Geology of the Haskell Peak - Sierra Buttes Area, Northern Sierra Nevada
Start Date: Sunday, July 24, 2022
Instructor: Betsy and Scott Mathieson
Term: Summer 2022
Join us to explore the geologic history, formations, and landforms of the crest of the Sierra Nevada near the Field Campus. In a series of evening lectures and day trips, students will learn the basics of geology, travel back in time from Pleistocene glacial deposits through Tertiary volcanic and sedimentary rocks to Paleozoic metamorphic rocks, and learn about the rich history and impacts of gold mining in this beautiful region. The course will require some moderately strenuous hiking at high elevations as we learn about the ground beneath our feet. Students with any level of geologic knowledge – or none – are welcome. Bring your observational skills and your camera! (Students will drive their own vehicles from the Field Campus to field sites and trailheads. If you have a choice of vehicles, bring a high-clearance one.)
Betsy and Scott Mathieson
Geologists Betsy and Scott Mathieson met at a summer geology field course at the Field Campus during their undergraduate years. They learned the basics of geologic field mapping in the mountains we’ll be exploring during this course. Betsy subsequently earned an A.B. in Geological Sciences from Harvard University and an M.S. in Engineering Geology from Stanford University. As an engineering geologist based in the San Francisco Bay Area, she worked around the U.S. Scott earned a B.S. in Physical Geology and an M.S. in Environmental Geology from California State University (CSU) Hayward (now CSU East Bay). His master’s thesis involved mapping and analyzing 200 square miles of glacial deposits in and around the areas we’ll be exploring. He worked as a geologist at the U.S. Geological Survey in Menlo Park, California, and later taught high school earth science, environmental science, and physics. Betsy and Scott have enjoyed hiking over rock outcrops and glacial moraines in the Field Campus area for many summers.
Arrive Sunday evening for dinner and a 7:00 p.m. introductory lecture. Each day, after breakfast and making bag lunches, we will meet in the parking lot at 8:30 a.m. to caravan/carpool to our field visit sites. We will return to the field campus in the late afternoon. After dinner, starting at 7:00 p.m. we’ll have a discussion about what we’ve seen during the day and a short lecture about what we plan to see the next day. Class will finish early- to mid-afternoon Friday.
Planned Field Site Visits
This itinerary is designed to showcase this spectacular region’s geology, working generally from the youngest formations to the oldest. We’ll begin with glacial moraines and cirques, continue into ash-fall tuffs and flows that filled a major paleovalley crossing the boundary between the Basin-and-Range and Sierra Nevada geomorphic provinces, explore the underlying granitic rocks, and work our way through a thick sequence of pillow basalts, breccias, and intrusives that formed in a volcanic arc environment and that were metamorphosed before emplacement of the granitic rocks. Along the way we’ll learn about the geologic origins of the region’s gold deposits and the placer, hydraulic, and hard-rock mining operations conducted by the first non-indigenous settlers in the region.
Monday: Glacial overview -- Gold Lake Road, Lower Sardine Lake, Frazier Falls, glacial features, and Young America Mine view. Drive and easy hikes at 5700 and 6200 feet elevation.
Tuesday: Locke Mine ridge – Tertiary-aged conglomerates and volcanic rocks (including readily accessible Basalt of Haskell Peak), and Jurassic-aged granitic rocks and garnets. Drive and moderately easy hike at 7200 to 7500 feet elevation.
Wednesday: Westall Diggins and Mills Peak Lookout – Hydraulic mine site, Mohawk Fault escarpment, Basin-and-Range overview, Lakes Basin overview with glacial features, and Paleozoic-aged metavolcanic and metasedimentary rocks. Drive and easy hikes at 6800 and 7200 feet elevation.
Thursday: Fern Falls Loop and Gold Lake roadcut – Paleozoic-aged metavolcanic rocks, Cretaceous granitic rock, and glacial features. Moderate hike at 6000 to 6200 feet elevation. Possible tour of Kentucky Mine Museum near Sierra City.
Friday: Sierra Buttes Lookout via Packer Saddle – Paleozoic-aged metavolcanic rocks, glacial features, and spectacular views from 8600-foot peak. Moderately strenuous hike on trail and 4WD road from 7000 to 8600 feet elevation. Optional ice cream at Bassetts Station afterward!
Workshop Supplies List
Optional Field Gear
Walking stick, 10x hand lens (geologists’ magnifying glass) on a lanyard, binoculars, real camera, notebook and pencils.
Lodging and Camping Supplies
Camping gear if you are staying on campus:
- tent and sleeping pad (unless you are staying in our tent with a cot provided)
- warm sleeping bag
- pillow, toiletries, and towel
- flashlight and lantern
- alarm clock
Field gear for everyone:
- day pack
- insect repellant
- water bottles
- plastic containers for packed lunches
- sense of humor
You might also want to bring:
- hand lens
- camp chair
The weather in the Sierra Nevada can vary greatly, even in a single day. Be prepared for chilly temperatures at night, even below freezing early in the summer. Rain is a possibility any time, whether forecast or not. Variable weather clothing that can be layered is best: long pants and a long-sleeved shirt, warm sweater and jacket, t-shirt and shorts or skirt, sturdy shoes or hiking boots, sun hat, rain gear, and a warm hat or gloves for cold weather and/or night activities. And, if you come later in the season, bring your swimsuit for afternoon dips in the lakes!