Which of the following statements best describes Wegener’s idea of continental drift? Continents are subsiding into the seas. Global oceans were draining, which exposed stationary parts of the seafloor we now call continents. Continents were building up through sedimentation. Ancient organisms had undergone mass migrations to reach the continents where they are found today. Continents were formerly in different positions on the Earth and have shifted to their present locations over time. How was the fossil record of ancient life used to support Wegener’s hypothesis about Pangaea? Fossils of identical organisms were found on several continents, indicating the continents were once joined. Organisms used a series of islands to “leap frog” to another, stationary continent. The identical fossils are all marine fossils, indicating that the continents were all once covered by a global sea. Fossils are evidence of mass migrations of organisms in search of resources on other continents. Organisms on multiple continents independently evolved to have the same appearance.
Late Paleozoic sedimentary rocks often contain extensive coal seams that were used to support the existence of Pangaea. What would the climate have been at that time and at the location where the coal deposits were formed, and what would it indicate about the continent’s past latitude? When matching up once-joined continents such as South America and Africa, the coastlines do not fit together as nicely as the continental shelves. Why might this be the case? Separation of the continents resulted in deformation of the coastlines. Large volumes of sediment eroded from the continent fills in the gaps between the shelves. The coastlines have been altered by vast deposits of lava. The continental shelves are the edges of the continent. The shoreline simply shows where the sea level is in relation to topography. What evidence supports that the glaciers on the southern continents were once part of a single, massive ice sheet? Earth’s lithospheric plates are composed of crust and which of the following layers?
Which of the following processes can be observed at the margins of lithospheric plates? All of the responses are correct. In studies of rock obtained from ocean basins all over Earth, the oldest ages obtained are approximately 200 million years before the present. Why have no older oceanic rocks been discovered? Due to tectonic activity, rocks on the ocean floor are continually recycled. As the lithospheric plates move around, most of the ocean floor rocks are pushed up to form mountains. Scientists haven’t sampled enough sites to find older rocks. The age of Earth is 200 million years. Ocean floor is dispersed by volcanic eruptions. Currently the Juan de Fuca plate is interacting with the North American plate where inland volcanoes and deep focus earthquakes are occurring. What type of plate boundary is this? Where are tectonic plates located? What are the three types of plate boundaries? Which of the following statements about earthquakes with magnitude greater than 4.0 is most accurate?
Earthquakes with magnitude greater than 4.0 occur in a pattern than correlates closely with plate boundaries. Earthquakes with magnitude greater than 4.0 occur in a pattern than correlates loosely with plate boundaries. Earthquakes with magnitude greater than 4.0 occur in a pattern than correlates closely with hot spots. Earthquakes with magnitude greater than 4.0 occur in a pattern than correlates loosely with hot spots. Which plate boundary is NOT associated with volcanic eruptions? Which phenomenon can explain the presence of volcanoes in the middle of the Pacific Ocean? Which type of plate boundary is most closely associated with uplifting continental regions and mountain building? The convergent plate boundaries are formed when two lithospheric plates move toward each other. The nature of a convergent boundary depends on the type of plates that are converging. When two oceanic plates converge, the denser of the two subducts into the mantle. The subduction results in the partial melting of lithospheric rock above the area of subduction, leading to the formation of volcanoes. When an oceanic plate converges with a continental plate, the oceanic plate, being denser, subducts to form volcanic mountains. When two continental plates converge, neither of them subducts as they have a density that is much lower than the mantle, resulting in the formation of a collisional mountain chain. Identify each type of convergent plate boundary. Drag the appropriate convergence labels to their respective targets. Depending on the type of plate convergence, different features could result. Examples of these features include volcanic island arcs, continental volcanic arcs, and a collisional mountain chain.