Earthly ChangesWithin and On The Face of the Earth
Objectives• Students will explain how scientists classify the earth’s major physical characteristics.• Students will describe the physical processes that affect the earth’s crust.• Students will explain how mechanical and chemical weathering affect a place’s physical landscape.• Students will explain how the physical process of erosion alters the landscape.
Vocabulary I• core - the earth’s center, consisting of very hot metal that is dense and solid in the inner core and molten or liquid, in the outer core• mantle - a thick layer of mostly solid rock that grows in swampy ground along coastal areas• crust - the solid, rocky surface layer of the earth• continent - any of the seven large landmasses of the earth’s surface: Africa, Antarctica, Asia, Australia, Europe, North America, and South America• relief - the differences in elevation, or height, of the landforms in any particular area• weathering - the chemical or mechanical process by which rock is gradually broken down, eventually becoming soil
Vocabulary II• plate tectonics - the theory that the earth’s outer shell is composed of a number of large, unanchored plates, or slabs of rock, whose constant movement explains earthquakes and volcanic activity• erosion - the movement of weathered materials, including gravel, soil, and sand, usually caused by water, wind, and glaciers• sediment - particles of soil, sand, and gravel carried and deposited by wind and water• loess - ﬁne-grained, mineral-rich loam, dust, or silt deposited by the wind• moraine - a ridge-like mass of rock, gravel, sand, and clay carried and deposited by a glacier
Physical Characteristics• Forces on & in the earth account for most of the changes in the landscape • Geology is the study of those changes• Earth has many layers • The core (both inner and outer), mantle, and crust • These do not exist in a vacuum - changes in each affect the others!
Spheres of Life• Geographers see several spheres that describe life on Earth • Lithosphere - soil, rocks, landforms, and other surface features • Atmosphere - layer of air, water and other substances above the surface • Hydrosphere - water in oceans, lakes, and rivers, and underground • Biosphere - world of plants, animals, and other living things that occupy the land and waters of the planet
Landform Relief• As we can now see from earth, most of planet is water (70%)• Large landmasses between oceans are the continents we live on • By classifying landmasses by their relative height, or their relief, we can better understand their impact on our lives • Mountains, plains, valleys canyons, rivers, peninsulas, etc.
Physical Processes• Volcanoes• Folds• Plate Tectonics• Continental Drift• Seaﬂoor Spreading• Plate movement• Ring of Fire
Surface Changes• Changes below surface responsible for major adjustments in the landforms • Smaller, but more frequent and quicker, forces acting on those landforms help to shape and determine their scope • Broadly categorized into weathering and erosion
Weathering• Process of breaking down rocks at or near the earth’s surface into smaller pieces• Two types: mechanical and chemical• Mechanical weathering occurs when rock is actually broken or weakened physically • More often than not by water (freezing); frost wedging• Chemical weathering weakens or changes the make up of the rock through exposure to water and carbon dioxide that alters its chemical make up; leaching/acid rain
Erosion: Water• The movement of weathered material such as gravel, soil, and sand • Largely responsible for the creation of soil• Moving bodies of water largely responsible for transport or weathered material and creating landforms; carries with it this sediment • Effect is like sandpaper (carving the landscape and breaking down sediment into smaller particles)• Ocean waves also play signiﬁcant part in erosion
Erosion: Wind• 2nd major cause of erosion is wind• Following major droughts in the early 1930s, most of Kansas saw dried up soil in great dust storms • Flip side is the loess that is deposited onto new area • Minerals and weathered material that is broken down is picked up in the wind and deposited
Watch video athttp://www.youtube.com/watch?v=xAQsGdcLl4c
Erosion: Glaciers• Huge, slow-moving sheets of ice • Carry dirt, rocks, and boulders with them as they move; movement also wears down the terrain• Glaciers scooped out huge sections of earth as they moved (millions of years) and left water that ﬁlled them as they melted (Great Lakes)• Also left behind ridge-like piles of rocks and debris: moraines