Earth’s Changing Surface Part 1

1. Earth’s Changing Surface Part 1 (Lessons 1-5)

2. Lesson 1 Weathering

3. Think About It… Do rocks last forever?

4. Focus Question… What forces weather rocks?

5. Types of Weathering… 1. Physical weathering is the process by which rocks and minerals break down into smaller pieces. http://www.kidsgeo.com/geology-for-kids/0066-mechanical-weathering.php

6. Physical Weathering… a. Frost wedging … when water in the cracks of rocks expands as it freezes, it wedges the rock apart and splits it! http://mail.colonial.net/~hkaiter/wxerosglacier.html http://www.gly.uga.edu/railsback/FieldImages/ClavaWeathering.jpeg

7. Physical Weathering… b. Exfoliation… when overlaying rocks have been removed by erosion, pressure is reduced, outer layers crack and are stripped away. http://hays.outcrop.org/GSCI320/lecture3.html

8. Chemical Weathering 2. Chemical weathering is the process by which… rocks / minerals undergo changes in composition as the result of chemical reactions. Water is a major factor in weathering. http://i.ehow.co.uk/images/a05/ne/08/factors-affect-chemical-weathering-1.1-800X800.jpg

9. Chemical Weathering: Water a. Water can dissolve many kinds of minerals and rocks. This results in the formation of clayminerals. kaolinite Clay comes from felsic rocks and can be molded and heated into pottery.

10. Chemical Weathering: Oxygen b. Iron in rocks and minerals combines with oxygen in the atmosphere. This results in rust. Oxidized rocks in the American Southwest. http://web.mit.edu/12.120/www/pics/

11. http://www.wdt.edu/Plus50/Plus_50_content/Plus50_National_Park_Service_Partners.aspxhttp://www.wdt.edu/Plus50/Plus_50_content/Plus50_National_Park_Service_Partners.aspx Chemical Weathering: Carbon Dioxide • Carbon Dioxide… Carbon dioxide combines with water in the atmosphere or soil forming a weak carbonic acid. This results in clay or caves. Wind Cave in South Dakota

12. Chemical Weathering: Acid Precipitation • Acid precipitation is rain, snow, sleet mixed with gases that turn it into a weak acid with a pH of less than 5.0. • sulfur dioxide and nitrogen oxide • The most common source – coal-fired power plants • It is also known as acid rain, • Acid rain causes lakes to become more acidic than organisms can handle AND…chemically weathers nonliving things such as statues and buildings See next slide…

13. Effects of Acid Rain… Acidification of soils causes the death of these trees. This changes the ecology of the area greatly.

14. Factors That Affect Weathering…Climate • Chemical weathering occurs readily in • climates with warm temperatures, abundant rainfall, and lush vegetation. • Places such as Central America and Southeast Asia. Note the intensely weathered soil. http://www.geotimes.org/july08/trends1.jpg

15. http://www.uwsp.edu/geo/faculty/ozsvath/images/cleopatras_needle.htmhttp://www.uwsp.edu/geo/faculty/ozsvath/images/cleopatras_needle.htm Cleopatra’s Needle… Cleopatra’s Needle has undergone severe chemical erosion since it was moved from the very dry climate of Egypt to New York City.

16. A. Factors That Affect Weathering…Climate 2. Physical weathering occurs readily in • Cool or dry climates. • Places such as Appalachian Mountains in the winter experience frost wedging.

17. http://www.travelpod.com/travel-blog-entries/gensphoto/1/1280057679/tpod.htmlhttp://www.travelpod.com/travel-blog-entries/gensphoto/1/1280057679/tpod.html B. Factors That Affect Weathering…Rock Type and Composition • Sedimentary rocks are more easily weathered than… • …harder igneous and metamorphic rocks. • Coal layers are weathered more easily than limestone layers because…coal is softer and limestone is harder & more resistant. The Badlands

18. C. Factors That Affect Weathering… Surface Area • As pieces of minerals and rocks get smaller, their surface area increases. • This means that… More total surface area available for chemical weathering which speeds it up. http://www.mrsciguy.com/sciimages/surfacearea.jpg

19. D. Factors That Affect Weathering… Topography http://www.geoproducts.org/App-SlopeErosionControl.aspx • Materials on level (flat) areas are likely to remain in place as they undergo changes. • Material on slopes have a greater tendency to move as a result of gravity. Controlling weathering/erosion on slopes can be big business!

20. Lesson 2 Erosion by Running Water

21. Think About It… Why could it be said that rivers carry mountains to the sea?

22. Focus Question… What features are eroded or deposited by running water?

23. Introduction… 1. What is erosion? • process that transports Earth’s materials from one place to another 2. Why is gravity associated with many agents of erosion? • It pulls all materials down slope! Five forces or agents of erosion include: running water, glaciers, wind, gravity, and human activity. Elephant Foot Glacier http://www.awi.de/en/news/press_releases/detail/item/scientists_expect_increased_melting_of_mountain_glaciers/?cHash=10a73716ccb3df05543dca09d1f65e50

24. Erosion By Running Water… 1.Water has more power than wind to move large objects. • Rill erosion… when small channels carved by water form on the side of a slope. • Gully erosion… when a rill becomes deep and wide. http://www.soils.umn.edu/academics/classes/soil2125/img/10riller.jpg Gully Erosion http://plantandsoil.unl.edu/croptechnology

25. http://www.learner.org/courses/envsci/visual/visual.php?shortname=gully_erosionhttp://www.learner.org/courses/envsci/visual/visual.php?shortname=gully_erosion Erosion by Running Water… 4. Gully erosion is usually caused when too much vegetation is removed. Gully erosion from over cultivation, Sahel, West Africa

26. Erosion by Running Water… • Rocks exposed to their surrounding environments are slowly weathered away then… • streams andrivers carry these sediments to coastal areas. The Nile River http://earthasart.gsfc.nasa.gov/mississippi.html http://www.sciencekids.co.nz/pictures/earth/nileriverdelta.html

27. Deposition by Running Water… http://farm1.static.flickr.com/121/259022625_5073e03db2.jpg 1. The Mississippi River carries sediment into the Gulf of Mexico. • It drains about 43% of the USA! • It drains the land west of the Appalachians and east of the Rockies.

