CHAPTER 3 UNIT B LESSON 3.1 “EARTH HAS SEVERAL LAYERS” EARTH IS MADE UP OF MATERIALS WITH DIFFERENT DENSITIES !

What’s that you Say? SCIENTIST BELIEVE THAT THE EARTH FORMED ABOUT 4.6 BILLION YEARS AGO. THEY THINK A LARGE EXPLOSION “A BIG BANG” OCCURRED SENDING LARGE AMOUNTS OF MATERIAL THROUGH THE UNIVERSE. THE EARTH FORMED AS THE MATERIAL COLLIDED AND STUCK TOGETHER. THE HEAVIER/MORE DENSE MATERIAL SANK TOWARD THE CENTER OF THE EARTH. THE LIGHTER MATERIAL FLOATED TOWARDS THE TOP.

THE EARTH HAS 3 MAIN LAYERS WITH THE CORE DIVIDED INTO TWO PARTS CRUST – THIN LAYER OF COOL ROCK THAT SURROUNDS THE EARTH; TWO TYPES OF CRUST 1) CONTINENTAL INCLUDES ALL THE LAND ON EARTH 2) OCEANIC INCLUDES ALL THE OCEAN FLOORS. MANTLE- EARTH’S THICKEST LAYER. THE TOP IS MADE OF COOL RIGID (HARD) ROCK, WHEREAS THE LOWER MANTLE IS SOFT AND THICK. IT MOVES LIKE TOOTHPASTE. OUTER CORE – IS A LAYER OF LIQUID METALS THAT SURROUND THE INNER CORE. THE OUTER CORE IS LIQUID BECAUSE IT IS NOT AS HOT, AND IT HAS A LOWER PRESSURE THAN THE INNER CORE. INNER CORE – IS A SOLID HOT BALL OF METAL. TEMPERATURE AND PRESSURE HERE IS THE GREATEST. THIS ALLOWS THE INNER CORE TO REMAIN SOLID.

EARTH’S MAIN LAYERS AT A GLANCE ! WHICH LAYER FORMED 1 ST ? 2 ND ? 3 RD ? & LAST?

LITHOSPHERE AND THE ASTHENOSPHERE THE EARTH’S CRUST AND THE VERY TOP OF THE MANTLE MAKE UP THE LITHOSPHERE. THE TECTONIC PLATES MAKE UP THE LITHOSPHERE. THE LITHOSPHERE SITS ON TOP OF THE ASTHENOSPHERE. THE ASTHENOSPHERE IS THE HOTTER SOFTER ROCK IN THE MANTLE. IT FLOWS LIKE HOT TAR OR TOOTHPASTE.

EARTH’S LAYERS & TECTONIC PLATES : TWO VERY IMPORTANT DISCOVERIES