Geology of Lake Tahoe

Instructor: Jeff Tolhurst, Ph.D.
Office: Sugar Pine 119
and Fir 6
Office Hours:
TuTh 8:20-9:40am in Sugar Pine 119; M 4:30-6:00 pm in Fir 1 or 6 or by appointment
Phone: (209) 588-5235 office (+ msg); (209) 588-5104 (fax)
Email: tolhurstj@yosemite.edu
Course Credit: 2 semester hours
Prerequisites: None
Day and Time: Thursday-Sunday; 8am-5pm
Room: Field
Text:
Geology by Frank H. T. Rhodes, published by St. Martin's Press, 175 Fifth Ave., New York, NY, 10010, www.stmartins.com.


Facebook Earth Sciences Program Page

Field Trip Forms


Suggested Reading

Geologic Trips: Sierra Nevada by Ted Konigsmark, published by GeoPress, P.O. Box 964, Gualala, CA 95455.  This book is also available through Mountain Bookstore or from Bored Feet Press, P.O. Box 1832, Mendocino, CA 95460; (888) 336-6199, www.boredfeet.com.

The Field Guide to Geology by David Lambert and the Diagram Group; Facts On File, Inc., 11 Penn Plaza, New York, NY 10001.

Objectives: Given information on the geological history and the main geologic processes occurring in the Lake Tahoe region, you will be able to explain/describe the main geologic processes that have formed and continue to shape the Sierra Nevada mountains and Lake Tahoe basin.  You will also be able to describe some of the current geologic events and issues in the Tahoe Basin.

Procedures: We will meet two times: 1) in class for the orientation and first class meeting (Tuesday, September 15th); and for the trip (Thursday through Sunday September 21-24). The pre-trip meeting will cover information on what to bring, what to expect, and what to turn in for credit. We will also cover some information on the geological background of the Sierra to prepare us for the trip. A trip itinerary will be given.

Note: Hot spring fees will be $6.00 per person at Grover Hot Springs in Markleeville – bring a swim suit and towel.  Camping fees for all 3 nights will be approximately $20-25 depending on how many students there are.

Itinerary:

Thursday September 21: We will meet at the student dorms on campus side so that you may have a place to leave your vehicles overnight until we return Sunday. Loading time will begin at 7:45 am and we will leave shortly thereafter (by 8:00 am), once all heads have been counted and gear loaded. We will travel up Highway 49 to Highway 88 in Jackson, then head up Hwy 88 to examine some of the geology in the Sierra/greater Tahoe region. We will hike to an EarthCache near Kirkwood Meadows and gather enough information to log the cache. We will then

Friday September 22: We will find and log several EarthCaches in and around the Lake Tahoe basin - along the south and west sides of the lake.  We will do some short hiking at around 6-7,000 feet elevation to examine some of the outcrops and see some of the story of Tahoe's geology.

Saturday September 23
: We will explore more of the geology in the Tahoe region - mostly along the northwest side of the Lake Tahoe region. We will do some more hiking at around 6-8,000 feet elevation to examine some of the outcrops and see some more of the story of Tahoe's geology.

Sunday September 24
: We will explore the Markleeville and Ebbetts Pass area to examine geology of the east side as well as observe features related to the geologic formation of the Sierra Nevada Mountains. Included are a hike up Horsethief Creek to examine faulting, then a stop at the evidence for a jokulaups and faulting at Woodfords. We will be at Grover Hot Springs in the afternoon, so bring a bathing suit & towel and $6 (this is what it cost last year). We should arrive back at campus by approximately 5 pm.

What to Bring:

-- clothing for both warm and cold/wet weather
-- camping gear (tent, sleeping bag/pad, tarp, etc.)
-- foodbreakfast, lunch, and dinner plus snacks for each day (click here for more detail)
-- sturdy hiking/walking shoes
-- sunscreen/chapstick
-- mosquito repellent
-- sunglasses
-- a hat
-- money for miscellaneous items
-- a learning log (to be turned in for credit)
-- any medications you might need
-- earplugs so that you can sleep at night
-- a camera - you'll need to turn in 8 photos of the trip documenting some of the things you learned

-- other

What to Expect:

Expect hot/warm days down at lower elevations and cool/possibly wet (thunderstorms) up at higher elevations. The weather is usually nice this time of year, but who knows what will happen! The region is prone to afternoon thunderstorms and it will be difficult to say what the weather will be like. Be prepared for a range of weather.

