Earth, Inside & Out The Earth is divided into three layers 1. Crust 2. Mantle 3. Core
A. Crust 1. This is the outermost layer of the Earth and it is the layer we walk on. 2. Cool, rocky skin 3. Temperature runs from 0-700 o C. 4. Average thickness is 6-70 km 5. If we think of the Earth as an egg, the crust would be like the shell on an egg.
And what type of crust would you like with your Earth? 6. There are two types of crust
a. Continental Crust: 1. Makes up the continents 2. Contains light colored rocks such as granite. 3. Floats high on the mantle
b. Oceanic Crust 1. Makes up the ocean floor 2. Contains the dense rocks such as basalt Thinner than the continental crust
B. Mantle 1. Hotter (800-4400 o C) and denser 2900 km thick) than the crust because the deeper you go inside the earth, the temperature & pressure increases. 2. Made of solid rock. 3. The Mantle is made of two zones: the lithosphere and the asthenosphere
Mantle Zones a. Lithosphere The greek prefix “litho” means “stone” or “rock” Cool, rigid and connected to the crust Floats on the athenosphere (lower mantle), and slides around very slowly. The upper part of the lithosphere melts rocks, forming a substance called magma (remember this?). Broken into large and small slabs of rock called tectonic plates
Magma (remember this is melted rock) Magma 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
b. Asthenosphere Greek “asthenes” means “weak” directly under the lithosphere Hotter, softer rock that flows at a very slow rate like tar –The hot molten rock rise like hot air, cools and falls again creating motion called convection currents
3. Core Deep within the Earth is the core The core is made mostly of nickel & iron Twice as dense as the mantle. Main source of heat that triggers the convection currents Made of two layers
The core is made of two layers a. Outer core: –molten metal responsible for the Earth’s magnetic field. –2300 km thick –4400-6100 o C. b. Inner core: – solid due to pressure –2400 km in diameter –7000-8000 o C.
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