United States Department of Agriculture, Forest Service
Pacific Southwest Research Station
Sierra Nevada Research Center
Rock Glaciers and Periglacial Rock-Ice Features in the Sierra Nevada:
Classification, Distribution, Hydrology, and Climate Relationships; Their Significance for the West in a
Climate-Change Context
The Research:
Rock glaciers and related periglacial rock-ice features (RIF) are widespread
landforms in arctic and alpine environments with cold temperatures, low
humidities, and abundant shattered rock. Compared to typical ice glaciers,
however, rock glaciers are little understood and studied. Rock glaciers are
especially significant in the context of a warming world: While ice glaciers
have been retreating worldwide, water contained in the ice of rock glaciers or
RIFs is protected from rising air temperatures by insulating rock mantles. As
a result, thaw of ice in rock glaciers significantly lags behind ice glaciers. For
this reason, rock glaciers are likely to become increasingly critical alpine water
reservoirs as temperatures rise.
Rock glaciers and RIFs are ubiquitous in the high Sierra Nevada south of the
Lake Tahoe region, but no previous information exists on their classification,
rangewide distribution, hydrology, or modern climate relations. Because
these features are rock-covered and often appear similar superficially to
rockfalls, talus, and scree slopes, their presence and hydrologic significance
have been widely overlooked. A few focused studies on paleoclimate and
glacial advances have been conducted on a subset of glacigenic (debriscovered) rock glaciers in the southern Sierra Nevada, but beyond this, rock
glacier implications have not been incorporated into studies that estimate
regional distribution and extent of stored ice, assess timing and abundance
of mountain streamflows, model changes in water yields under warming
climates, or define wetland alpine refugia for biodiversity. As elsewhere, rock
glaciers in the Sierra Nevada remain “...landforms whose wide distribution,
occurrence, and significance often go unnoticed”.
Our studies seek to fill research gaps and address the distribution and
significance of these alpine features in a climate-change context.
Objectives:
Relative to rock glaciers and RIFs in the Sierra Nevada, our study goals are
to:
• Develop a regional classification and nomenclature
• Compile a geo-referenced database with type localities and photos derived
from field-mapping
• Analyze geographic and climatic relations (modern and historic) of the
mapped features
• Formulate and test hypotheses of process and origins
• Initiate reconnaissance-level monitoring of rock glaciers and RIF
movement; meltwater, including flow, seasonal persistence, temperature,
water age, and chemistry; lichen and plant cover and ages
Our Mission:
Sierra Nevada Ecosystems are
complex and our knowledge
of them is incomplete.
As a result, the long term
outcome of any given land
and resource management
strategy is uncertain. We
will provide assistance to
land managers and policy
makers by addressing this
management dilemma
through targeted research,
emphasizing an integrated,
ecoregional approach to
examine particular physical,
ecological, and socioeconomic issues, across a
range of appropriate spatial
and temporal scales specific
to each issue.
This unit will represent the
collective research expertise
and interests of scientists
located in Fresno, Davis
and Albany as well as other
scientists within the Pacific
Southwest Research Station.
With a full spectrum of
research, from long term,
fundamental research
to short-term, tactical
applications, this Center
is intended to support
conservation, restoration,
and sustainable utilization of
the lands within the Sierra
Nevada ecoregion.
Application of Research Results:
We expect contributions from the ongoing work to basic science as well as regional
water and resource management and alpine biodiversity conservation. The role of
rock glaciers is of critical importance in arid mountain ranges as snowpacks decrease
and ice glaciers retreat. Due to their lag with climate and the insulating role of rock
mantling, rock glaciers may soon become the primary sources of persistent year
round groundwater from high mountain regions, in particular the Sierra Nevada . We
anticipate that elucidating the ubiquity, distribution, role of climate and hydrology in
high mountains to have diverse applications under changing climates. Among the most
important will be to improve input into hydrologic and especially groundwater models
and future simulations, and to document the significance of rock glaciers as sources
of water for alpine wetlands and biodiversity.
Location:
High Sierra Nevada,
cismontane, but mostly
east of the Sierran
crest; extending from
the Tahoe Basin to the
southern extent of the
alpine Sierra, south of
Mt. Whitney. Emphasis
is on the central Sierra
north of Bishop to
Bridgeport latitudes.
Publications:
PDFs available at http://www.fs.fed.us/psw/programs/snrc/staff/millar
• Millar, C.I. and R.D. Westfall. In review. Rock glaciers and periglacial rock-ice features in the Sierra Nevada; Classification, distribution, and climate relationships. Quaternary International.
• Poster: Modern and Paleoclimate Relations of Rock Glaciers and Related Rock-Ice
Features (RIFs) of the Sierra Nevada, California, USA.
• Poster: Rock Glaciers and Periglacial Rock-Ice Features in the Eastern Sierra Nevada; Updates on Classification, Mapping, Climate Relations, and Monitoring.
http://www.fs.fed.us/psw/programs/snrc
USDA Forest Service
Pacific Southwest Research Station
Sierra Nevada Research Center
Albany Location:
800 Buchanan Street
Albany, CA 94710
For further information contact:
Dr. Connie Millar
cmillar@fs.fed.us
Mailing Address:
P.O. Box 245
Berkeley, CA 94701
Dr. Peter Stine, Program Manager
Phone: 510-559-6300
Fax: 510-559-6440
Davis Location:
2121 Second Street
Suite A101
Davis, CA 95616
Phone: 530-759-1700
Fax: 530-747-0241
Fresno Location:
2081 E. Sierra Avenue
Fresno, CA 93710
Phone: 559-323-3200
Fax: 559-297-3355