1. Relative Age
The age of a rock unit or event __________ to the age of another rock unit or event.
In other words which layer or event came __________, __________, __________…
Ex. Mr. Jensen is older than you are or the sandstone was deposited before the fault occurred

2. Principle of Uniformitarianism
What?
“The is the Key to the ”
What geologists can see going on today are the same that occurred in the past.

3. ________ at the Bottom; ________________ on Top
Law of Superposition
The Oldest Layers are deposited first (on the bottom) and subsequent layers are deposited on top.
________ at the Bottom; ________________ on Top
This assumes there has been no ______________

4. The rock must be there so it can be _____________
Crustal Deformation
All __________, __________, or __________ happened after the layers were deposited
The rock must be there so it can be _____________
This includes ___________ _______________ that changes the rock that was “touched” by magma or lava

5. Absolute Age
An actual year or a range of years (sometimes expressed as a __________ __________)
Can be determined with ____________ dating
Can be determined with the use of ________ __________ and __________ __________ __________

12. Index Fossils
Index fossils (like fads) can help us determine the __________ __________ __________ that the rock formed
The best index fossils are those that lived for a relatively _________ period of time and over a __________ area.

13. Volcanic Time Markers
Volcanic ash is sent into the __________ _______________ and is carried all over the Earth
__________ of volcanic ash are created all over the Earth.
They can be linked to the __________ and __________

16. Not every Fossil is an Index Fossil
Some fossils are not useful for determining the age of a rock because they …
Lived for _____ ________ a period of time
Too __________ of an area