BIG IDEA 6: Earth Structures

1. BIG IDEA 6: Earth Structures Description   Over geologic time, internal and external sources of energy have continuously altered the features of Earth by means of both constructive and destructive forces. All life, including human civilization, is dependent on Earth's internal and external energy and material resources.

2. Benchmark Number & Descriptor • SC.7.E.6.1 • Describe the layers of the solid Earth, including the lithosphere, the hot convecting mantle, and the dense metallic liquid and solid cores. • SC.7.E.6.2 • Identify the patterns within the rock cycle and relate them to surface events (weathering and erosion) and sub-surface events (plate tectonics and mountain building). • SC.7.E.6.3 • Identify current methods for measuring the age of Earth and its parts, including the law of superposition and radioactive dating. • SC.7.E.6.4 • Explain and give examples of how physical evidence supports scientific theories that Earth has evolved over geologic time due to natural processes. • SC.7.E.6.5 • Explore the scientific theory of plate tectonics by describing how the movement of Earth's crustal plates causes both slow and rapid changes in Earth's surface, including volcanic eruptions, earthquakes, and mountain building. • SC.7.E.6.6 • Identify the impact that humans have had on Earth, such as deforestation, urbanization, desertification, erosion, air and water quality, and changing the flow of water. • SC.7.E.6.7 • Recognize that heat flow and movement of material within Earth causes earthquakes and volcanic eruptions, and creates mountains and ocean basins.

3. INSIDE THE EARTH

4. EARTH’S LAYERS • The Earth is divided into FOUR main layers: • Crust • Mantle • Outer Core • Inner Core

5. EARTH’S CRUST • Outer layer of Earth’s surface • Makes up 1% of Earth • 2 types of crust: • Oceanic • Continental • Earth’s crust is broken down into pieces known as tectonic plates.

6. Mantle • Earth’s largest layers • Made mostly of silicon, oxygen, magnesium and iron • Pieces of mantle can be obtained by erupting volcanoes.

7. OUTER CORE • Is about 3000 miles beneath the Earth’s crust • Said to be made up of molten lava • Iron • Nickel • This lava flows very slowly inside the Earth, creating a magnetic field.

8. INNER CORE • Deepest part of Earth • Smallest section inside Earth • Solid mass due to intense pressure • composed of iron and nickel

9. BOUNDARIES between LAYERS • Moho Discontinuity • Located between the crust and mantle • Plastic Like Layer • Part of the upper mantle • Shadow Zone • Part of the liquid outer core

10. KNOWLEDGE CHECK • How many layers make up Earth? • Which layer of Earth contains tectonic plates? • Which is Earth’s largest layer? • Which elements in Earth’s core helps create a magnetic field?

11. KNOWLEDGE CHECK • How many layers make up Earth? 4 • Which layer of Earth contains tectonic plates? Earth’s crust • Which is Earth’s largest layer? Mantel • Which elements in Earth’s core helps create a magnetic field? Nickel and Iron

12. It’s Just a little rock.

13. Earth’s Past and Future • Earth has been transforming for the past 4.5 million years. • The energy for this constant transformation comes from the Earth's molten interior. • Earth will probably continue to evolve for another 4-5 billion years into the future. • This energy from Earth’s interior has driven the Earth's physical/chemical evolution, and been ultimately responsible for all the rocks, continents, mountains, foreland basins, etc.

14. The Rock Cycle • Rocks are naturally occurring. • Rocks contain minerals, organic material, and glass. • There are 3 types of rocks: • Igneous • Metamorphic • Sedimentary • Each type of rock can become a new type by traveling through the rock cycle. http://www.volcanoworld.org/vwdocs/vwlessons/lessons/Metrocks/Metrocks2.html

15. IGNEOUS ROCKS • Origins: • Come from volcanoes • When magma(inside)/Lava (outside) cool • Types of Lava/Magma: • Due to location of Volcano • Basaltic – Hawaii, non-explosive volcanoes • Andesitic – Pacific ocean volcanoes • Granitic – very explosive volcanoes • Categories of Igneous Rocks: • Intrusive • Formed inside Earth • Found when volcano erupts and are pushed out or through mining • Contain large mineral grains • Extrusive • Form outside surface • Lava cools quickly • Rocks generally contain holes; gas escapes

16. EXAMPLES OF IGNEOUS ROCKS Granite: Igneous, Intrusive Obsidian - volcanic glass that is formed by very rapid cooling of lava Pumice is lava that had a lot of gases in it and cooled quickly on the surface of the Earth.

17. METAMORPHIC ROCKS • Origin: • Rocks that form from change in temperature and pressure • Earth Processes: • Heat and Pressure • Rocks are beneath the surface; heat and pressure increases. • Rocks do not melt, but they do exchange minerals creating new rocks. • Fluids • Fluids carrying dissolved minerals react with rocks. • Chemical reaction occurs, and new rocks are formed. • Earth’s Relation • They can form from tectonic processes such as continental collisions. • They are also formed when rock is heated up by the intrusion of hot magma from the Earth's interior. • Metamorphic rocks become exposed at the Earth's surface by erosion and uplift. • Studying metamorphic rocks tells us about the temperatures and pressures that occur at great depths within the Earth's crust.

