Formation of Earth Birth of the Solar System Nebular Theory Nebula compresses Rotation flattens nebula Collapse into center formed solar nebula and finally, the sun Condensation formed planets, planetesimal, moons and asteroids during planetary accretion around 4.6 billion years ago (Meteorites are iron-rich or rocky fragments left over from planetary accretion) See Fig. 1.9 (a), (b) and (c) http://www.psi.edu/projects/planets/planets.html

Orion Nebula See Fig. 1.9 www.hubblesite.org www.geol.umd.edu/~kaufman/ ppt/chapter4/sld002.htm www.psi.edu/projects/ planets/planets.html See Fig. 1.9

Formation of the Planets Nuclear fusion began within the mass at the center of the solar system forming the sun The inner planets were hotter and gas was driven away leaving the terrestrial (rocky) planets The outer planets were cooler and more massive so they collected and retained the gasses hence the “Gas Giants” Terrestrial Planets ? Gas Giants www.amnh.org/rose/backgrounds.html

Differentiation of the Planets The relatively uniform iron-rich proto planets began to separate into zones of different composition: 4.5bya Heat from meteor impact, pressure and radioactive elements cause iron (and nickel) to melt and sink to the center of the terrestrial planets See Fig 1.10

Further Differentiation of Earth Deepest Mine Deepest Well Continental Crust (Silicic) Lighter elements such as Oxygen, Silicon, and Aluminum rose to form a thin, rigid crust The crust, which was originally thin and basaltic (iron rich silicate), further differentiated to form continental crust which is thicker, iron poor, silica rich and lighter Oceanic Crust (Basalt) Mid-Ocean Ridge (New Crust) See Fig. 1.11

Composition of Earth and Crust     Composition of Earth and Crust Before and After Differentiation   Element (Atomic #) Chemical Symbol % of whole Earth % of Crust (by Weight) Change in Crust Due to Differentiation Oxygen (8) O 30 46.6 Increase Silicon (14) Si 15 27.7 Increase  Aluminum (13) Al <1 8.1 Iron (26) Fe 35 5.0 Decrease  Calcium (20) Ca 3.6 Sodium (11) Na 2.8 Potassium (19) K 2.6 Magnesium (12) Mg 10 2.1 All Others ~8 1.5  

Crust and Mantle Lithosphere and Asthenosphere The uppermost mantle and crust are rigid solid rock (Lithosphere) The rest of the mantle is soft but solid (Asthenosphere) The Continental Crust “floats” on the uppermost mantle The denser, thinner Oceanic Crust comprises the ocean basins Figure 1.11, Detail of crust and Mantle

A Large Variety of Rocks (and Sediment) Products of an Active Planet Crust: Rigid, Thin Earth’s structure leads to intense geologic activity Inner core: Solid iron Outer core: Liquid iron, convecting (magnetic field) Mantle (Asthenosphere) : plastic solid, iron-magnesium silicate, convecting Crust (Lithosphere): Rigid, thin O, Si, Al, Fe, Ca, Na, K, Mg… Mantle: Plastic, Convecting 47%, 28, 8, 5, 4, 3, 3, 2

Lithospheric Plates See Kehew, Figure 1.19 The Lithosphere is broken into “plates” (7 maj., 6 or 7 min.) Plates that “ride around” on the flowing Asthenosphere Carrying the continents and causing continental drift

Lithospheric Plates Fig. 1.13 and 2.14

Three Types of Plate Boundaries Divergent Convergent Transform See Fig. 1.14 and 1.13

Things to Know About Plate Tectonics Composition and properties of Zones Iron core (solid & liquid, convecting, magnetic field) Mantle: Plastic solid, convecting, ultramafic (Si, O, Fe,Mg) Composition and Properties of the Crust Oceanic Crust: Basalt, Thin (5-10km) (O, Si, Fe, Mg, Ca) Continental Crust: Granitic, Thick (10-50km) (O, Si, Al, Na, K)

Things to Know About Plate Tectonics Features and Geologic Phenomena Convergent: trenches, mountain chains, granitic magma, granitic rocks, composite volcanoes, Divergent: Mid ocean ridges, rift valleys, shallow earthquakes, basaltic magma and lava, basalt, lava floods (volcanoes rare)

Things to Know About Plate Tectonics Features and Geologic Phenomena Transform: Offset ocean ridges or mountain chains, shallow earthquakes, no magma or lava Hotspots: Shallow earthquakes, basaltic magma and lava, basalt, lava floods, sometimes shield volcanoes

