1. Weathering, Erosion, and Deposition
Half dome photo, public domain, from Jan. 9, 2010

2. Half dome photo, public domain, from http://www. nature. nps
Half dome photo, public domain, from Jan. 9, 2010

3. Map, public domain, from: http://www. nps
Map, public domain, from: Jan. 9, 2010

4. Photo of Bridal Veil Falls, Yosemite National Park, public domain, from Jan. 9, 2010

5. How do you think these amazing landforms were created
How do you think these amazing landforms were created? Here in Yosemite, most of the rock is granite. How does granite form? (it is intrusive igneous rock) So you know how the rocks formed, but why is there only half a dome? Was the underground magma in this shape when it hardened, or did some other force shape it after it came to the surface?
Photo of El Capitan, Yosemite National Park, public domain, from Jan. 9, 2010

6. What forces do you think might break down rock?
I. Weathering
Weathering is the process of breaking rocks into smaller pieces.
Mechanical Weathering happens when a physical force breaks rocks apart.
What forces do you think might break down rock?
Have sandpaper and wood blocks for students to use.

7. I. Weathering
Weathering is the process of breaking rocks into smaller pieces.
Mechanical Weathering happens when a physical force breaks rocks apart.
Abrasion
Abrasion happens when rocks bump or scrape each other and break off pieces of each other.
Wind, flowing water, or glaciers can cause abrasion.
Have sandpaper and wood blocks for students to use.

8. What happens to the wood when you sand it. How does it feel
What happens to the wood when you sand it? How does it feel? That’s what abrasion does: it smoothes out the surface.
Sanding image, U.S. Navy, public domain, from (Jan. 9, 2010)

9. What factors do you think affect how much abrasion happens in a river?
These river rocks were smoothed by abrasion as the river water made the sand and rocks bump into each other.
(Photo by Valerie Armstrong, 2009)

10. What could have cracked up these rocks
What could have cracked up these rocks? (I’m pretty sure it wasn’t my jokes.)
Ice Wedging – Have you ever left a soda can or a glass bottle in the freezer? What happened? The same thing happens when water gets inside cracks in rocks and freezes. When it expands, it cracks the rock a little more and a little more. When the sun comes out, the ice melts, the water gets further down, and when it freezes, it cracks the rock some more!
(Photo by Valerie Armstrong, 2009)

11. I. Weathering
Weathering is the process of breaking rocks into smaller pieces.
Mechanical Weathering happens when a physical force breaks rocks apart.
Abrasion …
Ice Wedging

12. I. Weathering
Weathering is the process of breaking rocks into smaller pieces.
Mechanical Weathering happens when a physical force breaks rocks apart.
Abrasion …
Ice Wedging
Plant root growth

13. These plants on the hillside are weathering the rocks underneath them.
(Photo by Valerie Armstrong, 2009)

14. As the roots grow down into cracks in the rocks, they push the cracks open wider and wider.
(Photo by Valerie Armstrong, 2009)

15. I. Weathering
Weathering is the process of breaking rocks into smaller pieces.
Mechanical Weathering happens when a physical force breaks rocks apart.
Abrasion …
Ice Wedging
Plant root growth
Animal Actions

16. As this prairie dog digs his burrow, he breaks apart weakened rock, causing weathering. When he moves it outside, he is causing erosion.
(Photo by Valerie Armstrong, 2009)

17. Why are these rocks that red-orange color?
Do you think rocks are more or less likely to break if they contain rusted iron?
Why are these rocks that red-orange color?
Chemically weathered iron photo from: (2009)

18. I. Weathering
Weathering is the process of breaking rocks into smaller pieces.
Mechanical Weathering …
Chemical Weathering happens when chemicals in a rock react with other chemicals around it making the rock weaker.
Iron in rocks can rust. (oxidation)
Acid rain can react with carbonate in rocks.
Use baking soda and vinegar to demonstrate the chemical reaction between carbonates and acid. Explain that limestone contains carbonates that can be damaged by acid rain.

19. Limestone sample, public domain, from: https://www. dmr. nd
Limestone sample, public domain, from: Jan. 9, 2010

20. Caves form when acid in rainwater dissolves limestone
Caves form when acid in rainwater dissolves limestone. These cool stalagmites in the Carlsbad Caverns form when the water dries and deposits.
Carlsbad Caverns photo, public domain, from: Jan 9, 2010

21. Caption: Pock marks in marble columns, south side of U. S
Caption: Pock marks in marble columns, south side of U.S. Capitol building. Silicate mineral inclusions in the marble loosen and fall out when the calcite around them is dissolved by acid rain.
Photo of column, public domain, from: Jan. 9, 2010

22. II. Erosion Erosion occurs when rock or soil is carried away.
Causes of Erosion
Water running down hill (rivers, streams)
Glaciers (rivers of ice)
Wind
Gravity (landslides, mudslides)

23. How was this landform created?
The Nile River Delta is an example of an effect of deposition. An alluvial fan has the same shape, but it is at the base of a mountain stream rather than the mouth of a river.
Nile River Delta Image, public domain, from: Jan. 9, 2010

24. III. Deposition
Deposition occurs when soil or rock are set down in a new location.
Effects of Deposition
Rivers and streams create deposits called deltas and alluvial fans. (creates fertile soil)

25. What is the source of the soil deposited in this delta?
The Nile River Delta is an example of an effect of deposition. An alluvial fan has the same shape, but it is at the base of a mountain stream rather than the mouth of a river.
Nile River Delta Image, public domain, from: Jan. 9, 2010

26. III. Deposition
Deposition occurs when soil or rock are set down in a new location.
Effects of Deposition
Rivers and streams create deposits called deltas and alluvial fans.
When wind deposits sand, it forms dunes.

27. Sand dunes image, public domain, from: http://www. nature. nps
Sand dunes image, public domain, from: Jan. 9, 2010

28. III. Deposition
Deposition occurs when soil or rock are set down in a new location.
Effects of Deposition
Rivers and streams create deposits called deltas and alluvial fans.
When wind deposits sand, it forms dunes.
When waves deposit sand on the shore, beaches form.

29. How did this piece of wood get here? What about all that other stuff?
Can you see where the waves have deposited shells and other material on the beach? This is the same way they deposit sand there. Under different circumstances, waves also cause erosion along the shoreline, especially during a storm.
(Photo by Valerie Armstrong, 2009)

30. III. Deposition Effects of Deposition
Rivers and streams create deposits called deltas and alluvial fans.
When wind deposits sand, it forms dunes.
When waves deposit sand on the shore, beaches form.
Sediments form layers that can eventually become rock. (lithification)

31. Sedimentary rock layers image, public domain, from: http://rst. gsfc
Sedimentary rock layers image, public domain, from: Jan. 9, 2010

32. Weathering and Erosion Supe r Hero Cartoon