Field Trip to Mono Lake, California, June 2009

Rafael and Sidney with geologic map.
Rafael and Sidney with geologic map of the Mono Craters Quadrangle.

Mono Lake is located in the Mono Basin, eastern California, and is flanked on the west by the impressively beautiful eastern Sierra Nevada Mountain Range. Repeated glacial cycles over the past few million years have left their imprint on these mountains, as evidenced by spectacular moraines that extend down from the mountain-tops towards the lake. The lake itself, known primarily for the tufa towers that spring up at the edge, is host to a relatively simple eco-system, and yet is the stopping point for thousands of birds that migrate over the area every year. South of the lake is a line of craters- the Inyo and Mono craters- of which Panum Crater is the farthest north. On the northern edge of the lake is a succession of lake sediments inter-bedded with ash layers; these sediments hold clues to past climate fluctuations in the lake and are evidence of the lake having been much larger in the past, during glacial times. Luckily, the Tioga Pass was open early this year, and so we were able to spend a day in Yosemite National Park! Overall, this area allows for a look at a range of geologic processes from very old that occurred deep within the Earth to those occurring today, e.g. the formation of the Tufa Towers. The sub-fields of earth science represented in this area include tectonics, volcanology, petrology, geochemistry, paleoclimate and ecology, and thus provided a fantastic overview of many geologic processes for the graduate students

Seminar

A student-led seminar series based on extensive literature reviews was a critical component of the preparation for this field trip. The students met for a total of 16 hours and each of the participants presented a topic of interest to the rest of the group. The seminar laid a good foundation for our field studies and helped to foster the discussion of various features and phenomena we observed in the field. The seminar also provided a basis for general overviews included in this guide. Below is a list of the topics we presented and associated papers (full references can be found in the field guide).

Meeting 1 (April 13): Introduction to Mono Lake

TOPICS: Geology, Tectonic Setting, Glacial History, Lake Setting, Ecology

READINGS:

Scholl et al (1967) Age and Origin of Topography Beneath Mono Lake
Russell, Israel (1889) Quaternary history of the Mono Valley, California
Susan Zimmerman’s PhD Thesis (Columbia University, 2006) Introduction
Wiens et al (1993) Lessons from Mono Lake (sections on ecosystem and environmental issues)
John McPhee, Basin and Range (excerpt) optional
Reheis etl al (2002) Drainage reversals in Mono Basin during the late Pliocene and Pleistocene

Meeting 2 (April 20): Mono Lake History and Glacial Features

TOPICS: Geomorphology, Aqueous chemistry, Lake-level reconstruction, Climate

READINGS:

Zimmerman et al (2006) Revised chronology for late Pleistocene Mono Lake sediments based on paleointensity correlation to the global reference curve.
Stine (1990) Late Holocene Fluctuations of Mono Lake, Eastern CA
Benson et al (1998) Correlation of Late-Pleistocene Lake-Level Oscillations in Mono Lake, California, with North Atlantic Climate Events
Council and Bennett (1993) Geochemistry of Ikaite formation at Mono Lake, Ca: implications for the origin of tufa mounds.
Stephen L. Harris (1988) The Ice: How a Glacier Works, from Fire Mountains of the West
Putnam, 1949 and 1950 (maps or moraines and June Lake geology)
Bursik and Gillespie (1993) Late Pleistocene Glaciation of Mono Basin, CA
Davis (1999) Pollen Analysis of a Late-Glacial and Holocene Sediment Core from Mono Lake

Meeting 3 (April 27): Volcanics and Sierra Geology

TOPICS: Volcanism in the Great Basin region, Chronology

READINGS:

Stephen L. Harris (1988) The Fire: How a Volcano Works and The Mono Lake-Long Valley Region from Fire Mountains of the West
Schweickert and Lahren (1999) Triassic Caldera at Tioga Pass
Cousens et al (2008) Geology, geochronology, and geochemistry of the Miocene-Pliocene Ancestral Cascades arc, northern Sierra Nevada, California and Nevada.
Sieh and Bursik, 1986, Most recent eruption of Mono Craters, eastern central California
Gilbert et al (1969) Structural and Volcanic History of Mono Basin, California-Nevada 

Meeting 4: pre-trip meeting May 28

Meeting 5 (wrap-up after return to CU):  Putting together a field guide with notes and photographs from the trip.

Yosemite

Itinerary

Day 1 - Volcanics

Panum Crater
Obsidian Dome
Inyo and Mono Craters
Mammoth area; Horseshoe Lake and CO2 kill
Long Valley Caldera

Hot Springs at Hot Creek

Day 2 - Mono Basin

Tufas and Modern Lake Level History
Wilson Creek Formation
Glacial history (Lundy Cayon; Lee Vining Canyon, Bloody Canyon)

Day 3 - Yosemite

Geology
Ecology

Day 4 - Convict Lake and Bishop Tuff

Bishop Tuff
Convict Lake
Volcanic Tablelands

Field Guide

After returning from the trip, each of the participants was assigned a section to write and prepare for the field guide. This field guide includes assigned readings for the seminars that we attended prior to the trip, daily itineraries, and a geologic overview of the different areas that we visited.