The study of the earth's interior and solid surface is called geology. The age of the earth
is probably closest to 5 billion years and the structure of the Earth from the surface to the center of the earth is crust, mantle, outer liquid core, and inner solid core
. The existence of the layers inside the earth has been inferred from studies of seismic waves. The Mohorovicic discontinuity is a level of the mantle marked by a significant change in density
and an abrupt increase in the velocity of seismic waves. The earth's surface consists of several continents. The outer crust of the earth is generally thicker beneath the continents
and thinner beneath the oceans. It is largely granite beneath the continents and largely basaltic beneath the oceans. The continental crust
of the earth consists of granites and the oceanic crust of the earth consists of basalts. The heat energy trapped below the surface of the earth is called geothermal energy. Thickness of the earth's
continental crust varies from 2070 km. It was discovered that a portion of the earth's core is liquid by determining that some types of seismic waves do not pass through the core. The donutshaped zones
of energetic particles surrounding the earth are called Van Allen belts.
Rocks are materials of the lithosphere. Rocks that have cooled from molten lava are called
igneous rocks. The composition of the mantle is believed to be different from the crustal rocks because the speeds of P and S waves
increase significantly. The most important factor in distinguishing the lithosphere and asthenosphere is temperature. Rock consists mostly of minerals.
The
earth's magnetic field is probably due to the existence of electric currents in the outer core and the earth's magnetic field has experienced reversed polarity
and it can happen again. The earth's magnetic field is thought to arise from currents in the molten outer core.
Wagener's theory
on continental drift was lacking in a propelling mechanism. In relation to the earth's surface, the term "plates" refers to the large moving sections of the earth's crust. Limestone
may be formed from skeletal remains of shellfish and coral reefs. Continental drift is not provided by glaciation. New crustal material is formed along midocean ridges. The continents are
drifting because of the motion of the earth's plates. Wegener proposed that the landmasses of the earth were once joined together into a single supercontinent called Pangaea.
The
Earth's landscapes have been modified most significantly throughout history by liquid water. The outline of tectonic plates can be determined by the distribution of the world's earthquakes
. The focus of an earthquake is the area where the actual disturbance originates. The major earthquake belts of the earth are located along the coasts of the Pacific Ocean. An earthquake epicenter
is the point on the surface directly above where the rupture along the fault occurred. Richter devised the logarithmic scale used to measure earthquake magnitude. Tectonics plates
move in centimeters per year, which is considered to be geologically fast movement
of the plates. The process in which one tectonic plate is forced under another plate along the line where the two plates meet is called subduction.
When two continental plates collide, most likely the result is folded mountains. The overall result
of plate tectonics on the earth is that (i) large continents are broken up into smaller ones (ii) small continents are assembled into larger ones (iii) folded mountains are produced when continents collide. It is believed that Continental drift is caused by
heat flowing out from the center of the earth.
Plate motion
on the earth is responsible for most earthquake and volcanic activity. Believe it or not, Earthquakes are the most important tool for scientists because they allow the study of the earth's internal structure.
The two basic types of weathering are mechanical and chemical. Perhaps the most outstanding example of differential weathering and erosion
is the Grand Canyon. The process by which water fills the cracks in rock surfaces, freezes, and splits the rock apart is known as frost wedging. The most important agents in the processes of
chemical weathering are water, oxygen, and carbon dioxide.
The earth has fewer impact craters than the moon because the craters are erased by geological activity. The Meteor Crater in Arizona is the
oldest feature on earth. The Comet and the asteroid collisions with the earth might have caused mass extinctions. Astronomers are optimistic about the existence of at least primitive life elsewhere because the number of
planets is very large. SETI is an abbreviation of Search for Extraterrestrial Intelligence. The best way of communicating with extraterrestrial civilizations is using radio telescopes.
