Aim: How can glaciers erode and deposit on Earth’s surface? Do Now: What is the driving force of glacial movement?
Glaciers: Erosion and Deposition: Glacier: A large mass of moving ice and snow.
Types of Glaciers: Valley/Alpine Glaciers: glaciers form in mountain valleys at high elevations. Example locations: Alps (Europe), Rockies (U.S.) Himalayas (India), Andes (Chile)
Continental Glaciers: form over vast area of land and radiate outward. Example locations: Greenland and Antarctica
Ice Age Continental Glaciers: • In the geologic past, a much colder climate resulted in ice sheets covering much of Earth’s surface.
There is evidence of at least 4 major ice ages during the last 2 million years. The time period between ice ages is called interglacial periods. The most recent ice age ended only about 11,000 years ago (Pleistocene)
Glacial Erosion • Glaciers are the most powerful erosional agent because of their great size, weight, and density.
Profile view of Valley Glacier Plucking: removal of pre-existing rock
Glacial Erosion Features • Striations/Grooves: When glaciers with embedded rocks move over bedrock valley walls, they grind out parallel scratches into the bedrock.
Striations provide evidence of past glacial movement and establish its direction of movement.
Cirque: Bowl-shaped depression on side of mountain. Arête: Knife-like ridge where two cirques meet. Horn: Sharp peak after three cirques meet.