Earth's Age Flashcards
the preserved remains or traces of an organism that lived in the past.
fossil
a timeline that organizes major events in Earth’s history, beginning with when Earth formed and continues to present time.
Geologic Time Scale
is the sum of all of the fossils, or evidence of living things, on Earth. Geologists study the fossil record to make inferences and draw conclusions about environments on Earth at different times in Earth History.
Fossil Record
the permanent dying out of a species or larger group of organisms
Extinction
a fossil that is useful for dating geologic layers because the organism lived for only a short period of time.
Index Fossil
states that in undisturbed sedimentary rock layers, older layers of rock lie under younger rock layers.
Law of Superposition
the age of an object or event in comparison to another object or event.
Relative Age
the process of comparing objects or events to determine which are younger or older, without knowing their specific ages.
Relative Dating
the actual age, in years, of a rock or fossil
Absolute Age
measures the age of a material by comparing the amount of a radioactive substance with the amount of its decay product
Radioactive Dating
Which BEST describes a fossil that helps determine the relative age of a rock layer?
A. Trace fossil
B. Index fossil
C. Radioactive fossil
D. Unconformity fossil
B. Index fossil
What method do scientists MOST OFTEN use in determining the age of Earth?
A. Comparing the amount of uranium remaining and the amount of lead formed in radioactive dating of rock layers
B. Counting the number of sedimentary rock layers
C. Observing folds, plate shifting, and unconformities in rock layers
D. Using index fossils to determine the age of rock layers
A. Comparing the amount of uranium remaining and the amount of lead formed in radioactive dating of rock layers
