🕰️ Relative Dating
This type of age tells whether something is older or younger than something else.
What is relative age?
This type of rock forms when sediments are compacted and cemented together.
What is sedimentary rock?
A fish fossil most likely tells scientists that the area once had this type of environment.
What is a water/ocean environment?
This type of age gives the actual age of an object in years.
What is absolute age?
Scientists estimate that Earth is approximately this old.
What is 4.6 billion years old?
In undisturbed rock layers, this layer is the oldest.
What is the bottom layer?
This type of rock forms when magma or lava cools and hardens.
What is igneous rock?
Scientists study fossils to learn about this.
What are past environments?
This is the amount of time it takes for half of a radioactive substance to decay.
What is half-life?
Scientists can use these objects to help determine Earth's age because they formed around the same time as Earth.
What are meteorites?
This law states that the oldest sedimentary rock layer is at the bottom and the youngest is at the top.
What is the Law of Superposition?
This type of rock is most likely to contain fossils.
What is sedimentary rock?
A rock contains fern fossils. What type of environment might this rock have formed in?
What is a forested or land environment?
Uranium-238 has a half-life of 704 million years. After one half-life, what percentage of uranium remains?
What is 50%?
This is a gap in the rock record caused by erosion or a period when sediment was not deposited.
What is an unconformity?
A fault cuts through several rock layers. Is the fault older or younger than the layers?
What is younger?
Magma pushes into existing rock underground and cools. What is this feature called?
What is an igneous intrusion?
This fossil is a spiral-shelled organism commonly associated with marine environments.
What is an ammonite?
A radioactive material has a half-life of 100 million years. How old is a rock if two half-lives have passed?
What is 200 million years?
This type of fossil is widespread, common, and existed for a relatively short period of time.
What is an index fossil?
An igneous intrusion cuts through three sedimentary layers. What relative dating principle tells you the intrusion is younger?
What is cross-cutting relationships?
A rock forms from layers of sediment deposited in an ancient ocean. What type of rock is it most likely to be, and why?
What is sedimentary rock, because sediments were deposited in layers?
Scientists find the same fossil in two different rock layers. What can this evidence help scientists determine?
What is that the rock layers may be approximately the same age?
A rock has gone through 3 half-lives. If its radioactive material has a half-life of 50 million years, how old is the rock?
What is 150 million years?
A volcanic ash layer is dated at 100 million years old. A fossil is found below the ash layer. Is the fossil older or younger than 100 million years?
What is older than 100 million years?