Review: What are mountains made of? Rocks How are rocks made into mountains? Plate tectonics What do you think happens to rock once it is exposed to the surface of the Earth? Weathering and Erosion
Weathering is the process that breaks down rock and other substances at Earth’s surface. Heat, cold, water, ice, oxygen, and carbon dioxide are elements of weathering. Can you think of examples of weathering?
Chemical weathering is the process that breaks down rock through chemical changes. Causes include action of water, oxygen, carbon dioxide, living organisms, and acid rain
Chemical weathering can change or produce new minerals as it breaks down rock Example: granite is made of several minerals (feldspar, quartz, & mica) During chemical weathering, the feldspar minerals are changed to clay minerals.
Chemical weathering creates soft spots or holes in rocks so the rock breaks apart more easily Chemical and mechanical weathering work together how? Mechanical weathering creates more surface area to be exposed to chemical weathering
Weathering is? the process that breaks down rock and other substances at Earth’s surface. Erosion is? the removal of rock particles by wind, water, ice and gravity.
Uniformitarianism is? the principle that states that the process we see today are the same as those in the past. Mechanical Weathering is? when rock is physically broken into smaller pieces.
Chemical weathering is? the process that breaks down rock through chemical changes. Chemical and mechanical weathering work together how? Mechanical weathering creates more surface area to be exposed to chemical weathering
Read about the 5 types of chemical weathering. In the same notes we have been working on, tell how each of these elements helps to break down rock.
Water: dissolves rock Oxygen: when in contact with iron it oxidizes (rusts) makes rock crumbly and brown/red. Carbon dioxide: dissolves in water and creates weak acid (carbonic acid). Easily weathers rocks
Living Organisms: Plant roots can produce weak acids that break down rock Acid rain: chemicals from burning fossil fuels (sulfur, carbon, nitrogen) combine with water vapor and fall as acid rain. Acid easily breaks down rock.
Slate tombstones from the 1700s are less weathered and easier to read than marble tombstones from the 1800s. Why?
Factors that affect the rate of weathering are the type of rock and the climate. 1. Type of rock: type of minerals determine how fast a rock weathers Permeable rocks (those with air holes) allow water to seep in
2. Climate: Average weather in an area Both chemical and mechanical weathering occur faster in wet climates. Chemical reactions occur faster at higher temperatures Hot, wet climate = faster rate of weathering
Bellwork # ? 1-13-14 Write briefly about a scientific observation you made recently.
With a partner, or on your own: 1: Read over section 2 2: make a visual glossary for the highlighted and/or bold terms 3: Complete the soil section of our handout from Friday. 4: Answer the assessment questions on page 254
Soil: loose weathered material on Earth’s surface in which plants grow Bedrock: solid layer of rock beneath the soil The base for the soil above.
Soil is a mixture of rock particles, minerals, decayed organic material, water, and air. Humus: The dark-colored substance that forms as plant and animal remains decay. Humus has nutrients Fertile soil has all of the nutrients plants need to grow.
Sand, silt, and clay are the three types of rock that make up most soil. Clay=holds too much water, could drown plants Sand=not enough water/nutrients Loam=Just the right combination. Crumbly, holds air and water Equal parts sand, clay, silt
Soil is constantly being formed. Soil Horizon: a layer of soil that differs in color and texture from the layers above or below. Topsoil: crumbly, thick, brown mixture of clay, humus, and other minerals. Subsoil: contains clay and other particles, but little to no humus.
Look at the map and reading on page 251 and answer the following questions: 1. What affects the type of soil that forms from bedrock in a region? 2. Why might different soils in Arctic regions have similar characteristics? 3. Which soil would be similar to that in prairie region of the U.S.- a soil in the Brazilian rain forest or a soil in the grasslands of Argentina? 4. Which soil type exists where we live? What climate and vegetation types occur in our region? 5. Why does soil type vary across the country? 6. In which part of the country are tundra soils found?
Same as before: pages 252-253 1. How does organic matter like litter become humus? 2. Where does most of the organic matter go? 3. Why does Humus remain? 4. Why is humus essential for plant growth? 5. How are the organisms in the illustration adapted to living in soil? 6. In which part of the soil would you expect to find the fewest examples of plant and animal life? Explain.
Natural resource: anything in the environment that humans use. Soil is one of the Earth’s most valuable natural resources because everything that lives on land, including humans, depends directly or indirectly on soil.
Soil is a limited natural resource because there is limited supply and: Less than 1/8 of the land on Earth is well suited for farming. It takes a long time for it to form Hundreds of years for a few centimeters to form
The value of soil is reduced when soil loses its fertility and when topsoil is lost due to erosion. Soil is exhausted when it loses its fertility Over farming of the cotton crop depleted and exhausted thousands of acres of farms in the South George Washington Carver discovered that certain plants (peanuts, beans, and other legumes) replaced these nutrients and farmers returned to the South.
Wind and rain can quickly erode exposed soil Soil with plants on it are stronger against erosion because they break the force of the rain and their roots hold the soil together against the wind and rain
Late 1800s farmers settled the Great Plains The region has very fertile soil, but also experiences extensive droughts Farming (plowing) exposed the soil.
During droughts the soil dried, turned to dust, and blew away 1930 a great drought dried the soil and blew millions of tons of topsoil across the U.S. (as far as NYC!) Farmers began to help conserve soil after this!
3. Crop Rotation: planting different crops in a field every year Cotton and corn absorb a lot of nutrients. The following year a low-absorption crop (like oats, barley or rye) is planted The year after that a plant that restores nutrients, such as legumes, is planted.