Geology Exam #4
What is the source of natural carbon-14?
Cosmic ray collisions and neutron-capture involving atmospheric nitrogen.
Which of the following is the best measure of the wetness or dryness of a region?
Difference between annual precipitation and evaporation potential
Which of the following denotes the divisions of the geologic time scale in correct order of decreasing lengths of time beginning with the longest time interval and ending with the shortest?
Eon, era, period, and epoch
How do explosive volcanic eruptions affect global temperatures?
Explosive volcanic eruptions lower global temperatures.
What accounts for the increase in atmospheric nitrous oxide ("laughing gas")?
Fertilizers
How many spheres are involved in the exchanges of energy and moisture that occur in Earth's climate system?
Five
Which of the following is formed from the abrasion of rocks by windblown sand?
Ventifacts
Which one of the following statements concerning rock weathering is true?
Warm temperatures and high soil moisture accelerate chemical weathering
Which of the following statements concerning dry lands is FALSE?
Wind is the dominant agent of erosion and sediment transport
What are inselbergs?
bedrock hills in a highly eroded desert landscape
Which one of the following is determined by the angle of repose for dry sand?
Inclination angle of a dune slip face
Which one of the following does not characterize the early development and specialization of primitive mammals?
Increase in stomach capacity
With what other element dissolved in water was most of the Earth's first free oxygen combined, as observed in Precambrian rocks?
Iron
Where is it thought that Earth's primitive atmosphere came from?
It was expelled from within the Earth.
What continent dominated the Northern Hemisphere during the late Paleozoic, combining present-day North America, Europe, western Asia, Siberia, and perhaps China?
Laurasia
What fundamental concept states that, "in a horizontal sequence of conformable sedimentary strata, each higher bed is younger than the bed below it"?
Law of superposition
What is the final stable breakdown product of the radioactive isotopes uranium-238, uranium-235, and thorium-232?
Lead
What type of deposit consists of glacial rock flour from blowing winds?
Loess
Which sand dunes are long, high, and parallel with the prevailing wind direction?
Longitudinal
How will increased levels of atmospheric CO2 ultimately affect the pH of global oceans?
Lower
Would the average surface temperature of Earth's atmosphere be lower, higher, or unchanged if it contained no greenhouse gases?
Lower
Which era is sometimes called the "age of dinosaurs"?
Mesozoic
Which two Paleozoic periods used in North America are combined into the Carboniferous period in Europe and elsewhere?
Mississippian and Pennsylvanian
Are eccentricity, obliquity, and precession considered to be natural, human, solar, volcanic, or astrological causes of climate change?
Natural
Who made the first clear statement of the law of superposition? When?
Nicolas Steno; 17th century
Which gaseous element comprises the greatest percentage of the air that we breathe?
Nitrogen
Assume that man's recorded history can be stretched back to 4600 years before the present. This is approximately what fraction of geologic time?
One millionth.
What term means "the era of ancient life"?
Paleozoic
Which single supercontinent had formed by the close of the Paleozoic?
Pangaea
During which time period did large tropical swamps extend across North America, eventually becoming the vast coal deposits of eastern North America and Europe today?
Pennsylvanian
Which geologic period was supposedly a time of major extinctions, including those of 75 percent of amphibian families?
Permian
In which process of fossilization are the internal cavities and pores of the original organism filled with mineral matter?
Petrification or fetrifaction
Which regions of the Earth will experience a greater adverse response to global warming?
Polar
Fossil fuels are notably absent from rocks from which time period listed below?
Precambrian
In rocks of which age does most of Earth's iron ore exist?
Precambrian
Which era of geologic time spans about 88 percent of Earth's history?
Precambrian
Which one of the following represents the greatest expanse of geological time?
Precambrian
Which rocks are devoid of fossils, which hinders the correlation of rock units?
Precambrian
What concept states that "ancient life forms succeeded each other in a definite, evolutionary pattern and the contained assemblage of fossils can determine the geologic age of the strata"?
Principle of faunal succession
What term means "planets in the making"?
Protoplanets
What term means "the sun in the making"?
Protosun
What is the name of the lines of indirect evidence that scientists use to reconstruct past climates?
Proxy data
What instrument records vertical changes in temperature, pressure, wind, and humidity?
Radiosonde
What were the first true terrestrial animals?
Reptiles
Which one of the following concerning desert lands is FALSE?