28. The Mighty Mississippi! http://www.nps.gov/miss/riverfacts.htm

29. Deposition by Running Water… 2. Deltas are formed when rivers deposit sediments in the mouth of a bay or gulf. • This forms a triangular-shaped deposit. • New Orleans is built on the Mississippi Delta. The Mississippi River Delta – picture taken by Landsat 7 http://earthasart.gsfc.nasa.gov/mississippi.html

30. Deposition by Running Water… • An alluvial fan is… a fan-shaped deposit that forms when running water carries sediment through a narrow mountain valley. http://pages.uoregon.edu/millerm/fan.html

31. Deposition by Running Water… www.skywalker.cochise.edu Eroded olivine forms a green sand beach in Hawaii. www.lovingthebigisland.wordpress.com

32. Deposition by Running Water… Eroded basalt forms a black sand beach in Hawaii.

33. Deposition by Running Water… Eroded coquina forms a tan sand beach in N. Florida or Cuba.

34. Deposition by Running Water… Eroded limestone forms a white sand beach in Florida. http://www.beach.com/destinations-captiva-island-florida-usa-vacations

35. http://yogaonsiestabeach.com/the-legend-of-siesta-key-sand/ Deposition by Running Water… Eroded quartz forms a white sand beach in Florida (Siesta Key). Siesta Key beach sand is 99.9% quartz from the Appalachian Mountains!

36. Lesson 3 Erosion by Glaciers

37. Think About It… What frozen force of nature acts like a giant bulldozer to move boulders and carve out mountain valleys?

38. Focus Question… What features do glaciers carve out or deposit to change Earth’s surface?

39. http://www.geocaching.com/seek/cache_details.aspx?guid=50953ee7-2a7a-4cf9-b8f5-964ec62c8913http://www.geocaching.com/seek/cache_details.aspx?guid=50953ee7-2a7a-4cf9-b8f5-964ec62c8913 Introduction… 1. Glaciers change Earth’s surface by… • scraping and gouging out large sections of Earth’s landscape. • carrying huge rocks and piles of debris over great distances • scraping and grinding some surfaces and polishing others! http://www.physicalgeography.net/fundamentals/10af.html Glacial Grooves on Kelly’s Island in Lake Erie (one of the great lakes!)

40. Introduction: Glacial Erosion… 2. Many features of glacial erosion are found in the states of New England and the Midwest. This is an esker – a landform left by glacial erosion in the Adirondacks. http://merryatsyracuse.blogspot.com/2010/09/stillwater-esker.html

41. http://www.geographypages.co.uk/a2glac.htm Introduction: Glacial Erosion… 3. What is a glacier? • A large moving mass of ice! • Glaciers are the most powerful erosive force on Earth. The Jungfrau Glacier in Switzerland

42. Introduction: Glacial Erosion… 4. There are two types of glaciers. A valley glacier forms in mountainous areas • Valley glaciers will carve U-shaped valleys. • Valley glaciers are found in the Rocky Mountains. Valley glaciers in the Rocky Mountains

43. Glacier National Park, Montana

44. Introduction: Glacial Erosion… 5. A continental glacier covers large continent sized areas. • They are also called ice sheets. • Examples include Greenland and Antarctica. http://web.arc.losrios.edu/~borougt/ContinentalGlaciers.gif

45. Glacial Erosion… 1. Glacial erosion can carve out the following features… • Cirque – a bowl shaped depression • Arête – sharp, steep ridge • Horn – pyramid-shaped peaks Glacial Features online… http://rst.gsfc.nasa.gov/Sect17/Sect17_5a.html http://www.scienceclarified.com/landforms/Faults-to-Mountains/Glacial-Landforms-and-Features.html

46. 2. Glacial Grooves… • Caused by … glaciers plucking up large rocks and dragging them over the bedrock.

47. Glacial Deposition… 1. Glacial till is the mixed debris that glaciers carry embedded in their ice. 2. A moraine is a ridge of glacial till that’s been bull-dozed by a glacier. http://rst.gsfc.nasa.gov/Sect17/moraine.jpg

48. Glacial Deposition… 3. An outwash plain is a plain where glacial melt water and debris are deposited. http://rst.gsfc.nasa.gov/Sect17/outwash_plain_DDS21_Cooper_river_region_Alaska.jpg

49. Glacial Deposition… 4. Two types of lakes formed by glaciers include… Kettle lakes and cirque lakes • Our most famous lakes are the Great Lakes which are moraine-dammed lakes • Huron, Ontario, Michigan, Erie, Superior See next slide for pictures…

50. Glacial Lakes… Cirque Lake in the Wind River Range, Wyoming www.themountainculture.com Kettle Lakes in the Northwest Territory of Canada www.physicalgeography.net The Great Lakes – Moraine-dammed (in the geological sense) http://www.coastwatch.msu.edu/