Weathering

Weathering is the breaking down of rocks.

Mechanical weathering is the break down of rocks by physical means.

Examples of mechanical weathering Ice wedging Abrasion – grinding & wearing away of rock by mechanical means water 2) wind 3) gravity Repeated freezing & thawing of water that cracks rocks Plants & animals Pg 280

Chemical weathering is the break down of rocks by chemical reactions.

Examples of chemical weathering (p. 281) water Acid precipitation Air (oxidation)

What about climate? How does it affect weathering? Turn to page 286. The more humid the climate, the faster weathering will take place.

Erosion

Erosion is the movement of sediments from one place to another.

Let’s take a look at an erosion video!

There are 4 agents of erosion

WATER Moving water (waves, river, and streams) can carry sediments from one place to another. Faster moving water carries larger sediments while slow moving water carries small ones.

WIND Wind carries sediment from one place to another. Like water, faster moving wind can carry large sediments. Wind can carry sediments far distances.

GLACIERS Glaciers can carry lots of sediments because they are so large. They move very slow and travel over land. http://video.nationalgeographic.com/video/player/national-geographic-channel/all-videos/av-2340-3040/ngc-growing-glacier.html

Gravity pulls sediments and materials down slope. This is called mass movement. The steeper the slope, the faster it will move.

The following pictures are of fast mass movements

rockfall

rockfall

When a piece of land becomes detached and slides downhill. slump When a piece of land becomes detached and slides downhill.

mudflow& Lahar

The following picture is of slow mass movement

Slow downhill movement of weathered rock creep Slow downhill movement of weathered rock

Deposition

Deposition is the dropping of sediments.

All agents of erosion (water, wind, glaciers, gravity) can also be agents of deposition.

When water loses energy, it drops its load. This can form deltas.

WIND When wind loses energy, it drops its load. These sediments begin to pile up. They can form loess deposits or dunes.

When glaciers begin to melt, they drop their load.

GRAVITY Gravity pulls sediments to the bottom of slopes and they begin to pile up.