Earth s Interior and Plate Tectonics. Physical Science Section 17.1

Transcription

1 Earth s Interior and Plate Tectonics Physical Science Section 17.1

2 This is how the continents formed. Vx32M&list=PLABDC7B24FAFE33FD

3 The Earth is like a parfait, it has layers If you cut the earth in half, it would look very much like a parfait, with different layers and compositions based on density The earth has three main layers, the crust, the mantle, and the core

4 The Crust We live on this layer Its is cool, and made of solid rock Oceanic crust is thinner and denser than continental crust. The crust is the least dense portion of the earth and only about miles thick

5 The Mantle Layer of rock that is denser than the crust About 1800 miles thick Outer mantle is solid rock Inner mantle the rocks are extremely hot and bendable like gum (plastic)

6 The Core The center of the earth Made mostly of iron and nickel The inner core is solid metal while the outer core is liquid metal

7 The Earth heats up with depth At only 2 miles down the temperature increase to 120 F The core is much hotter than the mantle In the core, temperatures reach over 10,000 F

8 The earth heats up with depth The earth gets warmer towards the core because it contains so many radioactive isotopes These unstable isotopes are constantly breaking down, releasing huge amounts of energy, which in turn heat the earth

9 How do plates move?

10 Evidence #1: The Pangea Puzzle In the 20 th century, Alfred Wegener noticed that eastern S.America fits into western Africa He also noticed that several of the other continents fit together like puzzle pieces He also found that fossil evidence showed that several of the same organisms are found on continents now separated by oceans He theorized that 250 million years ago all the continents combined to form the giant land mass he named pangea

11 How did this happen? The earth s outer shell, called the lithosphere is made of the crust and upper portion of the mantle. This lithosphere is very rigid and consists of 7 large pieces and a few small ones that fit together like a puzzle These large pieces are called tectonic plates

12 Plate Tectonics These plates fit together like puzzle pieces and move in relation to each other these plates move away, towards, or alongside each other Tectonic plates move about 6 inches per year

13 Divergent Plate Boundaries In some areas, the plates move away from each other When this occurs, hot liquid rock called magma rises and cools, forming new lithospheric rock

14 Convergent Plate Boundaries Less dense continental plate floats over more dense oceanic plate This process is called subduction As this more dense rock goes down into the mantle, it heats up and melts The magma rises and pushes up the crust, forming volcanic mountains also earthquakes

15 Subduction - two plates meet, the more dense plate (oceanic crust), dives beneath the less dense plate (continental crust)

16 Continental vs. Continetal Same density so no subduction Builds nonvolcanic mts. Earthquakes

17 Oceanic vs. Oceanic Similar density, but subduction anyway Earthquakes, trenches, volcanic island arcs

18 Transform Fault Boundaries These are areas where plates move along side one another As plates move, they can cause cracks in the lithosphere called faults As plates move along side each other at these faults, the plates cause a great deal of force and create earthquakes

19 RECAP Divergent Plate Boundaries Divergent means plates MOVE AWAY from each other Convergent Plate Boundaries Convergent means plates MOVE TOWARD each other Transform Fault Boundaries areas where plates move along side one another like this or this

20 Earth is made of 3 main layers Crust- cool, thin, made of rock, miles thick Mantle, denser than crust, 2500 miles thick, 80% of earth s volume: inner mantle solid rock, outer mantle bendable gummy rock Core- center of earth, made of iron and nickel, made of 2 layers: inner solid metal, outer liquid metal

21 Pangea- 250 million years ago all the continents combined to form the giant land mass called Pangea Lithosphere (earth s outer shell) is made of the crust and upper portion of the mantle. lithosphere -very rigid and consists of 7 large pieces (called tectonic plates) and a few small ones that fit together like a puzzle

22 Plate Tectonics These plates fit together like puzzle pieces and move in relation to each other these plates move away, towards, or alongside each other Tectonic plates move 6 inches per year

23 Evidence 2: Biogeographical

24 Final views nnxoo4&feature=player_embedded#!