The 3 rock types form at convergent plate boundaries Igneous Rocks: When rocks melt, Magma is formed, rises, cools and crystallizes. Sedimentary Rocks: All rocks weather and erode to form sediments (e.g., gravel, sand, silt, and clay). When these sediments accumulate they are compressed and cemented (lithified) Metamorphic Rocks: When rocks are compressed and heated but not melted their minerals re-equilibrate (metamorphose) to minerals stable at higher temperatures and pressures Sedimentary Rocks Metamorphic Rocks Igneous Rocks Magma

The Rock Cycle Geological Materials Transformation Processes Geologic materials (blocks) Are transformed and transported By geologic processes (arrows) To form other geologic materials Driven by internal and external processes Fig. 3.1 See Fig. 1.15

Igneous and Sedimentary Rocks at Divergent Boundaries and Passive Margins Igneous Rocks (basalt) are formed at divergent plate boundaries and Mantle Hot Spots. New basaltic, oceanic crust is generated at divergent plate boundaries. Sedimentary Rocks are formed along active and passive continental margins from sediments shed from continents Sedimentary Rocks are formed on continents where a basin forms and sediments accumulate to great thicknesses. E.g., adjacent to mountain ranges and within rift valleys.

Learning Plate Tectonic Geography 1. Continents and Subcontinents [in brackets] The Western Hemisphere: North America, South America, [Alaska], [Greenland]  The Eastern Hemisphere: Europe/Asia (Eurasia), Africa, [Arabian Peninsula], [India] Don't forget these continents: Australia, Antarctica Other important regions [not continents]: Middle East, Central America (part of the North American Continent) 2. Oceans and Major Seas Atlantic, Pacific, Arctic, Indian, Mediterranean Sea, Red Sea http://www.berann.com/panorama/archive/index.html#Ocean_Floor_Maps 3. Major Mountain Belts and Ranges(See Figure 20.2 and 20.3 pg. 499-500) Ranges of Americas : Appalacians, Rocky Mnts., Cascade Range (part of the North American Cordillera, see Fig. 4.5, pg 81), Sierra Nevada, Basin and Range (Nevada), Andes Other Mountan Belts around the world: Himalaya, Alps, New Zealand Alps 4. Major Island Arcs and Other Islands [in brackets] Philippines, Virgin Islands/West Indies (part of the same island arc, see Box 4.5, pg. 95), Aleutian Islands (island arc southwest of Alaska), New Zealand, Japanese Islands, Indonesia, [Iceland], [Hawaiian Islands],  http://www.berann.com/panorama/archive/image/PN_W_09.jpg B. Learning the Plate Boundaries Once you know your continents, Oceans, and mountain belts it is easy to learn the major tectonic plates and their boundaries. 1. The Major Tectonic Plates Every continent "rides" on a tectonic plate.  Eurasia is a single plate (the earth's largest).  African Plate, Eurasian Plate, North American Plate, South American Plate, Antarctic Plate, Indian-Australian Plate (they are both on the same plate separated by the Indian Ocean) 2. The Pacific Plate The only major plate without a continent is the Pacific Plate.  In all that makes 7  major plates (6 with continents and 1 without) 3.  Divergent Plate Boundaries Every ocean and sea listed above has a Divergent Plate Boundary and a mid ocean ridge. For example, see figure 18.15 and 18.16 on pages 448 and 449. Mid-Atlantic Ridge, East Pacific Rise, Mid-Indian Ridge, Arctic (not usualy shown). 4. Convergent Plate Boundaries (Ocean-Ocean) Each Island Arc is associate with an Ocean-Ocean Convergent Plate Boundary (The Hawaiian Island chain is not considered an Island arc).  Notice that each of these island arcs have a Oceanic Trench associated with them; why do you think that is? 5. Convergent Plate Boundaries (involving continents) The mountain belts listed above in bold face are at ocean-continents Convergent Plate Boundaries (North American Cordillera, Andes) or continent-continent Convergent Plate Boundary (the Himalayas are the best example of this type of plate boundary). 6. Transform Plate Boundaries The classic Transform Plate Boundary is the one that passes beneath North American Plate in western California causing the San Andreas Fault. (See Box 16.3 on Pg. 407) Also, Every mid-ocean ridge is offset along its length by transform boundaries Brushing up on basic geography will help you learn Plate Tectonics Once you know your basic geography and ocean basin features (Mid Ocean Ridges, -Oceanic Trenches) you can Learn the 7 major plates Learn the types of plate boundaries Learn why those features are where they are