Geoscience Reference
In-Depth Information
associated with receding glaciers could lead to proactive public participation and
implementation of adaptive management strategies designed to adjust to short-term
climate change.
Keywords
Rock glaciers
·
Mass wasting
·
Geospatial techniques
5.1 Introduction
Rock glaciers, tongue-shaped or lobate masses of consolidated rock and ice, are
abundant in the Colorado Rocky Mountains (Vitek and Giardino
1987
;Barsch
1996
;
Haeberli
2000
; Janke
2005a
). Although they have not been as intensely studied
compared to temperate glaciers, rock glaciers have many important functions in
the alpine ecosystem. They serve as a source for construction material, a backdrop
for residential areas, dam abutments, drill sites, shaft and tunnel portals, and a water
source for urban areas (Giardino and Vick
1987
; Burger et al.
1999
). Measurements
of the movement of rock glaciers provide geomorphologists information about land-
form development, flow, age, or ice content. Slope failures induced by climate
change can increase the hazard potential for nearby communities or roads, mod-
ify aquatic ecosystems, or affect drinking water quality by increasing suspended
and solute concentrations (Kääb et al.
1997
; Konrad et al.
1999
; Kääb and Vollmer
2000
; Degenhardt and Giardino
2003
; Williams et al.
2006
; Williams et al.
2007
).
The movement of rock glaciers has been measured using field surveying tech-
niques, such as tape measurements, triangulation, or laser ranging (White
1971
;
Haeberli
1985
; Benedict et al.
1986
; White
1987
; Sloan and Dyke
1998
; Konrad
et al.
1999
; Krainer and Mostler
2000
; Leonard et al.
2005
; Janke
2005a
; Serrano
et al.
2006
). Recent studies have utilized photogrammetry and computer algo-
rithms to observe flow of the entire surface of rock glaciers, effectively increasing
the density of sampling points and extending the period of analysis (Kääb et al.
1997
; Kaufmann
1998
; Kääb
2002
; Kaufmann and Ladstädter
2002
; Janke
2005b
;
Wangensteen et al.
2006
). Differential Global Positioning Satellite (GPS) tech-
nology has been used on some rock glaciers to detect seasonal motion (Lambiel
and Delaloye
2004
; Bauer et al.
2005
; Krainer and Mostler
2006
; Wangensteen
et al.
2006
). Using a GPS receiver as a reference station and one as a rover (Real
Time Kinematics), rapid and accurate measurements of <1 cm can be obtained
(Hofmann-Wellenhof et al.
1994
; Eiken et al.
1997
; Little et al.
2003
).
The climatic response of rock glaciers is unique compared to temperate glaciers.
Rock glaciers typically have a debris cover (1-3 m thick in some instances), which
acts as an insulator and protects internal ice. This debris filters short-term climate
anomalies and is not as sensitive to yearly fluctuations in temperature or snow-
fall compared to temperate glaciers. As internal ice melts, some rock glaciers will
experience deceleration because the ice is becoming too thin to flow effectively.
Other rock glaciers may show accelerating horizontal velocities as ice warms. Warm
