Final Flashcards
When light rays are split into two parts as they enter a crystal it is called?
double refraction
What is the ability of a mineral to resist scratching called?
hardness
How many minerals are referred to as rock forming minerals?
8
Which of the following was NOT a property used to identify minerals in the “Mineral Identification” lab?
Density
Which of the following minerals is a mineral that acts as a magnet?
magnetite
How many kinds of minerals have scientists identified?
about 3000
The easiest way to observe the streak of a mineral is to
rub some mineral against the streak plate
When magma cools quickly, _______ crystals form, and when it cools slowly, ________ crystals form.
small, large
The color of a mineral in powdered form is called the mineral’s
streak
Cleavage is the tendency of a mineral to
split along specific planes, forming flat surfaces.
Which of the following is a question that scientists would ask to determine if a substance is a mineral?
Does the substance occur naturally?
A mineral is a natural solid that usually is
inorganic, with characteristic physical properties.
Density is the ratio of
the mass of a substance to the volume of the substance
The words uneven and splintery describe a mineral’s
fracture
The hardest mineral on the Mohs hardness scale is
diamond
What mineral property involves iron
magnetism
The word waxy, pearly, and dull describe a mineral’s
luster
A _______ is a solid in which the atoms are arranged in repeating patterns.
crystal
Which of the following is NOT one of the four criteria for determining whether or not a substance is a mineral?
it has a shiny surface
A mineral is described as fluorescent when it
it glows under uv light
If a mineral has unrestricted space to grow, what size crystals will develop?
large crystals
What mineral is the softest on Mohs hardness scale
talc
Light that is reflected from a mineral’s surface is called
luster
What mineral fizzes when it comes into contact with hydrochloric acid?
calcite
Color alone is generally
not a reliable clue for identifying a mineral sample.
What kind of streak do metallic minerals generally have?
dark
Which of the following groupings list only minerals?
sulfur, quartz and talc
The common minerals are called
?
What are the two main lusters of minerals that we used in class?
metallic and non metallic
Which of the following is NOT one of the three major types of rocks?
obsidian
Magma forms when rock
melts
Which of the following is NOT a type of sedimentary rock?
volcanic
Most metamorphic rock forms as a result of
regional metamorphism.
One reason that minerals precipitate is because of
evaporation
Which of the following is NOT a type of clastic rock?
fossil
The process by which different minerals melt at different temperatures is called
partial melting.
Sedimentary rock that forms when minerals precipitate from a solution or settle from a suspension is called
chemical sedimentary rock.
The first minerals to melt have the
lowest melting point.
Rock that is formed from magma that is light in color and contains a lot of silica is known as
felsic rock.
How does the cooling process of magma compare with the melting process?
The cooling process is the reverse of the process of partial melting.
Which of the following does NOT change the form of existing rock?
light
What type of sedimentary rock is composed of angular fragments
breccia
The solid part of Earth is made up of material called
rock
Adding fluids to hot rock generally
decreases the melting point of certain minerals in the rock.
What type of sedimentary rock is formed from minerals that were once dissolved in water?
chemical
Magma or igneous rock that is rich in feldspar and silica is
felsic
Which of the following is not a type of metamorphism?
geochemical metamorphism
An example of a nonfoliated rock used as a building or sculpting material is
marble
Which type of rock forms from cooled molten rock?
igneous
Which of the following does NOT change the form of existing rock?
light
Two examples of chemical sedimentary rocks are
gypsum and halite.
The series of changes that describes how geologic forces cause rock to change from one type to another is known as
rock cycle
Sedimentary rock that is made up of rock fragments that become compacted or cemented together is
clastic
Intrusive igneous rocks are characterized by a coarse-grained texture because they contain
large crystals.
The crystallization and removal of different minerals from cooling magma is called
fractional crystallization.
The process in which one type of rock changes into another type of rock because of chemical processes or changes in temperature and pressure is called
metamorphism.
What type of rock texture results when extreme pressure causes minerals in metamorphic rock to realign, or when minerals separate out into dark and light bands?
foliated
As temperature drops, the first minerals to crystallize from magma have
the highest freezing point.
What are four factors that determine whether rock melts?
Heat, pressure, mineral content, and the presence of fluid.
Rock melts when
its temperature rises above the melting point of minerals in the rock.
Which of the following is NOT an igneous texture?
felsic
Light-colored igneous rocks are generally part of the
felsic family.
