VocabularyRunoff Precipitation that flows across the land’s surface or falls into rivers and streams.Watershed Area from which water is drained; region that contributes water to a river or river system.Sediment Pieces of material carried and deposited by water or wind.Meander Bends or s-shaped curves in a river.Flood plain Land that is likely to be underwater during a flood.Delta Fan-shaped region formed by deposits of sediments found at the mouth of a river.Lithosphere The hard outer layer of Earth, about 100 km thick.Hydrosphere Earth’s water, found in continents and oceans, including the fresh water in ice, lakes, rivers and underground water.atmosphere The blanket of gases that surrounds Earth.
How do rivers Change the Land?• One of the most important causes of change on Earth is running water.• Rivers begin high in mountains or hills as small tributaries.• Runoff is water that runs off Earth’s solid surface.• An area from which water is drained is called a wetland.
Wetlands• Airboat point of view through swamp/wetlands with p
• The force of gravity keeps water flowing downhill.• Pieces of material carried by moving water are called sediment.• The force of running water with its load of sediment can erode a stream bed. Yukon River• Meanders are bends or S-shapes in rivers.
• Some of the world’s most important agriculture areas are found in flood plains.• Over time, sediments build up, creating fertile farmlands.
• The place where a river empties into an ocean is called the mouth of the river.• The river slows down so much at its mouth, that it unloads most of its sediment there.• A fan-shaped deposit of sediment is called a delta.
How do Water Gaps, Canyons, and Valleys form?• Small channels that are deepened and widened by erosion form river valleys.• Small gullies become deeper and wider as their walls are eroded and sediments are carried away.
• Where downward cutting is greater than valley widening, narrow V- shaped valleys form.• Deep V-shaped valleys are usually called canyons.• Usually more than one process is involved in the formation of canyons and other landforms.
• The Grand Canyon would not exist if the surrounding plateaus had not been pushed upward as the Colorado River cut deeper and deeper.• Grand Canyon National Park - Fly-through
• Over time, a river that slowly cuts its way across and down into resistant rock can form a water gap.• Water gaps are rare.• It was formed by the river flowing over a sediment-covered plain. As geological forces pushed the land upward, the river began cutting deeper into the plain.• Eventually, much of the surrounding area eroded away. Delaware Water Gap
How do Beaches, Dunes, and Landslides Form?• Water, gravity, wind, waves and glaciers are all agents of erosion.• Beaches form when sediments are deposited on shorelines.• Waves can erode land along coast lines or deposit sand and sediment forming beaches.
• Dunes are created when wind picks up sand particles and carries them until obstacles, such as sand and pieces of shell, slow the wind speed.
• Rapid landslides can be set off by earthquakes, volcanic activity, and heavy rains •Gravity can pull rocks and soil down slopes.
How do you read Topographic Maps?• Topographic maps use contour lines to show the shape of Earth’s surface.• A contour line is an imaginary line drawn on a map. It connects points of equal height above or below sea level.• Sea level is the main level of the surface of the sea between high and low tides. It is considered as 0 elevation.
• Contour lines that are closer together indicate a steeper slope.• Contour lines that are farther apart indicate a gentler slope.• Bodies of water, such as oceans, rivers, and lakes, are indicated on topographic maps.• Symbols are used to show buildings, roads, forests, and railroad tracks.
Look at page C24-C25• Read the pages. Write about what you notice on the topographic map, and the relief map.• What is the difference between the two maps?• Are there any similarities?
What are Earth’s Major Layers?• Earth has a solid surface layer, mostly covered by a layer of water, and surrounded by a layer of gases.
The Lithosphere• The hard outer layer of Earth is the lithosphere.• The rocky surface that makes up the top of the lithosphere is the crust.• The crust is thinnest under oceans, and thickest at continents.• The crust includes the soil and many other resources; such as minerals that help support life on Earth.
Hydrosphere• This is Earth’s water- trillions of liters of water. There is so much water it covers most of the lithosphere.• Most of the water is in the oceans. Ocean water is salty because of minerals that have been deposited over the ages.• It includes all of Earth’s fresh water found in lakes, rivers, streams, and groundwater, and ice.• It acts as a big heat absorber. Water changes slowly compared to land.• Oceans keep Earth temperatures from changing too drastically.
Atmosphere• Layers of gases that surround Earth.• There are 4 major layers of the atmosphere.• The troposphere-is closest to Earth, it contains oxygen needed for living things, and is where almost all of Earth’s weather occurs.• The other layers of the atmosphere help protect Earth against harmful energy from the sun.
Why it matters?• The Earth changes, renews, and recycles itself through natural processes.• Running water and the sediments it carries are vital to the environment and the quality of our lives.• The constant cycling of water and sediments provides fresh water and fertile soils.• Before we remove vegetation, build dams, or re- channel streams and rivers, we must consider the short-term benefits and the long term effects on Earth.