Geo-hikes Geologic Maps Foundation

Wed, Oct 1 · 5:15 PM PDT

Shelf Road Geo-hike

Valley View Preserve - Shelf Rd Trailhead (at Gridley Rd), Gridley Rd, Ojai, CA, US

Geo-hike along Shelf Road above Ojai. About 3.0 miles round trip with a few hundred feet of elevation gain. Easy hike with several geology stops. Hike is in and out along the same route. Dusk ends about 7:15 PM. We should be done by then but bring a headlamp or flashlight just in case we go slow.

Hike starts at the trailhead parking area along Gridley Road. We'll hike out to the trail head at end of North Signal Street, turn around, and return the way we came in.

There is no sweep.

https://youtu.be/16J-FfmhI3c?feature=shared

The geology of Ojai Valley will be discussed along the way. Shelf Road is in uppermost portion of the Eocene-age Coldwater Formation* and in a few places along the contact with the overlying Oligocene-age Sespe Formation**, and their sandstone dominated outcrops will be observed and discussed. Shelf Road is within a map-scale structure called the Matilija overturn that is due to folding above the San Cayetano thrust fault*** that lies just below the earth's surface. The overturn is a band of rock layers where the stratigraphic order has been reversed and older strata lie above younger strata. This is due to large amounts of crustal convergence (shortening) during the last several million years.

Summary photo:

Looking east from Shelf Road near Gridley Road Parking. East Santa Ynez Range with Topa Topa Ridge on extreme left and eastern Ojai Valley on right. The giant Santa Ynez anticlinorium is shown by the tilted strata.

Hike is along a well-hiked dirt road that's free of auto traffic. Be on the look out for rattlesnakes while hiking- watch where you step, and don't reach out or sit down without looking first. Snakes are commonly out in the evening, and if it's mild or warm, just about any time of year.

*Coldwater Formation

https://en.wikipedia.org/wiki/Coldwater_Sandstone

**Sespe Formation

https://en.wikipedia.org/wiki/Sespe_Formation

***San Cayetano fault

https://en.wikipedia.org/wiki/San_Cayetano_Fault

T.Davis Newsletter with local geo-hikes descriptions, diagrams, photos and videos: https://tdavisgeo.substack.com/publish/home

DOGS ARE OK BUT PLEASE KEEP THEM ON A LEASH DURING HIKE

NO GUESTS, HAVE THEM JOIN

DISCLAIMER / RELEASE OF LIABILITY*

(IMPORTANT, PLEASE READ BELOW IN ITS ENTIRETY):

The hike host is a volunteer and not responsible for the group. Safety should be a priority for everyone in the group. Please treat this meet-up as hiking with a group of friends. If you become fatigued and unable to continue the hike, it is expected you will advise the hike host of this and return to our starting point on your own. If you are able to proceed, it is expected that you will maintain line of sight with other members of the group at all times and help to promote the group’s safety and fitness goals.

Outdoor sports and other events we plan can be inherently dangerous and accidents may happen. By participating in any posted event, you are taking responsibility for your own safety and well-being. The Geo-hikes Meetup Group and its organizers are not trained leaders and we do not confirm the qualifications of any of its members to lead or participate in trips. All participants take full responsibility for their own actions.

If you choose to sign up for this or any Geo-hikes Meetup event, you are releasing the Geo-hikes Meetup Group and its organizers from all liability in case of possible injuries. Your personal safety depends on your own judgment and experience.

• Anyone 18 yrs. or younger must be accompanied by a parent or legal guardian.

Fri, Oct 3 · 1:00 PM PDT

Tour of Mitchell Caverns and Geology/Hiking Trip Mojave National Preserve

Hole in the Wall Visitor Center, Black Canyon Road, San Bernardino County, ca, US

This will be a small group Geo-hike event with a reserved tour of the Mitchell Caverns and a Geology/hiking trip to the eastern Mojave Desert, mostly within the Mojave National Preserve: https://www.nps.gov/moja/index.htm

Please do not sign-on unless you are committed to making the trip

Highlights:
10/3, Hike the Rings Loop Trail at Hole-in-the-Wall and discuss the geology/flora. https://californiathroughmylens.com/rings-trail/
If time allows a drive and short hike with geology/flora along the Wild Horse Canyon Road and Mid-Hills.

10/4, Hike and geology of the Bonanza King Mine in the AM. https://mojavedesert.net/desert-fever/providence.html
https://ngmdb.usgs.gov/Geolex/UnitRefs/BonanzaKingRefs_12404.html
Afternoon tour of the Mitchell Caverns followed by a short hike and geology/flora of the Providence Mountains, https://www.parks.ca.gov/?page_id=615

10/5, Kelso Dunes hike and geology in the AM, https://www.nps.gov/moja/kelso-dunes.htm
visit to the Kelso Train Station,
and visit to the Cima Volcanic Field (aka Cinder Cone Lava Beds) and Lava Tubes, https://www.nps.gov/moja/planyourvisit/lava-tube.htm

I will be explaining the geology and natural science of the area along our hikes using maps and diagrams. A guidebook will be provided.
This is a Fund Raiser for the Geologic Maps Foundation, a 501.3.C nonprofit. Tickets are $195/person. Includes guided cavern tour, guided geology field trip, campsite cost, and a geology guidebook (.pdf copy). Please pay by check, made out to the Geologic Maps Foundation at the beginning of the trip.

