Wegener and his Viewing the Nature of Continents - Thesis Example

1. Wegener wanted to prove that the continents were once joined and believed that the continents were able to push through the rock of the seafloor and resume their current position. He noted the coastline perimeters of South America and Africa and he discovered that mountains in South America and Africa and coal fields in Europe and North America matched or lined up. He also found matching reptilian fossils on both sides of the ocean which indicated the continents were once joined together. He also noted that the shallower an ocean, the younger its geological age. 2. A. We are able to determine information about the earth’s core through the study of the paths and characteristics of seismic waves from earthquakes and also through experiments on surface minerals and rocks at high pressure and temperatures. This core spins and creates the earth’s magnetic field. B. P waves and S waves are seismic waves that scientists use to allow them to study the inner core of the earth. Computer models along with seismological data allow scientists to study convection within the earth’s core. 3. A. When the rock is new, the grains may align themselves with the prevailing magnetic field; as the rock cools the grains are frozen and the sea floor expands. B. When the seafloor expands, the banding of rocks is striped with rock orientated in different directions. This proves that the magnetic poles have reversed many times. 4. Continental crust is lighter than oceanic crust and is granite while oceanic crust is basaltic. Oceanic crust subducts while continental crust does not. Oceanic crust is also much younger in geological age. 5. A. Subduction processes result in the melting of the mantle which produces a volcanic arc as lighter rock is forcibly submerged. B. 6. A. Divergent boundaries form rifts. B. As the plates spread apart, new crust is created. One theory for this is the push-pull theory and the other theory is convection. 7. In a reverse fault one side moves up and in a normal fault one side moves down. A normal fault is a fault in which the hanging wall has moved downward relative to the footwall. A reverse fault forms when the hanging wall moves up. Forces that create reverse faults are compressional while forces that create normal faults are extensional. 1. 2 A. Andean Mountains form along the Western side of the South American continent where the Nazca tectonic plate is colliding with the South American plate. B. Volcanoes form here because this is a subduction zone. 3. A. Viscosity of magma is controlled by the degree of silica content; higher silica will lead to higher viscosity. B. Higher silica magmas lead to more violent eruptions; basaltic magmas are much less viscous and tend to erupt and flow when erupted versus exploding. 4. Energy is stored in the rock as it deforms and when the forces exceed the strength of the rock along the fault, the fault will slip and the place where the fault slips first is the focus of the earthquake. 5. A. The wave slows down as it approaches the shore. B. The pressure forces the water up and increases the size of the wave. C. The force behind the wave becomes concentrated on a smaller area which results in higher pressure. 6. A Thermal expansion, wind erosion, biological weathering and pressure release. B. Thermal stress comes from expansion or contraction of rock which is caused by temperature changes. Repeated heating and cooling can cause outer layers to peel off in thin sheets. In pressure release overlying materials are removed, which causes underlying rock to expand and fracture parallel to the surface. Biological erosion occurs when plants and animals create chemical weathering through release of acidic compounds, most commonly are the release of chelating compounds. Erosion removes soil and rock by natural processes such as wind and then the soil and rock are deposited in other locations. 7. The reaction of carbonic acid with limestone. Carbonic acid is formed as rain passes through the atmosphere picking up CO2 which then dissolves in the water. Once it reaches the ground, it passes through the soil that can provide much more CO2 to form a carbonic acid solution which dissolves calcium carbonate. 8. The transport of wind, ice or water. Rainfall, vegetation, temperature, deforestation, and topography. 9. A Striations are scratches or gouges cut into bedrock by glacial abrasion. They are usually multiple, straight, and parallel. B. Striations represent the movement of the glacier using rock fragments and sand grains as cutting tools. 10. The ice age is attributed to several factors; atmospheric compositions, changes in the earth’s orbit around the sign also known as milankovitch cycles, the motion of tectonic plates resulting in changes in the relative location and amount of continental and oceanic crust on the earth’s surface, variations in solar output, orbital dynamics of the earth-moon system, large meteorites and super volcanoes. 1. Minerals are solid, inorganic, they have a definite chemical structure, are naturally occurring, and a crystalline structure. 2. A. Grains are known to be either euhedral or anhedral. Anhedral ones have no shape and euhedral ones show their true shape. B. Slower rates of cooling create larger crystals, rapid cooling allows little time for element accumulation in the crystal and crystal are smaller. 3. A. Ingenious, sedimentary and metamorphic B. Sedimentary rocks are secondary and the accumulation of small pieces of broken off rock; metamorphic rocks are found parallel to preexisting rock. 4. They are clastic, chemical or organic, make up the majority of the crust, and are secondary. 5. Organically, mechanically and chemically 6. Deposition of particles, compaction from overburden and lithostatic pressure, cementation of the particles by the precipitation of minerals out of the solution which surrounds the particles 7. Transform, divergent, convergent, and hot spots 8. Contact, dynamic, and regional 9. Recrystallization, phase change, neocrystallization, pressure solution and plastic deformation 1. They are abundant, easy to identify, short lived, widely distributed, and occur in many types of rocks. B. Sediment may contain the same species of fossil 2. Thermal deformation, recrystallization and foliation from heat and pressure make it difficult for the fossil to remain identifiable 3. A. This is the principle that answers to the past can be found in the present, meaning that everything is uniform in how it works. B. This helps geologists through the thought process of believing, so that rain would fall similarly as it did in the past. 4. A. The time it takes for half the atoms of that isotope to decay B. Carbon-14 5. A. Hydrogen, nitrogen, and helium B/C The addition of oxygen through the photosynthesis of cyanobacteria in the ocean’s surface zone, as oxygen levels raised molecules, rose to the stratosphere and reacted to form ozone, which shielded the lower atmosphere from ultraviolet light; this allowed life to evolve into higher forms in the ocean 6. The earth’s annual temperature shifted upwards and downwards, ice sheets begin to expand and diminish, widespread crop failure and loss of human life occurred during the most recent little ice age. Some tropics became both cooler and drier. 7. Satellite imagery shows a round crater at the coast of the Yucatan peninsula, an iridium layer that is 65 million years old coincides with the extinction of the dinosaurs; there is also evidence of a megatsunami that would have been caused by the impact because the asteroid crashed into the ocean. Debris and terrestrial rock have been far into what was the sea. 8. A. Temperatures on some islands has decreased from as low as 13 degrees to 4 degrees. The cretaceous period was considerably warmer and had a high degree of CO2, ocean temperatures also dropped. B. Rainfall increased and lush vegetation covered much of the earth, Benettitalean cycads, ferns, and tree ferns (leaves perched high atop thin trunks), conifers, and giant club moss dominated the forests and marshlands. 1. A. Photosynthesis B. Light energy is converted to chemical energy C. Fossil forms emerged when organisms died and were buried under layers of sediment and as sediment built up, this material transformed into hydrocarbons. 2. Animals may be killed and many trees burned 3. A. Ethanol and diesel B. Petroleum C. Most environmental problems can be traced to fossil fuels. 4. A. The number of people, other living organisms, or crops that a region can support without environmental degradation B. If the population exceeds the carrying capacity, unless the carrying capacity is only theoretical and thus in practice proven wrong, the ecosystem will slowly diminish. There wont be enough life forms to support the population and all life forms will die. 6. A. Natural resource reduction, not enough food, not enough space, wildlife reduction. B. The environment is affected through the use of fossil fuel and environmental pollutants which are needed to maintain the population Read More