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Slide 2 Breaking it Down Weathering & Erosion Slide 3 Do Now Breaking it Down Key Question: What is weathering, and what are some examples? Initial Thoughts: 5 minutes Slide 4 Evidence: Weathering Large rocks and landforms first need to be broken down into smaller pieces in order to be worn away by erosion. This is accomplished by weathering - the breaking down of rock by chemical or mechanical processes Slide 5 Mechanical Weathering Definition: Breaking up of rock by physical forces, such as the action of wind and moving water. The rock itself does not change; it just gets broken into smaller pieces. Process NameWhere does it occur? What is it? Slide 6 Go to the website, which can be found on my links page under Mechanical Weathering, and click NEXT twice: http://ees.as.uky.edu/sites/default/files/ele arning/module07swf.swf http://ees.as.uky.edu/sites/default/files/ele arning/module07swf.swf Slide 7 Slide 8 Exfoliation or unloading - rock breaks off into leaves or sheets along joints which parallel the ground surface; caused by expansion of rock due to uplift and erosion; removal of pressure of deep burial Slide 9 Organic activity Organic activity (TREES/root-pry, burrowing animals, human activities) Slide 10 Abrasion & Gravity Abrasion & Gravity: rocks falling and colliding with other rocks Slide 11 Contraction Contraction due to crystallization The surface pattern on this pedestal rock is honeycomb weathering, caused by salt crystallization. This example is at Yehliu, Taiwan. Salt weathering of building stone on the island of Gozo, Malta Slide 12 Chemical Weathering Definition: wearing away of rocks by chemical processes, such as dissolving or oxidation. (in your journal vocab) Its a breaking down process Slide 13 Acids or water dissolve the rocks. Sources: Acid rain from pollution, plant roots, water & limestone (example caves), Water: Dissolves minerals out of rocks making them weaker Dissolving Slide 14 Acid: Dissolves minerals in rocks examples: carbonic acid, acid rain, and plant acid Chemical weathering Slide 15 Lichens such as these growing on the rocks in the picture can produce weak acids that react with the rock. Slide 16 Slide 17 3000 year old Egyptian Obelisk 3000 year old Egyptian Obelisk after 100 years in NY Slide 18 Oxidation Oxidation or rusting - some minerals contain metals, like Iron or sulphur, that can rust when exposed to oxygen. Just like an old car, nail, or piece of metal left outside. Slide 19 Oxidation Slide 20 Evidence 2: Weathering Lab Each group will be assigned one of the 4 treatment groups: 1.Crushed tablet vs. Whole tablet 2.Heated water vs. room-temp water 3.Vinegar vs. water 4.Heated vinegar vs. room temp vinegar Slide 21 Make a hypothesis If we test (treatment group) then the time it takes for the tablet to completely dissolve will be faster/slower. Use 150 ml of liquid Record the time it takes for the tablet to dissolve Slide 22 Class Data Recreate this table in your journal Treatment GroupAverage time in minutes:seconds to dissolve Crushed tablet vs. Whole tablet Heated water vs. room-temp water Ice cold water vs. room temp water Vinegar vs. water Slide 23 Analysis Qs 1.Compare & contrast mechanical and chemical weathering. (a venn diagram or chart is o.k.) 2.A) Which of the treatment groups in the lab represented mechanical weathering? B) Which were chemical weathering? 3.Why do you think the obelisk (slide 17) showed more weathering during the 100 years in New York than it did in the 3,000 years it was in the desert in Egypt? Slide 24 Summary What did you think about how weathering works before this lesson? What did you learn about how weathering works from this lesson? (Minimum of 3 sentences!!!) What are some further thoughts or questions you have about how weathering works? Slide 25 Reflection Explain how mechanical and chemical weathering are similar to the process of mechanical & chemical digestion. Use words, pictures, or both. Slide 26 Big Idea Rock landforms can be broken down by the natural processes of mechanical & chemical weathering. Slide 27 Do Now 4-14-14 New Seats Turn in your Paper Plate Rock Cycle Update your grades page: 4/1 Rock Cycle 4/3 Vocabulary Read the Learning Target 4 minutes Slide 28