2Do Now5 minutesBreaking it Down Key Question: What is weathering, and what are some examples? Initial Thoughts:
3Evidence: WeatheringLarge 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
4Mechanical 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?Break an Alka-Seltzer tablet with a hammer
5Go to the website, which can be found on my links page under “Mechanical Weathering, and click “NEXT” twice:
7Exfoliation 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
8Organic activity (TREES/root-pry, burrowing animals, human activities)
9Abrasion & Gravity: rocks falling and colliding with other rocks
10Contraction 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
11Chemical WeatheringDefinition: wearing away of rocks by chemical processes, such as dissolving or oxidation. (in your journal vocab)It’s a breaking down process
12Dissolving 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
13Chemical weatheringAcid: Dissolves minerals in rocks examples: carbonic acid, acid rain, and plant acid
14Lichens such as these growing on the rocks in the picture can produce weak acids that react with the rock.
19Evidence 2: Weathering Lab Each group will be assigned one of the 4 treatment groups:Crushed tablet vs. Whole tabletHeated water vs. room-temp waterVinegar vs. waterHeated vinegar vs. room temp vinegar
20Make a hypothesisIf we test (treatment group) then the time it takes for the tablet to completely dissolve will be faster/slower.Use 150 ml of liquidRecord the time it takes for the tablet to dissolve
21Class Data Recreate this table in your journal Treatment GroupAverage time in minutes:seconds to dissolveCrushed tablet vs. Whole tabletHeated water vs. room-temp waterIce cold water vs. room temp waterVinegar vs. water
22Analysis Q’sCompare & contrast mechanical and chemical weathering. (a venn diagram or chart is o.k.)A) Which of the treatment groups in the lab represented mechanical weathering? B) Which were chemical weathering?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?
23SummaryWhat 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?
24ReflectionExplain how mechanical and chemical weathering are similar to the process of mechanical & chemical digestion. Use words, pictures, or both.
25Big IdeaRock landforms can be broken down by the natural processes of mechanical & chemical weathering.
26Do Now 4-14-14 New Seats Turn in your Paper Plate Rock Cycle Update your grades page:4/1 Rock Cycle4/3 VocabularyRead the Learning Target4 minutes