Presentation on theme: "Changing the earth’s relief Evolution of the landscape Textbook p. 314, 333-335."— Presentation transcript:
Changing the earth’s relief Evolution of the landscape Textbook p. 314,
Changing the earth’s relief: mountain formation Relief = shape of the earth surface Formation of mountains = Orogenesis through convergent tectonic plate movements mountain: - steep slopes - at least 600m high Mountains in the making: ➔ Himalaya, Rocky mountains, Alps
Laurentians Rocky Mountains Why are they different? ?
Montreal streets : After the winter: worn down
Laurentians Rocky Mountains Laurentians a lot older have been worn down ! Why are they different? ?
Weathering Gradual destruction of rock on the earth surface. N0Y N0Y
Mechanical weathering The power of water: Rock is fragmented, but not changed in its composition
Mechanical weathering Fragmentation of rock through: - Variations in temperature and pressure - water example: freeze thaw cycle of water -wind Composition of rock does not change
Minerals in rock are dissolved and changed. Chemical weathering
Chemical Weathering Dissolving and changing minerals in rocks Composition of rock changes. Through: - washing out of certain minerals enhanced through acid rain
Biological Weathering Living organisms destroy rock.
Biological weathering Plant roots can break rocks Living organisms release acids changes and weakens the rock
Practice: what kind of weathering? 1. Mechanical 2. Chemical 3. Mechanical + Chemical 1 2 3
Erosion of soil Soil Erosion rates on farmed land between 17 and 40 tons per ha and year average natural soil production only 1 ton per ha and year !!!
Journey’s end: Deposition
The three stages of Erosion Erosion 1.) Weathering 2.) Transport: water, wind, ice 3.) Deposition: in lake, stream, ocean
Changing the earth’s relief: Erosion Erosion is the gradual wearing away (destruction and /or removal) of land surface material, for example rock or soil. Three step process: – Weathering of rock (destruction of rock) – Transportation of soil and rock debris (through water, wind, glaciers). – Deposition of material at another location
View from the mountain:
Effects of erosion Hole on Sherbrooke May 2012 Caused by hole in water collecting pipe What happened?
homework Worksheet to be collected next class
Categories of Weathering / Erosion Mechanical Weathering – Composition of rock does not change – Through: - Variations in temperature and pressure example: freeze thaw cycle of water - Wind and water Chemical Weathering – Composition of rock changes – Through: - washing out of certain minerals enhanced through acid rain Biological Weathering – Living organisms release acids change + weaken the rock – Plant roots can break rocks.