Changes Within the Earth

 Geology - study of the earth’s physical structure and history - looks at changes of the earth, causes and effects, predictions- all from the history of the earth (about 4.6 billion years)

 The inside of the earth is made up of three separate layers - core - mantle - crust

 Core - center of the earth consists of very hot metal (mainly iron/some nickel) - inner core- dense, solid - outer core- molten, liquid  Mantle (1,800 miles thick) - located around the core - thick layer of rock - mostly solid  Crust - thin, rocky surface - located below the oceans (5 miles thick) - located below continents (22 miles thick)

 Physical geographers study elements of the earth’s natural environment (spheres)- and look at how they operate and interact with each other and with people - lithosphere - atmosphere - hydrosphere - biosphere

 Land - continents (7)- large landmasses in the oceans  Water - 70% of the earth’s surface

 Land covers about 30% of the earth’s surface  Land is made up of four main kinds of Landforms – natural features of the earth’s land surface - Mountains- Plateaus - Hills- Plains *Each landform is described by: - Elevation – height above sea level - Relief – the difference in elevation between the highest and lowest points

 Mountains are the highest of the world’s landforms *mountains generally have a high relief

 Hills are lower than mountains *generally, have a low relief

 Plateaus are raised areas of flatland (or almost flat) *most of them have a low relief

 Plains are large areas of flat or rolling land *they have a low relief

 Forces that shape landforms - Volcanoes - forms when magma breaks through earth’s crust - lava- molten rock located on the surface - Movements in the Crust - fold- rock layers bend and buckle - faults- breaks in the earth’s crust

 Plate Tectonic Theory

 Continental Drift Theory - Alfred Wegener (1900s) - German scientist - Pangaea- supercontinent - it began to break up into separate continents about 180 million years ago *What evidence was believed to be found to support his theory?

 Plate Movement - convection  When Plates Meet - spreading - subduction - convergence - faulting

 Explaining Volcanoes -Ring of Fire - a circle of volcanoes surrounding the Pacific Ocean - “Hot Spots” - hot regions deep within the earth’s mantle - as molten rock rises towards earth’s surface, the magma may heat underground water and produce hot springs or geysers