Section 2- Relative Age of Rocks Flashcards
What is the relative age of a rock?
The rock’s age compared to to the ages of other rocks.
What is the absolute age of a rock?
The number of years since the rock formed.
What is the law of superposition?
A law that states that the oldest rocks would be found at the bottom and the youngest at the top.
How do geologists determine the relative age of rocks besides the position of rock layers?
They study extrusions and intrusions of igneous rock, faults, and gaps in the geological record.
What is the difference between an extrusion and an intrusion?
An extrusion hardens on the surface of the earth and an intrusion hardens underground.
What is a fault?
A break in Earth’s crust.
What is an unconformity?
Where old rock is eroded away and new rock forms.
What is an index fossil?
A fossil widely distributed and that represents a type of organism that lived for a brief period of time.
What does ‘paleo’ mean in ‘paleontologist’?
It means ancient.
What are the names of a downward fold and an upward fold?
Anticline and syncline.
What are cross-cutting relationships?
A rule that states that all folds and cuts in Earth’s surface are younger than the rock the fold or cut is in.
Compare rocks and natural forces that Mr. Phillips talked about in class to books.
Rocks are like the history book of Earth.
Missing pages in the book is like unconformity.
When a bad student tears out pages, that is like erosion.
If you keep a journal and you forget to write in it one day, what is that an example of?
Unconformity.
Which is older: the tree or the soil?
The soil because there has to be soil there before anything grows.
What is Michigan’s State Fossil? Please state the common name and the scientific name.
Common name: American Mastodon.
Scientific name: Mammut americanum.
What is Michigan’s state stone?
Petoskey stone
