GEO 101 1st Edition Lecture 5 Outline of Last Lecture 1. Minerals: Building blocks of rocks 2. What is a mineral? 3. Composition of Minerals 4. Chemistry Refresher a. Structure of Atom b. Chemical Bonding i. Ionic ii. Covalent iii. Metallic iv. Van Der Walls 5. Structure of Minerals 6. How do we Identify Minerals a. Diagnostic Properties i. Crystal Form/Shapeii. Lusteriii. Coloriv. Streakv. Harnessvi. Cleavage vii. Fractureviii. Specific Gravity ix. Other Properties 7. Mineral groups8. Categories of Silicate Minerals9. Non-Silicate Minerals Outline of Current Lecture 1. Divergent Plate Boundaries 2. Divergent Plate Boundaries: Rifting 3. Driving Mechanisms 4. Testing the Theory: Evidence 5. Importance 6. The Rock Cycle These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Current LecturePlate Tectonics: The New ParadigmDivergent Plate Boundaries- Oceanic ridges and seafloor spreadingo Seafloor spreading occurs along oceanic ridge system- Spreading rates and ridge topographyo Ridge systems exhibit topographic differenceso Differences controlled by spreading ratesDivergent Plate Boundaries: Rifting- Why is there continental rifting?- Why did Pangaea break up?- Lithosphere thickness impedes flow of heatDriving Mechanisms- Density variations of plates overlying mobile (fluid) asthenosphere drive Plate Tectonics- Forces that drive plate motion:o Slab-pullo Ridge-pusho Slab suction- Models of plate-mantle convectiono Acceptable model must be consistent with observed physical and chemical properties of mantleo Models: 1. Layering at 660 kilometers- Accounts for physical properties (layering) 2. Whole-mantle convection- Tries to account for physical properties (layering) 3. Deep-layer modelTesting the Theory: Evidence- Hot spots and mantle plumeso Caused by rising plumes of mantle materialo Volcanoes can form over them (Hawaiian Island chain)o Mantle plumes Long-lived structures Originate at great depth, mantle-core boundary- Paleomagnetism and plate motionso Plate motions determined from paleomagnetism stored in rocks Direction Rate- Measuring plate velocities from spaceo Establishing exact locations on opposite sides of a plate boundary and measuring relative motionso Method: Global Positioning SystemImportance- Provides explanations foro Earth’s major surface processeso Distribution of earthquakes, volcanoes, and mountainso Distribution of ancient organisms and mineral deposits- Problem:o Plate/Mantle interactions, convection models, not well known- Provides framework for GEO 101 concepts:o Think of plate tectonics for remainder of courseThe Rock Cycle- What is a Rock?o Has to be natural – Not man made such as concrete or bricko Solid/Coherent (i.e. held together)o Made of minerals (or less commonly, glass)- 3 Basic Types of Rockso Igneous Rocks Usually very hard/ very solid Cooling and solidification of magma Granite and basalto Sedimentary Rocks Layered Accumulate in layers at Earth’s surface Sediments derived from weathering of preexisting rock Compaction and precipitation  Sandstone and limestoneo Metamorphic Rocks Swirly, and hard Formed by heat and pressure Changing preexisting igneous, sedimentary of other metamorphic rock Heat and pressure