Geology and Earth’s Structure

Leave enough space between each title to write notes!!! On your foldable underneath each picture of the layer please write the following titles for your notes: Composition Thickness Temperature State of Matter Other facts Leave enough space between each title to write notes!!!

The Science of Geology Geology Geologists The study of planet Earth, including its origin, history, composition Physical and Historical Geologists Scientists who study Earth and the processes that have shaped Earth over time

Earth’s Four Spheres Atmosphere Hydrosphere Geosphere Biosphere Blanket of gases that surrounds the Earth’s surface Hydrosphere All the Earth’s water with the exception of water in the gaseous form 71% or Earth’s surface is water 97% is salt water found in the oceans and 3% is fresh water found in lakes, rivers, streams, glaciers, ice sheets, and ground water Geosphere Solid part of the Earth that includes all of the rocks and soil Also includes the solid and molten interior of the Earth Biosphere All the life forms found within the other three spheres Includes any organic matter that has NOT completely decomposed

Forces that Change Earth’s Surface Constructive Forces shape the surface by building up mountains and other land areas Destructive Forces slowly wear away mountains and eventually every other feature on Earth’s surface

Uniformitarianism The principal of uniformitarianism states that the processes affecting Earth today are the same ones that affected it in the past Example- at active volcanoes we can observe lava cooling to form layers of basalt Therefore, any time we see layers of basalt, we can assume that they formed from cooling lava

The Earth as we normally see it

Our Understanding Scientists use indirect methods to study the Earth’s interior Seismic waves- vibrations that travels through the earth Caused by earthquakes

A Cross Section of the Earth Earth is divided into four main layers 1. Crust 2. Mantle 3. Outer Core 4. Inner core … Similar to the cross section of a hard boiled egg

A Cross Section of the Earth Which of these layers holds life? Think about it…where do we live? … Similar to the cross section of a hard boiled egg

The Crust SOLID Outermost layer on which life exists Thinnest layer Composition: Covered in soil, rock (silicates), and water Thinnest layer The Earth's Crust is like the skin of an apple The crust is thickest under the continents and thinnest under the oceans Thickness: 5 to 64 kilometers (thinner in the oceans) Temperature Varies from air temp on the surface to 870° C in the deepest part of the crust

Types of Crusts (Make a T-chart in your foldable) Oceanic Crust Rock that makes up the ocean floor Made of more dense rock (basalt) Average thickness: only 7 km Ranges from 5-10 km Continental Crust Rock that makes up the continents Made of less dense rock (granite) Average thickness: 40 km Ranges from 8-75 km

The Crust The crust “floats” on the mantle because it is less dense Think of oil and water It is broken into sections called tectonic plates These plates move very slowly Results in the physical features found on the surface These plates move because of convection currents

Convection Currents Caused by the very hot material at the deepest part of the mantle rising, then cooling and sinking and then heating and rising again A conveyor belt in a factory moves boxes like the convection currents in the mantle moves the plates of the Earth

The Mantle Hot but SOLID rock that flows (plastic) Composition: Thickness: Approximately 2850 km thick Thickest of all Earths layers approximately ~85% of the Earth's volume Composition: Composed of minerals rich in Fe, Mg, Si, and O (silicates) Considered solid but has plasticity Rock can flow like a thick liquid Temperature Varies from 870°Cto 2200 °C

Three Divisions of the Mantle 1. Lithosphere- layer of relatively cool, rigid rock Includes the uppermost part of the mantle and the Earth’s crust (100 km thick) Broken into plates 2. Asthenosphere- (middle mantle) layer of softer, weaker rock that can flow like taffy (plastic) Produces magma 3. Mesosphere- (lower mantle) stronger layer made of stiff rock that extends to the upper surface of the core

The Outer Core LIQUID Thickness: Approximately 2270 km thick Composition: Consists mostly of the liquid metals iron and nickel 16% of the Earth's total volume Temperature Ranges from 2200° C to 4982°C Flowing iron of outer core produces electric current and creates the Earth’s magnetic field

The Inner Core SOLID Thickness: Approximately 1216 km thick Composition: Consists of solid nickel-iron alloy Temperature Stays around 4982° C Pressures are 45,000,000 pounds per square inch This is 3,000,000 times the air pressure on you at sea level!!! If you were to make it to the center of the Earth you would be squished into the size of a marble

How the Earth is Represented Visually

Side by Side Comparison Crust Mantle Core Lithosphere Asthenosphere Mesosphere Outer Core Inner Core

Density, Pressure, and Temperature Density, pressure, and temperature ALL INCREASE as you go further into the Earth’s layers