10 14 2013 Geology Test 2 Study Guide Chapter 6 How does a clastic sedimentary rock form Solid fragments and grains that are cemented together Form through weathering erosion transportation deposition and lithification compaction and cementation How do grain size and shape sorting sphericity and angularity change as sediments move downstream As sediment moves away from the source it becomes rounded and well sorted How does a biochemical sedimentary rock form Corals produce shells of calcium carbonate which then turns into limestone How does an organic sedimentary rock form Composed of carbon and organic chemicals from plants What kinds of conditions produce evaporites Evaporites are composed of salts that stay behind as the water evaporates How and in what conditions do ripple marks and dunes form Ripple marks are wave like ridges and troughs at right angles to the flow direction A dune is a pile of sand generally form by deposition from the wind How do cross beds form How can you read the current direction from cross beds Cross beds are inclines laminations inside main beds How does a turbidity current produce graded bedding A graded bed is a layer of sediment in which grain size varies from coarse at the bottom to fine at the top Can you tell about past environment from sedimentary settings Yes Chapter 7 What is metamorphism The process of changes Which processes does a rock take to become a metamorphic rock Recrystallization change in shape and size but no change in mineral composition Phase change change in crystal structure by rearranging atoms in the crystals but no change in composition Metamorphic reaction chemical reactions produce new mineral crystals that differ from the protolith Pressure solution under high pressure and in the presence of water dissolution on the pressurized surfaces migration through the water precipitation in places with low pressure Plastic deformation under high pressure and high temperature soft plastic minerals change in shape without breaking What cause metamorphism Heat pressure pressure and temperature compression and shear and hot water How are metamorphic rocks classified Foliation What is metamorphic foliation and how does it form Layering formed by mineral grain alignment or by compositional banding What is metamorphic grade and how can it be determined As pressure and temperature increase the metamorphic grade increases Where does metamorphism occur Thermal or contact metamorphism where magma intrudes Burial metamorphism where sediments get deeply buried Dynamic metamorphism where a fault slides at depth Dynamo thermal or regional metamorphism large mountain ranges build Hydrothermal metamorphism hydrothermal fluids react with rocks Where would you go if you wanted to find metamorphic rocks exposed at the surface Younger mountain belts continental platforms precambrian shields How did metamorphic rocks return to the surface Interlude C What is the rock cycle Progressive transformation of Earth materials from one rock type to another then another and so on What drives the rock cycle in the Earth System Chapter 8 What causes earthquakes Sudden formation of a new fault sudden slip of an existing fault sudden changes in mineral structures of rock movement of magma in a volcano explosion of a volcano giant landslides meteorite impacts underground nuclear bomb tests What are seismic waves Through the earth s interior Compressional waves vibration and propagation are parallel Shear waves vibration and propagation are perpendicular Along the earth s surface Rayleigh wave Love wave How can we measure seismic waves Seismograph How can we find earthquake locations Find the time difference between P and S wave arrivals find epicenter distance from travel time curves draw circles from three different stations How can we define the size of an earthquake Modified Mercalli Intensity Richter Scale Moment magnitude scale What are the basic types of faults Normal fault reverse fault thrust fault and strike slip fault Where and why do earthquakes occur Seismic belts divergent and transform plate boundaries convergent plate boundaries continental rifts and collision zones How do earthquakes cause damage Ground shaking landslides liquefaction fire and tsunamis What are the efforts to predict an earthquake Identification of seismic zones recurrence interval seismichazard maps detection of foreshocks and measurement of ground deformation What are the earthquake safety rules Interlude D What are the characteristics of seismic wave propagation Seismic waves travel at different velocities in different rock types S waves cannot travel through a liquid and P waves travel more slowly in a liquid than a solid What are the scientific findings about earth s interior using seismic waves Crust mantle boundary core mantle boundary the nature of the core and the inner core How do seismic waves vary increasing depth Chapter 9 Why does rock deform Rocks bend or break in repines to compression tension or shearing Whats the difference between strain and stress Strain is a change in shape and stress is the amount of force applied per unit area of rock Stress causes strain Whats the difference between brittle deformation and ductile deformation Brittle deformation is when rocks break usually a sudden change in cold rock shape like an earthquake Ductile deformation flattens rock and occurs with warm rocks high pressure and is a slow change like mountain building What controls deformation Temperature pressure deformation rate and composition Deformation depends on the stress developed at a location not on the total force involved in the plate interaction What are the characteristics of joints faults folds and foliations Joints are natural cracks that occur when rock cools and contracts when rock undergoes a decrease in pressure and when rock layers bend Faults include strike slip and oblique slip Fold is a bend or curve of a rock layer Types of folds include anticline syncline a train of folds monocline plunging fold dome and basin What is isostasy The state of gravitational equilibrium between the earth s lithosphere and asthenosphere Where can we find mountain ranges Along convergent plate boundaries continental collision zones and continental rifts How can measure mountain building GPS measurements of shortening 10 14 2013 10 14 2013