Transcript What is Physical Geology?

Earth SC-202 Physical Geology
Instructor
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Prof. Steven Dutch
Office: RH 352
Phone: 465-2246
Email: [email protected]
Home Page: www.uwgb.edu/dutchs
What is Physical Geology?
Erosion
Soils
Weathering
Fossils
Wind
Water Oceans
Glaciers
Underground Surface
Sedimentary
Earth History
Rocks
Volcanoes
Metamorphic
Earth’s Interior
Igneous
Plate Tectonics
Earthquakes
Mountains
Mineral Resources
Other Planets
Intrusions
Syllabus
• Introduction to the course
• Minerals
• Igneous Rocks and
Volcanoes
• Weathering and Erosion
• Evolution of Landscapes
• Sedimentary Rocks
• Evolution, Fossils,
Geologic Time
• Glaciers
• Wind and Wave Erosion
• Metamorphism and
Deformation
• Earthquakes and Earth's
Interior
• Continental Drift and
Plate Tectonics
• Resources from the Earth
• Geology of other Worlds
Exams and Grading
Midterm I
Midterm II
Lab
Final
Field Trip
50 points
50 points
100 points
80 points
20 points
Total
300 points
A
AB
B
BC
C
D
270+
255-269
240-254
225-239
210-224
200-209
Field Trip
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Dates
Mandatory – Absence Excuse Required
8:00 LS Parking Lot, Return 4:15
Casual Clothing – No strenuous hiking
Bring a lunch and fluids
Rest stops provided
Put on your calendar! No excuses!
Lab
• Instructor: Dawn
Walczyk
• Enroll in one
section
• 100 points total
Geology and Other Sciences
Physics
•Geophysics
•Seismology
Astronomy
Chemistry
•Mineralogy
•Petrology
•Geochemistry
Geology
Biology
•Paleontology
•Paleo????ology
•Historical Geology
•Planetary Geology
•Economic Geology
•Geomorphology
•Helioseismology
•Hydrology
•Oceanography
•Engineering
Geology
•Structural Geology
•Volcanology
Who Geoscientists Are:
• About 30,000 in the U.S.
• Globally, in rich and poor countries, about
one per $50 million GNP.
• Mostly male but changing rapidly (now
about 25% female in U.S.)
• Still less than 10% minority in U.S.
(moving up slowly)
Where Geologists Work
• 40 % Private Sector
• 30 % Academic
• 30 % Government
What Geologists Do:
• Locate Geologic Resources
• Geologic Hazard Mitigation
– Geological and Mining Engineering
– Site Study
– Land-Use Planning
• Environmental Protection
– Environmental Impact
– Ground Water and Waste Management
• Basic Research (Furnishes fundamental
knowledge for the applications)
Some Unique Aspects of
Geology
Importance of Relationships
• Sequential
• Spatial
Importance of Time
Distinctive Problems of Evidence
• Slow Rates
• Rare Events
• Destruction of Evidence
• Inaccessibility
Some Geologic Rates
Cutting of Grand Canyon
• 2 km/3 m.y. = 1 cm/15 yr
Uplift of Alps
• 5 km/10 m.y. = 1 cm/20 yr.
Opening of Atlantic
• 5000 km/180 m.y. = 2.8 cm/yr.
Uplift of White Mtns. (N.H.) Granites
• 8 km/150 m.y. = 1 cm/190 yr.
Some Geologic Rates
Movement of San Andreas Fault
• 5 cm/yr = 7 m/140 yr.
Growth of Mt. St. Helens
• 3 km/30,000 yr = 10 cm/yr.
Deposition of Niagara Dolomite
• 100 m/ 1 m.y.? = 1 cm/100 yr.
1 Second = 1 Year
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35 minutes to birth of Christ
1 hour+ to pyramids
3 hours to retreat of glaciers from Wisconsin
12 days = 1 million years
2 years to extinction of dinosaurs
14 years to age of Niagara Escarpment
31 years = 1 billion years
Some Unique Aspects of
Geology (Continued)
Reliance on Inference and Deduction
Intrinsically "Unsolvable" Problems
• Ancient Landscapes
• Mass Extinctions
• Ancient Ocean Basins
Scientific Principles in Geology
• Parsimony (K.I.S.S.)
• Superposition
• Uniformitarianism
Using these, plus observation, we establish
facts about Earth Processes
Parsimony
• The simplest explanation that fits all the
data is preferred
• Doesn’t guarantee that things must be
simple!
• Theories with lots of ad hoc or unsupported
ideas are probably wrong.
Parsimony: What is the best
interpretation of this well data?
Parsimony
• This?
• Or This?
Parsimony
• Rock layers
throughout NE
Wisconsin are
nearly flat and
little disturbed
• Glacial deposits
are always on top
of bedrock
• Therefore this is the
most likely
interpretation
One Implication of Parsimony
How do we know the laws of nature are the same
everywhere?
• Out to the farthest stars, everything seems to obey
the same laws of nature
• We find nothing in the rocks to suggest the laws of
nature were different in the past
Either:
• The laws of nature change but just happen to
produce effects that look like the presently-known
laws of nature – or –
• The laws of nature really are the same everywhere
Another Implication of
Parsimony
• We live in a universe of patterns
• If someone claims there is an exception
to a known pattern, the simplest
explanation is that he/she is wrong
• Therefore the burden of proof in
science is on the challenger
Superposition
Whodunit?
• Last night, one of Green Bay’s premier beer
can collections was stolen
• The only clue is footprints in the snow
• The thief was the last person to leave the
premises
The Suspects
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The Nephew
The Maid
The Cook
The Handyman
The Butler
Has a seeing-eye dog
Drives a car
Rides a motorcycle
Rides a bike
Walks to work
The Crime Scene
• The
Nephew has
a seeing-eye
dog
• The Maid
Drives a car
• The Cook
Rides a
motorcycle
• The
Handyman
Rides a bike
• The Butler
Walks to
work
Contacts
A Contact:
Mindoro Cut,
Wisconsin
Uniformitarianism
Continuity of Cause and Effect
• Apply Cause and Effect to Future Prediction
• Apply Cause and Effect to Present Technology
• Apply Cause and Effect to Past Uniformitarianism
Uniformitarianism does not
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Catastrophes never occur
Physical Conditions on Earth never Change
Earth has always been the same
Physical processes always occur at the same
rate or intensity
• Laws of Physics have always been the same
Uniformitarianism does mean:
Using our knowledge of physical laws, we can
test:
• Whether catastrophes have occurred
• Whether physical conditions on earth have
changed, and if so, how (ice ages, warm periods,
high or low sea level, etc.)
• Whether physical laws themselves have changed
in time, or elsewhere in the universe.