What is the structure of Earth?

Notes: The Earth System A system is a group of parts that work together as a whole. The constant flow, or cycling, of matter through the Earth system is driven by energy. Energy is the ability to do work. Energy that drives the Earth system has two main sources: 1.) heat from the sun 2.) heat flowing out of Earth as it cools pg. 69

Earth’s System Has 4 Main Spheres: 1.) Atmosphere- Earth’s outermost layer made up of a mixture of gases: mostly nitrogen and oxygen. Contains dust, cloud droplets, water vapor, rain, snow, earth’s weather pg. 69

2.) Geosphere- the solid rocks and metals that make up the Earth. Four parts: crust, mantle, outer core, inner core pg. 69

3.) Hydrosphere- Contains all of Earth’s water. Water covers about ¾ of Earth’s surface.  97% is salt water  2% is frozen in the polar ice caps  1% is drinkable (fresh water) pg. 69

4.) Biosphere- the parts of Earth that contain living organisms pg. 69

Notes: Constructive Vs. Destructive Forces Lands are constantly being created and destroyed by competing forces. Constructive Forces Destructive Forces Forces that construct and shape the land’s surface by building up mountains and other land masses. Examples: Forces that destroy and wear away landmasses. Examples: pg. 68

Notes: Earth’s Layers How do Geologists Learn About Earth’s Layers? A. They use two main types of evidence to learn about Earth’s interior: 1.) direct evidence from rock samples a. Geologists have drilled holes as deep as 12.3 km into Earth. b. The drills bring up samples of rock. These rocks give geologists clues about Earth’s structure and conditions deep inside Earth. 2.) indirect evidence from seismic waves. a. When earthquakes occur, they produce seismic waves. b. Geologists record the seismic waves and study how they travel through Earth. pg. 71

What Are the Features of Earth’s Layers? B.The three main layers of Earth are the crust, mantle and core. 1.) The layers vary greatly in size, composition, temperature, and pressure. 2.) The deeper down inside Earth, the greater the pressure. 3.) The temperature inside earth increases as depth increases. C.The Layers of the Earth 1.) Crust – a layer of solid rock that includes both dry land and the ocean floor (Earth’s outer skin) a.Oceanic Crust – the crust that lies beneath the ocean; mostly composed of basalt (a dark, fine-grained rock) b.Continental Crust – the crust that forms the continents; mostly composed of granite (a rock that is usually light in color and has coarse grains) 2.) Mantle – a layer of rock that is solid, and very hot

a. Lithosphere – made up of the crust and upper mantle; strong, hard and rigid rock b. Asthenosphere – below the lithosphere; the material is hotter and under more pressure; the material can bend but is still considered a solid 3.) Core – below the mantle; made mostly of the metals iron a nickel; consists of 2 parts a. Outer Core – molten/liquid metals of iron and nickel b. Inner Core – dense ball of solid metals iron and nickel

Draw and Label the Layers of the Earth Pg. 70 Mantle Crust Outer Core Inner Core Asthenosphere Lithosphere

3 Types of Heat Transfer 1.) RADIATION – transfer of heat that is carried in rays or waves Examples : 2. ) CONDUCTION – transfer of heat between materials that are touching Examples : 3.) CONVECTION – transfer of heat by the movement of a fluid Examples : Pg. 73

Convection Currents in Earth Heat from the core and the mantle itself causes convection currents in the mantle. Mantle rock rises slowly from the bottom of the mantle toward the top. The hot rock eventually cools and sinks back through the mantle. Over and over the cycle of rising and sinking takes place. Convection currents like these have been moving inside Earth for more than four billion years!

I. Plate Tectonics A. ___ Continental Drift ______ 1. Many early scientists have noticed that the Earth’s continents seemed to fit together. 2. ___ Alfred Wegener ____- proposed the theory of continental drift a. _ Permian Period _ - about 225 million years ago 1.) all the continents formed a supercontinent called Pangaea 2.) ____ Panthalassa ____ was the major ocean b. __ Triassic Period ____ - Pangaea was split in two 1.) _____ Laurasia _____ in the north (North America, Eurasia) and Gondwanaland in the south ( India, Africa, and South America) 2.) Panthalassa broken in two, one part becomes the ____ Tethys Sea ______ pg. 75

c. Wegner theorized that continents moved horizontally to their present location. B. Evidence of Continental Drift 1. Fossil and Climate Clues a. The reptile ___ Mesosaurus ____ 1.) fossils found in South America and Africa 2.) lived on land and water but would have been impossible for this animal to have swam across an entire ocean b. A fern _____ Glossopteris ________ 1.) fossils found in Africa, Australia, India, South America, and Antarctica 2.) found in areas that vary greatly in climate, scientists believe these regions once were connected and had similar climates c. Fossils of warm weather plants were found in Arctic Ocean Islands d. Glacial deposits have been found where no glaciers exist today

