Santa Monica Mountains National Recreation Area Gets First Youth Paleo Intern

By: Hailey Gregory, Santa Monica Mountains National Recreation Area, SAMO Fund Youth Program

Introduction

As a paleontology intern for Santa Monica Mountains National Recreation Area (SAMO) (Figure 1), I work closely with NPS Southern Network Paleontologist Aubrey Bonde. My role at SAMO is to assist in protecting the resources and preserve the park’s rich paleontological history. One of my primary goals is to make paleontological resource monitoring more efficient by sorting through thousands of paleontological GIS localities, consolidating data, and working toward establishing a clear definition of what constitutes a fossil locality. This will help us prioritize significant fossil sites and make long-term monitoring more manageable.

Figure 1. SAMO paleo intern Hailey Gregory holding up a fish fossil she found in the Modelo Formation containing fish scales and disarticulated bone fragments.

SAMO is home to more than 3,000 fossil localities (and counting), making it one of the richest fossil parks in the United States. Despite this, paleontological resources management at SAMO has been historically under-served, with the first (and last) comprehensive paleontological resources inventory occurring in 2004 (Koch et al.). My work aims to close this gap by managing and expanding our paleo database, ensuring that we capture the full scope of the park’s fossil record, and developing a manageable monitoring program.

During my time at SAMO, I have focused on consolidating specimens and localities in our database, reducing duplicates, and identifying clusters of sites that can be easily monitored due to their proximity. These efforts are essential for building a strong foundation for future research and resource protection.

Another aspect of my work is monitoring localities located in burn areas in the mountains, documenting localities, and assessing damages. When vegetation is burned the soil-root network is lost, slopes destabilize, and the hillside sluffs fossil talus downslope. Documenting these new fossil localities helps us to improve our management strategies and minimize theft and further damage to the fossils in the burn areas.

Yet another facet of work that I have undertaken is a bucket list project for SAMO and partners to catalog a unique collection of fossils from subaqueous volcanic deposits.

Conejo Volcanics contain fossils – a lot of them!

Within SAMO, some geological formations are less documented than others regarding paleontological resources. As it turns out, we now know that one of these formations is the Conejo Volcanics, formed by a significant episode of Miocene volcanism that is exposed in the western and central portions of the Santa Monica Mountains. A large suite of the rocks in the Santa Monica Mountains are from the Miocene Epoch and range from approximately 23 to 5 million years old. The Conejo Volcanics are from the Middle Miocene. They erupted and accumulated on the sea floor, forming a volcanic complex of shield volcanoes that gradually rose above sea level (KellerLynn 2016). Today, this exposure marks one of the largest accumulations of Middle Miocene intrusive and extrusive rocks in Southern California.

Figure 2. Turritella snail shell impressions and fragmented shell material embedded in a limestone lens of the Conejo Volcanics found in the field at SAMO.

Why the Volcanics?

The Conejo Volcanics are primarily comprised of volcanic materials such as basalt and andesite, and are interbedded with sandstone, siltstone, and limestone. Fossils in volcanic rocks are, in general, exceptionally rare; however, the Conejo preserves an incredible number of fossils, which makes this formation particularly exciting (Figures 2 and 3). The 2008 geological resource scoping summary reported more than 200 fossils found just in a small portion of the Malibu Canyon section of SAMO (KellerLynn 2016). Just as fossils being found in volcanic materials is uncommon, it is also rare to have a record of sedimentary rocks in a location of submarine volcanics. This project raises an important question: how many fossils do the Conejo Volcanics truly contain? Answering this will help us understand the significance of this formation and why it deserves further research. And to complete this additional research I worked with out close partner, the Natural History Museum of Los Angeles County.

Figure 3: Pectinid (scallop) with intact shell material and shell hash from the Conejo Volcanics NHMLAC-IP collections (left), and sponges with silicon impressions from the Conejo Volcanics NHMLAC-IP collections (right).

A Collaborative Effort

In order to monitor these localities and protect the rich fossil history of the park, it is crucial to know where these localities are. My recent work on the Conejo Volcanics has been a collaborative effort with the Natural History Museum of Los Angeles County (NHMLAC) Invertebrate Paleontology (IP) Collections Manager, Juliet Hook (now NHMLAC vertebrate Collections Manager), and geologist and NHMLAC-IP volunteer John Alderson, who has been documenting fossils and mapping the Santa Monica Mountains for more than 50 years. This project focuses on fossil localities from the Conejo Volcanics whose specimens are housed in the NHMLAC-IP collections. These specimens were all collected and mapped by John Alderson and Robert Stanton many years ago. This collection of hundreds of specimens from the volcanics have sat in the collections uncatalogued, remaining a wish-list project of NHMLAC-IP (until now!).

The NHMLAC-IP collections from the Conejo Volcanics consist primarily of gastropods and bivalves, with occasional crab fragments and a few sponge and bryozoan specimens. A majority of these specimens were found in limestone lenses preserved within the volcanics.

Over the span of three weeks, I georeferenced more than 100 fossil localities from John’s hand-drawn topographic maps and integrated them into our database. After initial mapping, I had the opportunity to sit down with John to review each point, cross-referencing his extensive knowledge, field notes, and photographs to confirm the precise locations of these fossil sites. This information will be added to both the NHMLAC-IP and SAMO databases, creating a more accurate and comprehensive depiction of fossil localities within the park and specifically for the Conejo Volcanic deposits. These efforts represent a meaningful step toward filling gaps in the SAMO fossil record.

For the Future

The Conejo Volcanics project represents an important step toward understanding and preserving the paleontological history of the Santa Monica Mountains. By consolidating data, digitizing historic maps, and collaborating with our partners, we are creating a more accurate and manageable record of fossil localities. These efforts not only fill gaps in the SAMO fossil record but also lay the groundwork for future research and long-term resource protection. Looking ahead, our goal is to expand this work beyond the Conejo Volcanics to other under-documented formations within SAMO. Each new locality we identify gives us a better understanding of the park’s complex geological and paleontological history. This information will help us develop targeted monitoring strategies, prioritize high-sensitivity sites, and ensure that these important resources remain protected.

Extended for a second time, I will be continuing my work at SAMO, consolidating our paleo data and maximizing paleontological resource monitoring efforts. Through locality-confirming field surveys and previous monitoring data comparisons, our hope is to create a database that is both accurate and manageable for myself, park partners, and future SAMO paleontologists.

References

KellerLynn, K. (2016). Santa Monica Mountains National Recreation Area: Geologic Resources Inventory Report. U.S. Department of the Interior.

Koch, A. L., Santucci, V. L., & Weasma, T. R. (2004). Santa Monica Mountains National Recreation Area Paleontological Survey. Geologic Resources Division NPS.