What two methods are used for determining the age of rocks and fossils?
A.
Relative and Absolute Dating
B.
Absolute and Resolute Dating
C.
Carbon and Water Dating
D.
Relative and Absent Dating
A. Relative and Absolute Dating
Which is true about relative dating?
A.
Relative dating uses the half-life of isotopes to get the exact age of a rock or mineral.
B.
Carbon-14 dating is used on rocks and minerals that are relatively young.
C.
Potassium –Argon dating is used on very old rocks and minerals.
D.
The law of superposition is used to determine a rocks relative age.
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Select an answer
D. The law of superposition is used to determine a rock's relative age.
What is "half-life"?
A.
The length an organism lived in prehistoric times.
B.
The time it takes for the radioactivity of a specific isotope to fall to half its original value.
C.
Half the life of an organism.
D.
The time it takes for a geologist to determine the age of a rock or mineral.
B. The time it takes for the radioactivity of a specific isotope to fall to half its original value.
The correct answer is A. Relative and Absolute Dating.
The correct answer is A. Relative and Absolute Dating.
To determine the age of rocks and fossils, scientists primarily use two methods: relative dating and absolute dating.
1. Relative dating: This method involves determining the age of rocks and fossils by comparing their positions in relation to other rocks and fossils. It relies on the principle of superposition, which states that in undisturbed rock layers, the oldest rocks are at the bottom and the youngest are at the top. By examining the layers and their order, geologists can estimate the relative age of the rocks and fossils found within them. Relative dating is useful for establishing the chronological sequence of events but does not provide an actual numerical age.
2. Absolute dating: This method involves determining the exact age of rocks and fossils using various techniques that measure the decay of radioactive isotopes within them. One widely used technique is radiometric dating, which relies on the fact that certain isotopes of elements decay at a predictable rate. By measuring the ratio of parent isotopes to daughter isotopes in a sample, scientists can calculate its age. Different isotopes are used for dating different types of rocks and fossils, depending on their known decay rates and the age range being investigated. Absolute dating provides a numerical age for rocks and fossils, allowing for more precise estimation of when they formed.
So, the two methods used for determining the age of rocks and fossils are relative dating and absolute dating, making option A the correct answer.