Weathering and Erosion

Weathering and ErosionHow landforms are made.Mechanical Weathering

Weathering TerminologyBedrock: unaltered rock of any kindRegolith: a layer of broken pieces of rock and slightly altered rock that overlies the bedrockSoil: a layer of altered mineral material usually mixed with organic materialWeathering due to physical changesIceAbrasionGravityWindWaterPlants AnimalsMechanical WeatheringFrost: water expands by ~10% when it freezes

Thermal expansion: differential heat expansion of minerals creates stress in rocks

Organic activity: tree roots to micro-organisms

This is a picture of the Half Dome. The rock is peeling away from the mountain in layers just like an onion. This is exfoliation.

Frost Action or ice wedging slowly breaks up this sedimentary rock into unusual shapes.

These rocks have been blasted by wind and sand causing them to become rounded.WIND ABRASION

Chemical Weathering

Weathering due to chemical changes of an object.WaterAcid RainAcid in the GroundwaterAcids in living thingsAirOxidationChemical Weathering

Why are deserts and Mars red?Oxidation of iron (rusting)This rock is red because of the oxidation of iron in the sediment when the rock was being formed.

In this picture the running water eroded the sides of this canyon and created the V-shaped valleys.

This is a picture of a landslide. A type of mass wasting.

In this picture the land has slumped into the road below.This is a diagram of creep. The hillside slowly slips over many years from temperature or water.

This is a picture of an avalanche. It is similar to a landslide with ice and snow instead of rock.

This is a picture of a glacier which carves out a U-shaped valley where it flows dragging rocks and boulders along the way.

Differential WeatheringProcess where softer, less weather resistant rock wear away and leave harder, more weather resistant rock.

What are the major factors that control weathering?

Composition, Structure (surface area)Climate, Soil and vegetation, Time

Principles of chemical weathering

Why do we use hot water to make coffee? Why do we grind coffee before brewing it?Why is the ocean salty?

Climate and WeatheringClimate is the average weather condition in an area over a long period of time.The rate of chemical weathering happens faster in warm, humid climates.