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Evidence of Erosion and Deposition Sarah Fink Minerva Central School 2006.

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Presentation on theme: "Evidence of Erosion and Deposition Sarah Fink Minerva Central School 2006."— Presentation transcript:

1 Evidence of Erosion and Deposition Sarah Fink Minerva Central School 2006

2 Agents of Erosion Running water Wind Ice (Glaciers) Gravity Waves

3 Quiz Yourself! For each of the following 13 pictures, write down the major agent(s) of erosion. Remember, your choices are: –Running water –Wind –Ice (Glaciers) –Gravity –Waves Note: sources for photos in the quiz are noted in the answers.

4 Example 1 Answer

5 Example 2 Answer

6 Example 3 Answer

7 Example 4 Answer

8 Example 5 Answer

9 Example 6 Answer

10 Example 7 Answer

11 Example 8 Answer

12 Example 9 Answer

13 Example 10 Answer

14 Example 11 Answer

15 Example 12 Answer

16 Challenge Question: Answer

17 How Did You Do?? Even if you didn’t get all of the answers correct, you should be able to recognize some patterns for the agents of erosion we discussed. Let’s see some more pictures and come up with some “rules” for identifying and classifying eroded rocks.

18 Running Water Abrasion of stream bed (can form potholes) Dissolution Scour (lifting of loose particles) Sandbars Point bars Meanders Floodplains Levees Deltas Alluvial fans

19 Water erosion – dry streambed on_JPG_JPG.jpg Stream gully Dry delta

20 Water erosion – river rock riverrock.jpg

21 Water erosion – kettle holes

22 Water erosion - Grand Canyon Colorado River

23 Water erosion on Mars?

24 Characteristics of erosion by running water:

25 Wind Deflation Abrasion Dunes Loess (layers of fine silt)

26 Wind erosion - ventifacts Flat sides show the prevalent wind direction

27 Wind erosion – sand dunes

28 Wind erosion – ripple marks

29 Wind erosion – desert pavement

30 Wind erosion in Antarctica

31 Wind erosion

32 Wind erosion – Sahara Desert

33 Wind-eroded rocks in Zion, UT

34 Sand dunes on Mars

35 Characteristics of erosion by wind:

36 Ice/Glaciers Ice wedging/Gravity Abrasion (striations, scouring, polishing) Plucking (carrying loose sediment) Till Moraine Drumlin Meltwater deposits

37 Glacial erosion – striations Striations (scratches) are parallel

38 Glacial erosion – striations

39 Glacial erosion – polish and erratic

40 Ice wedging icewedge.jpg watermarked/112/ jpg

41 Hoodoos – stone columns Find out more! End Quiz

42 Formation of Bryce Canyon A combination of frost wedging and rainwater are the sources of weathering and erosion that cause the “hoodoo” formations found in Bryce Canyon, Utah. “Acid” rain formed by carbon dioxide in the atmosphere dissolves the weaker calcite-based limestone, but the stronger mudstone, siltstone, and dolomite layers weather more slowly. This results in the layering found in the rock formations. The average rate of erosion is 2-4 feet per 100 years.

43 Characteristics of erosion by ice:

44 Gravity – Mass Wasting Slump Rock fall Landslide / debris flow Creep Solifluction (in areas with permafrost) Talus

45 Gravity as agent of erosion

46 Rock slides in Alaska

47 Gravity – talus slopes at cliff base

48 Soil creep caused by gravity

49 Solifluction – due to permafrost Alternate seasons of freezing and thawing of saturated permafrost results in gradual soil movement downhill.

50 Characteristics of erosion by gravity:

51 Waves (shoreline) Waves, tides, currents Pounding Abrasion Pressure Dissolution Scour Cliffs, arches, platforms, caves, stacks Beaches Barrier islands Spits Sandbars Bay-mouth bars Tombolos

52 Beach erosion by waves 1dx-21.jpg

53 Sea arches and stacks Wave action and changing tides cause these formations

54 Ripple marks – wave action

55 Ancient ripple marks preserved in sedimentary rock

56 Characteristics of erosion by waves:

57

58 Glacial till and outwash (deposited soil) Kringilsarrani%20.JPG


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