Earth’s Spheres, Landforms and Physical Processes What does it all mean? ©2012, TESCCC

Where might this event have taken place? What might have caused it? What evidence leads you to make these deductions? ©2012, TESCCC

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FLOODS Floods are one of the most common hazards in the United States, however not all floods are alike. Some floods develop slowly, while others such as flash floods, can develop in just a few minutes and without visible signs of rain. – Floods can be local- impacting a neighborhood or community – very large- affecting entire river basins and multiple states. Flash floods can occur within a few minutes or hours of excessive rainfall, a dam or levee failure, or a sudden release of water held by an ice jam. Flash floods often have a d angerous wall of roaring water carrying rocks, mud and other debris. Overland flooding, the most common type of flooding event typically occurs when waterways such as rivers or streams overflow their banks as a result of rainwater or a possible levee breach and cause flooding in surrounding areas. – It can also occur when rainfall or snowmelt exceeds the capacity of underground pipes, or the capacity of streets and drains designed to carry flood water away from urban areas ©2012, TESCCC

01-videos/floods 01-videos/floods ©2012, TESCCC

EROSION Wind, water, and ice are the three agents of erosion, or the carrying away of rock, sediment, and soil. Erosion is distinguished from weathering — the physical or chemical breakdown of the minerals in rock. However, weathering and erosion can happen simultaneously. Erosion is a natural process, though it is often increased by humans’ use of the land. – Deforestation – overgrazing – construction – road building often expose soil and sediments and lead to increased erosion. Excessive erosion leads to loss of soil, ecosystem damage, and a buildup of sediments in water sources. Building terraces and planting trees can help reduce erosion. ©2012, TESCCC

Weathering Weathering is the breaking down or dissolving of rocks and minerals on Earths surface. Water, ice, acids, salt, plants, animals, and changes in temperature are all agents of weathering. ©2012, TESCCC

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PLATE TECTONICS The theory of plate tectonics describes the motions of earth’s lithosphere, or outermost layer of hard, solid rock, over geologic time. Plate tectonics provides scientists with a great deal of information about the polar region’s past ©2012, TESCCC

Earth’s lithosphere is broken into seven major and many minor tectonic plates. These plates move in relation to each other, slowly changing the location of earth’s continents and oceans. ©2012, TESCCC

Plate Tectonics: View direction of the arrows showing movement of the plates. What can you deduce from this image? ©2012, TESCCC

Geological evidence from Antarctica supports the theory that all continents were connected approximately approximately 200 million years ago forming the supercontinent Pangaea. – Fossil evidence from this time period confirms that Antarctica was connected to Australia and South America and much warmer than it is today. The movement of the tectonic plates also means that they are associated with much of the world’s volcanic and seismic activity (earthquake). ©2012, TESCCC

Earthquake Seismic activity (earthquakes) is most often associated with tectonic plate boundaries. As plates slowly move, their jagged edges stick and suddenly slip, causing an earthquake. – Earthquakes could lead to Volcanic eruptions – Most earthquakes occur along the edge of the oceanic and continental plates ©2012, TESCCC

NEPAL (Country in South Asia) ark ©2012, TESCCC

VOLCANOES A volcano is simply an area where magma, or molten rock, from the earth’s mantle reaches the earth’s surface, becoming lava. Most volcanoes occur at plate boundaries, where two plates are moving away (diverging) or together (converging). A few volcanoes like the Hawaiian Islands form from a hot spot, or a weak spot in earth’s crust, where magma forces its way to the surface. Volcanic eruptions may be explosive (violent) or effusive (passive), depending on the lava chemistry (amounts of silica and dissolved gases There are 4 types of volcanoes ©2012, TESCCC

Shield Volcano A shield volcano has low levels of dissolved gas and silica in its magma. Its eruptions are effusive, and the very fluid lava moves quickly away from the vent, forming a gently sloping volcano. – E.g.) Mauna Loa in Hawaii ©2012, TESCCC

Cinder Cone Volcano A cinder cone volcano has low silica levels and high levels of dissolved gas, resulting in fluid lava that erupts explosively as a result of the immense pressure built in the magma chamber. – Example: Lava Butte in Orego ©2012, TESCCC

Lava Dome Volcano: A lava dome volcano has high silica levels and low dissolved gases in its magma. This results in effusive, viscous lava that forms a rounded, steep-sided mound – Example: Mt. St. Helens ©2012, TESCCC

Composite Volcano A composite volcano has high levels of dissolved gas and silica and erupts explosively. Composite volcanoes often resemble steep- sided mountains before erupting. – Examples: Mt. St. Helens and Mt. Rainier in Washington ©2012, TESCCC

Yellowstone (State of Wyoming) 6O8A 6O8A Mount St. Helen Eruption (Washington, 1980) states/washington/videos/mount-st-helens- erupts states/washington/videos/mount-st-helens- erupts ©2012, TESCCC

Insert Images for each of the spheres ©2012, TESCCC

Earth’s Spheres Atmosphere: located right above the Earth’s surface and includes layers of gases (clouds, air pollution, sand storms, hurricanes, etc.) It protects us by absorbing solar radiation. Biosphere: life on land, rivers and oceans (Biomes) deserts, forests, grasslands Hydrosphere: water in liquid and solid state (oceans, glaciers, snow, lakes, rivers, etc.) Lithosphere: solids of the Earth (rocks, soils, landforms, etc.) ©2012, TESCCC