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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


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


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


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


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


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.

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