Examine the cross section through a hypothetical ocean basin. Use the magnetic time scale at left to determine when continents A and B separated from one another. Justify your answer
What will be an ideal response?
Answer: Each side of the oceanic ridge shows the same pattern, but the left side is a mirror image of the right. Crust closer to the ridge is younger. It shows a "normal" magnetic polarity, and then there is a thin red ("reversed" polarity) stripe, a thinner white stripe (the Jaramillo normal subchron, and then a thicker red stripe (middle of the Matuyama reversed chron, and then another thin white stripe next to the continental crust. This last one must be the Olduvai normal subchron, which is 2 million years old. Therefore, the continents separated, and seafloor spreading initiated, around 2 million years ago.
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Which of the following occurred during the post-Soviet era of development?
A) an emphasis on oil and natural gas exports B) the creation of the Volga-Don Canal C) the completion of the BAM railroad link across Siberia D) a massive emphasis on clear-cutting of taiga forests to increase wood exports E) steel industry development
What texture is displayed by the igneous rock in this photograph?
A. breccia B. porphyritic C. glassy D. vesicles E. None of these choices are correct.
Much of what we know about the internal structure and composition of Earth has come from the study of ____
a. satellite imagery b. seismic waves c. volcanic eruptions d. Mars e. deep-ocean sediments
Studying or classifying climate requires data of no less than ________
A) several weeks B) 1 year C) 5 years D) several decades E) 100 years