1 Unit 4 The Dynamic Crust

2 A. The Earth in Cross Section I.There are 4 major zones that make up the Earth: A. : Outer, thinnest layer of the Earth. There are two types: 1. : -Thickness: -Composition: -Density: 2. : -Thickness: -Composition: -Density: _Continental_____________ __Oceanic______________ __30km (18.6 mi.)__ Granite_______ ___2.7g/cm 3 _____ _5km (3.1mi.)__ _Basalt______ __3.0g/cm 3 _______ _Lithosphere_______

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4 composed of that is composed of that is A. Crust OceanContinent basalt 5 to 6 km thick granite up to 30 km thick

5 B. _________________: Found below the crust. Has two parts: 1. _________________: Upper, “plastic” mantle. -partially melted material. 2. __________________: Rest of mantle; actual temperature is below the melting point. NOTE: The boundary between the crust and mantle is called the __________________ ________________________, or MOHO. C. _________________: Only liquid layer of the earth. Composed mainly of iron. D. _______________: Solid, innermost layer of Earth. Composed mainly of iron and nickel. Mantle Asthenosphere Stiffer Mantle Mohorovicic Discontinuity Outer Core Inner Core

6 is B. Mantle Asthenosphere Stiffer Mantle Partially melted Not melted

7 composed of C.Outer Core D.Inner Core Only liquid layer Iron Solid center of Earth Iron and Nickel

8 B. Crustal Movement I.Dynamic Crust -The crust and outermost part of the Mantle is called the _________________ A. The first theory of crustal movement was introduced in 1915 by Alfred Wegener, and was called _____________ _____________________________________ --Evidence for this theory include: 1. _____________________________ 2. Correlation of rock layers/fossils: _____________________________________ Lithosphere Continental Drift Continents match up like a puzzle Rock layers and fossils match up on the edges of different continents.

9 3. Mountain chains: ________________ _______________________________________ 4. Climate evidence: _________________ ______________________________________ Mountain chains on different continents match up. So do the fossils found in the mountain chains. Ice cores taken from glaciers on different continents match up.

10 Theory that the oceanic crust has been constructed by material from deep within the Earth that rises and spreads apart the mid-ocean ridges. 5. Crustal age: ___________________ ______________________________________ B.Sea Floor Spreading: _________________ ______________________________________ 1. Convection cell: __________________ ______________________________________ Circulation of heated fluid caused by differences in density. This is what moves the plates. The age of oceanic crust matches up at equal distances from mid-ocean ridges.

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12 2.Evidence a. Igneous Ocean Rocks: ______________ ______________________________________ Rock that is closer to the mid- ocean ridges is younger and age increases as distance from the ridge increases.

13 Every 10,000 years, the Earth’s magnetic field switches. This can be seen in the magnetic minerals within the basalt rock found on the ocean floor. b. Magnetic Reversal: ________________ ______________________________________

14 driven by evidence Sea Floor Spreading Convection Cells Igneous Ocean rocks Magnetic Reversal

15 C.Plate Tectonics: __________________ __________________________________ II.Plate Boundaries A. Convergent: ____________________ --3 Types: 1. __________________________: Two continental plates coming together. Ex: ______________________________ States that Earth’s lithosphere is made up of a number of solid pieces, or plates, that move in relation to each other. 2 plates coming together Continental-continental Himalayan Mtns. (Indian-Australian and Eurasian Plate

16 II.Plate Boundaries A. Convergent 2. ______________________: Oceanic and Continental plates coming together. --Typically will form an _____________ along an ________________________, where the ocean plate pushes under the continental plate. _________________ Ex: _____________________________ _______________________________________ Oceanic-continental Oceanic trench Island-arc

17 II.Plate Boundaries A. Convergent 3. _____________________: Two ocean plates coming together. --Typically will form an _____________ as one plate pushes under the other. Ex: _____________________________ Continental-Oceanic Ocean trench Peru-Chile Trench (Nazca and South American Plates

18 B. Divergent: ______________________ ___________________________ -Usually form ____________________ Ex: ________________________ 2 plates moving away from each other (Sea-floor spreading) Mid-Ocean Ridges Mid-Atlantic Ridge (North American and Eurasian/African Plates

19 meet at Examples Plate Boundaries Plate Tectonics moving plates Convergent Continental- Oceanic Oceanic- Oceanic Continental- Continental come together

