Glacier National Park
• 1,013,572 acres, 1584 square miles
• Established 1910
• International Peace Park - 1932
• George Grinnel - 1885
• Great Northern Railroad
Glacier National Park
• Northwestern Montana
• Continental Divide
• Going-to-the-Sun-Road
Glacier National Park
• Crown of the Continent Ecosystem
• Alpine Environments
• management
• Habitat fragmentation
GNP - The Mountains
• Why do the mountains in Glacier appear so abruptly?
• Northern Rockies - mountains without roots
• Thrust Faulting - crustal shortening
• Compression - convergent plate boundary
• Thrust belt
• Laramide OrogenyGNP - The Mountains
• The Lewis Thrust
• Precambrian sedimentary rocks over Cretaceous shales
GNP - The Rocks
• The Belt Series - 1 GYA to 600 MYA
• slightly metamorphosed sed. rx.
• Sandstone, shale, limestone, argillite
• Ancient reefs - stromatolites
• The Belt Sea - shallow tropical sea
GNP - The Glaciers
• Glaciated National Park
• Most of the work done - Pleistocene
• 2000 years ago - “Little Ice Age”
• Glaciers in GNP have shrunk - Why?
GNP - The Glaciers
• Glacial Recession
• Global Warming?
Glaciers
• What is a glacier?
• thick mass of ice that originates on land
• accumulation, compaction, and re-crystallization of snow
• Metamorphosed snow
• Two types - alpine and continental
• Modifiers of landscape
Alpine Glaciers
• accumulation of ice in the mountains (wet and cold)
• flow down pre-existing stream valleys
• mechanism for movement or flow = gravity
• Create mountains with very sharp & rugged features
• Landforms - erosion and deposition
Alpine Glaciers
• Movement = gravity
• DEPENDS ON => slope, precipitation, temperature
• Plastic Flow - plastic and viscouse
• Sliding - sliding along the base
• Always moving down slope - advance vs. retreat
• movement = balance between accumulation and ablation
Alpine Glaciers
• Glacial Erosion
• Plucking - ice in bedrock fractures
• Abrasion - scraping = -striations, -polish, -flour
• Erosional landforms - U-Shaped Valleys - glacial trough
Alpine Glaciers
Hanging valleys
Cirque
Arête
Horn