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Mrs. Wright Hugh B. Bain Middle School Cranston, RI SLOW Processes that Shape the Earth PART 1. WEATHERING.

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Presentation on theme: "Mrs. Wright Hugh B. Bain Middle School Cranston, RI SLOW Processes that Shape the Earth PART 1. WEATHERING."— Presentation transcript:

1 Mrs. Wright Hugh B. Bain Middle School Cranston, RI SLOW Processes that Shape the Earth PART 1. WEATHERING

2 Earth - developed over long periods of time through continual change processes. STUDENTS: Evaluate slow processes of 1) weathering 2) erosion and 3) mountain building. The following slides are on weathering. Determine how the earth has changed and will continue to change over time.

3 Weathering – What is it? Mechanical (physical) and chemical processes that break down rock at Earth’s surface Mechanical Weathering Chemical Weathering rock physically broken into smaller pieces rock breaks down from exposure to water and atmospheric gases (CO 2, O 2, and H 2 O vapor). uk ‑ stonehenge.jpg

4 What is it? Type of weathering where rock is physically broken into smaller pieces Mechanical Weathering

5 Causes of Mechanical Weathering Freezing & Thawing Release of Pressure Plant Growth Action of Animals Abrasion

6 Freezing & Thawing Ice wedging Water freezes in crack in rock Expands and makes crack bigger Process also causes cracks in sidewalks & potholes in streets

7 Freezing & Thawing a.org/wikipedia/commons/e/eb/Pothole_Small.jpg&imgrefurl

8 Release of Pressure Erosion removes material from rock Pressure on rock is reduced Causes outside of rock to flake off like layers of onion m/f/ /exfoliation1.jpg&imgrefurl

9 Plant Growth Roots enter cracks in rocks Grow Force cracks farther apart or pry them apart ts_breaking_rocks.jpg&imgrefurl

10 Plant Growth

11 Action of Animals Burrowing animals loosen and break apart rocks in soil beeholes.jpg

12 Water vole burrows brook-meadow.hampshire.org.uk Burrowing frog ‑ large.jpg Action of Animals Water Vole.jpg 567 × Water Vole dungevalley.co.uk

13 Action of Animals com/2010/11/ jpg

14 Abrasion grinding away of rock by rock particles carried by water, ice, wind or gravity What is it? riverrocks.jpg

15 Abrasion Sand & rock particles carried by wind & water, wear away exposed rock like sandpaper on wood. image002.jpgimage002.jpg 569 × wave action (mechanical weathering) photo courtesy of R. Weller skywalker.cochise.edu

16 What is it? Type of weathering where rock breaks down from exposure to water and atmospheric gases (CO 2, O 2, and H 2 O vapor). Chemical Weathering

17 Causes of Chemical Weathering Action of Water Oxygen (Oxidation) Carbon dioxide (CO 2 ) Living Organisms Acid Rain

18 Action of Water Most important cause of chemical weathering Dissolves rock _f520.jpg _f520.jpg 520 × formed by chemical weathering. Water dissolves the calcites in the rock... hubpages.com

19 Action of Water 278.Jpg278.Jpg form where water collects and accentuates rates of chemical weathering uregina.ca

20 Oxygen (Oxidation) Iron (Fe), or other metal, combines with oxygen in the presence of water If metal is Fe, causes rust Rock containing iron also rusts then crumbles apart Rusting causes Red/brown color What is it? jimeno2.glogster.com

21 Carbon dioxide (CO 2 ) CO 2 dissolves in rainwater Forms carbonic acid that seeps into soil Easily weathers rocks like limestone & marble chemical ‑ weathering ‑ process ‑ 3.1 ‑ 800X800.jpg Rain water and carbon dioxide create carbonic acid. This mild acid interacts... ehow.co.uk

22 Carbon dioxide (CO 2 ) Cheddar caves xtrawide.jpg... loses some of its dissolved carbon dioxide and deposits some of its... geolsoc.org.uk Water seeped into cracks in limestone & cracks enlarged gradually Rainwater became acidic as it dissolved carbon dioxide from the air and soil Dissolved away rock to form cave system Water dripping from cracks in cave roof, lost dissolved CO 2 & depositsCaCO 3 Formed stalactites, stalagmites or smooth flowstone

23 Living Organisms Lichens (plant-like organism) & roots of plants produce weak acids Slowly dissolve rock around roots trans_s_lichensndstn.jpg Stone colonized by lichens, which bit by bit dissolve the rock into.morning-earth.org

24 Acid Rain Coal, oil, gas burned past 150yrs S, C & N compounds put in air React chemically with water vapor in clouds Form acids Acids mix with raindrops & fall as acid rain Causes very rapid chemical weathering _Acid_rain_damaged_gargoyle_ ‑.jpg Silverchair — Acid Rain lyrics lyricsdog.eu

25 What is it? How fast weathering occurs Rate of Weathering

26 Most important factors determining how fast weathering occurs: Type of Rock Climate

27 Type of Rock Minerals that make up rock determine how fast it weathers If minerals dissolve slowly in water, rock weathers slowly. If minerals dissolve quickly in water, rock weathers quickly. Rocks.jpg edweb.tusd.k12.az.us

28 Permeability What is permeability?permeability Material is full of tiny connected air spaces that allow water to seep through it. Some permeable rock may weather more quickly Weathers chemically at faster rate because water easily seeps into it, dissolves it & removes material

29 Climate climate – refers to average weather conditions in area Chemical and mechanical weathering occur faster in wet climates Rainfall provides water needed for chemical changes & physical changes (freezing and thawing) High temperatures - Chemical reactions occur more quickly _ 470px ‑ ClimateMap_World.png

30 Rate of Weathering 278.Jpg water collects and accentuates rates of chemical weathering uregina.ca

31 Looking at the SLOW process of weathering, how has the earth changed over time? Give at least three examples and explain each. Is the earth still changing through weathering? How do you know? Give at least three examples and explain.


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