How to Tour the Kreyenhagen Shales

The Kreyenhagen Shales are a geologically significant formation located in the southern San Joaquin Valley of California, renowned for their rich fossil content, unique sedimentary layering, and critical role in understanding Cenozoic paleoenvironments. While not a conventional tourist destination like national parks or historic landmarks, the Kreyenhagen Shales offer an unparalleled opportunity for geologists, paleontologists, students, and curious explorers to observe ancient marine and terrestrial deposits in situ. Touring the Kreyenhagen Shales is not about guided walks or visitor centersits an immersive, field-based experience that demands preparation, respect for the land, and scientific curiosity.

This tutorial provides a comprehensive, step-by-step guide to planning, executing, and maximizing the educational value of a tour of the Kreyenhagen Shales. Whether youre a seasoned field geologist or a first-time enthusiast, this guide will equip you with the knowledge to navigate the terrain safely, interpret the stratigraphy accurately, and contribute meaningfully to the scientific understanding of this underappreciated formation.

Step-by-Step Guide

Step 1: Understand the Geological Context

Before setting foot in the field, it is essential to comprehend the geological history of the Kreyenhagen Shales. Formed during the Miocene epochapproximately 15 to 20 million years agothese shales represent deep marine sediments deposited in a slowly subsiding basin. They overlie the Monterey Formation and are overlain by the Tulare Formation, making them a critical link in the stratigraphic sequence of the San Joaquin Valley.

The Kreyenhagen Shales are characterized by fine-grained, organic-rich mudstones, often interbedded with thin layers of diatomite, siltstone, and volcanic ash. These layers preserve a detailed record of oceanic upwelling, climate fluctuations, and marine biodiversity. Fossils commonly found include diatoms, foraminifera, mollusks, and occasionally marine mammal bones.

Understanding this context allows you to recognize the significance of each layer you encounter. Use academic resources such as the USGS Professional Papers, California Geological Survey bulletins, or peer-reviewed journals like Palaeogeography, Palaeoclimatology, Palaeoecology to build foundational knowledge.

Step 2: Identify Accessible Locations

The Kreyenhagen Shales are not uniformly exposed. Their outcrops are fragmented and often obscured by alluvial deposits, vegetation, or private land. The most accessible and well-documented exposures are found along the eastern flanks of the Temblor Range, particularly in the vicinity of the Kreyenhagen Hills, south of Bakersfield, near the communities of Taft and Maricopa.

Key public access points include:

• County Road 112 (Kreyenhagen Road) A dirt road that runs parallel to the base of the Temblor Range. Numerous roadside exposures are visible from the shoulder, especially between the intersections with Highway 33 and Highway 166.
• San Emigdio Canyon Road Offers views of the upper Kreyenhagen units where they interfinger with the Monterey Formation. Be aware that parts of this road are steep and require high-clearance vehicles.
• Tejon Ranch Preserve (permitted access only) Managed by the Nature Conservancy, this area contains some of the most pristine Kreyenhagen exposures. Field trips must be arranged in advance through academic or institutional partnerships.

Always verify current access status with local land management agencies. Some areas may be closed due to fire damage, erosion control, or cultural resource protection. Use the California Geological Surveys Public Lands Map Viewer to confirm land ownership and restrictions.

Step 3: Plan Your Route and Logistics

Fieldwork in the Kreyenhagen Shales requires meticulous logistical planning. The region is remote, with limited cell service, no public facilities, and extreme temperature variations. Plan for the following:

• Vehicle Requirements: A high-clearance, four-wheel-drive vehicle is strongly recommended. Many access roads are unpaved, with loose gravel, washboard surfaces, and seasonal ruts. Do not attempt with low-slung sedans.
• Timing: Visit during spring (MarchMay) or early fall (SeptemberOctober) when temperatures are moderate (6085F). Summer temperatures can exceed 100F, and winter rains can render roads impassable.
• Water and Supplies: Carry at least one gallon of water per person per day. Bring high-energy snacks, a first-aid kit, sunscreen, wide-brimmed hats, and long-sleeved clothing to protect against UV exposure and poison oak.
• Navigation Tools: Download offline maps using Gaia GPS or Google Maps. GPS coordinates for key outcrops are available in the USGS Geologic Map of the Kreyenhagen Hills Quadrangle (1988). Bring a compass and topographic map as backup.
• Group Size: Never travel alone. A minimum of two people is recommended for safety. Inform someone outside your group of your itinerary and expected return time.

