Dynamic+Crust

Theory of Continental Drift (Alfred Wegener 1915) 1. Pangea a large landmass containg all of the continents which eventually broke into two landmasses a) Laurasia-N America, Europe, Asia b) Gondwanaland- Africa, S. America, Antartica, Australia, India Evidence Continents seem to fit together Fossils of individual species can be found on many different continents which are not close together (ex Lystrosaurus was located in Antarctica, S. America, Africa, India Deposits of certain Rocks and mineral types correlate among continents Appalachian MTS. found in Northeast of U.S are similar in age and structure as MTS. in Greenland and Scandinavia Structure of The Earth Density, Pressure and temperature increase as your move toward the Center of the earth Crust- The outer most layer of the earth a) continental Crust- Composed mainlly of Granite, Low in Density; Think b) oceanic Crust- Composed mainly of Basalt high in Density; Thin Lithosphere- Crust and Uppermost solid Part of the Mantle <span style="font-family: Verdana,Geneva,sans-serif;">Asthenosphere- Underlies the lithosphere, Composed of Partially Molten Rock <span style="font-family: Verdana,Geneva,sans-serif;">Moho- The boundary between the crust and the mantle <span style="font-family: Verdana,Geneva,sans-serif;">Mantle- The layer of Molten rock extending fromt he crust downward 2850 KM <span style="font-family: Verdana,Geneva,sans-serif;">OuterCore- between mantle and inner core composed of iron and nickel <span style="font-family: Verdana,Geneva,sans-serif;">Inner core- solid iron and nickel located at the center of the earth <span style="font-family: Verdana,Geneva,sans-serif;">Plate Tectonic: <span style="font-family: Verdana,Geneva,sans-serif;">Plate tectonics is the study of the formation and movement of plates <span style="font-family: Verdana,Geneva,sans-serif;">Plates are composed of Lithosphere <span style="font-family: Verdana,Geneva,sans-serif;">Continental=Thick <span style="font-family: Verdana,Geneva,sans-serif;">Oceanic= Think) <span style="font-family: Verdana,Geneva,sans-serif;">12 major and several minor plates <span style="font-family: Verdana,Geneva,sans-serif;">**P** <span style="font-family: Verdana,Geneva,sans-serif;">lates move because of convection cells in the asthenospere <span style="font-family: Verdana,Geneva,sans-serif;"> Convection cell- a circulatory motion-in a liquid or gas transferring heat energy that results from differences in density within the fluid <span style="font-family: Verdana,Geneva,sans-serif;"> Types of Plate Boundaries <span style="font-family: Verdana,Geneva,sans-serif;"> Divergent Convergent Transform <span style="font-family: Verdana,Geneva,sans-serif;"> Divergent Plate Boundary <span style="font-family: Verdana,Geneva,sans-serif;"> Place where two plates are moving apart from eachother <span style="font-family: Verdana,Geneva,sans-serif;"> a) mid-atlantic ridge- sea floor spreading at the mid ocean ridge's recorded by the reversal of the magnetic poles in mineral grains <span style="font-family: Verdana,Geneva,sans-serif;"> Paleomagnetism- the study of magnetism in ancient rocks <span style="font-family: Verdana,Geneva,sans-serif;"> Polar wandering- as metallic mineral grains align themselves with their magnetic poles rocks records show that the grains reverse the direction in which they point <span style="font-family: Verdana,Geneva,sans-serif;"> Convergent plate boundary <span style="font-family: Verdana,Geneva,sans-serif;"> When two plates move towards eachother <span style="font-family: Verdana,Geneva,sans-serif;"> Collision- when two plates carrying continents collide they push up usually causing mountains. (ex himalayas) <span style="font-family: Verdana,Geneva,sans-serif;"> Subduction: When both plates do not continents one of the plates is forced to sink under the other one <span style="font-family: Verdana,Geneva,sans-serif;"> The plate which subdues is composed of a more dense material <span style="font-family: Verdana,Geneva,sans-serif;"> Ocean- Continent- the ocean floor is more dense so it subdues to the continental causing offshore trenches mountains or volcanoes (EX.western Coast of S. America) <span style="font-family: Verdana,Geneva,sans-serif;"> Ocean- Ocean one plate will subdue to the other one usually causing a deep trench (ex. Mariana's trench) <span style="font-family: Verdana,Geneva,sans-serif;"> Transform plate boundary <span style="font-family: Verdana,Geneva,sans-serif;"> When plates slide past one another usually causing a build up of pressure which is released int he form of an earthquake <span style="font-family: Verdana,Geneva,sans-serif;"> San Andreas fault Many earthquakes are common along the fault where the north american plate is sliding past the pacific plate. <span style="font-family: Verdana,Geneva,sans-serif;"> Earthquake and Volcanic Activity Evidence <span style="font-family: Verdana,Geneva,sans-serif;"> Magma- Molten Rock Underground <span style="font-family: Verdana,Geneva,sans-serif;"> Felsic-Magmas with relatively high silica are thick, light colored and slow moving <span style="font-family: Verdana,Geneva,sans-serif;"> Mafic- Relatively low silica content, thiner, darker and flow more easily <span style="font-family: Verdana,Geneva,sans-serif;"> Magma contains dissolved gases that are