Geology Midterm

To show topography in a flat coastal area, the most appropriate contour interval would be

5 feet

What must be true in order for an ore mineral occurrence to be economically viable?

All the possible answers are correct- concentrated elements greater degree than average crystal abundance; enough ore mineral to make extraction profitable; sale price of element must be greater than costs of mining and extraction

The Public Land Survey System is used in all of the following states except

Massachusetts

Which of the following physical properties will change when you break a mineral into smaller pieces?

None of these properties will change despite how small the specimen becomes.

What changes take place during physical weathering?

Rocks are broken into smaller pieces.

What changes take place during chemical weathering?

The mineralogy of previously existing rocks

Magnetic anomaly "stripes" in the ocean are caused by

a combination of the Earth's current magnetic field and ancient magnetic fields at the time oceanic rocks are formed

Shear stress is what is generated when we use which of the following tools?

a pair of scissors

A seamount forms when

a volcano is eroded by waves and sinks as it becomes denser with time

Sedimentary rocks are formed in horizontal layers called

beds

In what ways does the formation of sedimentary rocks differ from that of a sedimentary rock or igneous rock?

changes from the previously-existing rock from which it forms all take place in a solid state

Geologists classify minerals into groups like silicates by their

chemical composition.

Biogenic sedimentary rocks are similar to ________ in that __________.

chemical sedimentary rocks; removal of dissolved ions from water is a very important process in their formation

What is the result when some of the chemical bonds in the minerals are stronger in some directions than in others?

cleavage

Grain size generally increases wit metamorphic intensity except in

dynamic metamorphism

The latitude and longitude is based on the

equator

The increase of temperature with depth within the Earth

is caused by the geothermal gradient.

Meridians of longitude

meet at North and South Poles

orders of magnitude

scientific notation (powers of 10)

The zero contour line is also known as

sea level

The texture of a rock includes its constituent grains

size, shape, and orientation

In making scale models to understand the Earth, the one factor that cannot be scaled down is

time

The agents of metamorphism include all except which of the following?

time

Which property of a protolith may change during metamorphism?

all of the possible answers are correct - grain size, grain shape, mineralogy

What can the formation of sedimentary rocks involve?

all of the possible answers are correct - precipitation of minerals when water evaporates; consolidation of many shells; transportation of fragments of rock weathered from previously existing rocks

biosphere

realm of living organisms

Strike and dip refer to

the orientation of a bed or fault

Why is vertical exaggeration often used on maps and map profiles?

to make topographic features like hills and valleys more visible

hydrosphere

water

On a map with a scale of 1:48,000, a distance of 1 mile would be represented by how many inches?

1.32

To show topography in a rugged, mountainous area, the most appropriate contour interval would be

100 feet

geosphere

solid earth

The texture of a rock is controlled by

the process of which it forms

You have been asked to draw a map of a part of your campus on a 8.5x11 sheet of paper. You first try a scale of 1:1,000, but the paper is not large enough. Which of the following scales might work better?

1:5,000

Which of the following is a possible origin of a metamorphic rock?

A sedimentary rock is buried deeply beneath other sedimentary rocks.

Sedimentary rocks are unique in that they form

by processes that operate at or near the Earth's surface

A good map must contain a way to accurately determine which of the following?

all of the possible answers are correct - distance between points shown on map, directions between points shown on map, location of points shown on map

A theory is

an explanation that has been tested many times and shown to be correct in all tests

Solidified lava flows and volcanic ash deposits are examples of

extrusive igneous rocks

The release of oxygen by green plants during photosynthesis is an example of

flux involving the biosphere and atmosphere

What causes the steep slope of stratovolcanoes (composite cones)?

large volumes of hot tephra that weld to one another

Which of the following physical properties of a mineral depends on the strength of the bonds that hold its atoms and ions together?

luster

Every mineral has a preferred habit (crystal shape) but most mineral grains do not display that shape because

many grains interfere with one another while they are growing.

in identifying rocks, geologists must consider its

mineral content and texture

foliation and lineation are terms that describe

the orientation of minerals in metamorphic rocks

At what type of plate boundary is there no vertical transfer material between the lithosphere and the asthenosphere?

transform fault

Where is the large-scale shear stress model found in the plate-tectonics model?

transform faults

A porphyritic texture indicates that the cooling rock had

two different cooling rates

Fault-block motion in a dip-slip fault is

up and down the fault plane

Contour lines on a topographic map

are usually brown

Well-rounded grains in a clastic sedimentary rocks indicate

numerous collisions between particles during extensive transportation

scientific method

observation, collecting data to ensure observation valid, hypothesis, test hypothesis

