2OBJECTIVES Identify and describe Earth’s layers. Recognize that Earth’s lithosphere is broken into plates that move slowly across Earth’s surface.Recognize that the rock record shows Earth’s continents have moved across time.
3MAIN IDEAEarth has a layered structure. Its outer layer is made up of moving plates.
5CORE Earth’s innermost structure. Divided into two regions. Outer core 1,400mi thick and is the only layer in liquid stateInner core 720mi thick is the hottest layer mad up of iron & nickel, but the pressure keeps the metal from melting
6CRUSTThin, nearly solid rock layer that is uppermost in Earth’s structure.Thinnest layerNearly solid rock.Thickness under the continents is 24milesUnder mountains 42milesUnder ocean-floor about 4mi.
7LITHOSPHEREArea where Earth’s solid upper mantle and crust combine to form a rigid shell.Floats on the mantle
8MANTLE Thick layer of Earth’s structure just below Earth’s crust. 2,900km (1,800mi) thickMakes up 2/3 of Earth’s massRock material is partially melted
10PLATE TECTONICSIdea that giant plates or rock are moving slowly across Earth’s surface
11Hot Inside Geysers – hot water shooting up for Earth’s surface. Water drains deep into Earth’s surface.How rocks heat up water until steam formsPressure forces the remaining water to eruptYellowstone National Park in Wyoming has may geysers.
12Earth’s TemperatureTemperature increases 2 – 3 degrees C for every 0.1km (300ft) below the surface.The deepest holes ever drilled are less than 15km (9mi).Geysers, Volcanoes, seismic waves help scientist learn about earth’s interior.
13MOVING PLATES - 1915 Alfred Wegener, German meteorologist & geologist Felt continents were moving slowly across Earth’s surfaceWegener’s theory is known as The Theory of Continental DriftHis theory was rejected
14MOVING PLATESScientist believed the lithosphere was broken up into giant slabs of rock called plates.This idea is called Plate Tectonics.They move an average speed of 4 inches per yearTwo kinds of plates: Oceanic plates & Continental plates
15PLATES Oceanic Plates Consist of dense ocean-floor material Continental platesMade up of lighter continental rock “riding” on top of denser rock
17Converging Boundaries Two plates move toward each other.One plate may move under the other in a process called subduction.Oceanic & Continental plates converge.Denser rock of oceanic plate slides under the lighter continental plate
18Diverging Boundaries Two plates move away from each other. Molten rock rises to fill the gap, creating new crust.Usually happens in the middle of the ocean floorReferred to as sea-floor spreading
19Sliding BoundariesTwo plates slide past each other, moving in opposite directions.This happens along what is known as a fault line.
20Evidence for Moving Plates RocksStudying the layers of rocks shows how they were depositedFossils – the physical remains or traces of plant or animal that lived long agoFossils found in sedimentary rock
21FossilsFossils of similar species have been discovered on opposite sides of an ocean.This helps scientist understand how plates move.Fossils of tropical plants and animals have been found in polar regions.PHOTO - CAMBRIAN TRILOBITE
27How can fossils provide evidence to support the theory of plate tectonics? Fossils of tropical plants and animals may be found in polar regions.
28List three ways scientist can learn more about what goes on beneath Earth’s surface. Study rocks drilled from the crustVolcanoesGeysers
29Measurements indicate that the distance between Africa and South America is increasing. What do these measurements indicate about the portion of Earth’s crust between Africa & South America?Africa & South America are located on different plates. There is a diverging boundary between the two plates.
30Explain what happens to rock along converging boundaries. Plates collide and rocks compress and break. One plate may move below the other plate.
31Besides plate movement, describe one process that can alter the structure of Earth’s mantle. Weathering, erosion, or depostion can create plateaus, mesas, caves, sand dunes, alluvial fans, barrier islands
32Describe evidence of high temperatures below Earth’s surface. Scientists encounter higher temperatures when they drill.Rocks melt below the Earth’s surface.Geysers spew hot water from beneath the surface.
33Describe one way mountains may have formed. Magma rose near the surface but did not break through.Faulting caused one plate to rise above another plate.Erosion by wind and rain rounded the surface over time.