Geologic Timescale
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What is the guiding principle in the study of the Earth’s history? It states that the present is the key to the past.
Uniformitarianism
Fossils are deposited in the sedimentary layers of rocks. True or False
True
New sedimentary rock layers are almost always flat. True or False
True
Sedimentary rocks are not formed from fragments of other types of rocks. True or false
False
This is used to determine whether an object or event is older or younger than other objects
Relative Dating
What kind of principle of relative dating states that sedimentary rocks are originally formed in Horizontal layers.?
Law of original horizontality
Horizontality occurs in an area of land that is forced to bend. True or False
True
What kind of principle of relative dating states that rock layers above are younger than the ones below it?
Law of superposition
What kind of principle of relative dating states that any rock or fault that cuts across other rocks is younger than those it cuts across?
Principles of cross-cutting relationship
What kind of principle of relative dating states that new forms in regions of separation?
Idea of unconformities
These are surfaces of erosions that separate younger rocks from older ones.
Unconformities
The method of measuring the absolute age of an event or object.
Absolute dating
To determine the absolute ages of rocks and fossils, what does scientists analyzes?
Isotopes of radioactive elements
These are atoms of the same element that have similar number of protons but different numbers of neutrons.
Isotopes
What do you call unstable isotopes in which they break down into stable isotopes or other elements?
Radioactive
What do you call an unstable radioactive isotope?
Parent isotope
What do you call a stable isotope produced by the radioactive decay?
Daughter isotope
The more daughter material there is, the older the rock. True or False
True
Time needed for half of a sample of a radioactive substance to undergo radioactive decay
Half-life
A method achieved by determining the absolute age of a sample based on the ratio of parent material to daughter material.
Radiometric dating
A kind of radiometric that uses potassium-40, which has a half-life of 1.25 billion years
potassium-argon
A kind of radiometric that uses uranium-238, which has a half-life of 4.5 billion years
uranium-lead
A kind of radiometric that uses rubidium-87, which has a half-life of 49 billion years
rubidium-strontium
A kind of radiometric that is used mainly for dating things that lived within the last 50,000 years, which has a half-life of 5,730 years.
carbon-14