Sample questions:
The earth's magnetic field is probably due to the
a. magnetosphere b. magnetic properties of the surface rock c. existence of electric currents in the outer core d. solid inner core
New crustal material is being formed
a. along mid-ocean ridge b. in young mountain chain c. along the island arc systems
d. wherever convection currents move downward
The composition of the mantle is believed to be different from the crustal rocks because
a. it is under great pressure b. the speeds of P and S waves increase significantly
c. the speed of P waves increases and no S waves are transmitted d. it has a greater density
The age of the earth is probably closest to
a. 1 million years c. 5 billion years b. 100 million years d. 10 billion years
The most important factor in distinguishing the lithosphere and asthenosphere is
a. age c. depth b. temperature d. composition
Earth's landscapes have been modified most significantly throughout history by
a. fire c. wind b. liquid water d. ice
About how thick is the earth's continental crust?
a. 1-5 km c. 600-1000 b. 20-70 km d. 3000-5000 km
The order of features from the surface to the center of the earth is
a. peel, outer mantle, inner mantle, core b. crust, mantle, outer liquid core, inner solid core
c. crust, mantle, outer solid core, inner liquid core d. crust, outer mantle, inner mantle, asthenosphere
The donut-shaped zones of energetic particles surrounding the earth are
a. Newtonian hyperbolas c. Jules Verne regions b. Shepard belts d. Van Allen belts
Rocks that have cooled from molten lava are called _____________ rocks.
a. igneous c. sedimentary b. primitive d. metamorphic
How fast do plates move relative to one another?
a. centimeters/second c. kilometers/year b. kilometers/hour d. centimeters/year
The process
in which one tectonic plate is forced under another plate along the line where the two plates meet is called
a. seduction c. sublimation b. subduction d. induction
When two continental plates collide, the likely result is
a. the plate to the west slides under the other plate b. the plate to the east slides under the other plate
c. folded mountains are created d. very young rocks emerge from below the crust
The overall result of plate tectonics on the earth is that
a. large continents are broken up into smaller ones b. small continents are assembled into larger ones
c. folded mountains are produced when continents collide d. all of the above are true
Continental drift is caused by
a. volcanic action in the crust b. heat flowing out from the center of the earth
c. the tidal force of the moon d. the heating of the crust by solar radiation
Plate motion on the earth
a. has now stopped because the continents are in the right direction
b. never results in continents colliding c. is responsible for most earthquake and volcanic activity
d. opens oceans, but never closes them
The earth has fewer impact craters than the moon because
a. large meteors are repelled by the larger mass of the earth b. the craters are erased by geological activity
c. most of the meteors hit the ocean and thus leave no marks
d. the earth's crust is so hard that craters cannot form in it
The Meteor Crater in Arizona is
a. older than lunar craters b. the oldest feature on earth
c. evidence that a comet struck the earth d. more eroded than lunar craters
Comet and asteroid collisions with the earth are now thought to have caused
a. mass extinctions b. the tilt of the earth's axis of rotation
c. sudden increases in plate motio d. differentiation of the earth's interior
In general, astronomers are optimistic about the existence of at least primitive life elsewhere because
a. our radio telescopes are becoming more sophisticated
b. life on Mars, when it existed, had the same chemistry as life o earth
c. the number of planets is probably very large
d. organic molecules clearly exist even in the atmospheres of some of the cold moons of the Jovian planets
SETI is an acronym for
a. Seeking an Essentially Tranquil Island b. Seeking Earth Type Ideas
c. Search for Extraterrestrial Intelligen d. Stellar Energy and Temperature Information
The most likely way of communicating with extraterrestrial civilizations is
a. sending manned space expeditions to the nearest stars b. using radio telescopes
c. launching unmanned space probes with messages d. using carefully targeted lasers to beam coded messages
The heat energy trapped below the surface of the earth is called
a. internal heat c. plate tectonics b. isotopes d. geothermal energy
The Mohorovic discontinuity is a level of the mantle marked by
a. a significant change in density b. an abrupt increase in the velocity of seismic waves
c. constant depth d. a and b only
Rocks are materials of the
a. lithosphere c. inner core b. asthenosphere d. outer core
Wegener's theory on continental drift was lacking in
a. a source of volcanism b. an explanation of Antarctica's location c. a propelling mechanism
d. all of the preceding
An earthquake epicenter is the
a. point where the seismograph is located b. point within the earth where movement along the fault occurs
c. approximate center of a group of related earthquakes
d. point on the surface directly above where the rupture along the fault occurred
Limestone may be formed from
a. cooled lava b. rock debris c. skeletal remains of shellfish and coral d. all of the above
