1. Rocks & Weathering
Chapter 3

2. Weathering
the process that breaks down rock and other substances

3. Erosion
the process by which bits of broken rock are carried away

4. Sediment
small particles of rock or soil, or the remains of plants and animals

5. Deposition
process in which sediment is laid down in new locations

6. Never ending cycle
Weathering, erosion and deposition act together in a cycle that wears down and builds up Earth’s surface.
As a mountain wears down in one place, new landforms build up in other places.

7. Cycle of Erosion and Deposition What are the steps in the cycle of erosion and deposition?

8. Physical weathering
type of weathering in which rock is physically broken down into smaller pieces

9. Chemical weathering
process that breaks down rock through chemical changes

10. Natural Agents of Physical Weathering
The Natural Agents of Physical Weathering: 1. Freezing and thawing 2. Release of pressure 3. Plant growth 4. Actions of animals 5. Abrasion

11. Natural agents of Physical Weathering

12. Abrasion
wearing away of rock by rock particles carried by wind, water, ice or gravity

13. Frost wedging
process that splits rocks when water seeps into cracks, then freezes and expands
This cycle of freezing and thawing not only breaks up rocks, but also can break up roads and highways causing potholes.

14. Agents of Chemical Weathering
The agents of Chemical Weathering include: 1. Water 2. Oxygen 3. Carbon Dioxide CO2 4. Living Organisms 5. Acid Rain

15. Weathering and Surface Area The diagram shows what would happen if a rock cube broke into smaller cubes. The smaller the rock the quicker the chemical reaction, because of the greater surface area.

16. Oxidation
a chemical change in which a substance combines with oxygen, as when iron oxidizes, forming rust

17. Oxidation of Rocks
One common example of this type of weathering is the alteration of the iron-bearing mineral magnetite to a rustlike material called limonite
Oxidation of minerals gives some rock layers a red color.

18. What planet looks Rusty?

19. Carbon Dioxide: Chemical weathering
Gas found in the air that we as humans produce called CO2
Carbon Dioxide. Mixes with water to form Carbonic Acid…this is also found in sodas.

20. Living organisms: Chemical Weathering
Plants like lichens produce an acid which dissolve rocks.

21. Acid Rain: Chemical weathering.
Pollution in the air from burning coal, oil and gas pollute the air with compounds like sulfur and carbon. These then mix with water particles to form acid rain. This is a weak acid which breaks down rocks chemically.

22. How Fast Does Weathering Occur?
The most important factors that determine the rate at which weathering occurs are the type of rock and the climate.
Climate refers to the average weather conditions in an area.
What kind of climate would speed up chemical weathering?
Hot and wet!

23. Permeable
characteristic of a material that contains connected air spaces (or pores) that water can seep through easily The spaces increase the surface area of the rock, speeding up weathering