1. GEOLOGIC HISTORY THE RULES OF THE GAME
© Copyright   M. J. Krech. All rights reserved.

2. Time
What is
time?

3. Time is… Either relative or absolute
Time is: a measured period during which an event, process, or condition exists or continues.

4. One Year =
the time it takes the Earth to complete one orbit around the Sun.

5. Geologic Time Based on the same time units
Generally much greater periods of time
100,000 years
1,000,000 years

6. Dating Techniques
One ways in which geologists look at time: Relative Dating

7. Relative Dating is..
…the measure of a sequence of events without knowing the exact date at which the events occurred.
What happened first?
What happened next?

8. Principles of Relative Dating
Principle of Superposition
Principle of
Cross-Cutting
Principle of Inclusions
Principle of Unconformities

9. Principle of Superposition
The youngest rocks are on the top.
The oldest rocks are on the bottom.

10. Principle of Superposition
Q#1
Which rocks are older?
Which rocks are younger?

11. Principle of Cross-Cutting
Any feature that cuts across another rock or structure is younger than what it cuts across.
You can't cut something until that something exists, therefore the cut has to be younger.
Volcanic vents cutting across
sedimentary rock layers -
Which is youngest?

12. Principle of Cross-Cutting
Q#2
What is younger?
The rocks or the fault line?

13. Principle of Inclusions
Rock layers which contain other rocks are younger than the inclusion.
The
inclusion
(the other
rocks) 
is older!

14. Principle of Inclusions
Q#3
Which is older? The rock layer or the rocks included in the layer?

15. Principle of Unconformities
Unconformities are surfaces that represent gaps in the geologic record.

16. Principle of Unconformities
missing rock layer = missing time

17. Where's the missing sediment?
Q#4
How do
you
know?

18. Where's the missing sediment?
Q#5
Where's the missing sediment?
How do
you
know?

19. What happened first?
Q#6
How do
you
know?

20. Where is the youngest rock?
Q#7
How do
you
know?

21. Where is the unconformity?
Q#8
How do
you
know?

22. What rock layer is the oldest?
Q#9
How do
you
know?

23. Which is younger? The fault or the rock layers?
Q#10
How do
you know?

24. Does this diagram show an unconformity?
Q#11
How do
you know?

25. Which is younger? The rock layer or the inclusion?
Q#12
How do
you
know?

26. The End
BONUS:
What do you see here?