Unit 1 Study Guide
Earth s Spheres
Biosphere All living things, plants, animals, (even you!) are part of the zone of the earth called the biosphere.
Hydrosphere Water covers ¾ of the earth, made up mostly by the oceans. The hydrosphere includes this and also all the lakes, rivers, water underground, in the air and even the frozen water trapped in glaciers and ice caps!
Lithosphere The lithosphere is the rocky outer later that covers the earth. It is much thicker than the biosphere and the hydrosphere. The lithosphere includes the continents, islands, and the entire ocean floor. It is made of mostly soil, rocks, magma and sand.
Atmosphere The atmosphere is a layer of gas that surrounds the earth. It is made of many gases, including the oxygen we need to breathe, as well as small liquid and solid particles. We call the atmosphere air! If you look at a picture of the earth from space, you can see clouds formed in the atmosphere.
Atmosphere The atmosphere traps energy from the sun, allowing the earth s surface to be warm enough for liquid water to exist. The atmosphere also provides protection from a harmful form of solar radiation and from material from space.
Magnetosphere The center of the earth is called the core. It is mostly iron and its liquid outer layer creates an invisible magnetic field that extends outside of the earth, surrounding the planet. This magnetic field is the magnetosphere.
Magnetosphere Even though we cannot see the magnetosphere, we can see the aurora (or northern lights) in the Northern and Southern Hemispheres. Scientists think an aurora is caused when charged particles from the sun enter the magnetosphere and become trapped.
Weathering and Erosion
Mechanical Weathering When physical forces wear away at rock it is called mechanical weathering. There are multiple types of mechanical weathering. Ice is one type of mechanical weathering. It can cause rocks to split. This is called ice wedging.
Mechanical Weathering Mechanical weathering can also be caused by flowing water and waves, quick drastic changes in temperature, particles in the wind causing friction, and even plants and animals!
Chemical Weathering Chemical weathering is the breaking down of rocks by chemical processes by affecting their atoms and molecules. Chemical weathering affects a rock s atoms and molecules. Chemicals in rainwater can react with the chemical make up of the rock. This weathering can even cause rust on rocks! Can you think of an example of this?
Working Together Mechanical and chemical weathering often affect the same rocks. Mechanical weathering can leave the inside of a rock exposed to chemicals OR chemical weathering can weaken a rock, allowing wind and water to have a greater effect breaking it down.
Climate s Effect Weathering occurs faster in warm, wet climates because the rain s moisture helps the chemicals dissolve rock easier and chemical reactions occur at a faster rate in high temperatures. Such climates also produce a large amount of vegetation, helping to cause chemical reactions with the soil and roots growing through the rocks. In temperate climates, where weather varies from hot to cold, ice wedging is often at fault.
Erosion Erosion is the gradual removal of the surface of the land by water, wind, or glaciers. As weathering breaks down the rock, water and wind carry it away.
Erosion by Waves Just like waves help to weather rock, they also help with erosion. As the water from the wave washes down the shore, it can carry sand and other rock pieces with it. The water may deposit the sand in other places along the coast.
Erosion by Ice and Wind Over time, ice and snow can build up to form glaciers. Glaciers move slowly over the land and as they do, they can pick up rocks and soil from the ground and carry them over long distances. Glaciers can carry rocks as large as houses! Winds can pick up and carry small rock pieces for thousands of miles or a strong wind can carry large rocks, but not very far.
Mass Wasting Landslides and mudslides involve the downslope movement of large amounts of rock and soil, which is called mass wasting. In some cases, an event such as an earthquake or volcanic eruption causes the slide.
Soil
Soil Formation This begins when organisms such as lichen and moss grow on rocks surfaces. These organisms contain acids that start to weather the rock. After some time, plants grow on the weathering rock. When these plants die, their remains mix with the rock sediments. Eventually, the soil is fully formed.
