Geological Time review Unit 7

In which situation would a scientist prefer to use the Law of Superposition over radioactive dating?

• To determine which mountain peak on Earth’s surface is the newest

• To determine the exact age of a human skeleton found in an ancient tomb

• To determine which layer of sedimentary rocks at the bottom of a lake is oldest

• To determine whether two dinosaurs whose fossils are found on different continents lived in the same time period

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NGSS.MS-ESS1-4

The diagram below is a cross-section of Earth’s sedimentary rock:

Based on the Law of Superposition, which statement best compares the relative age of two rock layers?

• Layer A is older than Layer D

• Layer C is older than Layer E

• Layer F is older than Layer D

• Layer B is older than Layer E

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NGSS.MS-ESS1-4

Since it is difficult to determine the age of once-living organisms, the scientists used radioactive dating on the igneous rocks that surrounded the remains to determine their age. Why would scientists use radioactive dating in order to determine the age of the fossil they discovered?

• Radioactive dating is an easier and less expensive method than applying the Law of Superposition for approximating the age of igneous rocks

• Radioactive dating is specific and gives the exact date that a rock was formed while the Law of Superposition gives an approximate date

• Radioactive dating gives an approximate estimate of the age of the igneous rocks, while the law of superposition will only reveal which is younger or older

• Radioactive dating determines whether the igneous rocks are older or younger than deeper layers of rock, while using the law of superposition depends on tectonic events

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NGSS.HS-PS1-8

The geologist records the relative ages of rocks. The bottom layer is listed as the oldest. The top layer is listed as the youngest. What did the geologist use to determine the relative ages of the rocks?

• Mineral content

• Radioactive decay

• The law of superposition

• The principle of unconformity

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NGSS.MS-ESS1-4

What would be the best way to compare the ages of layers of the same slice?

• By comparing the fossils in each layer, which will have the newest fossils on the bottom and the oldest fossils on top

• By using the law of superposition. Which says the oldest rock will be on the bottom and the newest rock on the top

• By using radioactive dating, which measures the amount of carbon-14 in an object and compares to its decay rate

• By comparing the rate of sedimentation, which says the layer that formed the quickest will be the oldest

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NGSS.MS-ESS1-4

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What is the approximate age of the Earth?

• 4.6 billion years

• 4.6 million years

• 46,000 years

• 4,600 years

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NGSS.MS-ESS1-4

Index fossils are used to date rock strata that would otherwise be very difficult to date. Which of these statements describes a key characteristic of index fossils?

• They existed in a unique location

• They are present in very small numbers

• They existed for a short span of time

• They are similar to other fossils

At one time, several kinds of camels lived in Florida. The evidence comes from fossils found in Florida. Which of these objects would be a fossil that shows that camels once lived in Florida?

• Sinkhole formed by a retreating glacier

• Sedimentary rock that formed a long time ago

• Crustal formation suspended from the ceiling of a cave

• Remains of an organism preserved by geologic processes

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NGSS.MS-LS4-1

Trilobites are a species of invertebrate fossils commonly found in places such as the Grand Canyon, a large landform made of many rock layers and coastal Florida. What does the evidence of the existence of the Trilobites provide scientists in determining how natural processes have changed Earth over time?

• Trilobite fossils are in both rocky and marine areas proving that Earth has changed by natural processes.

• Trilobite fossils are only in marine areas, showing how Earth has not been changed by natural processes.

• Trilobite fossils are found in rock layers that were laid down by natural processes which no longer occur today.

• Trilobite fossils are found in marine areas under the Earth’s surface compressed by natural processes over time.

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NGSS.MS-LS4-1

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How would a geologist determine the age of mountains formed by the upwelling of igneous rock?

• Use radioactive dating to date water in a lake in the mountains

• Use radioactive dating to date the igneous rock and the topmost layer of soil.

• Use radioactive dating to date Earth’s outer core below the mountains

• Use radioactive dating to date only the bedrock underneath the mountains

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NGSS.HS-ESS1-5