Geologic Time

States that younger rocks lie above older rocks if the layers have not been disturbed

• superposition

• cross-cutting

• unconformity

• uniformitarianism

Answer explanation

The principle of superposition states that in undisturbed layers of rock, younger rocks are found above older rocks. This fundamental concept helps geologists determine the relative ages of rock layers.

Tags

NGSS.MS-ESS1-4

Analyze the seashell found in the white layer. Which statement is true of the rock layer that contains this fossil?

• It could also contain a fossil from the bottom layer.

• It is older than the layers below it.

• It is younger than the layers above it.

• It is older than the layers above it.

Answer explanation

The correct statement is that the rock layer containing the seashell is older than the layers above it. This follows the principle of superposition, where younger layers are deposited on top of older layers.

Tags

NGSS.MS-ESS1-4

NGSS.MS-ESS2-3

Scientists test a mummified corpse and find that it has 50% of its C14 left. How long ago did the mummy die?

• 17,190

• 11,460

• 22,920

• 5,730

Answer explanation

The half-life of C14 is approximately 5,730 years. If 50% of C14 remains, it indicates one half-life has passed, meaning the mummy died about 5,730 years ago.

What is the law of superposition?

• The age of sedimentary rock not found in the original layers.

• Metamorphic rock is younger than the nearby igneous rock.

• Sedimentary rock in it's original position is older than layers above it.

• Metamorphic rock is older because it was deposited to nearby sedimentary rock.

Answer explanation

The law of superposition states that in undisturbed sedimentary rock layers, the oldest layers are at the bottom, and the layers above are progressively younger. Thus, sedimentary rock in its original position is older than layers above it.

Tags

NGSS.MS-ESS1-4

Layer B on side #1 (left) is a match to which layer on side #2 (right)?

• z

• y

• w

• there is no match

Answer explanation

Layer B on side #1 corresponds to layer w on side #2, as they share similar characteristics or functions, making w the correct match.

Tags

NGSS.MS-ESS1-4

Length of time for half the atoms of an isotope to decay

• Isotope

• Half-Life

• Radiometric Dating

• Absolute Dating

Answer explanation

The term 'Half-Life' refers to the length of time required for half of the atoms in a radioactive isotope to decay. This concept is fundamental in understanding radioactive decay processes.

Tags

NGSS.HS-PS1-8

How does absolute age differ from relative age?

• only absolute dating indicates which rock is older than another

• only absolute dating finds the age in years

• only relative dating finds the age in years

Answer explanation

Absolute age provides a specific age in years for a rock or fossil, while relative age only indicates whether one rock is older or younger than another. Thus, the correct choice is that only absolute dating finds the age in years.

Which type of dating method can be used on rock layers by applying the Law of Superposition?

• relative dating

• absolute dating

• radioactive dating

• radiometric dating

Answer explanation

Relative dating uses the Law of Superposition to determine the age of rock layers by comparing their positions. The oldest layers are at the bottom, while the youngest are at the top, making relative dating the correct choice.

Tags

NGSS.MS-ESS1-4

If I have a fossil that I predict to be around 500 million years old, what type of dating would I use to find the exact age?

• Carbon

• Ring Counting

• Law of Superposition

• Uranium

Answer explanation

For dating a fossil around 500 million years old, uranium dating is appropriate. Carbon dating is effective for younger fossils (up to 50,000 years), while ring counting and the law of superposition do not provide exact ages.

What type of rock is created through the compaction and cementation of rock pieces?

• Igneous

• Sedimentary

• Metamorphic

Answer explanation

Sedimentary rocks are formed from the compaction and cementation of rock pieces, minerals, and organic materials. This process distinguishes them from igneous and metamorphic rocks, which form through different geological processes.

Tags

NGSS.MS-ESS2-1