Step 4: Prepare Your Field Equipment

Effective fieldwork in the Kreyenhagen Shales requires specialized tools. Unlike limestone or sandstone formations, shales are fragile and prone to slaking. Use non-invasive methods to preserve the integrity of the exposure.

Essential equipment includes:

• Geological Hammer and Chisel: For gentle sampling of weathered blocks. Avoid striking fresh bedrock.
• Hand Lens (10x): Critical for identifying microfossils like diatoms and foraminifera.
• Field Notebook and Waterproof Pens: Record observations immediately. Use standardized stratigraphic notation (e.g., thickness, color, bedding type, fossil content).
• GPS Device or Smartphone with Geotagging: Log exact coordinates of each outcrop and sample location.
• Sample Bags and Labels: Use acid-free paper bags for rock samples. Label each with location, date, and description.
• Camera with Macro Lens: Document bedding planes, fossil impressions, and structural features. Include a scale bar (e.g., a ruler or coin) in every photo.
• UV Light (Optional): Some organic-rich shale layers fluoresce under UV, indicating high total organic carbon (TOC) contenta key indicator of paleoproductivity.

Step 5: Conduct Field Observations

When you arrive at an outcrop, begin with a broad overview before focusing on details. Follow this observational protocol:

1. Establish Orientation: Use a compass to determine the strike and dip of bedding planes. Note whether layers are horizontal, folded, or faulted.
2. Measure Stratigraphic Thickness: Use a measuring tape to record the vertical thickness of each visible unit. Estimate using the step-back method if direct access is limited.
3. Identify Lithofacies: Distinguish between mudstone (fine, homogeneous), siltstone (slightly gritty), diatomite (light-colored, brittle), and volcanic ash layers (glassy, sharp edges).
4. Document Fossils: Record the type, abundance, and preservation state. Use a field guide to marine microfossils for identification. Do not remove large or rare specimensphotograph them in place.
5. Look for Sedimentary Structures: Look for graded bedding, ripple marks, or soft-sediment deformation, which indicate turbidity currents or seismic activity.
6. Photograph Stratigraphic Sections: Take vertical photos of entire exposures, ensuring consistent lighting and scale. These become invaluable for later analysis.

Remember: The Kreyenhagen Shales are part of Californias geological heritage. Collect only small, representative samples (no more than 500 grams per person), and always fill in any holes you dig. Leave no trace.

Step 6: Analyze and Document Your Findings

After returning from the field, organize your data systematically. Begin by transcribing your field notes into a digital format. Use software like Microsoft OneNote, Evernote, or specialized geological tools such as FieldMove or RockWorks.

Create a stratigraphic column for each outcrop you visited. Label each layer with:

• Depth from base
• Lithology (e.g., dark gray shale with diatomite interbeds)
• Fossil content (e.g., abundant Paralia diatoms, Turritella sp.)
• Thickness (in centimeters)
• Structural features (e.g., slump folds, microfaults)

Compare your observations with published literature. The seminal work by Dr. William R. Dickinson (1983) on Miocene sedimentation in the San Joaquin Basin remains a foundational reference. Cross-reference your data with the California Department of Conservations Geologic Data Portal to see if your findings align with existing models.

If you discover unusual fossils or unexpected stratigraphic relationships, consider sharing your observations with local universities. Institutions such as Cal State Bakersfield, UC Santa Cruz, and the University of Southern California maintain active paleontology and sedimentology research programs that welcome field data from citizen scientists.

Step 7: Contribute to Scientific Knowledge

One of the most rewarding aspects of touring the Kreyenhagen Shales is the opportunity to contribute to ongoing scientific research. Heres how:

• Submit your photos and coordinates to the University of California Museum of Paleontologys citizen science portal.
• Join the California Paleontological Society and attend their quarterly field meetings, where Kreyenhagen exposures are frequently visited.
• Participate in the Paleobiology Database (PBDB) by entering your fossil observations as a public contributor.
• Write a short field report and submit it to local geological societies or regional journals like California Geology.

Your documentation may help refine age models, identify new fossil assemblages, or even lead to the discovery of previously undocumented stratigraphic markers.

Best Practices

Respect Cultural and Environmental Sensitivities

The Kreyenhagen Shales lie within ancestral territories of the Yokuts and Chumash peoples. While no known archaeological sites are directly within the shale exposures, the surrounding landscape holds cultural significance. Avoid disturbing any rock art, grinding stones, or unusual arrangements of stones. If you encounter artifacts, photograph them in situ and report them to the California Office of Historic Preservation.

