Module Exam- Earths geologic time line Flashcards
What are the 4 characteristics that make index fossils useful?
Easy to recognize
Wide spread
Abundant
Short periods of time
What is the geologic time scale?
Earths history based on fossils and rock evidence we have found
What are the 4 major units of time from longest to shortest?
Eon, Era, Period, Epoch
How are eras:eons different from hours:minutes?
Hours and minutes are for set amounts of time and eras:eons are different
What is relative dating?
Comparing rocks using like or as
The units of time are divided by what evidence?
Fossils
What are the 5 principles of relative age dating?
Superposition
Original horizontal
Lateral continuity
Inclusions
Cross-cutting relationships
Superposition states
In undisturbed rock layers the oldest are on the bottom
Original Horizontal states
Most rock forming materials deposit horizontally
Lateral Continuity states
Sediments are put down in large continuous sheets going in all directions
Inclusions states
If one rock has little bits of rock the big rock is younger
Cross-Cutting relationships states
If rock cuts through another rock the one being cut is older than the one cutting
What are the three Un-conformity’s ?
Angular
horizontal
nonconformity’s
How can a layer of iridium tell scientist about the cause of dinosaur extinction?
Fossils were only found under neither the layer shows something killed them off
How can fossils be evidence about how the environment has changed?
Different fossils of animals have different climates that they lived in
What is iridium rock?
Rock made by an asteroid
Angular is
When horizontal layer of sedimentary rock are later laid down on top of the tilted eroded layers they make an angular unconformity
Horizontal is
When a horizontal layer of sedimentary rock overlies another horizontal layer of sedimentary rock that has been eroded. This is also known as a dis-conformity
Nonconformity’s are
A gap in the rock record
