EAPS 106 Exam 1
The earth's four layers and their thicknesses - answer crust: radius = 6371 km,
thickness = 35 km
mantle: radius = 6336 km, thickness = 2850 km
outer core: radius = 3486 km, thickness = 2270 km
inner core: radius = 1216 km, thickness = 1216 km
How did Earth acquire its internal heat? - answer The process of planet accretion results from lots of collisions, each producing heat. Combined with heat from the decay radioactive elements, the interiors of all new planets become so hot inside that they melt.Earth will never lose its heat prior to the Sun going Red Giant stage Why is the interior of Earth layered? - answer When everything was melted, the dense elements like iron sank to the center forming an iron core, and the lighter elements like silicon and oxygen rise to form a rocky mantle and crust. Process is called differentiation. (spinning water bottle experiment) Why is the outer core a liquid and the inner core a solid? - answerThe outer layer is the only layer that remains hotter than its melting temperature. The inner core is at a higher temperature, but the melting temperature is also higher due to the greater pressure at the increased depth.What are the lithosphere and asthenosphere? - answerLithosphere is a strong outer shell of the Earth consisting of the cold crust and uppermost mantle. The breaking of the lithosphere into pieces or "plates" and the manner in which they move around the surface of the Earth gives rise to the term "plate tectonics".The asthenosphere underlies the lithosphere and is hot enough to flow like a fluid (even though it remains a solid). It is the weakness of the asthenosphere that allows tectonic plates to slide around the surface of the Earth.What evidence did Wegner use to suggest that the continents drift? - answerNorth and South America coastlines fit with Europe and Africa Identical volcanic flows appear on both sides of the Atlantic Fossils of non-swimmers found on both sides of the modern oceans How do we know that our magnetic field has reversed itself many times? - answerCrystals in lava record the direction to the magnetic poles at the time of each 1 / 2
eruption, There are also magnetic lineations on the seafloor that show new oceanic plates are created at mid ocean ridges, giving more evidence of continental drift.
Black bands: normal magnetic field
White bands: reversed magnetic field
Big bands - no volcanic rocks to date What is a mid-ocean ridge, a subduction zone, and a transform plate boundary - answerMid ocean ridges are places where magma comes up and forms new oceanic plates. They're referred to as divergent margins since the plates move away from each other.Subduction zones are the most important tectonic feature on Earth. Their relative motion gives rise to the highest mountains, the deepest valleys, the most active volcanoes, and the largest earthquakes. Oceanic plates get recycled back into the mantle at subduction zones, allowing continents to drift over the ocean basins.Subduction zones are referred to as convergent margins since the plates move toward each other.Transform plate boundaries are where two plates laterally slide past each other.What is a passive plate margin? - answerWhen a boundary between continental crust and oceanic crust is not a plate boundary, it is referred to as a passive margin. Passive margins are the locations where a continent split into two and an oceanic plate grew between them as the two parts drifted away from each other.What kind of plate boundary is the San Andreas Fault? - answerTransform plate boundary Where is Hawaii located relative to plate boundaries? - answerHawaii is located on the Pacific plate near the center which is far from the plate boundaries.Note: Volcanoes exist here because it's a hot spot not because of a plate boundary.What is a supercontinent? - answerA supercontinent is many continents joined as one.How did plate tectonics influence the evolution of whales and dolphins? - answerThe evolution of dolphins and whales appears tied to the shallowing of the Tethys Sea when India collided into Asia.What are the basic processes of conduction, convection, and radiation? - answerConvection: Heat transfer through fluid motions of liquids and gases, as well as solids that flow like a fluid (which is referred to as solid state convection).Conduction: Heat transfer through a solid through the spread of vibrations on the atomic scale.
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