GEO 401 EXAM 2 2025/2026 QUESTIONS
AND ANSWERS 100% PASS
The Earth's upper mantle is mainly made of peridotite, an ultramafic igneous rock with lots of
olivine crystals. Which type of magma can be produced when the upper mantle undergoes
decompression melting of the upper mantle peridotite at mid-ocean ridges? - ANS Basaltic
Seismic studies of the earth have shown that the platnet's interior is made of a few layers with
distinct seismic signatures and chemical compositions. The major layers of the planet include
(from innermost to the outermost layers) ____________. - ANS inner core, outer core,
mantle, crust
Melting occurs when a solid (rock) becomes a liquid (melt: magma). There are a number of
pressure, temperature, and compostioinal conditions that can cause a rock to melt. Which one
of the following conditions can cause a rock to melt in the Eath's deep interior? - ANS All of
the above
-addition of volatiles such as water inti the rock
- decompression (a decrease in pressure)
- and increase in temperature
The mineralogy of terrestrial planets evolves as a consequence of a range of physical, chemical,
and biological processes. Based on the statement, the number of minerals in the Earth would
________ as the planet evolves through time. - ANS increase
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, Which of the following metamorphic facies represents the highest temp? - ANS Granulite
A geothermometer is ____________. - ANS a mineral assemblage that reveals the maximum
temp attained by a rock
A number of geological principles such as Principle of Superpostion, Principle of Original
Horizontality, and Principle of Faunal Succession have been used to understand geological
records in rock formations. Based on these principles, which one of the following statements is
TRUE? - ANS In a sequence of undisturbed layered rock, the oldest rocks are on the bottom
Fossils are most common in which types of rocks? - ANS sedimentary
Unconformity is the surface between two layers that were laid down in a broken sequence.
Which of the following statements about the unconformity are TRUE? - ANS All of the Above
- Angular unconformity is an unconformity in which younger sediments rest upon the eroded
surface of tilted or folded older rocks
- Disconformity is an unconformity between beds that are parallel
- Nonconformity is an unconformity between stratified rocks above and unstratified igneous or
metamorphic rocks below
The principle of superposition states that _______________. - ANS undisturbed sedimentary
layers get progressively younger from bottom to top
Which of the following radioactive isotopes is the most useful for dating very young (<10,000
years old) wood and charcoal? - ANS carbon-14
A rock formed with 100 atoms of a radioactive parent element but contains only 25 radioactive
parent atoms today. Let's assume that the rock did not contain any daughter isotopes to start
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
AND ANSWERS 100% PASS
The Earth's upper mantle is mainly made of peridotite, an ultramafic igneous rock with lots of
olivine crystals. Which type of magma can be produced when the upper mantle undergoes
decompression melting of the upper mantle peridotite at mid-ocean ridges? - ANS Basaltic
Seismic studies of the earth have shown that the platnet's interior is made of a few layers with
distinct seismic signatures and chemical compositions. The major layers of the planet include
(from innermost to the outermost layers) ____________. - ANS inner core, outer core,
mantle, crust
Melting occurs when a solid (rock) becomes a liquid (melt: magma). There are a number of
pressure, temperature, and compostioinal conditions that can cause a rock to melt. Which one
of the following conditions can cause a rock to melt in the Eath's deep interior? - ANS All of
the above
-addition of volatiles such as water inti the rock
- decompression (a decrease in pressure)
- and increase in temperature
The mineralogy of terrestrial planets evolves as a consequence of a range of physical, chemical,
and biological processes. Based on the statement, the number of minerals in the Earth would
________ as the planet evolves through time. - ANS increase
1 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
, Which of the following metamorphic facies represents the highest temp? - ANS Granulite
A geothermometer is ____________. - ANS a mineral assemblage that reveals the maximum
temp attained by a rock
A number of geological principles such as Principle of Superpostion, Principle of Original
Horizontality, and Principle of Faunal Succession have been used to understand geological
records in rock formations. Based on these principles, which one of the following statements is
TRUE? - ANS In a sequence of undisturbed layered rock, the oldest rocks are on the bottom
Fossils are most common in which types of rocks? - ANS sedimentary
Unconformity is the surface between two layers that were laid down in a broken sequence.
Which of the following statements about the unconformity are TRUE? - ANS All of the Above
- Angular unconformity is an unconformity in which younger sediments rest upon the eroded
surface of tilted or folded older rocks
- Disconformity is an unconformity between beds that are parallel
- Nonconformity is an unconformity between stratified rocks above and unstratified igneous or
metamorphic rocks below
The principle of superposition states that _______________. - ANS undisturbed sedimentary
layers get progressively younger from bottom to top
Which of the following radioactive isotopes is the most useful for dating very young (<10,000
years old) wood and charcoal? - ANS carbon-14
A rock formed with 100 atoms of a radioactive parent element but contains only 25 radioactive
parent atoms today. Let's assume that the rock did not contain any daughter isotopes to start
2 @COPYRIGHT 2025/2026 ALLRIGHTS RESERVED.
