1. True or False: The Earth’s surface has stayed the same for thousands of years

2. The Earth’s surface is always changing!

8. Weathering The breakdown of the materials of Earth’s crust into smaller pieces.

9. What is Mechanical Weathering? What is Mechanical Weathering? Breakdown of rock into smaller pieces without any change in the chemical composition of its mineralsBreakdown of rock into smaller pieces without any change in the chemical composition of its minerals –Sometimes called “physical” weathering –Rock is torn apart by physical force, rather than by chemical breakdown –Smaller pieces do not move to a new location until erosion carries them away

10. Water causes weathering What evidence of weathering do you see in this picture?

11. Wind causes weathering What evidence of weathering do you see in this picture? Why wasn’t this mass of land weathered away?

12. Mechanical - Biotic Biotic – means lifeBiotic – means life –Weathering caused by living organisms –Plant roots act as a wedge and widen cracks –Other causes of biotic weathering are digging animals, microscopic plants and animals, algae and fungi.

13. Ice causes weathering Describe how ice causes weathering?

14. Mechanical - Ice Wedging  Ice Wedging –Water fills joints of rocks and freezes –Water expands 10% when it freezes, pushes rock apart –Repeated freeze and thaw cycles over the years causes rock to break along joint

15. Erosion The process by which water, ice, wind or gravity moves fragments of rock and soil. What evidence of erosion do you see in this picture?

16. What is Chemical Weathering? Breakdown of rock into smaller pieces because of change in the chemical composition of its mineralsBreakdown of rock into smaller pieces because of change in the chemical composition of its minerals –Chemical reactions break down the bonds holding the rocks together, causing them to fall apart –Chemical weathering occurs in all types of rock –Rock reacts with water, gases and solutions

17. Chemical - Oxidation Oxidation - oxygen combines with other elements in rocks to form new types of rockOxidation - oxygen combines with other elements in rocks to form new types of rock –New substances are usually much softer than original, easier for other forces to break rock apart –Causes a “rusting” of the rock, often causes a color change in the rock

18. Chemical - Carbonation Carbonation – Carbon dioxide (CO 2 ) is dissolved in water making carbonic acidCarbonation – Carbon dioxide (CO 2 ) is dissolved in water making carbonic acid –Weak acid is formed when CO 2 in the air mixes with rain. This is the same acid found in soft drinks. –Weak acid is formed when CO 2 in the air mixes with rain. This is the same acid found in soft drinks. –Acid is too weak to harm plants and animals but slowly causes feldspars and limestone to decompose

19. Erosion is Movement of Sediment ! This process, known as Erosion, is gradually wearing down the surface of the earth. Erosion is the process by which weathered rock and soil (sediment) are moved from one place to another. Erosion carves the Earth's surface creating canyons, gorges, and even beaches. What do you think has caused this rock to look this way?

20. Wind Erosion As the wind blows it picks up small particles of sand/sediment and blasts large rocks with the abrasive particles, cutting and shaping the rock. The intensity of wind erosion is determined by: Sum (amount) Speed Slope Surface

21. Wind Erosion

22. Water Causes Erosion runoff, rivers and, streams

23. Water causes Erosion When rain falls to the Earth it can evaporate, sink into the ground, or flow over the land as Runoff. When it flows over land, erosion occurs. Runoff picks up pieces of rock and "runs" downhill cutting tiny grooves (called rills) into the land. rills

24. Water causes Erosion How much erosion takes place is determined by the: Sum (amount) Slope Speed Surface Can you act increasing and decreasing the four S’s?

25. Ice Causes Erosion Glaciers wear down the landscape; by picking up and carrying debris that moves across the land along with the ice.

26. Ice Causes Erosion Glaciers can pick up and carry sediment that ranges in size from sand grains to boulders bigger than houses. Moving like a conveyor belt and a bulldozer, a single glacier can move millions of tons of material!

27. Ice Causes Erosion How much erosion takes place is determined by the: **Sum (Glaciers are massive!) Slope Speed Surface

28. Gravity causes erosion landslide clip.mpeg Creep, Slump, Landslides, Mudslides, and Avalanches. These are examples of mass movement (or called mass wasting) SlowerFaster

29. Gravity causes Erosion How much erosion takes place is determined by the: Sum **Slope Speed **Surface

30. Plants CAN CAUSE weathering

31. Plants CAN PREVENT erosion

32. Deposition Rock particles that are picked up and transported during erosion will ultimately be deposited somewhere else Deposition is the process by which sediments (small particles of rock) are laid down in new locations. Together, Erosion and Deposition build new landforms. Deltas Canyons Meanders Floodplains

33. Delta Where rivers meet the ocean is called the mouth of the river. Soil and dirt carried by these rivers is deposited at the mouth, and new land is formed. The new, soil-rich land is known as a Delta

34. Canyons This simple animation provides you with a visualization of how the Colorado River has "downcut" into the rock layers of the Grand Canyon. How long it took to carve the Grand Canyon is debated by geologists. Some estimates are between 6 and 8 million years, which is very recent by comparison. Canyons are large valleys created by a river or stream.

35. Meanders Meandering streams wander side to side as they constantly seek out the lowest elevation. This constant motion creates a series of S-shaped “loops”.

36. Meanders Stream Velocity varies from one side to the other side of the “S”, resulting in erosion in some places and deposition of sediments in others.

37. Floodplains Floodplains form along the banks of mid-order streams and larger rivers. These are low-lying areas along the sides of a river channel that have regular times of heavy waterflow to cause the river to spill over and flood the land.