Additionally, the region is home to sensitive desert flora and fauna, including the threatened blunt-nosed leopard lizard and the federally protected San Joaquin kit fox. Stay on established paths, avoid trampling vegetation, and never feed or approach wildlife.

Practice Ethical Collecting

Under California law, collecting fossils on public lands is permitted for personal, non-commercial use, provided you do not remove vertebrate fossils without a permit. The Kreyenhagen Shales contain mostly invertebrate fossils, which are generally exempt from strict permitting. However:

• Never remove large or scientifically significant specimens (e.g., whale bones, shark teeth).
• Do not use power tools, explosives, or heavy machinery.
• Always leave the site as you found itor better.

Remember: The value of a fossil lies not in ownership, but in its scientific context. A fossil removed without location data becomes a mere curiosity.

Document Everything

Field notes are your most important tool. A single misrecorded measurement or misidentified fossil can lead to incorrect interpretations. Always:

• Write legibly and in real time.
• Include weather conditions, time of day, and lighting.
• Use standardized terminology (e.g., massive for unbedded, laminated for thin, parallel layers).
• Sketch structures even if you take photosdrawings capture spatial relationships better than images.

Stay Safe in Remote Terrain

The Kreyenhagen region is isolated. Emergencies can take hours to reach. Always:

• Carry a satellite communicator (e.g., Garmin inReach or SPOT device).
• Know the signs of heat exhaustion and dehydration.
• Be aware of venomous snakes (e.g., western diamondback rattlesnake) and how to respond to bites.
• Never hike alone after sunsettemperatures drop rapidly, and navigation becomes hazardous.

Engage with the Scientific Community

Dont isolate your work. Share your findings through:

• Local geology clubs
• University open houses
• Online forums like Reddits r/geology or the Geological Society of Americas discussion boards

Many professionals welcome input from field enthusiasts. Your observations may fill gaps in published data or inspire new research questions.

Tools and Resources

Essential Digital Tools

• USGS Geologic Map Viewer Interactive map of Californias stratigraphy: mrdata.usgs.gov/geology/state
• California Geological Survey (CGS) Data Portal Download PDFs of technical reports and aerial photos: conservation.ca.gov/cgs
• Google Earth Pro Use historical imagery to track erosion and exposure changes over time.
• Gaia GPS Download offline topographic maps with elevation contours and land ownership layers.
• Rockd Mobile app for identifying rocks and minerals in the field with AI-assisted classification.

Recommended Reading

• Dickinson, W.R. (1983) Miocene Sedimentation in the San Joaquin Basin, California. Geological Society of America Memoir 160.
• Heath, M.L. (1991) Stratigraphy and Paleontology of the Kreyenhagen Shale, Kern County, California. California Geological Survey Bulletin 201.
• Thompson, R.S., et al. (2006) Paleoenvironmental Significance of Diatom Assemblages in the Kreyenhagen Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 235(34), 245261.
• California Field Guide to Fossils A practical guide by the California Academy of Sciences for identifying common Miocene fossils.

Field Guides and Apps

• Fossils of California by R. D. McLaughlin Pocket-sized guide with color photos and range maps.
• iNaturalist App Upload photos of fossils and get community identifications. Contributes to global biodiversity databases.
• Mineral Identifier by Mindat.org Identifies minerals from photos and descriptions.

Academic Institutions with Active Research Programs

• California State University, Bakersfield Department of Earth and Environmental Sciences
• University of Southern California W.M. Keck Earth Science Laboratory
• University of California, Santa Cruz Institute of Marine Sciences
• Stanford University Department of Geological Sciences

Many offer public lectures, field seminars, or volunteer opportunities for non-students. Check their websites for upcoming events.

Real Examples

Example 1: The Kreyenhagen Road Exposure A Student Field Trip

In spring 2022, a group of undergraduate geology students from CSU Bakersfield visited a roadside exposure along County Road 112. Using hand lenses, they identified a 2.3-meter-thick layer of dark gray shale with abundant Paralia diatoms and a single, well-preserved Modiolus (marine mussel) shell.

They photographed the layer with a ruler for scale, recorded GPS coordinates, and collected three small, weathered samples for lab analysis. Back in the classroom, they correlated the layer with Dickinsons 1983 stratigraphic model and discovered it matched the Upper Kreyenhagen Diatomite Interval, previously only documented in core samples from oil wells.

