WEATHERING: the process by which rocks are BROKEN down by the action of PHYSICAL or CHEMICAL processes. 2 Types of Weathering 1. MECHANICAL weathering:

WEATHERING: the process by which rocks are BROKEN down by the action of PHYSICAL or CHEMICAL processes. 2 Types of Weathering 1. MECHANICAL weathering: rocks are broken down into SMALLER pieces without being chemically changed. This is caused by several things.

Examples: ICE: FROST action repeated freezing and thawing ICE Wedging: frost action where WATER seeps into cracks during warm weather, then freezes, EXPANDS, and breaks rock during cold weather.

Examples ABRASION: other rocks or sand rub and WEAR away other rocks WIND - abrasion caused by the wind BLOWING sediments WATER abrasion caused by waves moving sediments GRAVITY: abrasion caused by rocks falling on other rocks and from mountains and hills.

PLANTS: ROOTS get into cracks, grow, expand, and break rocks ANIMALS: animals burrow & cause abrasion by BURROWING (digging) Wetting and Drying - c auses clay minerals to expand and contract, and salts may dissolve and re precipitate. Sheet Joining - surface sheets of material fracture and exfoliate because of pressure release. Exfoliation - The peeling of rounded thin layers from the rocks surface.

The rocks are essentially torn apart by physical force, rather than by chemical breakdown.

CHEMICAL weathering : rocks broken down into smaller piece and are BROKEN DOWN by a CHEMICAL reaction. WATER: (Hydrolysis) can chemically change rocks over millions of years ACID RAIN: caused by PRECIPITATION (or pollution)\ ACIDS IN LIVING THINGS: ex: LICHENS produce acids that break down rock. AIR- OXIDATION: OXYGEN in air reacts with iron in certain rocks to make RUST (oxide). Carbon Dioxide mixes with rain water to form Carbonic Acid. It dissolves rock and caves form underground. Sulfuric Acid is pollution from factories that dissolves in rainwater to weather metals and rocks.

Lichens produce acid that break down rock.

This depends on many things such as CLIMATE, elevation, and composition (what the rock is made of).

DIFFERENTIAL WEATHERING: when SOFTER rocks wear away from the weather & leave the HARDER and more weather- resistant rocks behind (ex: Devils Tower the softer part of the volcano is gone, but the harder rock is left behind.) THE SHAPE OF THE ROCK: the MORE rock that is exposed, the MORE it will weather away. CLIMATE: Chemical weathering happens FASTER in warmer, HUMID climates Mechanical weathering happens faster in COOLER climates where there is a lot of FREEZING & thawing ELEVATION: HIGHER rocks weather away faster because they are exposed to ICE, WIND & RAIN more The steeper the SLOPE of the mountain, the faster the SEDIMENTS will flow downhill and the faster the ROCKS will weather away

Chemical Weathering: Mechanical Weathering: Devils Tower: the softer outer part of the volcano is gone, but the harder rock is left behind

SOIL: a loose mixture of MINERAL fragments, ORGANIC material, water, & air that can support the growth of VEGETATION. PARENT ROCK: a rock formation that was the SOURCE of soil

O, -humus (dark soil full of nutrients from decaying plants and animals) A topsoil E- LEACHING occurs (water drains nutrients down) B - collects NUTRIENTS from upper layers C- a lot of WEATHERED bedrockbig chunks R- bedrock

1. Humus: 2. Leaching:

1. TEXTURE: size of the sediments SAND: has the LARGEST grains and water moves through it easily SILT: medium sized grain CLAY: smallest grains and WATER does not move through easily http://www.iconn.org/presentations/CECA_Fall2007/Roche_files/slide0074_image027.jpg

2. STRUCTURE: soil sediments can CLUMP in some areas and be loose in other areas 3. SOIL FERTILITY: the soils ability to SUPPORT plant growth- Humus is great for this

4. TEMPERATURE: plants cant GROW if the soil temperature is too high or too LOW 5. MOISTURE: depends on the soils texture

6. pH: influences which nutrients will be available to plants http://www.worsleyschool.net/science/files/pH/phscale.gif

7. Color: the DARKER the soil, the more organic and FERTILE reddish & yellow contain IRON, but are also fertile whitish contain SALTS & are not fertile for farming crops http://climatelab.org/@api/deki/files/190/=Biochar_dark_soil_betchkal.jpg http://eusoils.jrc.ec.europa.eu/projects/soil_atlas/images/1-39%2028_img_2.jpg http://www.wunderground.com/data/wximagenew/m/MikeTheiss /140.jpg

TROPICAL RAIN FOREST SOIL: not very fertile, too much LEACHING (water) from heavy rain, & too many PLANTS soak up nutrients DESERT SOIL: little RAIN, so little weathering occurs, but no rain to wash away SALTS TEMPERATE FOREST SOIL: BEST for crops & weathering ARCTIC SOIL: little water & COLD temperatures so there is little decomposition to provide nutrients

A method to PROTECT soil from EROSION & nutrient loss WHY DO WE NEED SOIL? For plant growth, for decomposers to live in

1. CONTOUR Plowing: planting ROWS of crops across HILLS instead of up & down to hold soil in place Minnesota." Online Photograph. Britannica Student Encyclopdia. 3 Oct. 2008.http://student.britannica.com/ebi/art-56029

2. Terracing: changing a steep slope into a series of FLAT stairs to plant crops on http://en.wikipedia.org/wiki/Image:Rice_terraces.png

3. NO-TILL Farming: leaving old, HARVESTED plants lay on the top of the field to hold soil down http://whyfiles.org/241GM_2/index.php?g=3.txt

Crop ROTATION: planting crops in DIFFERENT fields each year so that the NUTRIENTS of one field are not used up right away

COVER Crops: crops are planted in-between HARVESTS to replace nutrients & cover the GROUND to prevent erosion from wind & rain

Documents

WEATHERING: the process by which rocks are BROKEN down by the action of PHYSICAL or CHEMICAL processes. 2 Types of Weathering 1. MECHANICAL weathering: