Why don't all magmas erupt?
What will be an ideal response?
Answer: When rocks partially melt, the resulting liquid magma is less dense than the remaining solids and rises. If, however, the magma encounters less dense rock as it ascends toward the surface, then the magma stalls and crystallizes. Rock temperature decreases as magma moves near the surface. If magma does not rise quickly, then its heat is conducted to surrounding rocks and the melt cools and crystallizes before it can erupt on the surface. Most water-rich magma crystallizes below ground because the magma solidifies as it releases dissolved water at shallow depths.
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a. True b. False
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A) normal faults. B) divergent plate boundaries. C) faulting and folding. D) volcanic eruptions.
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A) passive solar heating B) radioactive solar heating C) conductive solar heating D) active solar heating
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A) gerrymandering. B) stacking votes. C) hanging chads. D) redlining. E) blockbusting.