Earth’s Interior p Chapter 5.1

Exploring inside the Earth Since we cannot travel deep inside the Earth scientist use evidence to learn about the Earth interior Since we cannot travel deep inside the Earth scientist use evidence to learn about the Earth interior 1. Direct evidence from rock samples 1. Direct evidence from rock samples Deepest mine: 3.8 kilometers or 6.1 miles Deepest mine: 3.8 kilometers or 6.1 miles Deepest hole dug: 12 km or 19 miles Deepest hole dug: 12 km or 19 miles 2. Indirect evidence from seismic waves Earthquake waves speed and path Earthquake waves speed and path

2 main layers inside Earth 1. Crust 1. Crust 2. Mantle 2. Mantle Core Core All vary greatly in temperature, size, composition, and texture All vary greatly in temperature, size, composition, and texture

Temperature Temperature- at 20 meters down you begin to feel warmth. Temperature- at 20 meters down you begin to feel warmth. After that every 40 meters down you go the temperature increase 1° C. After that every 40 meters down you go the temperature increase 1° C. The heat is from the formation of planet and radioactive materials in the Earth. The heat is from the formation of planet and radioactive materials in the Earth.

Pressure Increasing Depth = Increasing Pressure Increasing Depth = Increasing Pressure

Crust Outermost layer Outermost layer Includes dry land and the ocean floor Includes dry land and the ocean floor It is thickest under high mountains(up to 70 km) and thinnest under the ocean(5 km) It is thickest under high mountains(up to 70 km) and thinnest under the ocean(5 km) The average is 40 km thick The average is 40 km thick Crust under ocean is called oceanic crust (mostly basaltic rock-heavier) Crust under ocean is called oceanic crust (mostly basaltic rock-heavier) Land crust is called continental crust (mostly granitic rock-lighter) Land crust is called continental crust (mostly granitic rock-lighter)

Mantle At about 40 km down you cross a boundary into the mantle. It is divided into 3 very hot layers which together are about 3000 km thick. At about 40 km down you cross a boundary into the mantle. It is divided into 3 very hot layers which together are about 3000 km thick. Lithosphere Lithosphere Asthenosphere Asthenosphere Lower mantle Lower mantle

Lithosphere Uppermost layer Uppermost layer Lithosphere is crust and uppermost mantle together. Lithosphere is crust and uppermost mantle together. “Lithos” means “stone” in Greek and averages about 100 km thick. “Lithos” means “stone” in Greek and averages about 100 km thick. Very rigid Very rigid

Asthenosphere Less rigid Less rigid Like road tar in the sun it is soft, plastic-like and very bendable. Like road tar in the sun it is soft, plastic-like and very bendable. “Asthenes” in Greek means “weak” “Asthenes” in Greek means “weak” Still Solid Still Solid

The Lower Mantle Beneath the asthenosphere, the mantle is solid. Beneath the asthenosphere, the mantle is solid. Goes all the way to the core. Goes all the way to the core.

The CORE Made of iron and nickel Made of iron and nickel 2 parts 2 parts Liquid outer core Liquid outer core Solid inner core-squeezed so tightly the atoms cannot spread apart to be liquids Solid inner core-squeezed so tightly the atoms cannot spread apart to be liquids May also contain: oxygen, silicon, and sulfur May also contain: oxygen, silicon, and sulfur Together about 3486 km thick Together about 3486 km thick

Magnetic Field Movement in the liquid outer core forms the magnetic field for the Earth. Movement in the liquid outer core forms the magnetic field for the Earth. This produces a protective shield around the Earth and the whole planet acts as a bar magnet. This produces a protective shield around the Earth and the whole planet acts as a bar magnet. This means we have a north and south pole. This means we have a north and south pole. Over the course of history, the poles will actually switch Over the course of history, the poles will actually switch

Convection and the Mantle p

Heat Heat is energy in motion. This means the warmer the object the faster the particles are moving or the more energy they have. Heat is energy in motion. This means the warmer the object the faster the particles are moving or the more energy they have. Heat always is transferred from warm to cool. Heat always is transferred from warm to cool. When you open the door in the winter, are you letting the cold air in or the warm air out? When you open the door in the winter, are you letting the cold air in or the warm air out?

