Rates of Weathering Ch. 10 Section 2 Ch. 10 Section 2

Rates of Weathering Hard rocks weather slower than soft rocks. Hard rocks weather slower than soft rocks. This is also called differential weathering. This is also called differential weathering.

Devils Tower in Wyoming

What Happened? Long ago, magma cooled in the center of a volcano to form igneous rock. Long ago, magma cooled in the center of a volcano to form igneous rock. Over time, the outer rock, softer rock weathered away leaving only the harder inner rock. Over time, the outer rock, softer rock weathered away leaving only the harder inner rock.

Think about it! A rock will have a lower rate of weathering when the rock A rock will have a lower rate of weathering when the rock –A. Is in a humid climate. –B. Is a very hard rock, such as granite. –C. Is at a high elevation. –D. Has more surface area exposed to weathering.

Surface Area Because weathering occurs on the surface of rocks, the more surface area exposed to weather the faster a rock will weather. Because weathering occurs on the surface of rocks, the more surface area exposed to weather the faster a rock will weather.

Climate affects weathering. Climate is average weather condition in an area. Climate is average weather condition in an area.

Warm, humid climate Chemical weathering occurs faster in warmer, wetter climates. Chemical weathering occurs faster in warmer, wetter climates. Like Georgia Like Georgia

Water and Temperature More water and lower temperatures affect mechanical weathering. More water and lower temperatures affect mechanical weathering. If water freezes and thaws often then ice wedging occurs more. If water freezes and thaws often then ice wedging occurs more.

Mountain Tops Mountain tops weather faster because they are exposed to more wind, rain, and ice. Mountain tops weather faster because they are exposed to more wind, rain, and ice.

Think about it! Why does the peak of a mountain weather faster than the rocks at the bottom of the mountain? Why does the peak of a mountain weather faster than the rocks at the bottom of the mountain?

Think about it! Why does the peak of a mountain weather faster than the rocks at the bottom of the mountain? Why does the peak of a mountain weather faster than the rocks at the bottom of the mountain? –Answer: Rocks at the peak of a mountain weather faster because they are exposed to more wind, rain, and ice.

From Bedrock to Soil Ch. 10 Section 3 Ch. 10 Section 3

What is soil? Soil is a loose mixture of small mineral fragments, organic material, water, and air that can support the growth of vegetation. Soil is a loose mixture of small mineral fragments, organic material, water, and air that can support the growth of vegetation.

All soil is different Soil (weathered rock fragments) can be made of many different types of rock. The type of rock that the soil was made from is called parent rock. Soil (weathered rock fragments) can be made of many different types of rock. The type of rock that the soil was made from is called parent rock.

Parts of Soil

Bedrock Bedrock is the layer of rock beneath the soil. Bedrock is the layer of rock beneath the soil. Some soil is made from bedrock, so it remains above the parent rock. Some soil is made from bedrock, so it remains above the parent rock.

Humus Humus is the dark, organic material in soil that is formed from decayed remains of plants and animals. Humus is the dark, organic material in soil that is formed from decayed remains of plants and animals.

Soil Horizons Soil is usually layered with humus-rich soil on top, sediment below that, and bedrock on bottom. Soil is usually layered with humus-rich soil on top, sediment below that, and bedrock on bottom.

Think about it! What is the source of mineral fragments in soil? What is the source of mineral fragments in soil? The proportion of different sized particles in soil determines the soil’s The proportion of different sized particles in soil determines the soil’s –A. Texture –B. Fertility –C. Structure –D. Horizon

Think about it! What is the source of mineral fragments in soil? Parent Rock What is the source of mineral fragments in soil? Parent Rock The proportion of different sized particles in soil determines the soil’s The proportion of different sized particles in soil determines the soil’s –A. Texture –B. Fertility –C. Structure –D. Horizon

Soil Conservation Ch. 10, Section 4 Ch. 10, Section 4

Soil Conservation Soil Conservation is a method to maintain the fertility of soil by preventing erosion and the loss of nutrients. Soil Conservation is a method to maintain the fertility of soil by preventing erosion and the loss of nutrients.

Importance of soil Soil provides nutrients to plant life. Soil provides nutrients to plant life. If the soil loses these nutrients then the plants will not grow. If the soil loses these nutrients then the plants will not grow. All animals get energy from plants. All animals get energy from plants. –How can unhealthy soil effect us?

Housing and Water Soil is also important to providing shelter for animals that live in soil. Soil is also important to providing shelter for animals that live in soil. It also stores water for plants and animals, and helps prevent flooding. It also stores water for plants and animals, and helps prevent flooding.

Can you tell which is grown in healthy soil?

Land Degradation When soil is overused it loses its nutrients. When soil is overused it loses its nutrients. How could soil be overused?

Land Degradation When soil is overused it loses its nutrients. When soil is overused it loses its nutrients. –This can happen from poor farming techniques or overgrazing. Plants can’t grow in infertile soil. Plants can’t grow in infertile soil. Without plants and moisture the soil can be washed or blown away. Without plants and moisture the soil can be washed or blown away.

Erosion Erosion is the process by which wind, water, or gravity transport soil and sediment from one location to another. Erosion is the process by which wind, water, or gravity transport soil and sediment from one location to another. This happens when land is left unprotected. This happens when land is left unprotected. This happened in south Georgia long ago. The result was Providence Canyon. This happened in south Georgia long ago. The result was Providence Canyon. What was once cotton fields is now a 150 ft. deep canyon. What was once cotton fields is now a 150 ft. deep canyon.

Providence Canyon

Soil Conservation There are many ways that farmers help prevent erosion. There are many ways that farmers help prevent erosion. –Contour plowing –Terracing –No-till farming –Cover crops –Crop rotation

Contour Plowing

Terracing

No-till farming

Cover crops Cover crops are crops such as soy beans and peanuts that help restore important nutrients to the soil and prevents erosion. Cover crops are crops such as soy beans and peanuts that help restore important nutrients to the soil and prevents erosion.

Crop rotation Rotating crops from one year to the next. Rotating crops from one year to the next.

Think about it! Why is soil important? Why is soil important? How does crop rotation benefit soil? How does crop rotation benefit soil?

Think about it! Why is soil important? Why is soil important? Soil provides nutrients to plants; provides houses for animals; and stores water. How does crop rotation benefit soil? How does crop rotation benefit soil? Crop rotation helps prevent soil nutrients from being depleted. Alternation of crops in the same soil reduces nutrient loss.