18. EXAMPLES OF METAMORPHIC ROCK • Foliated • Mineral grains are flattened into layer. • Example - GNEISS: A foliated rock usually made from some type of granite • Non-Foliated • Smooth texture, no layers • Example - Quartzite

19. SEDIMENTARY ROCKS • Rocks created from sediments. • Materials that make up sediments: • Weathered and eroded rock • Plant and animal remains • Minerals that fall out of solution • Relationship to Earth • Sediments are formed by both weathering and erosion. • Sediments are then transported to their place of deposition by water, wind, mass movement, or glaciers. • Ways sedimentary rocks form: • Compaction • Sediments are pressed together. • Cementation • Sediments are glued together. • Deposition of minerals • Minerals in solution are left when water evaporates.

20. EXAMPLES OF SEDIMENTARY ROCKS • DETRITAL: • Made of broken fragments of other rocks • CHEMICAL: • Made of minerals dissolved in solution • BIOCHEMICAL: • Made of the remains of once-living things Breccia composed of sharp angled fragments Rock Salt: This is an evaporate after the water evaporated from saltwater. Fossillferous Limestone contains fossils of various fresh and or salt water shell fish.

21. KNOWLEDGE CHECK • Where is the beginning of the rock cycle? • NAME THAT ROCK: • This rock is formed from organic, inorganic, and rock fragments. • This rock is formed from heat and pressure. • This rock is formed from molten lava/magma.

22. KNOWLEDGE CHECK • Where is the beginning of the rock cycle? It is a cycle; therefore, there is no true beginning or end. • NAME THAT ROCK: • This rock is formed from organic, inorganic, and rock fragments. Sedimentary • This rock is formed from heat and pressure. Metamorphic • This rock is formed from molten lava/magma. Igneous

23. HOW OLD IS THIS BIG ROCK?

24. HOW OLD IS EARTH? • Rocks are an open window to Earth’s past. • James Hutton (18th century) believed Earth had to be much older then what was originally thought – probably millions of years old. • He proposed his principle of Uniformitarianism. • Big Idea: • Geological processes that we see occurring today are the same processes that occurred in the past.

25. DATING EARTH LAW of SUPERPOSITION • Superposition refers to, “placing on top of each other.” • Scientists use the Law of Superposition to determine whether a fossil or a layer of rock is older or younger than another fossil or layer of rock. • This law states that in a series of sedimentary rock layers, younger rocks normally lie on top of older rocks.

26. DATING EARTH RADIOACTIVE DATING Carbon – 14 Used to find the absolute age of rocks Carbon-14 has a half-life of 5730 years. It is only useful for dating materials that contain Carbon and lived no more than 50,000 years ago. • Scientist use the decay of radioactive elements to determine the age of rocks. • Radiometric dating indicates that the Earth is about 4.570 billion years old • Radioactive Decay: • Unstable elements that breakdown, or decay, by releasing particles and energy in the process and form another element

27. KNOWLEDGE CHECK • Describe the principle of Uniformitarianism. • When looking at a cross-section of the Grand Canyon, layers are noticed. What law best describes these layers? • What element must be present in order to use radioactive dating?

28. KNOWLEDGE CHECK • Describe the principle of Uniformitarianism. Geological processes that we see occurring today, are the same processes that occurred in the past. • When looking at a cross-section of the Grand Canyon, layers are noticed. What law best describes these layers? Law of Superposition • What element must be present in order to use radioactive dating? Carbon-14

29. WHY DOES EARTH LOOK THE WAY IT DOES?

30. HOW DID THAT GET HERE? • The Earth is said to be 4.57 billion years old. • In order for Earth to look the way it does today many factors are taken into consideration. • Physical geology is the study of the Earth's rocks, minerals, and soils and how they have formed through time. • Complex internal processes such as plate tectonics and mountain-building have formed these rocks and brought them to the Earth's surface. • Earthquakes are the result of the sudden movement of crustal plates, releasing internal energy that becomes destructive at the surface. • Internal heat and energy are released also through volcanic eruptions. • External processes such as glaciation, running water, weathering, and erosion have formed the landscapes we see today. http://www.cliffsnotes.com/study_guide/History-of-Physical-Geology.topicArticleId-9605,articleId-9456.html

31. EVIDENCE of EARTH’S EVOLUTION TYPES of EVIDENCE EXAMPLES of EVIDENCE Himalayas, Andes, Hawaiian Islands – all found at different plate boundaries. Stalactites and stalagmites are the remains of rocks which went through chemical weathering. Gullys, deltas, valleys, sand dunes, landslides are created through time as a result of moving water, ice, wind, and gravity. • Evidence located at PLATE BOUNDARIES • Evidence left behind from WEATHERING • Evidence left behind from EROSION AND DEPOSITION

