Glacial erosion is the process by which glaciers carve, scratch, and grind the Earth's surface as they move. Glaciers are massive sheets of ice that form from compacted snow and ice over long periods of time. As they move across the landscape, they erode the land through several processes, including plucking, abrasion, and quarrying.
Plucking: This is the process by which glaciers pick up rocks and debris as they move over the land. As the glacier moves, it pulls rocks and sediments from the ground, which become incorporated into the ice.
Abrasion: Glaciers also erode the land through abrasion, which occurs when the rocks and debris embedded in the ice scrape and scratch the underlying bedrock.
Quarrying: When glaciers move over the land, they can break off large pieces of rock from the bedrock, a process known as quarrying. These large pieces of rock, called glacial erratics, can be transported and deposited in different locations as the glacier retreats.
History and Nature of Science: A student should understand the history and nature of science. A student who meets the content standard should:
Develop an understanding that historical perspectives of scientific explanations demonstrate that scientific knowledge changes over time, building on prior knowledge.
Develop an understanding that scientific knowledge is ongoing and subject to change as new evidence becomes available through experimental and/or observational confirmation(s).