In regional metamorphism, the change in rocks is the result of
changes in temperature and pressure over a large area.
The idea that states that if sedimentary rock is left undisturbed will remain in horizontal layers is called
original horizontality
Why is radioactive decay used to determine the absolute age of rocks?
Radioactive decay happens at a relatively constant rate.
If the percentage of daughter isotopes present in a radioactive sample is greater than the percentage of parent isotope,
the rock is older.
The half life of U-238 is 4.5 billion years. How many years would 16 g of U-238 take to decay into 0.5g of U-23 and 15.5g of daughter products?
22.5 billion years
Scientists can assume that sedimentary rock layers that are not horizontal have been tilted or deformed by crustal movements after the layers formed by using the
Principal of Original Horizontality
Carbon-14 is an isotope
used to date objects less than 60,000 years old.
Relative age:
is the age of an object in relation to other objects.
Geologists estimate that the earth is about
4.6 byo
In radiometric dating, scientists compare the proportion of a radioactive parent isotope to a stable
daughter isotope.
What is the name of the Scottish scientist who came up with the idea of uniformitarianism?
James Hutton
The principle of uniformitarianism states that
current geologic processes can explain past processes.
The numeric age of an object is called
absolute age.
Which of the following is NOT a criteria for a fossil to be considered an index fossil?
The organisms from which the fossil formed must have lived during a long span of geologic time.
Methods for absolute dating of an object or event include:
studying ice cores
varve count
studying tree rings
Index fossils found in rock layers in different areas of the world indicate that the rock layers
formed during the same period of time.
If an igneous intrusion is observed through a layer of sedimentary rock, what geological law applies?
law of crosscutting relationships
The principle that Earth’s history can be explained by current geologic processes is
uniformitarianism.
Organisms that formed index fossils
lived during short spans of geologic time.
How is radioactive decay used to determine the absolute age of rocks?
Parent isotopes are compared to daughter isotopes.
Which is the smallest division of geologic time?
epoch
Fragments of existing rocks incorporated into other layers of rock are called
inclusive rocks
How many half-lives would be necessary for a sample of parent isotopes to decay to the point that only one-fourth of the sample is composed of parent isotopes?
2
What geologic unit of time is longer than an epoch but shorter than an era?
period
Younger layers of undisturbed sedimentary rock are above older layers according to
law of superposition.
A fault or body of rock is younger than any other body of rock it cuts through according to the law of
crosscutting relationships.
What isotope of carbon is used for radiometric dating?
carbon 14
The age of an object in relation to the ages of other objects is
relative age
The following lists the eons of geologic time in order from oldest to most recent
Hadean, Archean, Proterozoic, Phanerozoic
The scale that outlines the development of Earth and the life on Earth is called the:
Geologic time scale
A varve is most like a(n)
tree ring.
What is the study of the alignment of magnetic minerals in rock, specifically as it relates to the reversal of Earth’s magnetic poles; also the magnetic properties that rock acquires during formation?
Paleomagnetism
Which of the following plate boundaries are responsible for the formation of volcanic islands?
oceanic-oceanic convergent boundary
An example of a transform boundary is the
San Andreas Fault in California.
To map the ages of sea-floor rocks, scientists use
isochrons
Which of the following was NOT a piece of evidence Wegener found to support his hypothesis?
tracks of continents plowing through ocean floor rock
The Himalayan Mountains were formed in a collision at a
convergent boundary.
What is the theory that explains how large pieces of lithosphere, called plates, move and change shape?
Plate tectonics
Who proposed the idea of continental drift?
Alfred Wegener
The force exerted by the leading edge of a subducting plate is
slab pull
Wegener’s hypothesis on continental drift was strongly opposed by other scientists because
he proposed that the continents moved by plowing through the ocean floor.
Modern climates are a result of past movements of
tectonic plates.
What is the process by which new oceanic lithosphere (sea floor) forms as magma rises to Earth’s surface and solidifies at mid-ocean ridge?
Sea-floor spreading
The deepest deep-sea trench is called
mariana trench
The types of plate boundaries include
convergent divergent transform
Wegener’s hypothesis of continental drift was finally confirmed by
evidence supporting the idea of sea-floor spreading.
The most conclusive proof for continental drift was provided by
evidence of sea-floor spreading.
What is the region along a plate boundary where one plate moves under another?
subduction zone
Magnetic patterns on the ocean floor were puzzling because they
showed alternating bands of normal and reversed polarity.
