Geology 1500 Exam 1

Which of these statements is most consistent with the law of uniformitarianism?

"The present is the key to the past."

A typical rate of seafloor spreading in the Atlantic Ocean is ______.

2 centimeters per year

The current accepted age of Earth is ________ years.

4.6 billion years old

In the early part of the 20th century, _____ argued forcefully for continental drift

Alfred Wegener

Which example below represents relative age dating?

Angela is older than Karen.

Which of the following best describes the fundamental concept of superposition?

Any sedimentary deposit accumulates on top of older rock or sediment layers.

which one is an important fundamental assumption underlying the plate tectonic theory?

Earth's diameter has been essentially constant over time

Which of the following statements is TRUE?

Earth's magnetic field reverses over geologic time

A scientific theory is a tentative or untested explanation that is proposed to explain scientific observations.

False

According to the nebular hypothesis, all of the bodies in the universe evolved from a rotating cloud of gases and dust about 5 billion years ago.

False

As the South Atlantic basin widens by seafloor spreading, Africa and South America are moving closer together.

False

Earth's radius and surface area are slowly increasing to accommodate the new oceanic crust and being formed at mid-oceanic ridges.

False

Iceland is a good example of an island arc, formed from an oceanic-oceanic plate collision

False

Igneous rocks are produced largely by the deposition and consolidation of surface materials like sand and mud.

False

The asthenosphere is a relatively cool and rigid shell that overlies the lithosphere.

False

The currently accepted age of Earth is approximately 4.5 million years.

False

The rate of seafloor spreading is, on the average, about one meter per year.

False

______ was an important 18th-century English geologist and proponent of uniformitarianism.

James Hutton

Describe what happens during the rock cycle.

Magma (molten rock) > cooling and crystallization > Igneous ("fire-formed") rock > weathering, transportation, and deposition > sediment > compaction and cementation > sedimentary ("setting" rock) > heat and pressure > metamorphic ("changed form" rock) > melting

the _______ proposes that the bodies of our solar system formed at essentially the same time from a rotating cloud of gases and dust.

Nebular hypothesis

Linear, magnetic patterns associated with mid-ocean ridges are configured as _________.

Normal and reversed magnetized strips roughly parallel to the ridge

Deep oceanic trenches are most abundant around the rim of the ______ ocean basin.

Pacific

The _____ division of the geologic time scale is an era of the Phanerozoic eon.

Paleozoic

Former late paleozoic super continent is known as _______.

Pangaea

According to the rock cycle, any type of rock (igneous, sedimentary, or metamorphic) may be transformed into another type of rock, given enough time.

True

In general, rocks of the continental crust are less dense than rocks of the oceanic crust

True

Internally, the Earth consists of spherical shells with different compositions and densities.

True

Much of our modeling of Earth's interior comes from the study of seismic or earthquake waves.

True

Oldest rocks on the seafloor are much younger than the oldest rocks on the continents.

True

Seafloor spreading rates can be estimated if the geologic ages of the magnetic field reversals are independently known.

True

The doctrine of uniformitarianism implies that the current forces and processes shaping the Earth have been operating for a very long time.

True

The law of superposition applies primarily to sedimentary rocks and lava flows.

True

The lithosphere and asthenosphere are both layers of Earth defined by their composition.

True

The oldest of rocks of the oceanic crust are found in deep ocean trenches far away from active, mid-ocean ridges.

True

The volcanoes of Hawaii are localized above a deep mantle hot spot; they are not part of the East Pacific oceanic ridge.

True

Wegener's continental drift hypothesis was weakened because a viable mechanism for moving the continents was lacking.

True

All of the following are possible steps of a scientific investigation except for _____.

assumption of conclusions without prior experimentation or observation.

Beneath Earth's lithosphere, the hotter, weaker zone known as the _____ allows for motion of Earth's rigid outer shell.

asthenosphere

the ___________ is not a part of the Earth's physical environment.

astrosphere

The ______ refers to the sum total of all life on Earth.

biosphere

___________, a popular natural philosophy of the 17th and 18th centuries was based on a firm belief in a very short geologic history for Earth.

catastrophism

All of the following are evidence supporting the theory of plate tectonics except for ______.

changes in the moon's orbit due to shifting plates Correct answers: hot spots, measurements of plate motions and ocean floor drilling

All of the following provide evidence or clues to the composition of Earth's interior except for ________.

comets

Australia is composed of relatively old and thick _______ ______.

continental crust

The volcanoes and deep valleys of east Africa are related to a _______.

continental rift along which parts of the African continent are beginning to slowly separate

The Aleutian Islands occur at a ________.

convergent boundary on a volcanic arc above a northward-subducting Pacific plate

Juan de Fuca plate is interacting with the North American plate where inland volcanoes and deep focus earthquakes are occurring, What type of plate boundary is this?

convergent plate boundary

The relatively stable interior portion of a continent is a known as a __________.

craton

The _______ is the thinnest layer of the Earth.

crust

New oceanic crust and lithosphere are formed at ____________.

divergent boundaries by submarine eruptions and intrusions of basaltic magma

Which boundary is characterized as a long, linear rise in the seafloor, with shallow earthquakes and volcanic activity found along its length?

divergent boundary

Why have no older oceanic rocks been discovered?

due to tectonic activity, rocks on the ocean floor are continually recycled.