20 Plate Boundaries Divergent Move apart

21 I.Plate Boundaries C. Transform Fault:___________________ _______________________________________ -Forms where _____________________ _______________________________________ Ex: ____________________________________ 2 plates sliding past each other The Earth is cracked. San Andreas Fault (Pacific and North American Plate

22 Plate Boundaries Transform Move Horizontally Past Each Other

23 C. Evidence of Crustal Activity I.Crustal Activity A. Deformed Rock Strata --Originally, sedimentary rocks form ____ ______________________________________ However, observations made of Earth’s surface indicate that ___________________________________________________ This includes: 1. Tilting: _______________________________________ Rocks are pushed up at an angle. The horizontal layers have been changed. In horizontal layers called beds

24 2.Folding: __________________________ ____________________________________ 3. Faulting: __________________________ ___________________________________ Bends in the rock layers due to continental collisions. Breaks in rocks where plate movement has occurred.

25 B.Displaced fossils: ___________________ _____________________________________ II. Results of Crustal Activity A. Earthquakes: _____________________ _______________________________________ --focus: ____________________________ _______________________________________ --epicenter: _________________________ _______________________________________ Fossils of organisms that lived in the sea have been found on mountain tops. Any shaking, or rapid motion of Earth’s solid outer layers. The place underground where the earthquake occurs. The location at Earth’s surface just above the focus.

26 --Types of earthquake waves: 1.__________________: Also called compressional waves; the motion of the ground is parallel to the direction of wave motion. These waves can pass through ______________ __________________________________ P-waves Solids and Liquids

27 2. _______________: Also called longitudinal waves; the motion of the ground is perpendicular to the direction of wave motion. These waves can pass through _____________ ______________________________________ 3. ________________: Waves that ripple the surface of the Earth, causing most of the damage of an earthquake. S-waves SOLIDS ONLY Surface Waves

28 --When traveling through the same material, ___________ travel faster than ____________. -Since these waves travel at different ________ in different ___________ materials, we can use earthquake waves to tell us about the __________________________. -When an earthquake occurs, both __________ _________________. In many places on Earth, both waves are received; however, in other places, _________________________. -Since S waves cannot pass through a liquid, the conclusion is that _______________________ ______________________________________ S-waves P-waves speeds interior of the Earth. types of and S-waves are given off P-waves only P-Waves are received some parts of the Earth’s interior are liquid.

29 -If an earthquake occurs under the ocean, the energy is also released through the ocean water. When it reaches the coastline of a continent or island, it may form a large, fast moving wave called a _________________. They may move at speeds of _________ and may be ____________________high!!! Tsunami feet 500+ mph

30 B.Earthquake Strength -The strength of an earthquake can be determined in one of two ways: 1. ______________: Used to describe the amount of energy released by an earthquake. It ranges from ___ to ___, and each increase on the scale indicates a release of ____ times more energy!!! --To record earthquake waves, seismologists use a _______________, which can be used to record the arrival time of the waves and the intensity of the waves. Richter Scale seismograph

31 2.__________________: Used to describe the earthquake in terms of the amount of damage done. It ranges from ___ to ___. These are based on personal accounts. --Why is the Richter scale better to use when describing the intensity of an earthquake, rather than the Mercalli scale? _________________________ ____________________________________ Mercalli Scale Because the Richter scale uses actual measurements rather than the Mercalli scale which uses personal accounts which can change from person to person. XII I

32 C.Volcanoes: --How do they form? 1. Molten rock from within the earth, called _______, along with gases, begins to rise up through cracks and weak spots in the crust. 2. When this molten material, along with gases from inside earth, break through the surface, it may flow out on the surface, and then it is called _____. --Where do they form? 1. __________________________________ _______________________________________ 2. __________________________________

33 3. __________: Weak points in the crust, located over unusually high heat flow in the mantle. Although the crust may move, _____ _______________________________________ -Ex: ________________________________

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36 evidence Continental drift puzzle fit of continents correlation of rock layers mountain chains climate evidence crustal age

37 crustal activity deformed rock strata displaced fossils tilting folding faulting shallow fossils at high elevation deep fossils in shallow water areas

38 results of crustal activity Earthquakes types of waves P waves S waves L waves

39 Earthquakes measured using Richter Scale Mercalli Scale

40 erupts Volcanoes Shield Composite Cinder lava lava and ash ash and cinder