EAPS 112 Final Exam Review Questions
& Answers 2023/2024
Understand the basics of how the solar system formed. - ANSWER-Big bang is the accepted manner for
the formation of the solar system
Understand the composition, physical, and mechanical properties of each of the Earth's layers -
ANSWER-Crust (mechanically rigid, composed of silicon/oxygen), mantle (mechanically molten), outer
core (liquid), inner core (solid)
What is the evidence for continental drift cited prior to the development of plate tectonic theory? Why
was this idea originally discredited? - ANSWER-Evidence for continental drift - similarity of rock
sequences and mountain range, glacial evidence where glaciers seemed to be connected, fossils appear
on two continents even though they are land-dwelling
A fundamental premise of plate tectonics is that the Earth's surface is made of distinct plates. What are
the kinds of evidence/observations led geoscientists to conclude this? - ANSWER-Paleometric studies
and earth's magnetic field leads geoscientists to conclude that the plate tectonic theory makes sense;
evidence of magnetic reversal in ancient lava flows. Additionally, earthquakes and volcanoes occur at
places where plate boundaries are postulated to exist
Where these plates interact (at their active boundaries) is where a significant fraction of the tectonic
activity occurs. There are 3 basic active plate boundaries types. What are they and how would you
describe the large-scale motions at each? - ANSWER-Divergent - plates move apart; convergent - plates
move toward each other; transform - move horizontally past each other
What does the orientation of volcanic island chains indicate? - ANSWER-Orientation of volcanic chains
indicates direction of plate movement where a plate is subducting
What is convection, how does it work (think of the analogies we used in class)? - ANSWER-Magma is
heated under the surface and so it rises to the top causing other crust to be pushed out of down cooling
and once the magma reaches the surface, it cools and sinks starting the size over again
,Why is convection relevant to plate tectonics? - ANSWER-Convection leads to plate movement because it
causes the creation of crust
Be able to identify and explain seafloor features and other tectonic elements on continent and relate
these to convection and plate tectonics. - ANSWER-Mid-ocean ridges indicate the presence of a
divergent plate boundary
What is the difference between relative and absolute (numerical) dating? - ANSWER-Relative dating is
the process of dating in relation to other rocks; absolute dating is the process of determining the exact
age of a rock
Using the principles of original horizontality, superposition, lateral continuity, cross-cutting relationships,
inclusions, and unconformities could you determine a relative sequence of events for a complicated
outcrop as we did in class and lab? - ANSWER-Original horizontality - rocks are originally deposited flat
lying
superposition - older rocks are deposited first so younger rocks will be deposited on top
lateral continuity - sediment extends laterally in all directions
cross cutting relationships - any rock boy crosscut by a something must be older than the cutting body
inclusion - any rock included as a clast must be older than the rocks that contain it
unconformity - gap in rock record where parts of the rock record has been removed by a period of
erosion rather than deposition
Why and/or how are geologic periods identified separately from one another? What types of things
cause geologists to differentiate one period of time from another? - ANSWER-periods are separated by
major changes in fossils; while new eras are begun often by an extreme event - most commonly an
extinction such as Great Dying, K-P extinction
What is an isotope? What is the difference between an unstable parent and stable daughter isotope? -
ANSWER-Isotope - a version of an atom of some element
Stable daughter isotope - result of decay from unstable parent
Given measurements of parent and daughter isotopes and knowledge of the half-life of a given
radioactive system, how can we calculate the age of a rock? - ANSWER-Calculate age of rock using
amounts of daughter isotopes and half-lives and easily can determine age of the rock
,What are common numerical dating methods discussed in class and in the text, and what are the types
of events that they are each dating (i.e., what starts the clock?) - ANSWER-Radiometric ages
Consistent Isotope Variations
Surface exposure dating
Dating of now-buried surfaces
What is the exact definition of a mineral? - ANSWER-Mineral - solid, inorganic, naturally occurring,
ordered internal structure, specific chemical composition
What are the major kinds of rock-forming mineral families? - ANSWER-Carbonates (ex: limestone) and
silicates; also oxides, halides, sulfates
What kinds of elements are found in the crust and mantle, and what are the really major components? -
ANSWER-Crust - mostly composed of oxygen and silicon, and to a lesser extent aluminum
Mantle is composed of minerals like olivine and pyroxene
What are silicate minerals and why are they important? - ANSWER-Silicate minerals - formed form basic
SiO4 tetrahedron and are the fundamental building block of rock material
If there is more silica present it will attempt to bond to itself
What basic structure do Si and O take in silicate minerals? - ANSWER-Basic structure is a tetrahedron
What is the silica tetrahedron, and how do they combine in different structures as silica content is
increased? - ANSWER-Independent tetrahedra --> link up tetrahedra to form single chains --> more
linking to form double chains --> chains link up to form sheet silicates --> sheets bond with other
elements to form framework silicates
What is a rock? How is this idea related to "mineral"? - ANSWER-Rock - naturally forming, consolidated
material, composed of one or more minerals
, What is the Rock Cycle? What are the three basic types of rocks and how do they fit into the Rock Cycle?