Which of the following energy sources is thought to drive the lateral motions of Earth's lithospheric plates?

export of heat from deep in the mantle to the top of the asthenosphere

the Earthquakes that occur in southern California generally occur along a ______.

fault

which of the following processes can be observed at the margins of lithospheric plates?

faulting, earthquakes, volcanoes and mountain building

A very long lived magma source located deep in the mantle is called a ____________.

hot spot

Old Faithful Geyser at Yellowstone National Park in the United States acquires its energy from a _____ ______.

hot spot

The continental drift hypothesis was rejected primarily because Alfred Wegener could not ______.

identify a mechanism capable of moving continents.

In correct order from the center outward, Earth includes which units?

inner core, outer core, mantle, crust

The _________ is a logical evolutionary analog of the African Rift Valleys ten million years from now.

Red Sea

___________ ______ found in the Atlantic Ocean between North America and Europe is composed of dense and relatively young rock.

Seafloor crust

The ____ forms the relatively cool, brittle plates of plate tectonics.

lithosphere

the asthenosphere is actually a part of the _______ of the Earth.

mantle

The _______ is an example of an active, continent-continent collision.

northward movement of India into Eurasia

the _______ is thought to be a liquid, metallic region in the Earth's interior.

outer core

Slowing increasing distance between South America and Africa is due to __________ _______.

seafloor spreading

______ rocks always originate at the surface of the solid Earth.

sedimentary

Layered ________ _____ exposed by erosion can be seen when looking at the grand canyon in the United States.

sedimentary rock

Which statement is not correct?

sedimentary rocks may weather to igneous rocks

Which of the following most accurately describes the volcanoes of the Hawaiian Islands?

shield volcanoes fed by a long-lived hot spot below the Pacific lithospheric plate

deep ocean trenches are surgical evidence for

sinking of oceanic lithosphere into the mantle at a subduction zone

The composition of the core of Earth is thought to be _________.

solid iron-nickel alloy

The extremely deep ocean Marianas Trench is a result of ______.

subduction

Cooler, older, oceanic lithosphere sink into the mantle at ________.

subduction zones along convergent plate boundaries

Metamorphic rocks are created by _______________.

temperatures hot enough to change the rock in the solid state without melting it

Which of the following lithospheric plates is not included among the seven largest?

the Philippine plate

Which of the following is one of the remarkable realizations associated with the discovery of seafloor spreading?

the crust of the oceans is very young relative to the age of the continental crust.

Which sphere does the crust of Earth belong to?

the geosphere

Which of the following observations was included as evidence for Wegener's continental drift hypothesis?

the jigsaw-puzzle fit of the continents

Earth's lithospheric plates are composed of crust and which of the following layers?

the outermost portion of the mantle

deep-ocean trenches are formed by ________.

the subduction of lithosphere into the asthenosphere

A ______ is a well-tested and widely accepted view that best explains certain scientific observations.

theory

Compared to the age of Earth accepted as correct today, how did 17th and 18th century proponents of catastrophism envision the Earth's age?

they believed Earth to be much younger than current estimates.

During various times in the geologic past, the polarity of Earth's magnetic field has been reversed.

true

Himalayan Mountains are the tectonic product of a collision between India and Eurasia that began about 40 million years ago and still continues.

true

______ is often paraphrased as "the present is the key to the past."

uniformitarianism

________ is the process by which rocks breakdown in place to produce soils and sediments

weathering

Mount St. Helens and other Cascade volcanoes are _______.

young, active volcanoes built on a continental margin above a sinking slab of oceanic lithosphere

Which following statement applies to the asthenosphere, but not the lithosphere?

zone in the upper mantle that deforms by plastic flowage

_______ rocks form by crystallization and consolidation of molten magma.

Igneous

A transform plate boundary is characterized by

a deep vertical fault along which two plates slide past one another in opposite directions

Pull-apartm rift zones are generally associated with

a divergent plate boundary

When a researcher publishes research in a national journal, what part of the scientific method is he or she most likely involved with?

a hypothesis

The Hawaiian Islands were formed as a result of __________.

a mantle plume

Modern-day Red Sea is explained by plate tectonics theory because it is ____________.

a rift zone that may eventually open into a major ocean if Arabia and Africa continue to separate

Active mountain belts are mostly likely to be found _______.

along the margins of continents