This fossil is a hollow area in the shape of an animal/plant left behind
What is a mold
100
What is the approximate age of the Earth?
What is 4.6 billion years
100
The time scale is divided into what?
What are eras and periods
200
This type of fossil is an ant trapped in amber
What is preserved remains
200
This law says that the oldest rock layer is at the bottom and the youngest layer is at the top
What is Law of Superposition
200
A gap in the geologic record formed when sedimentary rocks cover an eroded surface is called a(n)
What is an unconformity
300
A fossil of wood is this type
What is petrified fossil
300
What % of a radioactive element would remain after 2 half-lives?
What is 25%
300
Identical index fossils are found in a rock layer in the Grand Canyon and in Utah (675 miles away). What can the scientist infer about the ages of the two rock layers?
What is they are about the same age
400
A footprint fossil is what type of fossil?
What is trace fossil
400
What is the difference between relative age and absolute age?
What is Relative age describes how old/young something is compared to something else. Absolute age tells exactly how old something is
400
What was used by geologists to define the starts and ends of the divisions of the geologic time scale?
What is major changes in life forms
500
This fossil looks like an imprint of a leaf left behind
What is carbon film
500
The time is takes for half a radioactive element's atoms to decay is