given off as the magma erupts. The most important of these gases are water vapor carbon dioxide and sulfer <span style="font-family: Verdana,Geneva,sans-serif;"> Magmas containing large amounnts of dissolved gases tend to produce mroe explosive eruptions <span style="font-family: Verdana,Geneva,sans-serif;"> Lava- Molten rock that has reached the surface <span style="font-family: Verdana,Geneva,sans-serif;"> Felsic lava- thick and stiff called AA lava. produce explosive eruptions <span style="font-family: Verdana,Geneva,sans-serif;"> Mafic Lava- Thin and fluid called Pahoehoe lava pours out smoothly (less explosive) <span style="font-family: Verdana,Geneva,sans-serif;"> Tephra- Solid fragments of lava produced from explosive eruptions <span style="font-family: Verdana,Geneva,sans-serif;"> Rift eruptions- occur at long norrow fractures int eh crust such as mid-ocean spreading centers <span style="font-family: Verdana,Geneva,sans-serif;"> When lava flows out smoothly and fluidly it forms a volcanic mountain with a broad base and gently sloping slides called a shield one <span style="font-family: Verdana,Geneva,sans-serif;"> Subduction bounfary eruptions: Are the result of thick magma that forms at subduction boundaries <span style="font-family: Verdana,Geneva,sans-serif;"> These eruptions are more explosive due to the large amount of gases in the magma <span style="font-family: Verdana,Geneva,sans-serif;"> Forms a cinder cone with very steep sides <span style="font-family: Verdana,Geneva,sans-serif;"> Hot spots are areas of volcanic activity in the middle of lithospheric plates <span style="font-family: Verdana,Geneva,sans-serif;"> Similar to rift eruptions. Smooth flowing lava and shields cones <span style="font-family: Verdana,Geneva,sans-serif;"> The hot spot stays int he same location as the lithospheric plate above it moves** <span style="font-family: Verdana,Geneva,sans-serif;">Earthquakes: <span style="font-family: Verdana,Geneva,sans-serif;">An earthwuake is shaking of Earth's crsyt caused by the release of energry <span style="font-family: Verdana,Geneva,sans-serif;">Eruption of a volcano <span style="font-family: Verdana,Geneva,sans-serif;">The collapse of a cavern <span style="font-family: Verdana,Geneva,sans-serif;">The impact of of a meteor <span style="font-family: Verdana,Geneva,sans-serif;">Sudden movement along a plate boundary caused by the release of stress <span style="font-family: Verdana,Geneva,sans-serif;">Depth of Earthquakes: <span style="font-family: Verdana,Geneva,sans-serif;">Focus: the point on a fault plane at which the firs movenment occurs <span style="font-family: Verdana,Geneva,sans-serif;">Epicenter: The point on Earth's surface directly above the focus <span style="font-family: Verdana,Geneva,sans-serif;">Earthquake waves <span style="font-family: Verdana,Geneva,sans-serif;">three basic kinds of waves <span style="font-family: Verdana,Geneva,sans-serif;">P-waves (primary) back and forth wave motion can travel through any material; fastest <span style="font-family: Verdana,Geneva,sans-serif;">S waves (secondary)- side to side wave motion; can travel through solids but not through liquids or gases <span style="font-family: Verdana,Geneva,sans-serif;">L-waves (surface)- from when P and S waves reach the surface which move slowly like ripples on a pond; slowest <span style="font-family: Verdana,Geneva,sans-serif;">Locating the Earthquake: <span style="font-family: Verdana,Geneva,sans-serif;">Seismograph- The instrument that detetects and records earthquake waves <span style="font-family: Verdana,Geneva,sans-serif;">Seismogram- teh sheet which displays the zig-zag trace of earthquake waves <span style="font-family: Verdana,Geneva,sans-serif;">**P waves always arrive before S waves** <span style="font-family: Verdana,Geneva,sans-serif;">P and S wave arrival time difference can then be used to determine the distance from the Recording station to the epicenter <span style="font-family: Verdana,Geneva,sans-serif;">Triangulation- <span style="font-family: Verdana,Geneva,sans-serif;">When then use the epicenter distance from at least 3 recording stations to locate the epicenter <span style="font-family: Verdana,Geneva,sans-serif;">You need to measure the distance to scale and drawing a circle from each station. once 3 circles are drawn they will intersect are one common point. This location is the epicenter <span style="font-family: Verdana,Geneva,sans-serif;">The shadow zone is a wide belt around Earth on the side opposite the focus of the earthquake. Seismic stations receive nether P nor S waves <span style="font-family: Verdana,Geneva,sans-serif;">The cause of the shadow zone is the earths outer core. S-waves can not travel through the liquid outer core. While P waves are refracted (bent) in a smooth arc back to the surface <span style="font-family: Verdana,Geneva,sans-serif;">
 * <span style="font-family: Verdana,Geneva,sans-serif;"> Volcanism: **
 * <span style="font-family: Verdana,Geneva,sans-serif;"> Kind of Eruptions: **
 * <span style="font-family: Verdana,Geneva,sans-serif;"> Hot Spots: **
 * <span style="font-family: Verdana,Geneva,sans-serif;">Reasons why they occur: **
 * <span style="font-family: Verdana,Geneva,sans-serif;">Locating an Epicenter: **
 * <span style="font-family: Verdana,Geneva,sans-serif;">Shadow Zone: **