How does plate tectonics affect the Rock Cycle? - ANSWER-Sedimentary rocks are buried and then
deformation and metamorphism leads to the creation of metamorphic rocks --> full melting followed by
solidification and uplift creates igneous rocks --> these rocks are weathered and eroded and transported
to regions where they are deposited as sedimentary rocks and the CYCLE BEGINS AGAIN
What is magma? How is this different from lava? What is the difference between plutonic and volcanic
rocks? - ANSWER-Magma is below ground, lava is above ground; plutonic rocks cool beneath the surface,
volcanic rocks cool at the surface
What is a pluton? A batholith? A dike, or a sill? - ANSWER-pluton is a medium to large body of plutonic
rock; batholith - massive rock body composed of many plutons; dike - volcanic intrusion that cuts
through a rock; sill - sheet intrusion of volcanic rock
Why does crystal size increase with cooling time, and what does this tell you about the history of a given
igneous rock body? - ANSWER-Crystal size increases with cooling time because rocks can grow as they
cool slowly therefore if a rock has larger crystals it means that it likely cooled under ground of many
thousands of years
What are the characteristics of mafic, intermediate, and felsic igneous rocks? Understand their names,
the relative silica content, and basic compositional differences. - ANSWER-a. Felsic: (>65% silica)
i. Plutonic - ex: granite
ii. Volcanic - ex: rhyolite
b. Intermediate
i. Plutonic - ex: diorite
ii. Volcanic - ex: andesite
c. Mafic:
i. Plutonic - ex: gabbro
ii. Volcanic - ex: basalt
d. Ultramafic: (<45% silica)
i. Plutonic - ex: peridotite
ii. Volcanic - komatiite
e. Darker rocks are more mafic; lighter rocks are more felsic
& Answers 2023/2024
Understand the basics of how the solar system formed. - ANSWER-Big bang is the accepted manner for
the formation of the solar system
Understand the composition, physical, and mechanical properties of each of the Earth's layers -
ANSWER-Crust (mechanically rigid, composed of silicon/oxygen), mantle (mechanically molten), outer
core (liquid), inner core (solid)
What is the evidence for continental drift cited prior to the development of plate tectonic theory? Why
was this idea originally discredited? - ANSWER-Evidence for continental drift - similarity of rock
sequences and mountain range, glacial evidence where glaciers seemed to be connected, fossils appear
on two continents even though they are land-dwelling
A fundamental premise of plate tectonics is that the Earth's surface is made of distinct plates. What are
the kinds of evidence/observations led geoscientists to conclude this? - ANSWER-Paleometric studies
and earth's magnetic field leads geoscientists to conclude that the plate tectonic theory makes sense;
evidence of magnetic reversal in ancient lava flows. Additionally, earthquakes and volcanoes occur at
places where plate boundaries are postulated to exist
Where these plates interact (at their active boundaries) is where a significant fraction of the tectonic
activity occurs. There are 3 basic active plate boundaries types. What are they and how would you
describe the large-scale motions at each? - ANSWER-Divergent - plates move apart; convergent - plates
move toward each other; transform - move horizontally past each other
What does the orientation of volcanic island chains indicate? - ANSWER-Orientation of volcanic chains
indicates direction of plate movement where a plate is subducting
What is convection, how does it work (think of the analogies we used in class)? - ANSWER-Magma is
heated under the surface and so it rises to the top causing other crust to be pushed out of down cooling
and once the magma reaches the surface, it cools and sinks starting the size over again
,Why is convection relevant to plate tectonics? - ANSWER-Convection leads to plate movement because it
causes the creation of crust
Be able to identify and explain seafloor features and other tectonic elements on continent and relate
these to convection and plate tectonics. - ANSWER-Mid-ocean ridges indicate the presence of a
divergent plate boundary
What is the difference between relative and absolute (numerical) dating? - ANSWER-Relative dating is
the process of dating in relation to other rocks; absolute dating is the process of determining the exact
age of a rock
Using the principles of original horizontality, superposition, lateral continuity, cross-cutting relationships,
inclusions, and unconformities could you determine a relative sequence of events for a complicated
outcrop as we did in class and lab? - ANSWER-Original horizontality - rocks are originally deposited flat
lying
superposition - older rocks are deposited first so younger rocks will be deposited on top
