VOLCANOES PLUTONS AND IGNEOUS ROCKS ACTUAL TEST PAPER COMPLETE QUESTIONS AND ANSWERS FULL SOLUTION

VOLCANOES PLUTONS AND IGNEOUS
ROCKS ACTUAL TEST PAPER COMPLETE
QUESTIONS AND ANSWERS FULL
SOLUTION

●● Which of the following textures indicates that a rock is volcanic in
origin?
Answer: Aphanitic


●● Which igneous texture has visible crystals that are a few millimeters
across?
Answer: Phaneritic


●● What is the geologic definition of texture?
Answer: Size, shape, and arrangement of mineral grains in the sample


●● What creates the small holes found in a vesicular texture?
Answer: Volatiles


●● What substance makes ion migration easier in the later stages of
magma crystallization, which allows abnormally large mineral crystals
to form and create pegmatites?
Answer: water

, ●● Which of the following best describes a pegmatitic texture?
Answer: Large crystals that form in a fluid-rich environment late in
crystallization


●● has a large percentage of voids and is lightweight, so therefore has
the ability to float in water.
Answer: pumice


●● An igneous rock with a ______ texture solidified deep within Earth.
Answer: Phaneritic


●● What factors influences the texture of an igneous rock?
Answer: -the rate at which the rock cools,
-the amount of silica that is present in the magma from which it forms,
and
-the amount of dissolved gases present in said magma


●● How do crystals in pegmatite grow so large?
Answer: Large crystals in pegmatites are the result of a high percentage
of the melt being composed of water, carbon dioxide, and other
materials. These materials enhance ion migration, allowing the crystals
to grow larger than usual.