SCGS Annual Field Trip No. 51 - Geology of the California Mother Lode

Registration:

Step 1 - Purchase ticket(s) through this Eventbrite page. Enter your name and email, do not leave these fields blank. If you are purchasing for multiple attendees, enter their names and emails when prompted.

Step 2 - Complete this waiver and T-shirt size form, using the same email address (one form per attendee). If you are purchasing multiple tickets, send this form to each of your attendees. https://docs.google.com/forms/d/e/1FAIpQLSfo6Kdw_LxOc8KaPoc0jlEEf0Lr530rFdeb_JxZJJHGV9h2UQ/viewform?usp=sharing&ouid=113774647636918750710

Register by September 19 (6 PM). Attendees who register after this date are not guaranteed to receive a T-shirt or their preferred size. Final deadline to register and complete the Google Form is October 3.

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Get ready! The South Coast Geological Society's Annual Field Trip is almost here! This year, we're heading to the iconic California Mother Lode Country from October 10-12. Mark your calendars and prepare for a fascinating journey through gold rush history and captivating geology.

Our trip will begin in Jackson, CA, and we'll traverse south along Highway 49 to Mariposa, CA, a route known as the "Golden Chain Highway" due to its historical significance and the rich geological features that define the Mother Lode. We'll be camping at the Glory Hole Recreation Area just outside of Angels Camp, CA.

Here are some of the key geological highlights and stops we anticipate:

• Kennedy Mine (Jackson, CA): We'll delve into the history and geology of one of the deepest and most productive hard rock gold mines in North America. The Kennedy Mine extracted gold primarily from quartz veins within the Mariposa Formation slate and greenstone, representing classic Mother Lode geology. You'll learn about the processes of gold deposition within these hydrothermal quartz veins and the immense engineering feats involved in deep mining.
• Melones Fault Zone: Highway 49 closely follows this major crustal suture that separates distinct geological terranes. We'll examine outcrops along the fault, observing the intense deformation, cataclastic fabrics, and various rock types (including serpentinite, chert, slate, and metavolcanic rocks) that characterize this significant tectonic boundary. This fault played a crucial role in localizing the gold-bearing quartz veins of the Mother Lode.
• Table Mountain (Tuolumne County): We'll explore the impressive flat-topped mesas of Table Mountain, a striking example of inverted topography. These mesas are capped by the Table Mountain Latite, a Miocene lava flow that once filled an ancient river channel (the "Cataract Channel" of the paleo-Stanislaus River). We'll discuss how subsequent erosion removed the softer surrounding rocks, leaving the more resistant lava cap as a raised plateau, and its relationship to the gold-bearing auriferous gravels found beneath.

Other Mother Lode Geological Features: Throughout our journey along Highway 49, we'll encounter a variety of features related to the Mother Lode's complex geology, including:

• Metamorphic Rocks: The region is characterized by a diverse assemblage of Paleozoic and Mesozoic metamorphic rocks, including slates, greenstones, and phyllites, which were subjected to regional metamorphism during the Nevadan Orogeny.
• Gold-bearing Quartz Veins: We'll observe examples of the signature milky white quartz veins that host the gold, understanding their formation through hydrothermal processes within fault zones and shear zones.
• Ancient River Channels: We'll discuss the role of ancient Tertiary river systems in concentrating placer gold deposits, which were later buried by volcanic flows and then exposed through erosion, leading to the early placer mining boom.
• Historical Mining Impacts: Beyond the natural geology, we'll see evidence of the extensive mining activities that shaped the landscape, from placer operations to the remnants of hard rock mines.

This promises to be an educational and enjoyable trip, offering a unique opportunity to experience the rich geological history of the California Mother Lode firsthand. We look forward to seeing you there!

Campground Location:

Glory Hole Recreation Area

6503 Glory Hole Road

Angels Camp, CA

38° 0' 27" N 120° 32' 25" W

Campsite notes: We have reserved sites 113, 115, 118, 125 at "Big Oak Loop". These sites accommodate RVs, however, no electrical hook-ups are available at this campground. Additionally, campground entrance gates are closed between 9 PM and 4 AM. Showers and flush toilets are a short walk from our sites.

Additional site info: Glory Hole Recreation Area, New Melones Lake - Recreation.gov

Visit the Recreation.gov site if you would like to make your own reservations at this facility before or after our field trip.

Cost:

Members - $200

Non-members - $240

Add on - Student Sponsorship - $100 (supports one student)

Students* - $100

*Amount will be refunded if student completes entire field trip.

Price includes the following:

• Shared Campsites (Friday and Saturday nights)
• Friday Dinner
• Saturday Breakfast, Lunch, and Dinner
• Sunday Breakfast and Lunch
• Refreshments
• T-Shirt
• Road Log and Digital Guidebook
• Entrance fee to Kennedy Mine