Vocabulary
Superposition
Index Fossils
Absolute Dating
Earth's Changes
100
The age of rock compared to the age of other rocks.
Relative age
100
Mr. Welden is older than his son, but younger than his father. What geology term would you use to describe Mr. Welden's position in his family?
relative age
100
The best index fossils have which two traits?
widespread geographically, short lifespan
100
Why are radioactive substances useful for measuring absolute age?
They decay at a constant rate.
100
What do fossils show about how life has changed over time?
Fossils show that life has changed from simple to more complex over time.
200
The age of a rock given as the number of years since the rock was formed.
Absolute age
200
Which rock layer in the diagram seems to be the oldest?
Layer A
200
In rock layers, trilobite fossils are found lower than coral fossils, and coral fossils are found lower than ammonite fossils. What can be determined from this information?
Trilobites are older than both corals and ammonites. Ammonites are the youngest here. Corals are older than ammonites, but younger than trilobites.
200
If a sample starts with 400 radioactive isotopes, how many are left after 3 half lives?
50 isotopes
200
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
300
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
300
List the layers of rock from oldest to youngest.
E, B, C, D, A
300
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.
300
True or False: Measuring the decay of radioactive elements is the most accurate way to measure a rock's age.
True
300
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.
400
The preserved remains or traces of an organism that lived in the past
fossil
400
What is the oldest layer in this image?
Layer Q
400
True or False Index fossils help determine relative age through correlating rock layers.
True
400
The time it takes for half of a radioactive isotopes to decay into stable isotopes is called the___.
half-life
400
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.
500
The process of determining the age of an object using the half-life of one or more radioactive isotopes.
radiometric or radioactive dating
500
What is the youngest feature in this image?
Igneous Intrusion B
500
How could I use fossil remains as a geologist?
To determine the age of rocks in the surrounding area.
500
Select the word that fills in the blank:
During (half-life / radiation / energy and particles / radioactive decay,) atoms of one element break down into another, more stable element.
radioactive decay.
500
When scientist find buried marine fossils at the top of a mountain, what does it suggest?
The rock layer was once submerged underwater.