Geology is the study of the solid Earth. Nicolaus Steno originated three basic principles of geology in 1669 - superposition, original horizontality, and lateral continuity. These principles established the foundation for determining the relative age of rock layers based on their position. In 1787, James Hutton introduced the principle of uniformitarianism, which states that the geological processes we observe today are the same as those that occurred in the past. Plate tectonics theory emerged in the 1960s and provides the modern framework for understanding Earth's geologic processes and events over its 4.6 billion year history.

1. Geology is a young science
Geology = study of solid Earth
Roots are in observations of
natural world

2. Nicolaus Steno
(1669)

3. 1669: Nicolaus Steno
Originated three basic principles:
1) Superposition
- in series of layers, oldest layer is
on bottom

4. Steno’s Basic Principles
2) Original Horizontality
- sediments (layers) are deposited
parallel to Earth’s surface
- forces act on rx after they were
deposited

5. Steno’s Basic Principles
3) Lateral Continuity
- sediment deposited to the edge
of its depositional environment
- rock layers continue laterally for
a distance

6. Lateral Continuity
Determined by field
mapping or drilling

10. Principle of
Uniformitarianism
1787: James Hutton
Physical, chemical, & biologic
laws unchanged through time
- forces which appear small can
produce features very large
Ex: Colorado River and Grand
Canyon

11. Uniformitarianism
Important: Processes are the
same, but the rates change
Ex: Earth’s harsh early
atmosphere & lack of plants
speeded erosion
Ex: Banded iron formations

12. Physical Geology
Studies:
1)Earth Materials
- minerals
- rocks

13. Physical Geology
Studies:
- changes on
Earth’s surface
& interior

14. Physical Geology
2) dynamic forces that cause
change (both external & internal)

15. THEME:
EARTH IS DYNAMIC!
(and)
Everything is connected

16. 4 parts to Earth’s system:
1) Atmosphere
- carbon dioxide (CO2)
- free oxygen (O2)
- water vapor (H2O)

17. 4 parts to Earth’s system:
2) Hydrosphere – includes:

18. 4 parts to Earth’s system:
3) Biosphere – all life
4) Geosphere – planet
Earth’s structure =
crust, mantle, core

19. 4 parts are interrelated:
Ex: Clear cutting a forest
Biosphere:
Atmosphere:
Geosphere:
Hydrosphere:

20. 4 parts are interrelated:
Ex: Volcanic eruption
Biosphere:
Atmosphere:
Geosphere:
Hydrosphere:

21. Uniformitarianism
Important: Processes are the
same, but the rates change
Ex: Earth’s harsh early
atmosphere & lack of plants
speeded erosion
Ex: Banded iron formations

22. All parts are interrelated:
Ex: building a dam
Biosphere:
Atmosphere:
Geosphere:
Hydrosphere:

23. Glen Canyon Dam

24. Science
Attempts to
understand, explain, and predict
events
- collects data to discover patterns
in natural world

25. Geologists at Work

26. Tools of Geology
Rock Hammer
Maps

27. Detective Analogy
Geologists are solving a mystery
Scene of Clues Crime
the Crime Solved

28. Scientific Process
Ask a question:
Why doesn’t my #!*#*! car start?
1) Collect facts by observation or
measurement
Gas gauge, lights, radio, etc.

29. Scientific Process
2) Explain how or why it happens
(hypothesis)
Battery is dead
3) Design experiment to test
validity of hypothesis
Try to jump start battery

30. Scientific Process
4) Accept, modify, or reject
hypothesis after extensive
testing
Theory – well-tested framework
that best explains the
observations

31. Scientific Revolution
New information leads to a better
explanation of observations
Occurs due to:
a) new approach to the
question
b) new technology

32. Scientific Revolution in
Geology

33. Continental Drift
1915:
Alfred Wegener
- hypothesized the
supercontinent
Pangaea (“all
land”)

34. Pangaea

36. 2 byo rx

37. Both 2 byo & ½ byo rx

42. Scientific Revolution
New information leads to a better
explanation of observations
Occurs due to:
a) new approach to the
question
b) new technology

43. WWII
New technology = fathometer
-used to map ocean floor
topography

44. Harry Hess
1962:
Hypothesized
sea-floor
spreading

45. Plate dynamics

48. Hydrothermal Vents

49. Plate map

50. Plate Tectonics Theory
Plate – rigid slab of lithosphere
Plates move independently

51. Types of Plate Boundaries
1) Divergent – plates pull away
from each other
- caused by magma rising to
create new seafloor
- “sea-floor spreading”

52. Types of Plate Boundaries
2) Convergent – plates collide
Can be marked by:
a) deep-sea trenches
b) mountains
c) volcanic activity

53. Types of Plate Boundaries
3) Transform
- plates slide laterally
- characterized by shallow EQ’s
Ex: San Andreas Fault

54. Geologic Time
“Deep time”
Earth = 4.6 billion years old
Relative Dating – putting
rocks/events in chronological
order
1st, 2nd, 3rd, etc.

55. Geologic Time Scale
Paleozoic Era (“ancient life”)
“Age of Invertebrates”
- ended with largest mass
extinction in Earth’s history
(over 90% organisms were extinct
by 245 mya)

56. Geologic Time Scale
Mesozoic Era (“middle life”)
“Age of the Dinosaurs”
- ended with extinction of
dinosaurs (66 mya)

57. Geologic Time Scale
Cenozoic Era (“recent life”)
“Age of Mammals”
Will the Cenozoic Era end?