About us
This group's goal is to get exercise while exploring and learning about the geology and natural science of the San Francisco Bay Area. The aim is the mid-point between the hiking groups that don't stop long enough to explore and learn about what they're passing and the nature groups that see lots of great stuff, but don't get that much exercise.
Hikes will be lead by members with knowledge of unique, exotic, or otherwise fascinating features of our area. If you have a favorite hike that you'd like to lead, drop a suggestion and I'll make you a leader (you just have to commit to coming on the hike and sharing your knowledge).
Everyone with interest is invited, and presentations should be aimed at people with interest but not necessarily a strong academic background in the subject (although some conversations occasionally get pretty deep).
Our primary focus will be on geology, but we won't pass up a good tidbit of information about the flora and fauna as we hike.
I've finally started putting together a website with more details on the geology of our hikes. You can find them at https://geology.trampleasure.net/ A few direct links to pages on my site include:
Upcoming events
2
Glen Park BART to Twin Peaks: Lots of chert
Glen Park BART Station, 2901 Diamond Street, San Francisco, CA, USFive miles, 800 feet of climbing, and lots of chert!
This route showcases some of San Francisco’s best exposures of Franciscan Complex ribbon chert, a deep‑ocean sedimentary rock later folded and uplifted by plate‑tectonic forces. If you’ve driven past the red‑and‑gray layers along O’Shaughnessy Boulevard, this hike lets you examine them up close.***
### 🧭 Route Overview
We’ll walk ~2.5 miles uphill on a mix of city streets and natural trails to Christmas Tree Point on Twin Peaks, then descend ~2.5 miles through Glen Canyon Park. (AllTrails map)
- Car‑Free Summit Loop: The east side of Twin Peaks Blvd is closed to cars, giving us quiet, wide views of the city and Bay.
- Chert Exposures: Along O’Shaughnessy Blvd we’ll stop at folded ribbon chert—thin layers of silica deposited on the deep ocean floor, later compressed and bent during subduction.
- Glen Canyon Geology: Fewer rock outcrops, but excellent examples of canyon incision, slope processes, and Franciscan mélange.
***
### 🪨 Geology Focus
- What is ribbon chert? Silica‑rich mud that settled on the ocean floor in rhythmic layers, later hardened into rock.
- Why is it folded? The Pacific Plate pushed these rocks into California, crumpling them as they were scraped off into the Franciscan Complex.
- What to look for: Color bands, tight folds, fractures, and how vegetation interacts with different rock types.
### ⏱️ Approximate schedule
- 10:00–10:15 AM: Welcome + short geology intro
- Hat passed for $2 requested donation to help with Meetup fees.
- 10:15 AM: Depart
- ~2:00 PM: Return (depends on geology stops and this group's pace)
- Pace: ~2 mph when you include observation breaks
***
### 🥪 Food, Water & Restrooms
- Bring lunch for the summit; no food is sold there.
- Canyon Market (Diamond St) is a good pre‑hike stop if you want to purchase lunch.
- Carry water; summit water is unreliable.
- Restrooms at Christmas Tree Point are automated and may require a short wait.
- Optional social gathering at the end at Cuppa for Boba and/or froyo.
***
### 👥 Group Policies
- Kids: Welcome if they can handle the distance and elevation.
- Dogs: Not permitted on our hikes.
- Attendance: SF hikes often have high RSVPs but actual turnout is typically 50–70%.
12 attendees
Death Valley; December 2026
Furnace Creek Campground, Airport Rd, Death Valley, CA, USWe normally open registration in early October, but this year we’re holding off until we know which roads will actually be open (hopefully no bad storms this year). Once we have that information and can plan our hikes accordingly, we’ll open registration.
General detail
We have reserved a few sites for our annual Death Valley camping/hiking trip**. It's happening this Decembe**
We don't have this year's itinerary set yet, but wanted folks to know we're on for 202
We have four sites reserved (eight cars), and are looking for people with National Parks Senior passes to help us get a couple more. If you have a Senior Pass, please let Lee know if you're comfortable with us using it. Each camping site is shared by two vehicle
If you prefer a hotel to camping, make your reservations as soon as you know you're coming to ensure you get a room.General details of our annual trip can be found here: https://geology.trampleasure.net/geology-trips-in-the-western-usa/dvn
We'll probably have a tentative itinerary decided by early October, but the typical plan i
- Dec 28th: Drive to Death Valley (it's a long drive that takes most of a day, meet folks in the late afternoon/eveni
- Dec 29-31: Three days of hikes around Death Valle
- Dec 31: Group 'no-host' dinner/drinks at the Last Kind Words Saloon to celebrate New Year's Ev
- Jan 1st: Optional drive to Racetrack Pla
- We'll drive rental Jeeps (about $150/persion for rental and gas) to this amazing feature at the far north end of the park. The last 30 miles or so is down washboard roads with a few large rocks that might damage the underside of a normal car. If you have a 4WD vehicle, you're welcome to join us and not take a seat in one of the rental Jeep
- If you don't want to (need to get back), Jan 1st would be your drive hom
- Jan 2nd: Pack up and drive hom
2 attendees
Past events
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