Presentation on theme: "Erosion and Deposition"— Presentation transcript:
1Erosion and Deposition Table of Contents4.4 & 4.5Wind ErosionFlorida LandformsMs. De Los Rios
24.3 Review Wave Erosion The Changing Coast What are the different landforms called? Were they formed by erosion or deposition?
3Vocabulary 4.4 & 4.5Deflation- The process by which wind removes surface materials. Sand Dune- A deposit of wind-blown sand. Loess- A wind-formed deposit made of fine particles of clay and silt. Flare in Latin means “to blow” 4.5 Limestone- A sedimentary rock formed from the remains of tiny sea animals. Ridge- Long raised strips of land that run parallel to the coast.
4How Does Wind Cause Erosion and Deposition? Pg. 138 Wind shapes the land by erosion=DeflationHow is it that can wind erode the land?Wind can be a powerful force in shaping the land in areas where there are few plants to hold the soil in place.Wind causes erosion mainly by deflation.Geologists define deflation as the process by which wind removes surface materials.VocabularyThe Latin word flare means “to blow.” How does the flare relate to the word deflation?
5Process of Deflation pg. 139 When wind blows over the land, it picks up the smallest particles of sediment such as clay and silt. (fine particle)The stronger the wind, the larger the particles that it can pick up. Slightly heavier particles, such as sand, might skip or bounce for a short distance. But sand soon falls back to the ground. (Medium particle)Strong winds can roll heavier sediment particles over the ground. (Large particle)
6Desert Pavement pg. 139In deserts, deflation can sometimes create an area of rock fragments called desert pavement.There, wind has blown away the smaller sediment leaving behind rocky material.
7Wind Erosion Figure 1 pg. 139 Wind Erosion 1.)Draw the particles that would be moved by the wind (hint use the key)2.) Wind moves particles in three ways. Which of the words--fine, medium, or large--correctly begins each sentence?
8How are most of the desert landforms formed? Abrasion pg. 139Abrasion by wind-carried sand can polish rock, but it causes relatively little erosion.How are most of the desert landforms formed?Geologists think that most desert landforms are the result of weathering and water erosion.
9All sediments picked up by wind eventually falls to the ground. Deposits by Wind pg. 140All sediments picked up by wind eventually falls to the ground.When does Wind deposition take place?Wind deposition takes place when the wind slows down or meets an obstacle, such as a boulder or clump of grass, that traps the windblown sediment.Wind erosion and deposition may form sand dunes and loess deposits.
10Where do we find sand dunes? Sand dunes Shape and Size (r pg. 140 2 P) Deposits by Wind pg. 140When the wind meets an obstacle, the result is usually a deposit of windblown sand called a sand dune.Where do we find sand dunes?Sand dunes occur on beaches and in deserts where wind-blown sediment has built up.Sand dunes Shape and Size (r pg P)They come in many shapes and sizes.The shape of them depends on: the direction of the wind, amount of sand, and the presence of plants.Sometimes plants begin growing on a dune. Plant roots can help to anchor the dune in one place.
11Deposits by Wind --Loess Deposits pg. 140 Sediment that is smaller than sand, such as:particles of clay and silt is dropped far from its source in large deposits.This fine, wind-deposited sediment is loess.Loess helps to form fertile soil.Areas with large Loess deposits:Central ChinaNebraska, South DakotaIowa, Missouri, & IllinoisMany areas with thick loess deposits are valuable farmlands.Fig. 2. & Apply itYellow Stone Loess Deposit
12Have you ever seen a lake just disappear? My Planet Diary!! Pg. 142Have you ever seen a lake just disappear?That’s what happened to Lake Jackson near Tallahassee, Florida, in 1999, and again in 2007.The lake formed in two sinkholes that are usually plugged. But during a drought, the water level underground drops and the sinkholes open. In days, all the water in the lake may drain out. After the lake drained through Porter Hole in 1999 (shown here), people had a running race in the lake bottom!
13What Landforms Are Found in Florida? Pg. 142 Did you know that no matter where you are in Florida, you’re NEVER more than 110 kilometers or closer to salt water.!!!About 25 million years ago, Florida was under water, and many of the state’s landforms are a result of the changing sea level.The Florida peninsula sits on a huge limestone platform. Limestone is a sedimentary rock formed from the remains of tiny sea animals. When the animals died, their shells and skeletons sank to the bottom of the ocean and accumulated into layers. Over millions of years, these layers hardened into rock.The size and shape of Florida changed repeatedly as sea levels rose and fell.
14What Landforms Are Found in Florida? Pg. 143 Scientists have identified distinct regions in Florida where different landforms are found.The three main regions are:1.) The northern highlands2.) The central highlands,3.) The coastal lowlands.Description of the 3 main regionsThe northern highlands consist of gently sloping plateaus.the central highlands are made up of long ridges.The surrounding coastal lowlands include dunes and beaches on the Atlantic and Gulf coasts, as well as vast wetlands at the southern end of the peninsula.
15Florida Landforms Fig. 1 pg. 143 Florida Landform Most of Florida is relatively flat, but over time the changing sea levels have shaped a varied landscape.1.) Look at the diagram and notice the changes it shows in Florida’s coastline. Record yourobservations. ________________________________________________2.) How have changing sea levels shaped Florida’s Landforms?________________________________________________
16Landforms Across Florida pg. 144 Over millions of years, ________ and _________ have shaped Florida’s landscape. Different types of landforms in Florida include: rivers, hills and ridges, coastal features, lakes, and wetlands. Florida’s streams and rivers carry (erosion) and drop sediment along the coast, helping to form beaches, barrier islands, and deltas (deposition). Long, raised strips of land called ridges run parallel to the coast. Florida’s ridges mark ancient shorelines. Waves and currents have shaped Florida’s long coastline, forming bays and building up sandbars and barrier islands. Many southern Florida beaches consist of coral from offshore reefs.
17Florida Landforms pgs. 144 & 145 Landforms Across Florida This map shows a few of Florida’s many landforms.
18Landforms Across Florida pg. 145 There are more than 7,000 lakes across Florida, most of which formed after erosion dissolved the limestone plateau beneath them. The Everglades is a large wetland that covers several thousand square kilometers. The Everglades formed on a flat block of limestone that tilts gently toward the south.