THERE IS WAITLIST AND THOSE THAT HIKE REGULARLY WITH GEO-HIKES WILL HAVE PRIORITY.

Trip will be a small group (10 or less). I have reserved and paid for two tent campsites (#20, #21) at the Hole-in-the-Wall Campground. There is only one vehicle allowed at each campsite but there is overflow parking. We will pre-arrange car-pooling as much as possible. More information on the Hole-in-the-Wall campground:
https://www.nps.gov/moja/planyourvisit/camping.htm

I have also reserved and paid for eight folks going on a ranger-guided tour of the Mitchells Caverns on 10/4 @ 1:30 PM (all cavern tours must be with a ranger). We can add two more people if needed. https://www.parks.ca.gov/?page_id=615

I will be driving, and I can take three folks with me, if you are willing to share gas costs, and pack all your gear in heavy bags or luggage so it can go in the bed of truck. I plan to leave Ventura about 8:00 AM on 10/3 and return to Ventura about 8:00 PM 10/5.

You must be prepared for tent camping, bringing and preparing your meals (there are no stores nearby), and hikes up to 5 miles with a ~2.0-hr pace. You need to be in good hiking shape.

You'll need to bring car camping gear: food, water (there is potable water at the campground), cooking gear, tent, warm sleeping bag (this place can be cold at night, it's above 5,000 ft), warm clothing, folding chairs are nice, and whatever else you need to be comfortable.

You'll need to bring your hiking gear: day pack, water bottles, hat, sun-screen, etc. Early October can still be warm during the day and hiking in the desert can be challenging as there are many things to maneuver around, like cacti and rock obstacles (best not to wear shorts).

I will bring some firewood for the evening campfire. If you have firewood please bring it too.

Please do not sign-on unless you are committed to making the trip, are willing to camp and hike with the group, and are in good hiking condition.

For the most part, there is no cell coverage within the Mojave National Preserve.

Thu, Aug 6 · 8:00 AM PDT

Santa Cruz Island Geo-hikes 5 days & 4 nights stay at the Christy Field Station

Island Packer Cruises, 1691 Spinnaker Dr #105B, Ventura, CA, US

This is a unique experience to learn about the natural sciences of the Northern Channel Islands and to make hikes to beautiful beaches and geologically interesting locations on the remote western portion of Santa Cruz Island. In addition, fall is the most favorable weather period to visit the islands and the ocean-water temperatures peak at this time.

This will be a small group event. Many of the geo-hikes are to and along pristine and lovely coastlines that provide a glimpse of what southern California beaches looked like hundreds of years ago. YOU'LL NEED TO BE IN GOOD HIKING SHAPE FOR THIS EVENT. The geology, history (including the prehistoric record), and flora and fauna of the island will be discussed. Thom Davis, the trip leader, is lead author on The Geological Society of America's 2020 Field Guide (#59) to Santa Cruz Island and the contents of the guidebook will be used extensively during the trip:
https://pubs.geoscienceworld.org/books/book/2279/chapter/126263829/Santa-Cruz-Island-field-trip-Geology-history-and

IF YOU ARE ADDED TO THE TRIP (FROM WAITLIST TO ATTENDEE LIST), SEND YOUR EMAIL ADDRESS AND FULL NAME ASAP TO GEOLOGICMAPSFOUNDATION@GMAIL.COM. YOU'LL NEED TO PROVIDE YOUR FULL NAME, NAME OF THE TRIP YOU ARE ON, & YOUR EMAIL ADDRESS (DON'T ASSUME WE HAVE OR KNOW YOUR EMAIL ADDRESS). IF WE DON'T RECEIVE YOUR EMAIL QUICKLY YOU'LL BE REMOVED FROM THE TRIP. FURTHER INFORMATION: BOAT RESERVATIONS, WAIVERS, WHAT TO BRING, ETC. ARE SENT TO YOU BY EMAIL.

DO NOT MAKE YOUR BOAT RESERVATION UNTIL YOU ARE CONFIRMED ON THE TRIP AND WE HAVE YOUR EMAIL ADDRESS AND FULL NAME.

Trip is designed for geologists and non-geologists. Key earth science concepts will be explained in a manner for all to understand. The cost is $490/person and covers the cost of our stay at Christy Ranch, vehicle rental, and vehicle fuel (cost does not include boat transportation). Payment will be by check to the Geologic Maps Foundation and payment instructions will be provided later by email.

