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
Devil's Slide in Pacifica; 5.1 miles, 900 ft.
Pacifica State Beach Parking Lot B, 5200 CA-1, Pacifica, CA, USJoin us for a 5.1-mile round-trip trek that serves as a front-row seat to the restless geology of the California coast (Alltrails map here). By starting in Pacifica, we avoid the crowded trailhead lots and gain a much deeper appreciation for the massive tectonic forces that pushed these cliffs out of the sea. As we climb 909 feet, we will travel through millions of years of Earth's history written in the stone.
Remember, the day before is No Kings day of protest.### Parking:
Parking lots can get full, arrive early to ensure you find a spot. Read all signs carefully. If the beach lot is full, there is street parking nearby, but make sure the block or lot you find is not time limited to only two hours. Please be mindful of neighbors and businesses.
### Geologic Highlights: What We Will See
- Ancient Marine Terraces: As we begin our hike from the Pacifica side, we will walk across broad, flat "benches" known as marine terraces. These were once the ocean floor, carved flat by wave action and then lifted hundreds of feet above sea level by the ongoing squeeze between the Pacific and North American plates.
- The Great Rock Collision: As the trail begins its steady 900-foot ascent, we will witness a dramatic transition in the ground beneath our feet. We will move from the dark, chaotic "melange" of the Franciscan Complex—scraped up from the deep ocean trench—into the massive, light-gray blocks of Montara Mountain Granodiorite.
- Slickensides and Fault Scars: Along the steeper sections of the climb, we will see "slickensides"—polished, grooved rock surfaces created by the immense friction of two rock masses grinding past each other during prehistoric earthquakes. These are the literal fingerprints of the San Gregorio fault system.
- The "Slide" in Action: Upon reaching the paved bypass, we will see the reason for the road's legendary instability. We will observe where weak, crumbly Paleocene shales have been thrust over the hard granite. This structural weakness, combined with winter rains and the pounding surf below, creates the massive landslides that eventually forced the abandonment of the old highway.
- Rapid Coastal Erosion: Looking out toward the ocean, we will see "sea stacks" like Egg Rock, which are the hardier remnants of the coastline that haven't yet succumbed to the waves. We will also see a WWII-era military bunker perched precariously on a sandstone pillar—a vivid reminder that these cliffs have retreated significantly in just the last 80 years.
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### Hike Logistics
- Distance: 5.1 miles (Round Trip)
- Elevation Gain: 909 feet
- Difficulty: Moderate (due to the steady climb from Pacifica)
- Kids: yes
- Dogs: no
- Starting Point: We are meeting in Pacifica to ensure easier parking and a more scenic approach to the Slide.
- Ending time: Is always approximate. Each group has a slightly different pace.
- Group size: We usually end up with 15-20 people. If the RSVPs look larger, we generally get several no-shows.
What to Bring: Sturdy shoes for the gravelly ascent, layers for the coastal wind, and your curiosity about the "Sierra-style" granite we’ll find right here at the ocean’s edge.
Why is Highway 1 now a path?
The Franciscan Complex rocks here have been sliding into the ocean for thousands of years, and CalTrans finally gave up on rebuilding the road after every slide and in 2013--they then opened a pair of tunnels that bypass this section...and creating an amazing hiking and biking trail on the old highway.
Past times we've done this (although a shorter route):You can find more details of the area here. (including the 30 minute "Devil's Slide Trail Guide" video).
24 attendees
Mt. Lassen hiking and camping
Location not specified yetJoin us for three days of exploring the geology of Lassen Volcanic National Park. We’ve reserved a group site at Lost Creek Group Campground for June 26–30, which accommodates up to 20 people.
We’ll begin accepting RSVPs in late March or early April, but wanted to share the dates now so you can add them to your calendar.
The trip will include three full days of hiking on June 27–29, with plans for:- A summit hike (about 5 miles with 2,000 feet of elevation gain)
- A hike through the park’s geothermal features
- One additional hike (details to come)
Most hikes will be moderate, though the summit hike is strenuous—it’s a steady climb most of the way up. Participants are welcome to skip any hike they’re not comfortable with, but campsite reservations will be prioritized for those planning to hike on at least two days.
If camping isn’t your preference, there are B&Bs and other lodging options available just outside the park’s north entrance. Those staying off-site are very welcome to join us for the hikes and unwind together around the campfire in the evenings.
We may also add an optional extension to explore Lava Beds National Monument, which would include one half-day and one full day of exploring. If offered, this extension will be listed as a separate trip.
More details about our trips can be found here.
Previous trips to Lassen include:- July 2021 (Mt Lassen & Lava Beds listed separately--this year there was smoke from a bad fire and we ended up not going to Lava Beds)
- August 2013
- July 2011
2 attendees
Past events
242
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