1. WEATHERING AND EROSION

2. WEATHERING Weathering is a type of erosion. Weathering happens when rocks are exposed to… – Atmosphere – Hydrosphere – Living Things

3. WEATHERING There are two types of weathering. The first we will discuss is physical. Physical Weathering is when rock or earth is broken down into smaller pieces without chemical change.

4. WEATHERING There are many examples of physical weathering. One example is root action. Root action is when roots grow through cracks and break the rock as they enlarge.

5. WEATHERING Another example of physical weathering is frost action. Frost action is when water seeps into cracks and expands as it freezes. When this happens again and again, rock breaks. This is how potholes in roads are formed.

6. WEATHERING A third example of physical weathering is called exfoliation. Exfoliation is when changes in temperature causes the rock itself to expand and contract. This often causes the rock to break.

7. WEATHERING A final example of physical weathering is called abrasion. This is when rocks or sediment grind against another rock. Sandblasting is an example of this.

8. WEATHERING The second type of weathering is called chemical weathering. This is defined as the breakdown of rock by a chemical change in the composition.

9. WEATHERING The first type of chemical weathering we will discuss is called oxidation. This is when elements in the rock react with O 2 or oxygen.

10. WEATHERING When rock is red, it is often because iron in it has rusted. When iron (Fe) combines with oxygen (O 2 ) Fe 2 O 2 is created. This is called iron oxide, commonly known as rust.

11. WEATHERING Another example of chemical weathering is called hydration. This is when elements in the rock interact with water (H 2 O). When a common mineral called feldspar is combined with water, clay is formed.

12. WEATHERING Another type of chemical weathering is called carbonation. This is when an element or a rock is dissolved by acid rain. The acids commonly found in acid rain are carbonic acid and sulfuric acid.

13. WEATHERING There are many factors that effect the speed and amount of weathering that takes place. The first thing that effects these both is the amount of exposure. This is how much of the rock or element is exposed to air, water and living things. Rocks near the surface are weathered more than rocks farther below.

14. WEATHERING Particle size is another factor that has to do with the amount and speed of weathering. When particles are small, they have a greater total surface area so their exposure is much greater. Therefore, they weather much faster.

15. WEATHERING Another thing that effects the rate and amount of weathering is the mineral composition of the material being weathered. Quartz for instance is very hard so it takes a very long time to weather. Talc is a very soft mineral, so it weathers very quickly.

16. WEATHERING Lastly, climate can greatly effect the amount of weathering. In warm, moist climates chemical weathering is most dominant. Where in cold climates frost action happens a lot. In very dry climates, little weathering happens at all.

17. WEATHERING Weathering can result in four types of sediment. The first type is solid sediment. This includes sand and pebbles.

18. WEATHERING A second type of sediment is called colloids. These are clay sized particles which are very small.

19. WEATHERING The third type is called ions. These are tiny particles dissolved in water. The salty oceans are an example. NaCl or salt is in abundance in the ocean.

20. WEATHERING The last type is soil which is mixture of solid sediment and organic matter. Dead plants and tiny rocks together are soil.