Earthquakes occur frequently at

ocean ridges, subduction zones, and transform faults

In the tectonic cycle, new lithosphere forms at ______ and is consumed at _______

ocean ridges; subduction zones

Contour lines on maps connect points

of equal elevation

In an anticline, the __________ rocks are exposed in an axial region of the fold, and beds typically dip __________ one another.

oldest; away from

Metamorphic foliation produced during compression will be

perpendicular to the compressional stress

Angular grains in a clastic sedimentary rocks indicate

rapid, typically short-distance transport

rocks forming today

recycle materials from previously existing rocks

Collision of two continental plates would cause

regional metamorphism

Igneous rock forms by

solidification of magma at the surface or within the Earth

The difference between a plunging and non-plunging fold is that

the hinge of the plunging fold is not horizontal.

Polymorphs (minerals like diamond/graphite with same chemical composition but are different minerals) exist because

their mineral structure differs based on the different temperature and pressure conditions under which they are formed.

Which of the following is LEAST likely to be associated with the eruption of a shield volcano?

a pyroclastic flow (nuee ardente)

Earth's internal structures includes

concentration of the densest materials in the Earth's core.

When the chemical bonds in a mineral are equal in all directions, what will the result be?

conchoidal fracture

Small tick marks (hachures) on contour lines indicate

depressions

what is true clastic sedimentary rock

mineral grains can come from many previously existing sedimentary rocks

A vertical exaggeration of 1.00x on a topographic profile means

the vertical scale of the map is the same as the map scale

Base lines and principal meridians are reference lines to the

township and range (Public Land Survey)

In a syncline, the ______ rocks are exposed in an axial region of the fold and beds typically dip ______ one another

youngest; towards

A benchmark is

a permanent marker on the ground that indicates location and elevation

A hypothesis is

a tentative explanation for a natural phenomenon or Earth material

Earth System

all Earth's materials - gases, liquids, solids, and life forms hy

Mohs hardness scale describes the relative hardness of ten minerals, not their absolute hardness. This means that

diamond will scratch talc, but talc won't scratch diamond

A direction of 315 degrees in the azimuth system corresponds to

northwest

Two maps have been drafted so that each fills a sheet of 8.5x11 paper, one at a scale of 1:24,000 and the other at a scale of 1:62,500. Which of the following statements correctly describes the map?

The map with the scale of 1:62,500 covers more area than the other.

What does the term metamorphic grade refer to?

the degree to which a metamorphic rock's protolith has changed

The eastern edge of the North American continent is not the same as the eastern boundary of the North American plate. The eastern edge of the North American continent is

the edge of the continental shelf because that is where the continental crust ends and oceanic crust begins

The presence of footprints in a sedimentary rock is compatible with the origin in all of the following environments except:

the floor of the Atlantic Ocean

What are the latitude/longitude and UTM systems used to describe?

the locations of points on a globe

The presence of tropical plants and animals hundreds of millions of years near the North Pole suggest that

the plate on which those organisms are found has moved from a different climate zone to its current Arctic position

The principle of uniformitarianism is

the present is the key to the past

The grain size of an igneous rock is determined primarily by

the rate of cooling, which controls the amount of time ions have to migrate the crystal seeds

Metamorphic index minerals help geologists determine

the temperature and pressure conditions during metamorphism

The asthenosphere is:

a layer of low rigidity that separates the rigid lithosphere from the rigid mantle

What is true of map projections?

all possible answers are correct - they needed to portray the nearly spherical of the Earth on a flat page; may significantly distort the shapes of continents and oceans; can be selected so that they show particular aspects of a landmass most accurately

What do lines separating different rock units on a geologic map represent?

all the possible answers are correct - faults, stratigraphic contacts between sedimentary formations, intrusive contacts between plutons and their host rocks

The Himalayan Mountains formed when

an ocean that once separated India and Asia closed by subduction

cryosphere

frozen water, including snow

Why is the scientific study of our planet difficult?

All possible answers are correct; - (1) Earth's size is relative to humans is much greater that it is so hard to conceive the scale of some of its processes (2) Many of the processes responsible for forming some of Earth's features can be so slow we cannot detect them (3) Earth history extends more than 4.6 billion years into the past

At which locations is volcanic activity abundant?

