Earth Structure & Plate Tectonics Notes Earth on the Move Earth Structure & Plate Tectonics Notes Baker 7th grade science 2003-2004

Baker 7th grade science 2003-2004 Earth, Inside & Out The Earth is divided into three layers Crust Mantle Core Baker 7th grade science 2003-2004

Baker 7th grade science 2003-2004 Crust (1)  This is the outermost layer of the Earth. (2) This is the layer we walk on. (3) It is a thick, rocky skin. (4) If we think of the Earth as a billiard ball, this crust is as thin as a postage stamp stuck on a billiard ball. (5) At its thickest, which is under mountain ranges, the crust is only about 35km (22mi) thick. Baker 7th grade science 2003-2004

And what type of crust would you like with your Earth? There are two types of crust Baker 7th grade science 2003-2004

Baker 7th grade science 2003-2004 Continental Crust: 1. Makes up the continents 2. Contains light colored rocks such as granite. 3. Floats high on the mantle Baker 7th grade science 2003-2004

Baker 7th grade science 2003-2004 (i)    Oceanic Crust 1.       Makes up the ocean floor 2.     Contains the dense rocks such as basalt Thinner than the continental crust Baker 7th grade science 2003-2004

Baker 7th grade science 2003-2004 Mantle (1)  Hotter and denser than the crust because the deeper you go inside the earth, the temperature & pressure increases. (2) Made of solid rock. The Mantle is made of two zones Baker 7th grade science 2003-2004

Baker 7th grade science 2003-2004 Mantle Zones (a)  Lithosphere (i)    Thin, uppermost part of the mantle; cooler & less rigid (ii) Floats on the athenosphere, and slides around very slowly. (iii)  The upper part of the lithosphere melts rocks, forming a substance called magma. Baker 7th grade science 2003-2004

Baker 7th grade science 2003-2004 Magma 1.  Magma (melted rock) moves like hot oatmeal. Uneven heating causes material in the mantle to constantly and slowly rise & fall in convection currents. Convection Current: process by which hot fluid rises to the surface, and then sinks again, like soup being heated in a saucepan Baker 7th grade science 2003-2004

Baker 7th grade science 2003-2004 (a)  Asthenosphere Hot, weak zone directly under the lithosphere Flows at a very slow rate Baker 7th grade science 2003-2004

Baker 7th grade science 2003-2004 Core i)       Deep within the Earth is the core ii)    The core is made mostly of nickel & iron iii)  Twice as dense as the mantle. Main source of heat that triggers the convection currents Baker 7th grade science 2003-2004

The core is made of two layers (1)  Outer core: molten & is responsible for the Earth’s magnetic field. Inner core: solid Baker 7th grade science 2003-2004