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

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 __________ __________ __________

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.

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 __________

                                    

                                    

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