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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The Appalachians, the European Alps, and the Himalayas are examples of mountain ranges formed by
A) normal faults. B) divergent plate boundaries. C) faulting and folding. D) volcanic eruptions.
Every winter morning when the sun is shining bright, a man living in Montana pulls back the drapes on a large south-facing window. In this way, he helps heat his home using ________
A) passive solar heating B) radioactive solar heating C) conductive solar heating D) active solar heating
The process of redrawing legislative boundaries to benefit the party in power is called
A) gerrymandering. B) stacking votes. C) hanging chads. D) redlining. E) blockbusting.
Haze can scatter light from the rising or setting Sun in a way that produces bright light beams, called anticrepuscular rays, radiating across the sky
a. True b. False