ch 5-7

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Dec 6, 2023

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Chapter 5 2. List and explain the evidence presented by Wegener to support his continental drift hypothesis. This theory states that a super landmass called Pangaea broke apart and the minor land pieces (today's continents) moved to their present locations. For example, the presence of the same types of fossils in different continents or how coastlines fit together can be used as lines of evidence to support continental drift theory. Therefore the four types of evidence used by Wegener were climate clues, rock clues, fossil clues and coastlines. 5. Compare and contrast the three types of convergent plate boundaries and name a location where each type can be found. When oceanic and continental plates collide or converge, they often produce a young volcano after a long period of time. A subduction zone will be produced, because oceanic crust is denser compared to continental crust. When an oceanic plate collides with another oceanic plate it can manufacture a sort of volcanic island arcs or underwater volcanoes that will soon emerge as an island with volcanic peaks. Finally when a continental plate collides with another continental plate it produces mountains and mountain ranges. 7. List the evidence used to support the plate tectonics theory and briefly describe each. Coastlines on opposite continents appear to fit together like puzzle pieces, indicating that they were once joined. Rock and fossils found in South America match those found in Africa, although there is an ocean in between. This also indicates that the two continents were once joined. Other evidence of plate tectonics include Seafloor spreading, which involves the creation of new crust at divergent plate boundaries. 8. Describe the three ideas for WHY the lithosphere moves. There have been three mechanisms that cause the lithosphere to move, these are t hermal convection, ridge push, and slab pull. Chp 6 1. Define: earthquake, epicenter, and focus An earthquake is what happens when two blocks of the earth suddenly slip past one another. The focus is the place inside Earth's crust where an earthquake originates. The point on the Earth's surface directly above the focus is the epicenter .
4. Explain how scientists locate the epicenter of an earthquake. The difference in arrival time between the two types of seismic wave can be used to calculate the distance of the earthquake's epicenter from the seismometer, as the further away an earthquake is, the greater the lag time between the detection of the S waves relative to the P waves. 6. Compare and contrast brittle and ductile deformation. Brittle deformation generally is near the surface where there is less pressure and heat, while ductile deformation happens deep beneath the surface where heat and pressure is high. Brittle deformation is where rock fractures once its strength is surpassed, while ductile deformation is where a rock's size and shape changes without fracturing. 7. List and describe the major types of folds. There are three major types of rock folding: monoclines, synclines, and anticlines. An anticline consists of beds bent upwards with limbs dipping away from each other. A syncline consists of beds bent downwards with limbs dipping towards each other.This is a fold in which only one limb is bent. This is a case when a rock-bed bends abruptly and resumes the original attitude at the lower level. Chp7 1. Discuss the two different styles of volcanic eruptions. Volcanic eruptions can be explosive, sending ash, gas and lava high up into the atmosphere, or the magma can form lava flows, known as effusive eruptions 2. Discuss WHY some eruptions are explosive and others are effusive. This depends on how high or low the viscosity is. For example effusive eruptions involve the outpouring of basaltic magma that is relatively low in viscosity and in gas content. While explosive eruptions generally involve magma that is more viscous and has a higher gas content. 4. Describe the characteristics of a shield volcano. Shield volcanoes have a convex shape as they are flatter near the summit. Shield volcanoes are truly massive with volumes that dwarf other types of volcanoes, even large composite volcanoes. 5. Describe the characteristics of a composite volcano. Composite volcanoes are tall, symmetrically shaped, with steep sides, sometimes rising 10,000 feet high. They are built of alternating layers of lava flows, volcanic ash, and cinders.
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