Critical Thinking
Applying Concepts New oceanic crust is being produced in the Pacific Ocean due to a mid-ocean ridge that runs along the ocean floor. But the Pacific Ocean is not getting bigger. What must be happening in the Pacific Ocean?
Inferring How do scientists know about the structure and composition of Earth's interior?
Comparing and Contrasting What is the difference between magma and lava?
Analyzing Data
Use the graph below to answer Questions 27–29.
Using Graphs An earthquake occurs 2000 km from seismograph station A. How much later does the first P wave arrive at the station? How much later does the first S wave arrive?
Calculating What is the difference in time between the arrivals of the first P wave and the first S wave at station A?
Drawing Conclusions The first P waves of the earthquake arrived at seismograph station B about 2 minutes before the first S waves arrived. How far is seismograph station B from the epicenter of the earthquake?
Concepts in Action
Classifying A piece of the metamorphic rock gneiss is formed when a chain of mountains is created. The pressure and temperature surrounding the rock increase so that the gneiss melts completely and then hardens again. Is the new rock still considered a metamorphic rock? Explain.
Hypothesizing The fossils of tropical plants and animals have been found in Antarctica. Using your knowledge of plate tectonics, provide a possible explanation for this observation.
Applying Concepts When the volcano Krakatoa erupted in the 1880s, the eruption released so much volcanic ash into the atmosphere that temperatures temporarily cooled worldwide. Do you think that Krakatoa's eruption involved low-silica magma or high-silica magma? Explain.
Writing In Science Imagine you had to give a presentation on plate tectonics to a group of scientists who were still skeptical about the theory. Organize your talk into sections with the main points and evidence to support them. Be convincing.
Performance-Based Assessment
Classifying Gather about a dozen different local rock and mineral samples. Classify and identify each sample. Present your findings about your collection of rocks and minerals to the class. Indicate how you identified some of the more difficult samples.
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