Participants are responsible for their Island Packer's boat trip reservations and fare to the island and return. At present costs are $93.00/adult-roundtrip and $88.00/senior and military-roundtrip (call Island Packers, 805-642-1393). I will inform you of the correct boat time to reserve in early 2026.

We stay at the historic Christy Ranch on the western end of the island that has bathrooms with showers, a kitchen equipped with cooking and eating utensils, cups and glasses, stovetop, refrigerator, and a dining room with wifi. There is no microwave, toaster, or electric coffee maker. Outside there is a patio with tables and chairs and a large built-in BBQ. I will bring plenty of charcoal for all to use and BBQing has been very popular with past trips.

We cannot sleep inside Christy Ranch as the building is not seismically retrofitted. You will need to bring a sleeping bag (nightly lows are usually in the mid-50s degree F range), a tent, sleeping pad, and a backpacking-size ground tarp. You are responsible for bringing all your meals and drinks (potable water is available at the Ranch), preparing your meals, and clean-up. More information on what to bring will be provided later by email. There are no stores on SCI, and cell coverage is poor. Christy Ranch and the SCI Main Station.

PLEASE DON'T SIGN UP FOR TRIPS THAT REQUIRE OVERNIGHT ORGANIZATION AND EXPENDITURE THEN CANCEL-OUT RIGHT BEFORE THE TRIP. THIS CREATES EXTRA WORK FOR US AND THE UNIVERSITY RESERVE SYSTEM, PLUS IT DEPRIVES OTHERS FROM THE OPPORTUNITY.

Please watch the bio-security video provided by TNC, https://youtu.be/d8SLYWPOF2U?feature=shared

Here's a link to a March 27, 2025 geologic tour of Santa Cruz Island (including some of Santa Rosa Island too):
https://youtu.be/nvOv0DG0gec
This is a fund raiser for the nonprofit Geologic Maps Foundation (GMF), www.geologicmapsfoundation.org. GMF is a 501 (c) (3) organization and donations are tax deductible.

Itinerary:
First day, land at Prisoners Harbor, pick-up vehicles, orientation, driving tour of the Canada del Puerto to the UC SCI Main Field Station, check-in, lunch, followed by a drive to Christy Ranch along the Southern Ridge Rd. On the drive we will be stopping for landscape panoramas, discussions of geology, rock types, and flora and fauna. For example, at one point there is a very good view of gully offsets along active SCI fault that bisects the island, https://youtu.be/n5jfomHlgyA. At Christy Ranch we will set up our camp, possibly take a short beach hike, and prepare our dinners.

Second Day: We will drive out to Frazer Point and make a several hikes to view and discuss the geology, view the rich-assortment of bird life around the point, and discuss the marine terraces and sea-level changes during the late Quaternary. https://youtu.be/CbqIqdwGnbw

Third Day: We will make two geology hikes: 1) outcrops along southern stretch of Christy Beach, and 2) a sea-cliff exposure of the SCI fault along the northern stretch of Cristy Beach. If time allows we will visit the "Poway clast" outcrop and deepwater deposits at Sauces Beach and Kinton Point.

Forth Day: hike to Near Point-Pozo Beach or Laguna Beach. More information to be posted later.

Fifth Day: We will pack up, tidy up the Ranch portions we used and head back to the Main Research Station and Prisoner's Harbor via the Central Valley Road. If time allows and half-way back to the Main Station, we may make a detour to hike to the top of Diablo Peak (elevation=2450 ft) that provides a great panorama of the Northern Channel Islands, Santa Barbara Channel, and the Santa Barbara-Ventura coastline and mountains. The top of Diablo is also a great place to see and discuss the Santa Cruz Island Volcanic Complex that underlies most of the northern portion of SCI. When we return to Prisoners Harbor to catch the boat for the return to Ventura, and if time allows, we'll do an optional hike towards Pelican Bay.

DISCLAIMER / RELEASE OF LIABILITY*
(IMPORTANT, PLEASE READ BELOW IN ITS ENTIRETY):
The hike host is a volunteer and not responsible for the group. Safety should be a priority for everyone in the group. Please treat this meet-up as hiking with a group of friends. If you become fatigued and unable to continue the hike, it is expected you will advise the hike host of this and return to our starting point on your own. If you are able to proceed, it is expected that you will maintain line of sight with other members of the group at all times and help to promote the group’s safety and fitness goals.

Outdoor sports and other events we plan can be inherently dangerous and accidents may happen. By participating in any posted event, you are taking responsibility for your own safety and well-being. The Geo-hiking Meetup Group and its organizers are not trained leaders, and we do not confirm the qualifications of any of its members to lead or participate in trips. All participants take full responsibility for their own actions.

If you choose to sign up for this or any Geo-hiking Meetup event, you are releasing the Geo-hiking Meetup Group and its organizers from all liability in case of possible injuries. Your personal safety depends on your own judgment and experience.

• Anyone 18 yrs. or younger must be accompanied by a parent or legal guardian.