Earths Layers Anticipation guide Convergent boundaries occur where

Earth‘s Layers

Anticipation guide • Convergent boundaries occur where plates move apart • The outer core is liquid and the inner core is solid • Earthquakes generate seismic waves • The Richter scale measures the intensity of earthquakes • The lithosphere is found deep in the mantle

VA SOL • ES. 7 The student will investigate and understand geologic processes including plate tectonics. Key concepts include • geologic processes and their resulting features; and • tectonic processes.

Enduring Understanding • The core, mantle, and crust of the Earth are dynamic systems that are constantly in motion.

The Earth is divided into layers by density. As the Earth solidified during the formation of the solar system elements with higher density were drawn toward the center of the Earth by gravity.

Earth’s Interior • It has a pressure of 3. 2 -4 million times that of the surface and this pressure keeps the metals in solid state

Earth’s Interior • Inner Core is solid and is made of the densest material. • It is believed to be comprised of iron and nickel

The core of the Earth is composed of the elements Nickel and Iron, it makes up 19 percent of Earth's volume and 33 percent of Earth's mass. Earth’s Core

The core of the Earth is divided into two parts, the Inner Core and the Outer Core.

The Outer Core is liquid metal and the Inner Core is solid due to the pressure from the weight of all the matter in the Mantle and Crust.

The Inner Core is 5, 150 km deep with a temperature of 5000 degrees celsius. The Outer Core is 2, 900 km deep and is from 2200 - 5000 degrees Celsius getting hotter moving toward the center of the Earth.

The largest layer of the Earth is the Mantle. Earth's Mantle makes up 80 percent of Earth's volume and is made up of silicon, oxygen, and magnesium.

The crust of the Earth is a very thin solid outer layer of the Earth. It is only 1 percent of the volume of the Earth.

Earth’s Crust • Oceanic crust is comprised mainly of the rock basalt • Continental crust is comprised mainly of the rock granite

Earth’s Crust • Continental crust makes up the land masses. This thicker, less dense material allows the continents to rise above sea level and remain dry for very long periods

The Crust and the upper part of the Mantle together make up the Lithosphere Crust Upper Mantle

The Lithosphere is about 100 km thick and is broken up into several solid plates that are moved by convection currents within the mantle. The Asthenosphere is a plastic layer near the bottom of the Lithosphere.

Earth’s Interior • Most of the mantle is in solid or plastic form (think silly putty)

As the very hot core heats the material in the Mantle it causes the material to move in a circular pattern. The mantle material heats up and rises and then cools and sinks. This circular pattern of movement within the mantle (called a convection current) pushes the lithospheric plates as they float. The movement and interaction of these plates causes most of the large scale changes on Earth's surface.

Earth’s Interior • The motion of the liquid metals in the inner core is what generates the Earth’s magnetic field

Draw, color, and label these in your notes…

Next class you will have a quiz on the layers of the Earth. You need to know the following: Density increases: Crust Mantle Core is divided into molten outer core and solid inner core. Core is made of iron and nickel. Lithosphere is the crust and upper mantle. Asthenosphere is plastic (like playdough) and is part of the mantle. Both definitions and diagrams will be on this quiz.

Continental Drift and Sea Floor Spreading

Anticipation guide • There are 4 main layers of the Earth • Continental drift is a theory explaining how continents move over time • Mountains are created in random places on earth by random forces • All volcanoes are created by plates colliding • The oldest crust on Earth is found under the ocean

VA SOL • SOL 7 The student will investigate and understand geologic processes…. . . Key concepts include • A. tectonic processes (subduction, rifting and sea floor spreading, and continental collision).

Objective Outline the history of plate tectonics to include continental drift and sea-floor spreading. Explain how the lithosphere is divided into plates that are in motion (compression, tension, and shearing) with respect to one another (because of convection currents in the mantle).

Enduring Understanding • The core, mantle, and crust of the Earth are dynamic systems that are constantly in motion.

Continental Drift • Throughout the typical human lifespan the Earth’s surface appears to remain relatively unchanged.

Continental Drift • On the geologic timescale the surface is constantly moving back and forth swallowing and creating oceans and continental mass as it goes

Continental Drift • Early mapmakers were the first to suggest that the continents appear to have fit together at one time

Continental Drift • Alfred Wegener a German scientist was the first to propose this theory to the scientific community in the early 1900’s

Continental Drift • Pangea was the name for this supercontinent that began to break up about 200 million years ago

Continental Drift • Wegener’s theories were not accepted at the time because his explanations were not supported by physicists

Continental Drift • His explanation for movement was that the continents plowed through the seafloor crust like moving islands

Continental Drift • His explanation for the reason why the continents moved was the spinning of the earth

Evidence of Continental Drift • Although his explanations for the reason the continents drifted were incorrect there was still convincing evidence that they were indeed once together.

Evidence of Continental Drift • Rock formations in the Appalachian Mountains matched up with ones in Greenland.

Evidence of Continental Drift • Fossil evidence found in South America and Africa were especially strong

Evidence of Continental Drift • Bones from the Mesosaurus and Kannemeyerid were found in the same rock formations in Brazil and Chad

Evidence of Continental Drift • Even glacial striations from ancient Ice ages were found to match perfectly

Evidence of Continental Drift • Climatic evidence found that there were coal deposits in Antarctica suggesting that continent was at one time much closer to the equator

Sea Floor Spreading • Alfred Wegener died in 1930 never having seen the acceptance of his controversial theory

Sea Floor Spreading • In the early 1960’s new evidence revealed the process on how the continents could indeed move

Sea Floor Spreading • Advances in sonar technology in the 1940’s and 50’s allowed us to begin to accurately map the seafloor

Sea Floor Spreading • This evidence proved that the seafloor was not flat and featureless as once thought. Vast underwater mountain chains and deep trenches were discovered.

Sea Floor Spreading • Earthquakes and volcanic activity was prevalent in certain parts and missing in others

Sea Floor Spreading • The ocean floor was found to be much younger than the continental crust

Sea Floor Spreading • The thickness of the layers of sediments increased with the distance on either side of the ocean ridges

Paleomagnetism • Once scientists were able to bring sea floor samples to the surface they were able to determine that a record of the seafloor was being kept by Earth’s magnetic field

Paleomagnetism • Paleomagnetism is the study of this magnetic record using data gathered from iron-bearing minerals

Paleomagnetism • The magnetic records for the seafloor on either side of the mid-ocean ridges matched perfectly showing that the seafloor was growing outward from the ridges in both directions

Paleomagnetism • Isochron is a line on a map that connects points that are the same age

Paleomagnetism • Once scientists had compiled all the topographic, sedimentary, age and magnetic data an American scientist named Harry Hess proposed a theory that could explain the observations

Paleomagnetism • Sea Floor Spreading states that new ocean crust is formed at the ocean ridges, moves outward in both directions, then destroyed at the deep sea trenches.