The type of rock a soil forms from is known as the parent material. Here are three common types of soil: sand, silt, and clay. Notice how they differ in texture and grain size. Clay is made up of tiny particles, silt has slightly larger particles, and sand has the largest particles. Types of Soil
The Effects of Water Clay-based soils are much different from sandbased soils in two important ways porosity and permeability. Porosity refers to how much water a soil can hold in the empty spaces or pores between its grains. Soil with high porosity is better at holding water. Clay soil is able to hold a lot of water, so its porosity is high. Sand does not hold water as well as clay so its porosity is low.
The Effects of Water Permeability is the rate at which water passes through a material. Permeability is higher in materials with bigger grains. This is because the spaces are larger and more connected, so water can flow more freely. A soil s porosity and permeability determine how much water it can hold and for how long. Dense clay soil tends to hold water while water drains well from sandy soil. The right mix of sand and clay is required for growing different plants depending on how much water they need.
Loam The perfect soil for plants and soil organisms is a mixture of sand, silt, and an amount of clay. This soil is called loam. There are enough large and small spaces in loam for air and water to flow. Clay allows the soil to stick together, and sand allows space for the plant roots to grow through.
Tropical Biomes A biome is a large area dominated by characteristic plants and animals. Tropical soils form in warm biomes that get heavy rainfall because there is a faster rate of chemical weathering. Unfortunately, all that rain means nutrients in the topsoil become washed. What s left is quickly used by the numerous plants. This results in a thin top layer of soil. So, while tropical environments are covered with vegetation, the soils themselves do not hold a lot of nutrients.
Grasslands and Forests These areas are great for farming. They receive a moderate amount of rainfall, but not enough to wash away nutrients in the soil. The wet environment encourages high levels of chemical weathering, which contributes rock and nutrients to the soil. Grassland soils are good for growing many kinds of crops.
Desert and Arctic Biomes Soils in desert and arctic biomes cannot support much vegetation. Since deserts receive little rain, chemical weathering happens very slowly. Arctic soils also receive little rain. Plus the cold temperatures do not promote the decay of organic materials, so nutrients are limited. Also, many arctic soils have permafrost, a layer of frozen soil, which makes it difficult for plants to grow.
Scientists learn about soil in an area by studying a soil profile. A soil profile is a crosssection of the soil layers that rest on solid rock, called bedrock. Each soil layer is called a horizon. Soil Profiles
Soil Profiles The top layer is generally the darkest and is known as the A horizon. This layer, also called the topsoil, is loose and crumbly and contains most of the soil's humus. The A horizon is where crops and plants place their roots to get the best nutrients.
Soil Profiles The next layer down is the B horizon. This layer is dense and usually lighter in color than the A horizon. It has little or no organic matter but thanks to leaching - water carrying nutrients from one layer of soil to a lower layer, the B horizon is rich in nutrients. This layer is also called the subsoil.
Soil Profiles The C horizon marks the change between the soil above and the rock below. It is mostly made of weathered rock fragments.
Lesson Review B C KEY A = Horizon A B = Horizon B C = Horizon C D = Bedrock A B D A A C D
Mapping the Earth
Latitude Parallel lines like the rungs on ladder North and South degrees Equator divides the earth in half, 0 degrees North and south pole are highest points 90 degrees N and 90 degrees S
Longitude Vertical lines called meridians - long like we are tall! Run from the north pole to the south pole Start at Prime Meridian- 0 degrees and continue around the globe to 180 degrees E and W (are the same line)
Map Symbols Maps also use colors, patterns, and symbols to represent different places of interest. The meanings of symbols and sometimes the map scale are shown in a small section of the map called the map legend.
Topographic Maps Topography is the physical features of an area of land. Topographic maps contain information about land elevation, or the land s height above sea level. It s a challenge to show elevation on a flat map, so cartographers use contour lines which connect locations that are the same height above sea level.
Contours Notice how the island s shoreline is shown on the bottom image. Why is it marked 0? The next line is marked 10, so anywhere along that line the elevation is 10 meters above sea level. The contour interval is the difference in elevation from one contour line to the next. The lines become closer as the land becomes steeper. Steep slopes or cliffs are shown by closely spaced contour lines.