Types of Heat Transfer Three types of heat transfer: Three types of heat transfer: Radiation, convection, conduction Radiation, convection, conduction

Radiation Transfer of energy through space with no direct contact between the heat source and the object. Transfer of energy through space with no direct contact between the heat source and the object. Examples: energy from the sun, flame, fire Examples: energy from the sun, flame, fire

Conduction Heat transfer between objects in direct contact with one another. They must be touching. Heat transfer between objects in direct contact with one another. They must be touching. Example: touching a hot stove, cooking on the stove, etc. Example: touching a hot stove, cooking on the stove, etc.

Convection Heat transfer by a movement of fluids (liquid or gas) Heat transfer by a movement of fluids (liquid or gas) Differences in temp and density can cause convection. Differences in temp and density can cause convection. When something is heated the particles move fast and require MORE space, so they spread out. This cause the density to decrease. When something is heated the particles move fast and require MORE space, so they spread out. This cause the density to decrease. Cooler objects are closer and more dense. Cooler objects are closer and more dense.

Convection currents Is the flow that transfers heat in a fluid Is the flow that transfers heat in a fluid Heat rises and cool sinks. Heat rises and cool sinks. This continues as long as heat is added. This continues as long as heat is added. Also occurs in air Also occurs in air Have you ever looked at the pavement on a hot summer day? Have you ever looked at the pavement on a hot summer day?

Convection Currents in Earth Heat from the core and the mantle causes convection currents in the mantle. Heat from the core and the mantle causes convection currents in the mantle.

Drifting Continents 5.3 p

Continental Drift Continental Drift Early in the 1800’s when the first complete maps on the Earth’s surface were being made showing all the continents, something was noticed. The edges of the continents looked as if they could fit together like puzzle pieces. Early in the 1800’s when the first complete maps on the Earth’s surface were being made showing all the continents, something was noticed. The edges of the continents looked as if they could fit together like puzzle pieces.

Alfred Wegener thought that was no coincidence, and wrote the theory that all the continents were once joined together and had drifted apart. He called this theory the continental drift theory. Alfred Wegener thought that was no coincidence, and wrote the theory that all the continents were once joined together and had drifted apart. He called this theory the continental drift theory. He believed that 300 million years ago all the continents were together and they began to move horizontally apart. He called the large landmass containing all the continents Pangaea, which means “All Land.” He believed that 300 million years ago all the continents were together and they began to move horizontally apart. He called the large landmass containing all the continents Pangaea, which means “All Land.”

Evidence to back up the theory Wegener gathered evidence to support his theory. Wegener gathered evidence to support his theory. He used land features, fossils, and climate change. He used land features, fossils, and climate change. In 1915, he published The Origin of Continents and oceans. In 1915, he published The Origin of Continents and oceans.

Land Feature Evidence Mountain ranges lined up on different continents South America and Africa. Mountain ranges lined up on different continents South America and Africa. Coal fields in Europe and North America lined up. Coal fields in Europe and North America lined up.

Fossil Evidence Glossopteris is a fern fossil that has been found on several continents: africa, South america, Australia, Asia(India) and Antartica. Based on climate now: Some of these ferns could not have grown there, also plants could not have traveled across oceans. Glossopteris is a fern fossil that has been found on several continents: africa, South america, Australia, Asia(India) and Antartica. Based on climate now: Some of these ferns could not have grown there, also plants could not have traveled across oceans. Other fossils of fresh water reptiles had been found across oceans and they could not have swum those great distances. Other fossils of fresh water reptiles had been found across oceans and they could not have swum those great distances.

Climate evidence Climate changes as a continent moves but the fossils there remain. Climate changes as a continent moves but the fossils there remain. Tropical plant fossils have been found in the Arctic Circle. Tropical plant fossils have been found in the Arctic Circle. Glacier evidence was found in South Africa where it is very warm now. Glacier evidence was found in South Africa where it is very warm now.

Wegener’s theory rejected Though some believed him when he was alive, most accepted his theory after more evidence was discovered after his death in Though some believed him when he was alive, most accepted his theory after more evidence was discovered after his death in It was not widely accepted because he lacked evidence as to HOW the continents moved. It was not widely accepted because he lacked evidence as to HOW the continents moved.