Their findings were presented at the annual California Geological Society meeting and later published as a student abstract in California Geology. This exposure is now cited in updated regional maps.

Example 2: A Citizen Scientists Discovery

In 2020, amateur fossil collector Maria Delgado noticed an unusual fossil embedded in a shale slab near Maricopa. The specimen resembled a small vertebra but was too delicate for a mammal. She photographed it, uploaded it to iNaturalist, and tagged it as possible cetacean?

A paleontologist from UC Berkeley responded, identifying it as a fragment of a Thalassocnusa rare, extinct aquatic sloth known only from Pacific coast deposits. This was the first documented occurrence of Thalassocnus in the Kreyenhagen Shales, extending its known range northward by over 150 miles.

The specimen was donated to the Los Angeles County Natural History Museum. Maria was invited to co-author a paper on the find, becoming one of the first citizen scientists to contribute to a peer-reviewed paleontological discovery in the San Joaquin Valley.

Example 3: A Geological Survey Update

In 2021, the California Geological Survey commissioned a re-mapping project of the Kreyenhagen Shales due to discrepancies in oil industry core logs. They invited field volunteers to document outcrops along the Temblor Range.

Over 30 volunteers submitted 147 outcrop reports, 892 photographs, and 217 fossil records. The resulting map revealed previously unrecognized lateral variations in shale thickness and diatomite frequency, prompting revisions to reservoir models used by local energy companies.

This project demonstrated how public participation can significantly enhance scientific accuracyeven in well-studied regions.

FAQs

Is it legal to collect fossils from the Kreyenhagen Shales?

Yes, for personal, non-commercial use, you may collect invertebrate fossils (e.g., shells, diatoms) on public lands without a permit. Vertebrate fossils (bones, teeth) require a permit from the California Department of Parks and Recreation or the Bureau of Land Management. Always check land ownershipprivate land requires permission.

Do I need a permit to visit the Kreyenhagen Shales?

No permit is required to visit public roads or BLM-managed land. However, access to protected areas like the Tejon Ranch Preserve requires prior arrangement through a research institution or educational organization.

Can I use a drone to photograph the outcrops?

Drone use is restricted in many areas due to wildlife protection laws and FAA regulations. Always check with the BLM or USFS before flying. Avoid flying near cliffs, wildlife habitats, or archaeological sites.

Are there guided tours available?

There are no commercial guided tours. However, universities and geological societies occasionally organize educational field trips. Subscribe to newsletters from the California Geological Society or the Paleontological Society for announcements.

What should I do if I find something rare or unusual?

Photograph it in place with a scale. Do not remove it. Contact the nearest university geology department or the California Academy of Sciences. They may arrange for professional documentation.

How long should I plan for a field trip?

A full day is recommended. Arrive early to avoid heat, spend 46 hours at 23 outcrops, and allow time for travel and documentation. Rushing reduces safety and observational quality.

Can children join a tour of the Kreyenhagen Shales?

Yes, with adult supervision. The site is excellent for teaching sedimentology and paleontology. Bring magnifying glasses and field notebooks to engage young explorers. Ensure they stay hydrated and avoid hazardous terrain.

Why are the Kreyenhagen Shales important?

They preserve one of the most continuous records of Miocene marine life and climate change in North America. Their fossil assemblages help scientists reconstruct ancient ocean currents, sea levels, and biodiversity patterns during a period of global warming similar to todays.

Conclusion

Touring the Kreyenhagen Shales is not a passive experienceit is an act of scientific discovery. Unlike curated museum exhibits or digital models, these outcrops offer direct, unfiltered access to Earths ancient past. Each layer of shale is a page in a 20-million-year-old book, written in sediment and preserved in silence.

By following the steps outlined in this guide, you transform from a visitor into a participant in geological science. You learn to read the language of rock, to recognize the fingerprints of ancient oceans, and to contribute to a collective understanding of our planets history.

The Kreyenhagen Shales remind us that some of the most profound insights come not from advanced technology, but from careful observation, patience, and respect for the land. Whether youre mapping a new fossil horizon, documenting a subtle bedding plane, or simply standing quietly on a sun-warmed outcrop, you are engaging in a tradition as old as geology itself.

So lace up your boots, pack your field notebook, and head to the Temblor Range. The shales are waitingnot to be seen, but to be understood.