2. Sea-floor Spreading a. ___ Mid-Ocean Ridge ____- 1. using sound waves, scientists discovered a system of underwater mountain ranges in many oceans 2. The peaks of some of these mountains can form an island b. 1960’s scientist, _ Harry Hess _, suggested a theory of ___ sea-floor spreading ___ 1. Magma gets forced upward through cracks in the ocean floor 2. As new material comes up it pushes sections of the sea floor away from the ridge. 3. The magma solidifies and creates new sea floor c. Evidence for Sea-floor Spreading 1. Youngest rocks are located at the mid- ocean ridge 2. Reversals of Earth’s magnetic field are recorded by rocks in strips parallel to ridges Harry Hess

C. Plate Tectonics 1. Earth’s crust and upper mantle are broken into sections called __ plates _____ a. The crust and upper mantle are called the ______ lithosphere _________ b. Middle layer of the mantle is the _ asthenosphere __ - semi-molten rock, very plastic-like c. __ Convection Currents __ inside Earth cause plate tectonics – the cycle of heating, rising, cooling, and sinking of material inside Earth

2. Plate Boundaries a. Divergent Boundary - two plates move away from one another; ex. Sea-floor spreading b. Convergent Boundary -two plates move toward each other, there are three types: 1.) subduction zone- dense ocean plate sinks under light continental plate ex: deep sea trench, volcanic mountain chains 2.) two ocean plates collide ex: deep sea trench, volcanic island chain 3.) two continental plates collide ex: mountains, earthquakes common c. Transform Fault Boundary - two plates slide past each other; they can move in opposite directions or in the same direction

I. Plate Tectonics A. _________________________ 1. Many early scientists have noticed that the Earth’s continents seemed to fit together. 2. _____________________ - proposed the theory of continental drift a. __________________- about 225 million years ago 1.) all the continents formed a supercontinent called __________________ 2.) _____________________ was the major ocean b. ___________________ - Pangaea was split in two 1.) ____________________ in the north (North America, Eurasia) and ______________ in the south ( India, Africa, and South America) 2.) Panthalassa broken in two, one part becomes the _________________________ pg. 59

c. Wegner theorized that continents moved horizontally to their present location. B. Evidence of Continental Drift 1. Fossil and Climate Clues a. The reptile ____________________ 1.) fossils found in South America and Africa 2.) lived on land and water but would have been impossible for this animal to have swam across an entire ocean b. A fern ________________________ 1.) fossils found in Africa, Australia, India, South America, and Antarctica 2.) found in areas that vary greatly in climate, scientists believe these regions once were connected and had similar climates c. Fossils of warm weather plants were found in Arctic Ocean Islands d. Glacial deposits have been found where no glaciers exist today

2. Sea-floor Spreading a. _________________________- 1. using sound waves, scientists discovered a system of underwater mountain ranges in many oceans 2. The peaks of some of these mountains can form an island b. 1960’s scientist, ______________suggested a theory of _________________________ 1. Magma gets forced upward through cracks in the ocean floor 2. As new material comes up it pushes sections of the sea floor away from the ridge. 3. The magma solidifies and creates new sea floor c. Evidence for Sea-floor Spreading 1. Youngest rocks are located at the mid- ocean ridge 2. Reversals of Earth’s magnetic field are recorded by rocks in strips parallel to ridges Harry Hess

C. Plate Tectonics 1. Earth’s crust and upper mantle are broken into sections called ___________________ a. The crust and upper mantle are called the ____________________________ b. Middle layer of the mantle is the _________________- semi-molten rock, very plastic-like c. ______________________ inside Earth cause plate tectonics – the cycle of heating, rising, cooling, and sinking of material inside Earth

2. Plate Boundaries a. __________________ - two plates move away from one another; ex. Sea-floor spreading b. __________________ -two plates move toward each other, there are three types: 1.) subduction zone- dense ocean plate sinks under light continental plate ex: deep sea trench, volcanic mountain chains 2.) two ocean plates collide ex: deep sea trench, volcanic island chain 3.) two continental plates collide ex: mountains, earthquakes common c. _________________________ - two plates slide past each other; they can move in opposite directions or in the same direction