Glaciers (Ch. 19) Glaciers Miscellaneous Snowpack Measurement - SNOTEL
Defined Who cares Colorado glaciers? Mass balance / firn line Glacier movement video Inputs: Snow to firn to glacial ice Outputs: Loss / ablation Glacial types Erosional processes / landforms Depositional processes / landforms Hazards Miscellaneous Pleistocene glaciations Two Pleistocene events in Colo. Snowpack Measurement - SNOTEL Pleistocene glaciations Two Pleistocene glaciations in Colorado Rock glaciers Glaciers Defined Glaciers form where more snow falls than melts over a period of years, compacts into ice, and becomes thick enough to begin to move. Glaciers Who cares? 60 80% water for 70 mil. Since 1880s, ^ 8 inches
With total melt, 216 ft. increase. Glacier facts > about 70% of all fresh water locked in ice > 200 million people depend on glacial melt water for drinking. Especially those in Andes / Himalaya regions. > 80% of the fresh water in Peru originates from snow / ice melt > In the Western US, 30 million are snow / ice melt-dependent > Globally, ____% of all glaciers are retreating (Leemans and Eickhout, 2003) Glaciers Glacier Bay National Park Washington Cascades Glaciers AK, WA, WY, MT, CA, OR, ID, NV Glaciers Colorado glaciers???
There are more than 135 permanent snow or ice bodies mapped in Colorado, but only 7 of these are larger than 0.1 km2. Colorado has 14 named glaciers - all in the Front Range, most significantly in Rocky Mountain National Park. The total area of all the mapped snow and ice bodies in Colorado is about 4.8 km2. (Portland State University) Glaciers Colorado glaciers???
DEM of San Juan Mountain region, SW Colorado (tothemountains.com) Colorado glaciers??? Andrews Glacier (Larimer County) Arapaho Glacier (Boulder County) The Dove (Boulder County) Fair Glacier (Grand County) Isabelle Glacier (Boulder County) Mills Glacier (Boulder County) Moomaw Glacier (Boulder County) Peck Glacier (Grand County) Rowe Glacier (Larimer County) Saint Marys Glacier (Clear Creek County) Saint Vrain Glaciers (Boulder County) Sprague Glacier (Larimer County) Taylor Glacier (Larimer County) Tyndall Glacier (Larimer County) KML file (GNIS glaciers) from: David C. Percy, Mass balance Firn line ZONES: accumulation ablation Firn line Firn lines represent a seasonal boundary between old, exposed ice and fresh, recrystallized new snow. Firn lines are visible at end of melt season Image from: Glacier movement Snow accumulation / input
Net accumulation from: Snow Direct precipitation Wind loading Avalanching Supercooled vapor Rime ice Superimposed ice/water Rain, snow, slush flows across ice Snow accumulation / input Snow to firn Snow metamorphosis: After about 1 year, firn is formed Firn to glacial ice Conditions for glacial ice formation:
Lower layers of firn turn to solid, hard, compact ice under the weight of overlying firn and snow 1 to 1000 yrs. Ice slowly moves downslope Glacial ice New snow density: 0.05 g/cm3
Firn density: 0.5 g/cm3Ice density: 0.8 g/cm3Glacial ice density: 0.9 g/cm3 Loss of glacial ice Melting Sublimation from katabatic winds
Avalanche off ice (dry calving) Iceberg calving