1. Restless Earth Rock Cycle formation of different rock This cycle is involved with three types of rock a. Sedimentary b. Metamorphic c. Igneous schematic diagram rock cycle

2. Restless Earth Sedimentary Rock a. occurs near the Earth’s surface b. sediment settles to the bottom of the rivers, lakes, and oceans c. forms in layers called strata or stratification

3. Restless Earth Sedimentary Rock Cycle a. weather breaks down existing rock b. deposition c. compaction and cementation

4. Restless Earth Metamorphic Rock a rock type that has changed into another type a. occurs 2 to 16km deep in the Earth b. pressure is almost 4,000 times greater than at the surface c. temperature ranges from 150 0 C to 1000 0 C

5. Restless Earth Composition of Metamorphic rock heat and pressure play the significant roles in forming this type of rock Minerals + Heat and Pressure = New mineral New minerals formed at different temperatures at different depths

6. Restless Earth Igneous Rock formed from the cooling of magma a. melted rock is trapped in the earth then cools b. lava from a volcano erupts and then cools

7. Restless Earth Three ways that rock can become magma a. Temperature b. Pressure c. Composition

8. Restless Earth Igneous Rock formations Two process in which magma forms rock 1. Intrusive – coarse grained rock that developed after magma has cooled below the Earth’s surface after weathering of Earth's surface, these intrusions are apparent Shiprock, New Mexico extinct volcano dike Devils Tower

9. Restless Earth 2. Extrusive rock – very small crystalline rock that is formed on the Earth’s surface called lava or under the ocean’s surface, pillow lava

10. Restless Earth Earth’s story Two theories on the geologic processes which points to how the Earth’s landscape was/is formed 1. Uniformitarianism – James Hutton, 1795 developed the idea the landscape developed over long periods of time through a variety of slow geologic and geomorphic processes. a. deep soil profiles were formed by the weathering of bedrock over thousands of years b. slow uplift and subsidence of land surfaces cause changing topography

11. Restless Earth 2. Catastrophism - doctrine that the geological changes in the earth's crust have been caused by the sudden action of violent physical causes a. biblical floods b. asteroid impacts

12. Restless Earth Relative dating (and I am not referring to my family tree) uses the Principal of Superposition a. It is based on sedimentary rocks and fossils b. Oldest layers are at the bottom c. Helps in the order of events d. Produces a geologic column

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15. The Geologic column can have some very interesting formations. a. Faults - a crack in the earth's crust resulting from the displacement of one side with respect to the other

16. Restless Earth b. Intrusion – molten rock that seeps into crevices and cools

17. Restless Earth c. Folding – rock layers bend and buckle from internal forces

18. Restless Earth d. Tilting – internal pressures slants the geologic column without folding

19. Restless Earth Unconformity – a missing part of the geologic column mostly occurs due to: a. deposition b. erosion Three types of unconformities a. disconformity – rock layer is missing

20. Restless Earth b. Nonconformity – sedimentary layer sits on top igneous or metamorphic rock

21. Restless Earth c. Angular unconformity – layer between horizontal layer and tilted rock layer

22. Restless Earth Absolute Dating a process which establishes the age of an object The process uses radioactive decay the decay works this way: Unstable atoms turn into stable atoms Parent isotope – unstable isotope Daughter isotope – stable isotope

23. Restless Earth Radiometric dating percentage of parent unstable isotope to daughter stable isotope Uses half-life of isotope to date object Three methods of radiometric dating a. Uranium-lead method b. Potassium-argon method c. Carbon-14 method 32 64 16 8 4

24. Restless Earth The Earth may be described in two ways 1. Composition 2. Physical properties Let’s take a look at each one 1. Composition - the Earth is composed of three layers a. Crust – outermost layer b. Mantle – middle layer c. Inner and outer cores

25. Restless Earth There are two categories of crust a. Continental – about 30 km thick; granite b. Oceanic – about7 km thick; basalt

26. Restless Earth 2. Physical properties a. Lithosphere – outermost layer (tectonic plates) made up of 1. crust 2. upper part of mantle b. Asthenosphere – soft part of mantle c. Mesosphere – strong part of mantle, extends from asthenosphere to outer core d. Outer core – liquid layer of core e. Inner core – solid core 6 miles 60 miles 125 miles 400 miles

27. Restless Earth Rock a little geology lesson!!! Earth is made up of four layers a. inner core - mass of iron with a temperature of 7000 0 F b. outer core - electrical currents generated from this area produce the earth's magnetic field. c. mantle - slow moving molten rock or magma, 2000 0 F d. crust - layer from 4-25 miles thick consisting of sand and rock

28. Restless Earth Mapping the Earth layers a seismograph can be used to measure the thickness of each layer

29. Restless Earth The lithosphere is made up of tectonic plates; these are plates that float on the asthenosphere

30. Restless Earth Cross section of a tectonic plate

31. Restless Earth Continental Drift Wegener, Alfred – 1880 - 1930 theory that all of the worlds land masses were at one time together !!!!! called the land mass Pangaea – about 245 million years ago Evidence: a. continents fit together like a puzzle b. identical fossils on one continent are found on another e.g. plants on S. America, Africa, Antarctica and Australia c. glaciers

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34. Are the continents on the move??? Yes, about 2 to 3 inches per year How you ask... Sea-floor Spreading!!! As the continents move apart the mid-ocean ridge pulls apart and molten rock fills the gap That is how the geologists determine the age of the ocean floor

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36. As the magma makes new sea floor, the magnetic poles actually change direction At irregular intervals, averaging about 200-thousand years, the Earth's magnetic field reverses. The end of a compass needle that today points to the north will instead point to the south after the next reversal.

37. Restless Earth Theory of Tectonic Plates Two possible answers for tectonic plate shift a. gravity b. heat

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