Warm ups 9.01.2016*Describe the theory of plate tectonics.

*What are the four major types of tectonic plate interaction?

Lesson Objective: *compare the processes of chemical and mechanical weathering

*describe how water, wind, and glaciers cause erosion

The Power of Wind! *the soil of Hawaiian Islands consist of a type of clay that is older than the islands themselves

*What happened?

WeatheringWeathering: slow process of breaking down rocks of Earth’s surface into smaller and smaller pieces

*Did you know that the current Rocky Mountains are the 2nd Rocky Mountains?

Types of Weatheringmechanical weathering: rock is actually broken or weakened physically

*What causes of mechanical weathering can you think of?

Types of Mechanical Weatheringfrost wedging: water gets into cracks in rocks and expands when it freezes, causing chunk of rocks to break off

*the other most common form of mechanical weathering happens when seeds grow from cracks in rocks

*What causes of mechanical weathering can you think of?

Examples of Frost Wedging

Weathering Caused by Roots

*If you want to hear the cheesiest teacher joke ever, just ask…..or not.

Chemical Weathering

chemical weathering: rocks are altered by their chemical makeup being changed

*Any guesses what the most common forces are in chemical weathering?

Chemical Weathering

*water and carbon dioxide combine to create carbonic acid, which can completely dissolve certain types of rock

Results of Chemical Weathering

Other Types of Chemical Weathering

acid rain: chemicals in polluted air combine with water vapor and fall back to Earth

(nice job, humans)

Effects of Acid Rain

Erosion

Erosion: the movement of weathered materials; mainly caused by water, wind, and glaciers

Water-Caused Erosion*all canyons and valleys are created in part by water

*What else might help the water carve through the rocks?

Water-Caused Erosion*sediment: small particles of sand, soil, and gravel

*sediment acts like sandpaper as it is carried downstream, which greatly speeds up the carving that rivers do

*Fun Fact: it is estimated that the Mississippi River carries 500 million tons of sediment a year into the Gulf of Mexico!

Water Erosion Examples

Wind Erosion*loess: loess is a type of soil which has such fine particles, it can be blown all over the world

*wind also carries sediment, which acts like sandblasting surfaces to erode them

Wind Erosion Example

Glacial Erosion

glacier: huge, slow-moving “river of ice”

*Imagine how heavy a glacier is that is over 1,000 feet thick. Now, imagine what that does to the land underneath it as it slides downhill.

Glacial Erosion