Describe how layers of rocks (stratified rocks) are formed, Describe the different methods (relative and absolute dating) to determine the age of stratified rocks, and Explain how relative and absolute dating were used to determine the subdivisions of geologic time. The relative age of a rock is its age when compared with the ages of other rocksThe absolute age of a rock is a calculation of the number of years that have passed since the rock formed.

1. Rock Formation II:
Relative and Absolute
Dating
mirjam nilsson

2. A) Describe how layers of
rocks (stratified rocks) are
formed,
B) Describe the different
methods (relative and absolute
dating) to determine the age of
stratified rocks, and
C) Explain how relative and
absolute dating were used to
determine the subdivisions of
geologic time.
Objectives

3. 20XX presentation title 3
The relative age of a rock is its age when compared with the
ages of other rocks
The absolute age of a rock is a calculation of the number of
years that have passed since the rock formed.

4. How Layers
of Rocks Are
Formed

5. 20XX presentation title 5

6. .
20XX presentation title 6
How Sediments are formed and
sediments are turned into layers of new
rocks.
Existing rocks can be broken down into
small pieces called ________.
3 Main types of Weathering:
1.___________ - caused by temperature
changing.
2. __________ - when acid rain reacts with
substances in rocks.
3. __________ - plants or animals can
break up rocks.

7. Sediments can be move away by: _______, ______,
______, ______.
The combined process of weathering and transport is
called ________.
When sediments settle in warm place and some may sink
at the bottom of the sea and this called _______.
_______ when these layers the weight of the layers
above compressed the ones below and are formed into
sedimentary rocks.
_________when substance sips between the sediments
and hardened and glued together.
20XX presentation title 7

8. Methods to Determine the Age
of Stratified Rocks
Relative dating is a method
of arranging geological events
based on the rock sequence.
• Determining which fossils
or events came first,
second, third…etc…
20XX presentation title 8

12. Absolute Dating –
determining the actual
age of rock using
radioactive decay
20XX presentation title 12

13. • ABSOLUTE DATING
the process of
determining an age on a
specified chronology in
archaeology and geology
(RADIOACTIVE DECAY)
• RELATIVE DATING
the process of determining
if one rock or geologic
event is older or younger
than another, without
knowing their specific ages
(GEOLOGIC SEQUENCING)
20XX presentation title 13

14. PRINCIPLES OF RELATIVE DATING
• Law of
Superposition
States that each
layer of sediment is
piled on top of
another layer
making the one on
top of the strata the
youngest one, while
the layer at the
bottom of the strata
is the oldest.

16. The Law of Cross-Cutting Relationship
• States that igneous intrusion is always younger than the rock it
cuts across
• Extrusion – a lava that is cooled and hardened in a surface.
• Intrusion – a magma that is cooled and hardened beneath the
surface (hardened magma)

17. 20XX presentation title 17

18. 20XX presentation title 18

19. The Law of Inclusion
• The rocks that are mixed up in the formation of sediments are
called INCLUSION
• These rocks are always older than the layer of sediments it is
embedded.
20XX presentation title 19

20. Law of Horizontality
• Layers of sediments are originally deposited horizontally
under the influence of gravity. Those strata's that are not
found not in horizontal order may have been deformed
by the movement of the earth’s crust.
20XX presentation title 20

21. Absolute Age of Rocks
• RADIOMETRIC DATING – radioactive isotopes found in
fossils or rocks are used.
20XX presentation title 21

22. 20XX presentation title 22

23. • Radioactive decay – the process by which an atomic
nucleus of an unstable atom loses energy.
Alpha, Beta and Gamma
• The original unstable isotope is called the parent
isotope, and the more stable form is called the daughter
isotope. Isotopes decay at an exponential rate that that
can be described in terms of half-life.
• Half – life - it takes time for substance undergoing
decay to decrease by half.
20XX presentation title 23

25. 20XX presentation title 25

26. 20XX presentation title 26