This document summarizes various landforms and the geological processes that create them. It discusses both internal forces like earthquakes and volcanoes, as well as external forces like erosion, weathering, streams, glaciers and waves that shape the Earth's surface over time. Specific landforms are examined like mountains, plains, plateaus and valleys, as well as features caused by folding, faulting, volcanic activity, deposition and more. Examples throughout illustrate these concepts.

1. CHAPTER 3 Landforms

2. Study of the landforms and the processes that create them Geomorphology

3. Important Points Study of the Lithosphere Elements of surface have identifiable forms are called landforms Mountains Plains Plateaus Valleys Landforms constantly change Geographers study topography (shape of the earth’s surface)

4. Processes that create landforms Endogenic Processes Internal Forces Earthquakes Volcanoes Exogenic Processes External Forces Erosion Weathering

5. Alfred Wegener Theorized in 1912; proven after WWII 12 large tectonic plates float on the mantle 200 million years ago, all one continent (Pangaea) Plate Tectonics http://www.classzone.com/books/earth_science/terc/content/visualizations/es0807/es0807page01.cfm?chapter_no=visualization

6. Ring of Fire

8. Types of Boundaries Divergent boundaries Spread Apart Generally mid-ocean; causes sea floor spreading Underwater volcanoes, few quakes Convergent boundaries Push together Usually near continental edges Violent volcanoes near ocean, strong quakes Transform boundaries Grind together No volcanoes, mild to strong quakes (San Andreas) http://www.learner.org/interactives/dynamicearth/plate.html

12. Earthquakes Crust movement where plates meet 500,000 per year; 800 felt Seismic waves of energy (vibrations) Seismograph measures waves Earthquakes don't kill people, buildings (and gas mains) do Epicenter – point on the surface directly above the focus of an earthquake

14. Bam, Iran 12/26/2003

15. San Andreas “ San Francisco” M8.5 – April 18, 1906, 3,000 deaths $400 million in damage

16. Rock Formation Types Igneous – molten rock cools; basalt Sedimentary – rocks eroded from mountains; shale Metamorphic – exposed to heat/pressure and compressed; marble & slate Minerals (specific chemical compounds) Sima – Dense w/silicon & magnesium; ocean floor Sial – Less dense w/silicon & aluminum; makes up crust

17. Stress on Rocks Fault - a break in Earth’s crust where slabs of crust slip past each other. They usually occur along plate boundaries where the forces of plate motion compress, pull, or shear the crust so much that the crust breaks.

18. Normal fault The fault is at an angle, so one block of rock lies above the fault while the other block lies below the fault. Found near a divergent plate boundary

19. Reverse Faults Compression produces reverse faults. It is like a normal fault but the blocks move in the opposite direction. Near convergent boundaries

20. Reverse Fault - Appalachian Mountains

21. Strike-slip fault Strike-slip fault - shearing causes these faults. Rocks on either side of the fault slip past each other sideways with little up-or-down motion. They also form transform boundaries . Example - San Andreas fault

22. Mountain Building Over millions of years, fault movement can change a flat plain into a towering mountain range. Mountains Formed by Faulting When normal faults uplift a block of rock, a fault-block mountain forms. Teton Range near Wyoming and Idaho was formed this way.

23. Mountains Formed by Folding Have you ever skidded on a rug that wrinkled up as your feet pushed it across the floor? Folds - bends in rock that form when compression shortens and thickens part of Earth’s crust.

24. Mountains caused by Folding Himalayas Alps

25. Volcanoes Pressure on molten rock Shield volcanoes Made of basalt More calm and constant (runny lava) Along divergent boundaries or at hot spots Relatively less dangerous Composite volcanoes Violent and explosive (lava & ash) About 600 active (1000s dormant) Relatively hard to predict Can cause major climate changes Mauna Loa Shield Volcano

26. Mt. St. Helens 5/18/1980 Composite cone volcano

27. Exogenic Forces Reshape the Earth’s crust into new landforms

28. Weathering Process of breaking down rocks into pieces First step in the formation of soil Most mountains are going down faster than they’re going up Mechanical weathering breaks rocks into smaller pieces Frost action Salt crystals Roots Exfoliation Rock chemistry does not change

29. Frost Action

30. Weathering Chemical weathering changes the chemistry of rocks Oxidation (exposure to oxygen) Hydrolysis (exposure to water) Carbonation (exposure to carbon dioxide) Warmth and water encourage chemical reactions Weathering loosens rock particles, creates soil

31. Oxidation

32. Carbonation: Karst Formed by the dissolution of soluble rocks Karst regions contain aquifers that are capable of providing large supplies of water.

33. Erosion & Deposition Erosion carries particles away Surface Erosion – water carrying particles Rainfall Relatively slow Running water Constant water, floods Most important landform agent in deserts Floodplains, levees, and deltas Deposition deposits them

34. Streams are vital geologic agents Carry most of the water that goes from land to sea (groundwater & overland flow) Transport billions of tons of sediment to the ocean each year Transport billions of tons of soluble salts to the oceans each year Shape the surface of the Earth

35. Stream Flow Some of the consequences of natural stream flow present engineering and social challenges with which we grapple year after year, and have through civilization’s history. The flow of fresh water in channels on the Earth’s surface has been essential to the development of topography and most ecosystems.

36. Floodplain Delta Levee flat or nearly flat land adjacent to a stream or river that experiences occasional or periodic flooding deposit at the mouth of a river is usually roughly triangular in shape river's banks are built up above the level of the rest of the floodplain Meander

37. These are satellite images before and during Summer, 1993 floods of the Mississippi river north of St.Louis. Mississippi Floodplain

38. Alluvial fan fan-shaped deposit formed where a fast flowing stream flattens, slows, and spreads

39. Streams Locked in Valleys Streams like these (and the Potomac River at Great Falls) have virtually no (normal) floodplains. They have carved into rock so deeply, that their meandering and other characteristic evolutionary features are restricted.

40. Glaciers Rivers of ice Types Alpine Glaciers – snow accumulation over years Continental Glaciers – covers vast areas Carve out landforms from mountains Deposit material when they leave Moraines Outwash plain Past 200 years has seen glacial shrinking

41. Glacial landforms Outwash Plain- large volumes of rock and dirt debris that often spreads out in a great sheet Terminal Moraine - accumulation of boulders, stones, or other debris carried and deposited by a glacier Alaska Long Island, NY

43. Glacial landforms: California

44. Iowa is almost entirely covered by loose sediments left behind by the continental glaciers which has created fertile soil Glacial landforms: Iowa

45. Waves and coastlines Waves transfer energy through wind Energy moves particles down the coast (longshore current) Newer coastline=erosion Older coastline=deposition Tsunami – extremely long wave created by earthquake Barrier reef: only organically formed landform http://www.uky.edu/AS/Geology/howell/goodies/elearning/module14swf.swf

46. Longshore current Pacific Palisades Longshore currents affect shorelines by redistributing sand and sediment along their path.

48. Erosion vs. deposition Acapulco Cancún

49. Great Barrier Reef