Final answer:
Plucking and abrasion are two processes of glacial erosion. Plucking occurs when a glacier pulls rocks away from the bedrock as it moves. Abrasion is the process of a glacier grinding and scraping the bedrock beneath it.
Step-by-step explanation:
Plucking and abrasion are two processes of glacial erosion.
Plucking:
Plucking occurs when a glacier freezes onto rocks and pulls them away as it moves downhill. As the glacier moves, it entrains rocks and stones from the bedrock beneath it. The rocks freeze to the bottom of the glacier, and as the glacier moves forward, it plucks the rocks out of the ground. This process is aided by freeze-thaw weathering, where water enters the cracks in the rocks, freezes, and expands, further breaking them apart.
Abrasion:
Abrasion is the process by which a glacier grinds and scours the bedrock beneath it. As the glacier moves, it carries an abundance of rock fragments and fragments of its own ice, known as glacial flour. These rock particles act as tools of erosion, scraping and scratching the bedrock as the glacier moves, creating grooves and striations. Over time, abrasion can carve out deep basins, such as cirques and glacial valleys.