What to turn in for credit:

In order to assess your learning, I'll ask you to keep a field log for the trip. You will be expected to turn this in to me at the end of the class. This log should document the things you would like to learn before the trip as well as why you are taking the class (to be completed between the pre-meeting and the first day’s trip). You should also enter into your log the things you learned about: 1) the Sierra Nevada Mountains; 2) tectonics/faulting; 3) volcanism; 4) glaciers; and 5) geology of the Lake Tahoe region. You will be asked to make an entry at each EarthCache or non-EarthCache stop on the trip as well as add an additional entry at the end of each day (Thursday, Friday, Saturday & Sunday), reflecting on what happened during that day (i.e. what were your thoughts, feelings, and desires). A final summary of what you learned on the trip (4-5 pages maximum) will be required for full credit. All work will be due (in my mailbox) on Monday, October 9th, by 7:30 pm in my mailbox in Manzanita. To summarize, the learning log should include:

  1. a description of your background with a photograph of yourself

  2. a field log entry at each stop summarizing what you learned, as well as answers to the questions for each EarthCache (if appropriate)

  3. an entry in your field log at the end of each day reflecting on what your overall impressions of the day were

  4. a 4-5 page overall summary of the trip including what you learned about:
         1) the geology of the Sierra Nevada Mountains;
         2) tectonics/faulting in the Lake Tahoe basin;
         3) volcanism related to the Lake Tahoe region;
         4)
    glaciers/glacial landforms and how they shape the landscape;
         5) overall geologic history of the Lake Tahoe region;
        
    6) 8 photographs documenting important geologic phenomena;
         7) 3 hand-drawn diagrams (or computer generated by your own hand)
             depicting important geologic processes or phenomena observed
    .

    The summary will include a 4 page minimum, 5 page maximum, digital report, emailed to me. The 8 photographs may not be included on the 4-5 pages. They must be referred to in the text, but each must be placed on a separate page.  Also include 3 separate diagrams in the report – these, too, must each be placed on separate pages.

Grading Scheme:

A = satisfactory completion of 1-4 above with strong demonstration of understanding of geological concepts encountered on the trip; appropriate use of photos and diagrams to support concepts in the paper; paper is well organized (i.e. includes an overview of what will be discussed, a main body explaining primary concepts, and a summary/conclusion). Also, appropriate conduct and behavior expected of a college-level geology student will be factored into your grade.   (Click here to read the Student Code of Conduct from the Columbia College Catalog)

B = completion of summary without all photos and/or diagrams; less than 4-5 pages; not type-written; field log incomplete; lack of comprehension of geological concepts observed; poorly organized paper. Also, appropriate conduct and behavior expected of a college-level geology student will be factored into your grade.

C = completion of field log; no summary turned in or summary, but no field log; poor comprehension of geological concepts observed; poorly organized paper. Also, appropriate conduct and behavior expected of a college-level geology student will be factored into your grade.

D = attendance on field trip only; no field log turned in; no summary turned in. Also, appropriate conduct and behavior expected of a college-level geology student will be factored into your grade.

F = no attendance or left trip early and did not turn any work in. Also, appropriate conduct and behavior expected of a college-level geology student will be factored into your grade.

Note: I have had to add these statements based on past student behaviors: 

1) All campgrounds we stay in ask for quiet after dark.  If you (individually or  in a group at the campground) have to be asked to be quiet after 9 pm your grade will be dropped.  If you have to be asked again your grade will turn to an "F" and you will fail the course;

2) NO SMOKING during field lectures and activities.  If you cannot adhere to this requirement you should drop the course.  I'm serious about this - you can't smoke in class, so I ask you please not to smoked on the field trip. Fire hazard in California is very serious business and we need to be as safe as possible.

That having been said, I hope we all have a good trip! Feel free to contact me at the phone number or email address above if you have any questions before or after we leave.


Sierra Nevada Study Guide
(see Geologic Trips: Sierra Nevada by Ted Konigsmark, GeoPress, P.O. Box 964, Gualala, CA 95445 or Bored Feet Press, P.O. Box 1832, Mendocino, CA 95460)

Subjacent Series:
· Shoo-Fly Complex and Eastern Sierra Metamorphic Belt (Atlantic Margin) 
· Antler Orogeny 
· Calaveras Complex (Japanese margin) 
· Sonoma Orogeny 
· Foothills Terrane (Andean margin) 
· Nevadan Orogeny 
· Sierra Nevada Batholith (Andean margin) 
· Growth and Erosion of the Ancestral Sierra Nevada 

Superjacent Series:
· Ione Formation: Sand, clay and coal formed in subtropical environment along low flat coastline; Sierra crest 2,000-3,000 feet (40 my) 
· Valley Springs Formation: Ignimbrite, welded tuff; represents return of volcanism to Sierra region, and start of slow uplift (19.9-25 my) 
· Mehrten Formation: Andesite and basalt lava flows with lahar deposits common. Indicates Sierra high enough for snow (4-20 my) 
· Uplift of the Sierra Nevada: Francois Matthes (1930's) and modern perceptions

Glaciation of the Sierra Nevada:
· Modern day glaciers
· Tioga Stage: 9,990 - 25,500 ybp 
· Tenaya Stage: >30,700 ybp
· Tahoe Stage (Tahoe II): 56,000 - 118,000 ybp 
· Mono Basin (Tahoe I): >131,000 ybp
· Pre-Tahoe: Sherwin Stage: 690,000 ybp, 
· McGee Stage: 1.5 million years ybp (?) 

Physical and Chemical Weathering in the Sierra Nevada
· Domes and spheroidal weathering
· Exfoliation and jointing
 


Tahoe Environmental Research Center (TERC)

TERC Tahoe State of the Lake Report

Tahoe Research in California Agriculture Journal (2006)

Evidence for Megadrought in Tahoe


 

 

 

       
       

 
       
       
       

Hit Counter