lateral continuity - sediment extends laterally in all directions
cross cutting relationships - any rock boy crosscut by a something must be older than the cutting body
inclusion - any rock included as a clast must be older than the rocks that contain it
unconformity - gap in rock record where parts of the rock record has been removed by a period of
erosion rather than deposition
Why and/or how are geologic periods identified separately from one another? What types of things
cause geologists to differentiate one period of time from another? - ANSWER-periods are separated by
major changes in fossils; while new eras are begun often by an extreme event - most commonly an
extinction such as Great Dying, K-P extinction
What is an isotope? What is the difference between an unstable parent and stable daughter isotope? -
ANSWER-Isotope - a version of an atom of some element
Stable daughter isotope - result of decay from unstable parent
Given measurements of parent and daughter isotopes and knowledge of the half-life of a given
radioactive system, how can we calculate the age of a rock? - ANSWER-Calculate age of rock using
amounts of daughter isotopes and half-lives and easily can determine age of the rock
,What are common numerical dating methods discussed in class and in the text, and what are the types
of events that they are each dating (i.e., what starts the clock?) - ANSWER-Radiometric ages
Consistent Isotope Variations
Surface exposure dating
Dating of now-buried surfaces
What is the exact definition of a mineral? - ANSWER-Mineral - solid, inorganic, naturally occurring,
ordered internal structure, specific chemical composition
What are the major kinds of rock-forming mineral families? - ANSWER-Carbonates (ex: limestone) and
silicates; also oxides, halides, sulfates
What kinds of elements are found in the crust and mantle, and what are the really major components? -
ANSWER-Crust - mostly composed of oxygen and silicon, and to a lesser extent aluminum
Mantle is composed of minerals like olivine and pyroxene
What are silicate minerals and why are they important? - ANSWER-Silicate minerals - formed form basic
SiO4 tetrahedron and are the fundamental building block of rock material
If there is more silica present it will attempt to bond to itself
What basic structure do Si and O take in silicate minerals? - ANSWER-Basic structure is a tetrahedron
What is the silica tetrahedron, and how do they combine in different structures as silica content is
increased? - ANSWER-Independent tetrahedra --> link up tetrahedra to form single chains --> more
linking to form double chains --> chains link up to form sheet silicates --> sheets bond with other
elements to form framework silicates
What is a rock? How is this idea related to "mineral"? - ANSWER-Rock - naturally forming, consolidated
material, composed of one or more minerals
, What is the Rock Cycle? What are the three basic types of rocks and how do they fit into the Rock Cycle?
How does plate tectonics affect the Rock Cycle? - ANSWER-Sedimentary rocks are buried and then
deformation and metamorphism leads to the creation of metamorphic rocks --> full melting followed by
solidification and uplift creates igneous rocks --> these rocks are weathered and eroded and transported
to regions where they are deposited as sedimentary rocks and the CYCLE BEGINS AGAIN
What is magma? How is this different from lava? What is the difference between plutonic and volcanic
rocks? - ANSWER-Magma is below ground, lava is above ground; plutonic rocks cool beneath the surface,
volcanic rocks cool at the surface
What is a pluton? A batholith? A dike, or a sill? - ANSWER-pluton is a medium to large body of plutonic
rock; batholith - massive rock body composed of many plutons; dike - volcanic intrusion that cuts
through a rock; sill - sheet intrusion of volcanic rock
Why does crystal size increase with cooling time, and what does this tell you about the history of a given
igneous rock body? - ANSWER-Crystal size increases with cooling time because rocks can grow as they
cool slowly therefore if a rock has larger crystals it means that it likely cooled under ground of many
thousands of years
What are the characteristics of mafic, intermediate, and felsic igneous rocks? Understand their names,
the relative silica content, and basic compositional differences. - ANSWER-a. Felsic: (>65% silica)
i. Plutonic - ex: granite
ii. Volcanic - ex: rhyolite
b. Intermediate
i. Plutonic - ex: diorite
ii. Volcanic - ex: andesite
c. Mafic:
i. Plutonic - ex: gabbro
ii. Volcanic - ex: basalt
d. Ultramafic: (<45% silica)
i. Plutonic - ex: peridotite
ii. Volcanic - komatiite
e. Darker rocks are more mafic; lighter rocks are more felsic
