Weathering Test Date: 2/26/16

Weathering Is the breaking- down of rock and sediments over time Two Types: Mechanical weathering Chemical weathering

Mechanical Weathering Physically breaks rocks into smaller pieces Frost Wedging Exfoliation/Unloading Organic Activity

Frost Wedging When water freezes it expands 9 % If water is caught in cracks and freezes it puts stress on the rock and splits it .

Exfoliation & Unloading Rock weathers and erodes. There is less pressure and weight pushing down on the rock. *The rock expands upward and breaks into sheets and slabs.

Biological Activity Living organisms break down rocks. Roots Lichens Animals

Mechanical Weathering As a rock weathers it increases the surface area. This causes the weathering to speed up

Chemical Weathering Breaking down (Dissolving) of minerals in rocks Changing rocks/minerals into different substances. Occurs when rocks react to air, water, and other chemicals

Oxidation Rocks are exposed to oxygen and water. If the rock is exposed to water and oxygen. The Iron oxidizes and turns red. This is the same process that causes rust on metal.

Acid Reactions When water reacts with carbon dioxide it forms carbonic acid. The acid reacts with rocks that contain calcite (limestone). The rocks dissolve. Acid rain speeds this process up.

Factors affecting weathering 1. Composition of rock 2. Surface Area

3. Climate The warmer and more humid a region is, the more weathering occurs

SOIL

Factors affecting Soil Formation Climate Warmer and wet = More weathering Slope of the Land Erosion removes soil forming materials Types of rocks weathering Some rocks weather easier than others Types of Vegetation Vegetation adds organic matter and aids in soil formation Amount of Time More time = Richer Soils

Soil provides support and nutrients for plant growth

Weathering breaks down rocks to create soil. It can be caused by weather, water, or living things

There are five components of soil: 1. Rock 2. Sand 3. Silt 4. Clay 5. Humus Can you match each type of soil to its picture?

Rock is solid and made of minerals

Sand Sand is tiny grains of worn down rock. It doesn’t hold water or have many nutrients.

Sand ------------Silt---------------Clay Silt is very small, broken pieces of rock. It is larger than clay, but smaller than sand. It is powdery when dry. Sand ------------Silt---------------Clay (smaller particles) (larger particles)

Clay is used for adobe or brick houses. Clay holds water well. It is sticky and can be shaped when it is wet. But, it is very hard when dry. Clay has many nutrients. Clay is used for adobe or brick houses.

Humus Humus is made of leaves, twigs, small animals, or other decayed substances. Humus adds many nutrients to the soil. Humus is in the topsoil.

3 Layers of a Soil Profile Topsoil (The layer on TOP) Subsoil (The prefix SUB means under) Bedrock ( The type of bedrock determines the type of soil)

Soils are dynamic, they change over time Parent material Young soil Mature Old Time

As soils age, they form distinct soil horizons and a soil profile topsoil subsoil parent material

Soil Triangle for identifying soil 60% sand, 30% silt, 10% clay

Soil as a Natural Resource! Made by NATURE Cannot be replaced Must be conserved (saved)!

Ways to Conserve Soil Plant trees Plant grass Healthy farming Plant gardens to grow crops What else can you do to conserve soil?

Erosion Erosion - the transport of materials from one place to another. Erosion can be performed by water, wind, and ice (glaciers)

Erosion by water Major agent of erosion Rain carries away bits of soil and sediment Rain creates large valleys Erosion by water changes coastlines Grand Canyon created by water erosion

Erosion by wind Wind can carry dust, sand, and volcanic ash from one place to another Ex. Arches National Park

Erosion by Ice As glaciers move slowly over the land, they pick up rocks and boulders. These rocks are transported by the glacier. The glacier itself erodes the ground beneath.