GLACIAL LANDFORMS (pp. 262-265) Glaciers • Large Masses of Moving Land Ice Significance of Glaciers • Store 75% of World’s Freshwater – 90% of the ice… • Antarctica • Greenland Significance of Glaciers • Effect on Sea Level – During Ice Age • 10,000 yrs ago • Sea Level? – If all ice melts… +200’ rise in sea level • Problem? Significance of Glaciers • Shape the Landscape Types of Glaciers 1. Cirque Glacier – In a Glacially Carved Amphitheater Types of Glaciers 2. Valley Glacier – In an Old Stream Valley Cirque & Valley Glacier Cirque & Valley Glacier Types of Glaciers 3. Ice Sheet – Covers most of the land Glacier Formation 1. Need Perennial Snow 2. Snow Recrystallizes into Glacial Ice – Takes 10-100 yrs 3. 200’ Thick Ice Movement Zone of Accumulation (pg. 263) • Upper part of Glacier • More Snowfall than Melting Zone of Ablation (pg. 263) • Lower part of Glacier • More Melting than Snowfall Zone of Accumulation • Fresh Snow Cover • Very White Zone of Ablation • Covered with Debris • Dirty Grey Zone of Ablation Types of Movement 1. Basal Sliding Requires Meltwater Fastest for Warm Glaciers 2. Plastic Flow • Internal Deformation – Esp. in Middle of Ice – Top is Rigid • Cracks to form Crevasses Glacial Movement 1. Basal Sliding 2. Internal, Plastic Flow Crevasses in New Zealand Glacial Erosion (pg. 113) 1. Plucking – Ice Tears Out Rocks • Rocks Embed into the Ice 2. Abrasion – Rocks in the Ice Grind Rock Beneath Erosional Landforms (pg. 265) Erosional Landforms • Cirque – Glacially Carved Amphitheater Tarn • Lake in a Cirque Tarn Horn • Sharp Peak • Carved by 3 or 4 Glaciers • Matterhorn Horn Glacial • Carved by Valley Glacier Valley • U- Shaped Glacial Valley Hanging Valley • Small Glacial Valley – High Up the Side of Main Glacial Valley – Tributary Glacier Fed Main Glacier Hanging Valley Waterfalls Fjords • Long, narrow inlets of the sea Fjords • Glacial Valleys Submerged by the Ocean – West Coasts – 50oLat 75oLat – Norway… – New Zealand… Fjord & Hanging Valley New Zealand Depositional Landforms (pg. 115) • Moraines – Ridges of Glacial Debris – Terminal Moraine… Lateral Moraine • At Sides… Medial Moraines • When 2 Glaciers Join – 2 Lateral Moraines Medial Moraine Medial Moraines Continental Glaciation • Currently 2 Places Ice Age Ice Sheets • N. Amer. • Eroded Basins – The Great Lakes Outwash Plain • In Front of Ice Sheet • Sand & Gravel Deposited by Meltwater Streams KETTLE LAKES • Ice retreated unevenly at end of Ice Age • Ice blocks detached from retreating ice KETTLE LAKES • Glacial meltwater deposited sand/gravel in front of ice – Partly buries ice block KETTLE LAKES • Melting ice block leaves a depression – Land there wasn’t covered by glacial sediment – Depression collects water Kettle Lake KETTLE LAKE (NEW ZEALAND) Kettle Lakes - Minnesota “Land of 10,000 Lakes” .