1. Breaking it Down Weathering & Erosion

2. 4/30/15 Breaking it Down Key Question: What is weathering, and what are some examples? Initial Thoughts:

3. 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

4. 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? Frost Wedging

5. 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

6. Check yourself Process NameWhere does it occur?What is it? Frost WedgingCold, moist mountainsWater expands when it freezes, breaking apart rocks ExfoliationMountains with igneous rock Igneous rock pushes up, breaking off big sheets of rock Thermal expansion Desert regionsCrystals in rocks expand & contract with extreme temperature changes, weakening & breaking the rock. Crystal GrowthCoastal & desert regionsSalt crystals grow and weaken & loosen rocks Tree rootsWarm, moist regions that support forests Tree roots wedge into rocks and break them apart AbrasionWherever there’s water, wind, or ice Rocks falling and breaking or wearing down by the direct actions of other rocks

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

9.  Organic activity  Organic activity (TREES/root-pry, burrowing animals, human activities)

10.  Abrasion & Gravity  Abrasion & Gravity: rocks falling and colliding with other rocks

11.  Contraction  Contraction due to crystallization The surface pattern on this pedestal rock is honeycomb weathering, caused by salt crystallisation. This example is at Yehliu, Taiwan. Salt weathering of building stone on the island of Gozo, Malta

12. Chemical Weathering Definition: wearing away of rocks by chemical processes, such as dissolving or oxidation. It’s a breaking down process

13. Chemical Weathering Process NameWhere does it occur? What is it? Dissolution Oxidation Hydrolysis

14. 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

15. Acid: Dissolves minerals in rocks examples: carbonic acid, acid rain, and plant acid Chemical weathering

16. Lichens such as these growing on the rocks in the picture can produce weak acids that react with the rock.

18. 3000 year old Egyptian Obelisk 3000 year old Egyptian Obelisk after 100 years in NY

19. 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.

20. Oxidation

21. Evidence 2: Weathering Lab Each group will be assigned two of the 8 treatment groups: 1.Crushed tablet in water 1. Whole tablet in water 2. Crushed tablet in heated water 2. Whole tablet in heated water 3. Crushed tablet in vinegar 3. Whole tablet in vinegar 4. Crushed tablet in heated vinegar 4. Whole tablet in heated vinegar

22. 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

23. Class Data Treatment GroupAverage time in minutes:seconds to dissolve Crushed tablet vs. Whole tablet Heated water vs. room-temp water Vinegar vs. water Heated vinegar vs. room temp vinegar

24. Analysis Q’s 1.Compare & contrast mechanical and chemical weathering. (a venn diagram or chart is o.k.) 2.Which of the treatment groups in the lab represented mechanical 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?

25. 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?

26. Reflection Explain how mechanical and chemical weathering are similar to the process of mechanical & chemical digestion. Use words, pictures, or both.

27. Big Idea Rock landforms can be broken down by the natural processes of mechanical & chemical weathering.