What is erosion?

Shaping Earth
Lesson 3: Weathering and Erosion
What is weathering?
 Physical weathering occurs when a rock is broken into small pieces
 Chemical weathering occurs when minerals in a rock are changed into
different minerals
 Flowing water, rain and wind are some causes of weathering
 Vocabulary:
 weathering – the slow process that breaks rocks down into smaller pieces.
What is erosion?
 Gravity, moving water, glacier and wind are the causes of erosion
 Vocabulary:
 erosion – the slow process that weathers rock and carries it away
 deposition – the dropping off of weathered rock
How do glaciers shape the land?
 Glaciers are thick sheets of ice formed where snow collects quickly and
melts slowly.
 Year after year as the snow builds higher the weight of the mound puts
pressure on the snow below. The bottom slowly turns into ice.
 As the weight of the glacier increases, the glacier begins to move and it
tears rock from the ground.
 Vocabulary:
 terminus - the downhill end of a glacier where glacial till and other debris is
 glacial till – glacial debris that is a mix of small rocks, gravel, sand and clay
 moraines – a large body of weathered rock deposited at the edge of a glacier
How do people shape the land?
 Some ways people change the land are mining, making landfills and cutting
down forests.
 Helpful ways that people shape the land include planting trees and building