Volcanic activity is found at all of these locations - ocean ridges; subduction zones;

What does a map scale of 1:24,000 describe?

a map where 1 inch corresponds to 2,000 feet on the ground

Which rock transformations can occur in a rock cycle?

all of them - igneous-sedimentary; metamorphic-sedimentary; sedimentary-sedimentary

Which of the following describes the formation of chemical sedimentary rocks?

all of these describe the formation of chemical sedimentary rocks - their minerals form a crystalline texture; their minerals form by precipitation of ions from water; their minerals form from ions dissolved from previously existing minerals during chemical weathering

Which of the following shows the topography of a landscape?

all possible answers are correct - a digital elevation model; a Landsat satellite image; a contour map

The absence of preferred orientation in minerals in metamorphic rock may be due to which of the following?

all possible answers are correct - lack of stress during metamorphism; absence of platy minerals like mica; absence of rod-shaped minerals like amphibole

The presence of water

all possible answers are correct - lowers melting temperature during flux melting; helps magma rise towards surface; causes explosive volcanic eruptions

Why is quartz one of the most abundant minerals?

all possible answers are correct - made up of two most abundant materials; resistant to weathering; can form in igneous, sedimentary, and metamorphic rocks

Formation of large grains in an igneous rock is aided by

all possible answers are correct - magma with low viscosity, very slow cooling, and the presence of water in magma

What does a map scale of 1:24,000 indicate?

all possible answers are correct - one inch on map equals 24,000 inches; one centimeter on the map equals 24,000 centimeters on the ground; one foot on the map equals 24,000 feet on the ground

What does the assemblage of minerals in a metamorphic rock help to determine?

all possible answers are correct - the chemical composition of a protolith; the temperature at which metamorphism took place; the pressure at which metamorphism took place

Which of the following might clastic sedimentary rocks contain?

all these types of clasts - individual mineral grains separated from previously existing rocks during weathering; rock fragments made up of several minerals; fragments of volcanic glass

Most of Earth's volcanic and earthquake activity occurs

at the edges of lithosphere plates

Block diagrams used to portray geologic structures contain

both of the possible answers are correct - a map view, two cross-sectional interpretations

A fine-grained texture most likely formed when a magma cooled

close to the Earth's surface

The lithosphere is

composed of the entire crust and uppermost mantle

Intrusion of granite into layers of sedimentary rock would cause

contact metamorphism

In the plate-tectonic model, where is the large-scale compressional stress found?

convergent plate boundaries

__________ occurs at ocean ridges, whereas _______________ occurs at subduction zones

decompression melting; flux melting

Mineral assemblages generally become ______ the deeper in the Earth that metamorphism takes place

denser

Where is large-scale tensional stress found in the plate-tectonic model?

divergent plate boundaries

Isotherms on weather maps differ from contour lines on topographic maps in that they

do not show changes in elevation

The interaction of plates on opposite sides of a transform fault results in

dynamic metamorphism

Which of the following map elements is not shown on an aerial photograph?

elevations and slope steepness

The Earth's magnetic field

generates lines of force that run parallel to Earth's surface at the equator

In the Earth concept, minerals and rocks are found in the

geosphere

The principle of uniformitarianism is most useful for interpreting most ancient geologic events except those that

happened early in Earth history and do not occur today

Glassy igneous rocks

have no minerals

A mineral may have a high specific gravity because its atoms are either ________________ or ________________

high in atomic mass; packed closely together

The relative motion of fault blocks on opposite sides of a strike-slip fault is

horizontal

a glassy texture is most characteristic of

igneous rocks

Quartz is not a good index mineral because

it is stable over a very wide range of temperatures and pressures

The longitude of a location is based on the

prime meridian

Most fossils are found in sedimentary rocks because

sedimentary rocks form in the same environment where the plants and animals lived and died

The difference between sills and dikes is that

sills are parallel to layering in surrounding rocks while dikes cut out layering

all of the following properties of a mineral can be observed/measured when a mineral is found in a rock, EXCEPT its

specific gravity

Where are the intermediate igneous rocks (andesite and diorite) most commonly found?

subduction zones

The uplift of new mountains and the erosions of old ones

take place over millions of years

Which of the following mineral properties is chemical rather than physical?

taste

The major source of energy that melts the rock within the Earth, causes earthquakes, and builds mountains comes from

the Earth's internal heat

The eastern edge of the North American plate is

the Mid-Atlantic Ridge, because that is where seafloor spreading takes place.

Information on the borders of the topographic map includes all except

the types of rocks present in the map area

Cross-bedding and ripple marks are the result of ________ during deposition.

water or wind currents

A mature clastic sedimentary rock is characterized by what properties?

well-rounded grains, good sorting, and minerals resistant to chemical weathering

Volcanic arcs form above subduction zones

wherever oceanic lithosphere is subducted