1. Erosion and Weathering

2. From Last Class…
Part 1 and 2 SHOULD be completed by now, and working on part 3
Suggested due date for part 3- End of class tomorrow
Option to take home folder at end of class tomorrow
Part 4/FINAL due date is THURSDAY JUNE 15th! NO LATER! NO EXCEPTIONS!

3. Erosion and Weathering
Erosion: the wearing away and transport of the Earth’s materials
3 Major forms:
Mechanical Erosion: water, wind, ice
Chemical Erosion: chemicals in atmosphere/water
Biological Erosion: Living things

4. Erosion by Water
Occurs slowly or suddenly, can be gradual like streams/rivers through rocks; or quickly like overflowing rivers to break down riverbank
Called Mechanical Weathering: sand particles carried by water hit rock and wear away more pieces

5. Erosion By Wind Another form of Mechanical Weathering
Can erode soil and rock
Wears away at the top level of soil (gets picked up by wind) as well as rock that it beats against
Wind blown particles such as sand or soil wear away the rock

6. Erosion By Ice Another form of mechanical erosion
By larger masses of ice (such as glaciers) and by small droplets of ice (seeping into cracks)
Glaciers: Slowly moving and drifting down mountainside, wears away at rock layer beneath
Glaciers can also melt which pulls rock with it into large piles called moraines
Ice Droplets: water can seep into cracks and crevices of rock/land surfaces
As water freezes it expands, which puts pressure on the surrounding rock and causes it to widen

7. Erosion by Chemicals Also known as Chemical Erosion
Occurs when chemicals dissolved in water, rock & air REACT with the rocks
Causes the rocks to change chemical make up
Acid rain is a huge culprit of chemical erosion (due to pollution dissolved in air and then in rain droplets)
Many sculptures have been worn away for this reason

8. Erosion by Living Things
Also known as Biological Erosion
Lichen (a fungus/plant) grows on rock, uses minerals in the rock as its source of nutrients
Makes an acid that wears away the rock
When it dies it leaves a thin layer of dead material that becomes soil for other living things
Cracks in rocks can become home to plants and trees whose roots will penetrate into rock to find water and nutrients that can break off pieces of rock