32. EVIDENCE of EARTH’S EVOLUTION TYPES of EVIDENCE EXAMPLES of EVIDENCE Mountain ranges in Africa line up with those in South America. Fossils of the plant Glossopteris found in rocks on widely separated landmasses Fossils of tropical plants found near Arctic Circle • Evidence from LANDFORMS - PANGEA • Evidence of FOSSILS • Evidence from CLIMATE

33. KNOWLEDGE CHECK • Approximately how old is planet Earth? • List and explain 4 pieces of evidence supporting Earth’s evolution.

34. KNOWLEDGE CHECK • Approximately how old is planet Earth? The Earth is said to be 4.57 billion years old. • List and explain 4 pieces of evidence supporting Earth’s evolution. • Pangaea – Super continent • Fossils – Similar fossils found in different areas • Erosion and Deposition – formation of gullies, deltas, valleys, etc.

35. WE’RE FLOATING ON PLATES?

36. PLATE TECTONICS • The Earth’s crust and upper mantle are broken into sections called plates. • Plates move around on top of the mantle like rafts in a pool. • Earth’s plates are located on the lithosphere (crust and upper mantle). • The average thickness of a plate is 100 km (62 miles). • Most plates support both continent and ocean.

37. Alfred Wegener Proposed a theory stating that in the distant past, the Earth’s continents were all joined as a single landmass. When Wegener placed all the continents together like a puzzle, it formed a large landmass which he called Pangaea. Wegener stated that this supercontinent began to break up about 200 million years ago.

38. PLATE BOUNDARIES • Earth’s crust is made up of 7 major plates and several smaller ones. • Where the edges of these plates meet is known as a PLATE BOUNDARY. • How the plates are moving determines what type of boundary is between them.

39. CONVERGENT BOUNDARY TYPES of BOUNDARIES • Plates collide into each other. • These collisions produce mountains, earthquakes, and volcanoes. • Example: • Andes Mountains • Aleutians Islands

40. 3 TYPES of CONVERGENT BOUNDARIES • Ocean plate colliding with a less dense continental plate • Subduction Zone: where the less dense plate slides under the more dense plate • VOLCANOES occur at subduction zones. • Example: Andes Mountains 2. Ocean plate colliding with another ocean plate • The less dense plate slides under the more dense plate creating a subduction zone called a TRENCH • Example: Aleutian Islands 3. A continental plate colliding with another continental plate • a place where folded and thrust faulted mountains form • Example: Himalayas

41. CONVERGENT BOUNDARIES TYPE 2 TYPE 1 TYPE 3

42. DIVERGENT BOUNDARY TYPES of BOUNDARIES • Plates move away from each other. • Most of these boundaries are found in the oceans. • At divergent boundaries, mid-ocean ridges and rifts are formed.

43. DIVERGENT BOUNDARY • The best known of the divergent boundaries is the Mid-Atlantic Ridge. • This submerged mountain range extends from the Arctic Ocean to beyond the southern tip of Africa. • The rate of spreading along the Mid-Atlantic Ridge averages about 2.5 centimeters per year (cm/yr) or 25 km in a million years.

44. TRANSFORM BOUNDARY TYPES of BOUNDARIES • Plates slide past each other. • The sliding of these plates causes rocks to rub against each other. At times, these rocks break and inch past each other. These breaks are felt as earthquakes.

45. TRANSFORM BOUNDARY • The San Andreas Fault is a result of the Pacific and North American plates sliding past each other. • These plates are moving at about 5cm a year.

46. KNOWLEDGE CHECK • Explain the theory of plate tectonics. • How many plate boundaries are there? • Name the type of plate boundary each feature is located at: • Andes Mountains • Mid-Ocean Ridge • San-Andrea’s Fault

47. KNOWLEDGE CHECK • Explain the theory of plate tectonics. Earth’s crust is broken up into plates which float on top of the mantle. The plates support the continents and oceans. • How many plate boundaries are there? 3 types of plate boundaries • Name the type of plate boundary each feature is located at: • Andes Mountains - Convergent • Mid-Ocean Ridge - Divergent • San-Andrea’s Fault - Transform

48. MOUNTAINS, VOLCANOES, EARTHQUAKES – HOW THEY FIT IN THE PICTURE

49. Convection Currents • Hot magma in the Earth moves toward the surface, cools, then sinks again. • This movement creates convection currents beneath the plates that cause the plates to move. • When the plates move, mountains, earthquakes, and volcanoes form.

50. MOUNTAINS • Mountains are formed when uplift occurs (Forces within the crust lift the land above). • 3 types of mountains can form due to plate movement: • Folded mountains • Fault-Block mountains • Volcanic mountains • Yes, volcanoes are considered mountains.