Presentation on theme: "Evidence of Erosion and Deposition Sarah Fink Minerva Central School 2006."— Presentation transcript:
Evidence of Erosion and Deposition Sarah Fink Minerva Central School 2006
Agents of Erosion Running water Wind Ice (Glaciers) Gravity Waves
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.
Example 1 Answer
Example 2 Answer
Example 3 Answer
Example 4 Answer
Example 5 Answer
Example 6 Answer
Example 7 Answer
Example 8 Answer
Example 9 Answer
Example 10 Answer
Example 11 Answer
Example 12 Answer
Challenge Question: Answer
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.
Running Water Abrasion of stream bed (can form potholes) Dissolution Scour (lifting of loose particles) Sandbars Point bars Meanders Floodplains Levees Deltas Alluvial fans
Glacial erosion – striations Striations (scratches) are parallel
Glacial erosion – striations
Glacial erosion – polish and erratic
Ice wedging icewedge.jpg watermarked/112/ jpg
Hoodoos – stone columns Find out more! End Quiz
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.
Characteristics of erosion by ice:
Gravity – Mass Wasting Slump Rock fall Landslide / debris flow Creep Solifluction (in areas with permafrost) Talus
Gravity as agent of erosion
Rock slides in Alaska
Gravity – talus slopes at cliff base
Soil creep caused by gravity
Solifluction – due to permafrost Alternate seasons of freezing and thawing of saturated permafrost results in gradual soil movement downhill.