Presentation on theme: "Building Up Earth’s Surface"— Presentation transcript:
1Building Up Earth’s Surface Unit CChapter 6 Lesson 3C24 – C29
2ObjectivesRecognize that constructive forces build up Earth’s surface features.Recognize deposition to be the dropping of sediments by water, wind, or ice.Understand that gravity is always the final process in sedimentation.
3Main IdeaForces such as deposition and volcanic activity build up Earth’s surface features.
4Review In the last lesson we discussed how the earth wears down. The process of weathering and erosion.Erosion carries away sediment, but what happens to it then?When it is dropped or released in a new area this is called deposition.
5Deposition Deposition is a constructive force. This means it builds up the land.When the sediment is dropped in a new location, you are adding to the existing land there. You are building it up.
6River SystemsRecall that the source of a river is usually inland at some high elevation.The water picks up sediment as it flows downward.At the mouth of the river the water empties into a lake or ocean.The mouth is level, causing the water to lose energy and drop the sediment.
7Alluvial FansIs a fan-shaped land mass that forms after a river rushes down a steep slope, then slows over a flat plain.
8Delta A low plain that forms where a river enters an ocean. If the river is large, so is the delta.The Mississippi River has a large delta that extends out into the Gulf of Mexico.
9MeandersAs a river flows across a flat plain, its course begins to wind in curves called meanders.They increase in size as water erodes the outside of each curve and deposits sediment on the inside.
10Flooding Flooding of rivers on lowlands deposits sediment. This sediment builds up the flood plain.
11Why is sediment deposited as the slope of a river bed levels out? Because the sediment slows down and settles out.
12How are Earth’s surface features built up? Through forces such as deposition and volcanic activity.
13What is the difference between an alluvial fan and a delta? Both form when the flow of river water decreases quickly.An alluvial fan forms where a river flows down a steep slope onto a flat plain.A delta is a low plain, and forms where a river enters an ocean.
14Pushing up Earth’s Surface Surface features can be pushed up from below.Below earth’s surface the temperature is so hot it melts rock.Melted rock below the Earth’s surface is called MAGMA
15Magma Originates in a layer just below the crust. Pressure causes magma to push up Earth’s crust creating round, dome-shaped mountains.Mount Olympus
16Magma surfaces Magma can work its way through the crust. When it flows onto Earth’s surface it is called LAVA.As lava flows, it cools and hardens into rock.Kilauea, Hawaii
17Shield ConesLava that has built up to form a huge deposit with gentle sloping sides.Often form on the ocean floor.The Hawaiian Islands are the tops of shield cones.
18Hot Spots The Hawaiian Islands were formed due to a hot spot. As the Earth’s crust moves over the hot spot, new shield cones are formed.
19Building MountainsThe Himalaya Mountains in Central Asia were formed from a different constructive force than magma.As the Earth’s plates moved, they moved into each other.The pressure caused the crust to fold upward.
21Remains The remains of living things can build up Earth’s surface. The chalk cliffs of Dover, England are made of shells of tiny sea animals.The shells eventually raise to the surface.
22Coral ReefsAnother type of formation produced from the remains of living things.In shallow tropical waters, tiny animals called corals gather in colonies.As they die, their skeletons build up into a bumpy ridge called a reef.
23What process created the Himalayas? They formed when huge sections of Earth’s crust pushed into each other.
24How are chalk cliffs and coral reefs alike? How are they different? Both are formed from remains of living things.Chalk cliffs are made of the shells of tiny sea animals that were deposited on the sea floor millions of years ago, then raised to the surface.Coral reefs are the skeletons of tiny animals called corals that build up in tropical waters
25Glacial DepositsAs we learned in Social Studies thousands of years ago there were large glaciers over Asia, Europe, and North America.The ice chunks were forces of erosion.Huge amounts of soil & rock were pushed ahead of the ice and carried along in the glacier’s bottom layers.
26Glaciers The ice melts It had changed the landscape. Rock material deposited by a glacier is called till.Till is dragged along the icy base.
27Glacier MorainesMoraines are deposits of till at the front or snout of a glacier.Long Island, NY is the terminal moraine left when the last ice sheet melted.Exit Glacier in Kenai Fjords National Park near Seward, Alaska
28EskersSteams flowing through tunnels in melting glaciers deposit sand & gravel in ridges.These winding ridges are called eskers.