Weathering the process of rock breaking down into

Weathering – the process of rock breaking down into smaller pieces.

Chemical Weathering changes the chemical makeup of rocks or minerals. • Carbonation • Oxidation • Plant Acids • Acid Rain

Carbonation Carbon dioxide in the soil mixes with water to form carbonic acid which dissolves calcium carbonate in limestone rocks. Example: Cave Formations

Oxidation Oxygen in the air joins chemically with metals. Example: Iron turning red (rusting) Example: Copper turning green (tarnishing)

Plant Acids Plant roots produce acids (humic acids) which can dissolve rocks. Example: Lichens (fungus/algae) growing on rocks

Acid Rain Water in the air reacts chemically with excess carbon, sulfur, and nitrogen compounds to form acids.

Acid Rain 1908 Dissolving of statues 1969

Mechanical Weathering. Physical Weathering • Abrasion • Root Pry • Ice Wedging • Exfoliation • Animal Actions

Abrasion Sand other rock particles that are carried by wind, water, or ice can wear exposed rock surfaces, like sand paper on wood. Wind abrasion

Roots of trees and other plants enter cracks in rocks, forcing the cracks farther apart. Root Pry

Ice Wedging When water freezes in a crack in a rock, it expands and makes the crack bigger. (such as potholes on the street)

Exfoliation Extreme high temperatures cause the outside of the rock to crack and flake off, like layers of an onion.

Animal Actions Animals that burrow in the ground loosen and break apart rocks in the soil. Other animals erode landscape by walking on it.

Identify the forms of weathering shown below

Soil Formation Soil forms as rock is broken down by weathering and mixes with other materials on the surface.

Soil Texture Soil texture is determined by the size of the individual particles, which is directly related to the amount of pore spaces where water can be stored. • • • Gravel or rock 2 mm and larger Sand <2 mm Silt <1/16 th mm Clay <1/256 th mm Loam – soil that is made up of equal parts of sand, silt, and clay

Soil Profiles The arrangement of soil layers in an area, made up of individual layers or horizons. Soil horizon- An individual layer of soil that differs in color or texture from the layers above or below it.

Rate of soil formation • • The rate at which soil forms (weathering) depends on the climate and type of rock. Most rapid weathering occurs in warm, rainy climates. Limestone weathers faster than granite.

Life in soil Soil is one of Earth’s most valuable resources, because everything that lives on land depends directly or indirectly on soil. • Billions of organisms live in every cubic meter • • of soil. All organisms that live in soil enrich humus with their remains or waste. Animals and plant roots break up the soil, opening up spaces for air and water.

Erosion: movement of sediment by water, wind, gravity, and glaciers/ice u Water u Wind u Gravity u Glaciers/Ice

Moving Water The major agent of erosion that shaped Earth’s land surface. • Rain water carries away sediment leaving tiny grooves in its path. • Streams and rivers carve large channels into the landscape.

Wind Fast moving winds can carry sand dust that scour and weather the surfaces they strike. Wind is considered the weakest form of erosion. • Dust Storms • Blowing away of exposed sediments.

Gravity The force that moves rock and other materials down hill, causing mass Landslide movement. Mudslide

Glaciers A large mass of ice moving slowly over the land gathering rocks and soil as it erodes the land in its path.

Deposition The settling of eroded particles or sediment wherever they are transported by wind or water. • River deltas • Meander • Oxbow lake • Alluvial fan • Sand dunes • New beach sand • Sediments on ocean and lake floors

Ecoregions of Texas Activity u Turn to pgs. 29 -32 in your workbook u You will begin at the station assigned to you and a partner. u You will rotate as you complete a station. u Please no more than 4 people at a station at a time. u There are 14 stations. We will continue this activity on Wednesday.

Closing/Exit Ticket u Did we hit our learning target? u Exit Ticket u Don’t forget Computer Lab TOMORROW