Running water has little effect on shaping the landscape
What term refers to the "bouncing" mode of sand transport in a windstorm or stream?
Saltation
In which layer of the atmosphere does the temperature remain constant to an altitude of about 20 kilometers?
Stratosphere
In which zone of the atmosphere is ozone concentrated?
Stratosphere
What huge magnetic storms may be responsible for variations in temperature and precipitation?
Sunspots
Where are rain shadow deserts common?
The dry valleys of eastern California and Nevada
What happened to create an unconformity?
The older strata below were eroded before the younger layers were laid down.
Which of the following is an essential characteristic of an index fossil?
The organism only live for a short period of geologic time over a broad area.
Which of the following best characterizes an angular unconformity?
Tilted strata that lie below the unconformity; bedding in younger strata above is parallel to the unconformity..
What percentage of Earth's land area do desert and steppe lands cover?
30%
What is the age of Earth accepted by most scientists today?
4.6 Billion
According to most sources, what is the approximate age of Earth?
4.6 billion years old
Below which altitude measurement is 50 percent of Earth's atmosphere found?
5.6 km
Complex, invertebrate life forms are common as fossils beginning with marine strata of Cambrian age. How long ago did the Cambrian period begin?
542 million years
What is the maximum limit on carbon-14 dating?
70,000 and 75,000 years
What term refers to a measurement of the amount of radiation reflected by a surface?
Albedo
What mature desert landscape feature consists of coalesced alluvial fans?
Bajada
Which dune is crescent-shaped with its tips pointing downwind?
Barchan
Visualize five horizontal, sedimentary strata exposed in a cliff or canyon wall identified by consecutive numbers, 1 being the lowest bed and 5 being the highest. Which of the following statements concerning the strata are true?
Beds 1 and 3 are older than bed 4.
The percent of remaining parent isotope in a radioactive decay process is 40 percent. How many half-lives have elapsed since the material was 100 percent parent atoms?
Between 1 and 2
How much has sea level risen over the last 100 years?
Between 10 and 23 cm
Between which latitudes do most dry lands lie?
Between 20 and 30 degrees north and south of the equator
What term describes the amounts of methane (CH4), nitrous oxide (N2O), and chlorofluorocarbons (CFCs) present in greenhouse gases?
Trace
How are sand grains transported by the wind?
By saltation in the first few meters above the land surface
Which of the following is not a very long-lived, radioactive isotope?
C-14
Of the following, what material makes up much of the shells of numerous marine microorganisms called foraminifera?
CaCO3
What gases will be released as a result of the melting of permafrost and decomposing vegetation?
Carbon dioxide and methane
What acid forms when atmospheric CO2 dissolves in seawater?
Carbonic acid
During which era did mammals become the dominant land animals?
Cenozoic
What era is known as the "age of flowering plants"?
Cenozoic
Which of the following substances can be used as a paleothermometer?
Corals
Which of the following investigative processes do geologists use to identify and match sedimentary strata and other rocks of the same ages in different areas?
Correlation
What type of bacteria produces methane?
Anaerobic
Which type of bacteria thrive in environments that lack free oxygen?
Anaerobic
What type of unconformity is an erosional contact between tilted, older strata below and horizontal, younger strata above?
Angular Unconformity
What term refers to the temperature decrease in the troposphere?
Environmental lapse rate
During the early Paleozoic era, the current continents of South America, Africa, Australia, Antarctica, India, and perhaps China comprised which vast southern continent?
Gondwanaland
What is the major source of free oxygen in the atmosphere?
Green Plants
Where has the process of desertification been particularly well documented over the past 50 years?
The Sahel along the southern margin of the Sahara Desert
What is the environmental lapse rate that occurs going up in the troposphere?
The air temperature decreases 6.5°C/km
What important event in animal evolution occurred at the beginning of the Cambrian period?
The appearance of animals with hard parts
Which of the following geologic observations would not bear directly on interpreting the sequence of geologic events in an area?
The feldspar and quartz content of a granite
Sandstone strata and a mass of granite are observed to be in contact. Which of the following statements is correct?
The granite is older if the sandstone contains pebble of the granite.
In the names of geologic eras, what does the suffix "zoic" mean?
The suffix "zoic" means life (i.e., living things).
In which layer of the atmosphere do temperatures rise to more than 1000°C?
Thermosphere
Where did the great loess deposits in the central United States originate?
They originated as rock flour in Pleistocene glacial streams and rivers