What was Alfred Wegener’s big idea?
Continental drift
The location of plate boundaries can be identified by studying:
volcanoes and eartnquakes
At the center of a mid-ocean ridge is a(n)
rift
What new technology enabled scientists to map and discover new features on the ocean floor?
Sonar
Tectonic plates are blocks of
lithosphere
Frequent earthquakes in an area may indicate
tectonic plate boundaries.
What occurs at a transform boundary?
Two plates slide past each other horizontally.
Convection, ridge push, and slab pull work together to produce
constant tectonic plate motion.
Scientists discovered that the oldest rocks on the ocean floor were
180 myo
What often forms when continents collide?
major mountain chains
Scientists used the pattern of alternating normal and reversed polarity in rocks to create the geomagnetic
reversal time scale.
The theory that explains why and how continents move is called
plate tectonics.
Magma that is rich in feldspar and silica is called
felsic
What type of fault would you most likely see tension strain?
Normal
Vibrations in Earth that are caused by the sudden movement of rock are called
earthquake
What percentage of volcanic activity occurs far away from plate boundaries?
5
S waves travel
only through solids.
Scientists use the S-P travel time chart to determine the __________ of an earthquake.
distance to the epicenter
The majority of Earth’s mantle is made up of
solid rock
Which of the following is NOT a major volcanic area?
central continental plains
What causes magma to rise upward in a mantle plume?
The magma is less dense than the surrounding material.
An area of volcanic activity far from a tectonic plate boundary is called a(n)
hot spot.
Which of the following is the correct sequence of events leading to and after an earthquake?
stress, strain, elastic deformation, plastic deformation
Island arcs form when oceanic lithosphere subducts under
oceanic lithosphere.
Quiet eruptions
occur from magma that has a low viscosity.
Lava erupts through an opening in Earth’s crust called a
vent
Which type of volcanism produces the most lava annually?
divergent
To locate the epicenter of earthquakes, scientists use computers to
perform triangulations based on data from seismograph stations.
Which of the following is NOT a condition needed for magma to form?
Increase of pressure
The three primary tectonic settings are zones near convergent and divergent tectonic plates, subduction zones, and
mid-ocean ridges.
What body waves arrive last on a seismograph?
Secondary waves
What is the epicenter of an earthquake?
the point on Earth’s surface directly above the earthquake’s focus
What type of fault would you see a plate move downward in relation to the neighboring plate?
Normal
What type of fault would you see a plate move upwards in relation to the neighboring plate?
Reverse
Broad, gently sloping volcanoes with quiet eruptions are called
shield volcanoes
Most earthquakes have a
shallow focus
What happens to rock that undergoes elastic deformation once the stress is removed?
It returns to its original shape.
This area is both a major earthquake zone and volcano zone.
Pacific Ring of Fire
What type of fault would you most likely find a mountain range?
Reverse
If an earthquake has an intermediate focus, the depth of the focus is
between 70-300 km deep.
What is stress?
force per unit area
Which scale more accurately measures the magnitude of large earthquakes?
moment magnitude scale
What forms on the ocean floor in a subduction zone?
trench
P waves travel
through solids, liquids and gases.
Most types of felsic lava tend to have
a low temperature and high viscosity.
The eruption of Mount Pinatubo was
an explosive eruption.
The instrument a seismologist uses to record earthquakes is called a
seismometer
At what location does the first motion of an earthquake occur?
the focus
What are the fastest earthquake waves?
P waves
Plastic deformation occurs when
rocks are stressed and break.
A large depression formed by the collapse of a volcanic cone is called a
caldera
Which area is surrounded by the Ring of Fire?
the Pacific Ocean
Crater Lake in southern Oregon is not a crater but actually a ________ .
caldera
Magma that is rich in magnesium and iron is called
mafic
A characteristic of lava that determines the force of a volcanic eruption is
viscosity.
Why do earthquakes usually occur at plate boundaries?
Rock in environments near tectonic plate boundaries experience great stress.
The most explosive volcanoes are
composite cones
Which scale is used to measure the intensity of an earthquake?
Mercalli scale
If the temperature of rock rises above the melting point of the minerals the rock is composed of
the rock will melt.
How do scientists find the epicenter of an earthquake?
by comparing arrival times of P waves and S waves at several seismograph stations
All of the following affect the temperature at which magma forms EXCEPT ____.
viscosity
