hackberry Wash local fauna, associated with the Wild Horse Mesa Tuff. These sites represent lacustrine deposition near volcanoes; the rocks are sometimes identified as the informal Winkler Formation.

The Wild Horse Mesa assemblage includes logs and wood of Sequoia langsdorfii, other conifer wood and needles, grasses and reed-like fossils (SBCM records), ostracodes, and flamingo tracks (Reynolds et al. 1995). The Sequoia and ostracodes were first reported by Hazzard (1954). The Hackberry Wash local fauna includes fossils of a rodent, a pika, a dog, a felid, a rhino, camels, and a small deer-like artiodactyl (Reynolds et al. 1995; Tedford et al. 2004). These fossils were found in silicified shale interbedded with jasper (Reynolds et al. 1995). MOJA staff observed reed-like fossils preserved in the Wild Horse Mesa Tuff at Hackberry Wash near the excavation sites (Figure 5).

Figure 5. Reed-like fossils preserved in the Wild Horse Mesa Tuff.

NPS photo by Sofia Andeskie.

Summary

The findings of the Mojave National Preserve Paleontological Report constitute a baseline of paleontology resource data for MOJA, and reflect the current understanding of the scope, significance, and distribution of MOJA’s fossil record. This report provides a foundation for the management and protection of paleontological resources within MOJA and supports future education, interpretation, and research. For any questions, please reach out to MOJA’s Physical Scientist.

References

• Bahde, J., C. Barretta, L. Cederstrand, M. Flaugher, R. Heller, M. Irwin, C. Swartz, S. Traub, J. D. Cooper, and C. Fedo. 1997. Neoproterozoic-lower Cambrian sequence stratigraphy, eastern Mojave Desert, California: implications for base of the Sauk Sequence, craton-margin hinge zone, and evolution of the Cordilleran continental margin. Pages 1–19 in G. H. Girty, R. E. Hanson, and J. D. Cooper, editors. Geology of the Western Cordillera: perspectives from undergraduate research. Pacific Section, Society of Economic Paleontologists and Mineralogists, Los Angeles, California. Book 82.

• Bedford, D. R. 2003. Surficial and bedrock geologic map database of the Kelso 7.5 minute Quadrangle, San Bernardino County, California. U.S. Geological Survey, Reston, Virginia. Open-File Report 2003-501. Scale 1:24,000.

• Dunne, G. C. 1972. Geology of the Devil’s Playground area, eastern Mojave Desert, California. Dissertation. Rice University, Houston, Texas.

• Fedo, C. M., and J. D. Cooper. 2001. Sedimentology and sequence stratigraphy of Neoproterozoic and Cambrian units across a craton-margin hinge zone, southeastern California, and implications for the early evolution of the Cordilleran margin. Sedimentary Geology 141/142:501–522.

• Hagadorn, J. W., and C. M. Fedo. 2000. Terminal Neoproterozoic cloudiniids from southwestern North America. Abstracts with Programs - Geological Society of America 32(7):300.

• Hazzard, J. C. 1933. Notes on the Cambrian rocks of the eastern Mojave Desert, California with a paleontological report by Colin H. Crickmay. University of California Publications in Geological Science 23(2):57–78.

• Hazzard, J. C. 1954. Rocks and structure of the northern Providence Mountains, San Bernardino County, California. Pages 27–35 in R. H. Jahns, editor. Geology of southern California. California Division of Mines, Sacramento, California. Bulletin 170, chapter 4.

• Hazzard, J. C., and J. F. Mason. 1936. Middle Cambrian formations of the Providence and Marble Mountains, California. Geological Society of America Bulletin 47(2):229–240.

• Hewett, D. F. 1956. Geology and mineral resources of the Ivanpah Quadrangle, California and Nevada. U.S. Geological Survey, Washington, D.C. Professional Paper 275.

• Johnson, E., S. Andeskie, J. S. Tweet, and V. L. Santucci. 2023. Mojave National Preserve: Paleontological resource inventory (public version). Natural Resource Report NPS/MOJA/NRR—2023/2541. National Park Service, Fort Collins, Colorado. https://doi.org/10.36967/2299742.

• Mount, J. D. 1976. Early Cambrian faunas from eastern San Bernardino County, California. Bulletin of the Southern California Paleontological Society 8(12):173–182.

• Mount, J. D. 1980. Characteristics of Early Cambrian faunas from eastern San Bernardino County, California. Pages 19–29 in J. D. Mount, editor. Paleontological tour of the Mojave Desert, California-Nevada. Southern California Paleontological Society, Los Angeles, California. Special Publications 2.

• Reynolds, R. E., R. Hunt, and B. Albright. 1995. Rhinoceros in Lanfair Valley. Quarterly of San Bernardino County Museum Association 42(3):107–110.

• Stewart, J. H. 1970. Upper Precambrian and lower Cambrian strata in the southern Great Basin, California and Nevada. U.S. Geological Survey, Washington, D.C. Professional Paper 620.

• Tedford, R. H., L. B. Albright, III, A. D. Barnosky, I. Ferrusquia-Villafranca, R. M. Hunt, Jr., J. E. Storer, C. C. Swisher, III, M. R. Voorhies, S. D. Webb, and D. P. Whistler. 2004. Mammalian biochronology of the Arikareean through Hemphillian interval. Pages 169–231 in M. O. Woodburne, editor. Late Cretaceous and Cenozoic mammals of North America. Columbia University Press, New York, New York.

• Thompson, M. L., and J. C. Hazzard. 1940. Permian fusulinids from the Providence Mountains, California. Oil & Gas Journal 38(48):67.

• Thompson, M. L., and J. C. Hazzard. 1946. Permian fusulinids of southern California. Part III of M. L. Thompson, H. E. Wheeler, and J. C. Hazzard. Permian fusulinids of California. Geological Society of America, Boulder, Colorado. Memoir 17:37–53.

• Waggoner, B., and J. W. Hagadorn. 2005. Conical fossils from the lower Cambrian of eastern California. Paleobios 25(1):1–10.

Fossils and Paleontology