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50 terms

Science Take Home Test

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In any sequence of sedimentary rock layers that have not been subjected to stress, you would expect to find
both horizontal layers and older layers at the bottom and younger layers at the top
If you wished to date a rock thought to be namy millions of years old, which of the following would be the least useful?
carbon-14 method
An unconformity can be interpreted as
a buried surface of erosion
The precambrian witnessed the development of
all of these
The most important event during the cambrian period was the
ability of organisms toform an outer skeleton
The principle of superpostion states that the top layer of rock is
the youngest
The paleozoic era begins with the cambrian and concludes with the
permian period
The first time period for which abundant fossils have been found is the
cambrian
Radiometric dating is based on
proportions of radioactive isotopes and their decay products
Fossils are found in
sedimentary and some metamorphic rocks
The fossil record is the record of former life forms as preserved in the earth's rocks. which of the following is not representative of the fossil record?
the paleozoic era is credited with the emergence of life
The cenozoic era represents a period of
almost continuous tectonic activity
During the Pleistocene ice age
there were several episodes of glacial advance and retreat
You would expect to find the least number of fossils in rocks from the
precambrian era
The cenozoic era is known as the
age of the mammals
The time required for one-half of a radioactive material to decay is called the
half-life
The resetting of a mineral's time clock means that
the date obtained from a mineral that has undergone metamorphism will be the date of the metamophic event, not the date of the rock's formation.
An explanation for the discovery of ancient coal beds in antartica is that
at one time the climate of antarctica was mild enough to support swamplands.
Key event for the precambrian, which makes up about 85% of the earth's history, are
all of these
A surface of erosion between rocks that represents a gap in earth history is
an unconformity
According to most estimates, earth is approximately
4.5 billion years old
Uniformitarianism is the assumption that
present day processes also occurred in the geologic past
The carboniferioius period is most noted for the
evolution of the amniotic egg
The mesozoic era is known as the age of the
reptile
Correlation and relative dating of rock layers is made possible by the application of the principle of
all of these
An assumption that the earth processes occurring today have always occurred is the
theory of uniformitarianism
The process wherein an element changes spontaneously into a different element by changes in the nucleus of an atom is called
radioactive decay
The beginning of the paleozoic is marked by the emergence of
organisms with hard parts
During the precambrian, the development of the ozone layer helped
to shield the Earth's surface from harmful ultraviolet radiation
Granitic pebbles with a radiometric age of 300 million years are embedded in a sedimentary rock. A dike, dated at 200 million years, intrudes into the sedimentary rock. With all this info we can estimate the ae of the sedimentary rock to be
between 200 and 300 million years old
The cenozoic era represents a period of
almost continuous tectonic activity
Conditions for the preservation of fossils are best achieved
on the floors of shallow seas
During the Cenozoic era animals grew to great sizes and proportions. The wooly mammoth and the saber tooth tiger were much larger than animals we see today. Some of the causes for their extinction may be
dwindling food supplies, extreme climatic variation, and man's emergence
In a sequence of rock layers we find fossils of trilobites and dinosaurs. The trilobites are found at the bottom of the rock sequence in layer 1. The dinosaur fossils are found in layer 2, directly above the trilobite fossils. There are inclusions of trilobite fossils in layer 2. We conclude that
by inclusion and faunal succession, layer 1 is older than layer 2
The isotope most useful for dating rocks from the late Pleistocene is
carbon-14
The Ordovician period is most noted for the
great diversity in marine life
The climatic zones of Pangaea ranged from
glaciation in the south, and a mild temperate climate in the north
The rather simple idea that, unless disturbed, younger sedimentary layers overlie older layers, is referred to as the principle of
superposition
The emergence of terrestrial life, the earliest known being terrestrial plants, came about during the
Silurian era
The Earth's age has been determined to be
4.5 billion years old by using meteorites
Radiometric dating assumes that, once a mineral has crystallized, any daughter product results only from the decay of the original unstable parent. Some complications are
that after metamorphism the mineral's "time clock" will be reset. Also weathering and escape of argon gas lead to false age estimation.
The oldest rocks that have been dated by radioactivity are approximately
4 billion years old
The Paleozoic is noted for several worldwide rises in sea level. Which of the following is not a representative factor for sea level rise in the Paleozoic?
Ocean basins stood high on the asthenosphere due to slow but continuous seafloor convergence
In a sequence of sedimentary rocks we find the bottom layer to be the youngest and the top layer to be the oldest. This type of sequence suggests that the
beds must have been overturned by some structural disturbance
Dinosaurs were abundant during the
mesozoic era
Development of the Earth's early oceans was likely due to
volcanic outgassing in Precambrian time
An increase in the rate of seafloor spreading can result in a rise in sea level because
faster spreading rates equate to a warmer oceanic crust. This warm, new crust, less dense than colder older crust, rides high forcing water onto the continents
To date relatively young rocks and materials, we use the decay of
carbon-14 to nitrogen-14
At the end of the Precambrian, the Earth experienced a rise in sea level caused by
thermsal expansion of the crustal surface
Life forms in the Precambrian include
stromatolites and certain primitive blue-green algae.