Vocabulary
Superposition
Index Fossils
Absolute Dating
Earth's Changes
100
The age of a rock given as the number of years since the rock was formed.
Absolute age
100
Which rock layer in the diagram seems to be the oldest?
Layer A
100
In rock layers, trilobite fossils are found lower than coral fossils, and coral fossils are found lower than ammonite fossils. Order these 3 fossils from the youngest to the oldest.
-ammonites (youngest)
-corals
-trilobites (oldest)
100
If a sample starts with 400g of a radioactive isotope, how many are left after 3 half lives?
50g of the radioactive isotope
100
Scientists have found the same types of plants and fossils on different continents suggesting that they were all once joined in a single landmass called Pangea. What scientific theory was supported by this evidence?
Theory of Continental Drift
200
The preserved remains or traces of an organism that lived in the past
fossil
200
What is the oldest layer in this image?
Layer Q
200
True or False: Index fossils help determine relative age through correlating rock layers in different locations.
True— Index fossils are found in many places and lived during a short time period, so they help scientists match rock layers across different locations to determine relative age.
200
The time it takes for half of a radioactive isotope to decay into stable isotope is called the_______.
half-life
200
Scientists were digging holes in the desert of Peru and found shark teeth. What did these fossils tell scientists about the environment in which they were found?
This desert area used to be underwater.
300
The process of determining the age of an object using the half-life of one or more radioactive isotopes.
radiometric or radioactive dating
300
What is the youngest feature in this image?
Igneous Intrusion B
300
How could I use fossil remains as a geologist?
To determine the age of rocks in the surrounding area.
OR
Determine what the past environment/climate was like.
300
Select the correct term to complete the sentence:
During ________, atoms of one element break down into another, more stable element.
A. Half-life
B. Radiation
C. Energy and particles
D. Radioactive decay
D. Radioactive decay.
300
When scientist find buried marine fossils at the top of a mountain, what does it suggest?
The rock layer was once submerged underwater.
400
The age of rock compared to the age of other rocks.
Relative age
400
Is the age of the rock layers described using relative or absolute dating?
At Grand Canyon Park, the Kaibab rock layer is found on top of the Toroweap rock layer. This means the Kaibab layer is younger than the Toroweap layer.
relative dating
400
Which two traits make a fossil a good index fossil?
widespread geographically, short lifespan
400
Why are radioactive substances useful for determining the absolute age of rocks and fossils?
Because they decay at a constant, predictable rate, which allows scientists to calculate the exact age of the materials.
400
What do fossils show about how life has changed over time?
Fossils show that life has changed from simple to more complex over time.
500
The geologic principle that states that in layers of horizontal rock, each layer is older than the layer above it and younger than the layer below it.
law of superposition
500
List the layers of rock from oldest to youngest.
E, B, C, D, A
500
Trilobite fossils are found in Cambrian (older time period) rocks but not in Triassic rocks. Which statement best explains why trilobite fossils are missing from Triassic rocks?
They went extinct before the Triassic rocks were formed.
500
True or False: Measuring the decay of radioactive elements is the most accurate way to measure a rock's age.
True
500
Scientists were exploring a place in the Artic where it is very cold called the Dry Valleys and found fossils of moss, small shrubs, and insects. What can be inferred about the environment in the past?
For insects and plants to survive in this area, it had to be warmer and more welcoming to life than it is today.