Earth's interior, seismic evidence, crustal structure, plate tectonics, and mineral resources

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Geological activity Volcanism and plate tectonics may help recycle important materials and regulate atmospheric Page 15 of 45 carbon dioxide over long periods. Too much volcanic activity, however, can also create hazardous conditions. SPCE 70 Review Discussion Page 16 of 45 MODULE 3 THE STRUCTURE AND COMPOSITION OF THE EARTH AND MINERAL RESOURCES SPCE 70 Review Discussion Page 17 of 45 EARTH’S INTERIOR Scientists cannot directly observe most of Earth’s interior. Earth has a radius of approximately 6,371 kilometers, while the deepest human-made boreholes penetrate only a small part of the crust. The Kola Superdeep Borehole reached approximately 12.26 kilometers. Compared with Earth’s radius, this depth is extremely small. Therefore, direct drilling cannot provide samples from the mantle, outer core, or inner core. SPCE 70 Review Discussion Page 18 of 45 SCIENTIFIC EVIDENCES ABOUT EARTH’S INTERIOR 1. Direct Evidence Direct evidence comes from materials that scientists can physically collect and examine, such as: Surface rocks Mining and drilling samples Volcanic materials Xenoliths carried upward by magma 2. Indirect Evidence Indirect evidence includes: Seismic waves Earth’s gravitat...