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Changes Within the Earth . Coach Parrish 7 th Grade History Oxford Middle School. Physical Characteristics. Geology – the study of the earth’s physical structure and history. The Earth’s Layers Core – center of the earth that consists of very hot metal, mainly molten lava.
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Changes Within the Earth Coach Parrish 7th Grade History Oxford Middle School
Physical Characteristics • Geology – the study of the earth’s physical structure and history. The Earth’s Layers • Core – center of the earth that consists of very hot metal, mainly molten lava. • Mantle – a thick layer of rock that surrounds the core. Scientists measure the mantle at 1800 miles thick. • Crust – the outer layer of the earth. Scientists measure the crust to be about 5 miles thick.
Land, Air, and Water • The area on and around the earth is made up of “spheres.” • Lithosphere – Soil, rocks, landforms and other surface features. • Atmosphere – the layer of air and water about the earth. • Hydrosphere – consists of water in oceans, lakes, and rivers on the earth. • Biosphere – world of plants and animals on the earth.
Physical Processes • Physical processes help to shape the landforms on earth in the form of volcanoes and earthquakes. • Volcanoes – form when magma from the earth’s core break through the earth’s crust.
Explaining Volcanoes and Earthquakes • Most scientists agree that Volcanoes occur because of plate tectonics. • Plate tectonics – theory that the earth’s crust is made up of many movable plates that cause volcanoes and earthquakes.
Volcanoes • Over time, as volcanoes continually erupt, the lava cools and hardens adding layers to the Earth. These examples are from Mt. Fuji – Japan.
Ring of Fire • Ring of Fire – series of mountains created by volcanoes surrounding the Pacific Ocean.
Earthquakes • The movements of earth’s crust can sometimes cause earthquakes. When rocks on either side of a fault move suddenly, an earthquake occurs. The next slide shows where the fault lines are located on the earth and what they look like!
Continental Drift Theory • During the 1600s, people started noticing that the continents could have fit together at one time. • In the early 1900s, a German explorer and scientist named Alfred Wegener suggested the continental drift theory. • Continental Drift Theory – idea that at one time, earth only had one continent called Pangaea. Over time, the continents separated into what we know today.
Continental Drift Theory • Here is a picture of the continental drift theory.
