Download 1 Course description Geology lab Outcomes

Introduction to Geology
Earth Science web page:
www.centralia.edu
www.centralia.edu/academics/earthscience/index.html
Patrick Pringle
Instructor, NSC 318f
ppringle via centralia.edu
360360-736736-9391 x550
Websearch: Earth science Centralia
Course description
Geology lab
PHYSICAL GEOLOGY (4)
Explore earth materials, processes and
structures within a plate tectonics framework:
origin and structure of the earth, rocks and
minerals, geologic time, fossils and evolution,
earthquakes and volcanoes, ocean basins,
formation of landscapes, special topics.
Learn how to recognize earth materials,
features, and structures. Identification of
common rocks and minerals; topographic and
geologic maps.
Outcomes
Geology studies active
processes of the Earth
Improved quantitative reasoning skills as they pertain
to geology and solving geology problems
Improved spatial reasoning skills as related to
geologic processes and materials
Develop critical thinking skills in geology
Understanding of geologic time
Understanding of the interconnectedness of Earth
systems
Understanding of the scientific method as it pertains
to geology
Ability to communicate geologic information
Mount St. Helens, February 1983
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Mount Rainier volcano, from the west
Mount Hood volcano
Tree buried by past lahar
…and geology studies past history of the Earth
Geologic processes can be hazardous
and can profoundly influence humans.
Geologists keep discovering new things! Our knowledge of Mount
Rainier’s volcanic history has exploded in the past few decades.
Geology has become
interdisciplinary. These
scientists are using the study
of tree rings to estimate the
age of a geologic landform.
Bonneville landslide—dammed the
Columbia River in the mid 1400s
• Why Study Earth? --We are seeing
revolutionary changes in our understanding of the
Earth, the environment, and the universe!
• Plate tectonics – the Earth’s machine:
subduction, accreted terranes, etc-applications to geology of the planets…
• Interconnected Earth systems – rock,
water, ice, atmosphere, biosphere…
• Geologic and environmental history
Why study Earth?
Chapter 1 topics:
1.1 What is geology?
1.2 Why study geology?
1.3 How do we know … how to study Earth?
1.4 What does the principle of uniformitarianism
mean?
1.5 What is the theory of plate tectonics?
1.6 How does the concept of work apply to
Earth?
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Why study Earth?
Why study Earth?
Earth’
Earth’s surface is covered with soil that supports
natural and agricultural plant diversity
Earth materials are the source (either directly or
indirectly) of all natural resources
– Metals, plastics, timber, gemstones, building materials, etc.
Why study Earth?
Why study Earth?
Landforms derived from Earth processes:
And the #1 reason why we should study Earth:
– Provide the base for regional ecosystems
– Have aesthetic value to humans
We all live on it!
atmosphere
Hydrosphere (and
Lithosphere
cryosphere)
(geosphere)
biosphere
Fig 1.6mt
What is geology?
ge·
ge·ol·
ol·o·gy (Greek; geogeo- + -logi)
The scientific study of the planet Earth,
the materials of which it is made,
the processes that act on those materials,
the products formed,
1.1 What is geology?
The classic divisions
– Historical Geology – the study of physical,
chemical, and biological processes used to
interpret Earth’
Earth’s past development (ex: mountain
building, climate change, and the evolution of organisms as
preserved in fossils)
– Physical Geology – (the subject of this text)
and the history of the planet and its life
forms since its origin (including human
interactions)
Glossary of Geology, 2005, Neuendorf, Mehl, Jackson (Eds.)
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1.1 What is geology?
1.1 What is geology?
And where is it practiced?
The classic divisions
– Historical Geology
– Physical Geology – (the subject of this text) arose
from study of landforms and how they came to be.
Geologists study Earth
from one extreme …
Today, geology touches on many other sciences
Fig 1.2a
… to the other!
1.1 What is geology?
2.237 mph
2237 mph
1.1 What is geology?
The interior of our
Earth is layered. How
have we detected
and measured these
layers??
Fig 1.4
Processes are events that occur over time. This figure
shows the different rates of Earth processes.
Fig 1.3
One way to diagram
the layers is by
composition, and
another way is by
strength of the layers.
Why study Earth?
Earth is host of the water used for: power, irrigation,
consumption, recreation
Geologic investigations
produce maps and diagrams
of Earth’s geologic materials.
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Why study Earth?
1.2 Why study geology?
Geologists map the risks of geologic hazards
Earth interacts with
humanity
– Earthquakes – Volcanoes
– Landslides
– Floods
Assessing the risks of
hazards helps to make cities
safer, like San Francisco.
Fig 1.5
Orting
Buried tree
in Orting
Hazard zones for
lahars, lava flows,
and pyroclastic flows
from Mount Rainier
Hoblitt, R. P.; Walder, J. S.;
Driedger, C. L.; Scott, K. M.;
Pringle, P. T.; Vallance, J. W.,
1998, Volcano hazards from
Mount Rainier, Washington,
revised 1998: U.S. Geological
Survey Open-File Report 98-428,
11 p., 2 plates. [Accessed Feb.
11, 2002 at
http://vulcan.wr.usgs.gov/Volcano
es/Rainier/Hazards/]
We can use geologic info
to reduce risk to humans!
Electron Mudflow ~A.D. 15021502-3
Climate change—What
might be the effects on
glaciers, fluvial and
glacio-fluvial processes,
erosion and aggradation
patterns and rates, etc?
Geologic
processes are an
intrinsic part of
past climate
changes
1.3 How do we know … How to study Earth?
The Scientific Method (in brief)
– Ask questions (based on observations and/or data)
– Collect information (data)
– Review and analyze data (your own and others’
others’)
– State problems
– Formulate a hypothesis
– Test hypothesis for predictability and repeatability
– If tests refute … modify or make new hypothesis
– Publish results (refereed scientific journals)
Science is a process, not just a bunch of facts!
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1.3 How do we know … How to study Earth?
How do geologists do science?
– The scientific method is not a recipe
– Different questions/scenarios require modification
of the method
Field work – long the “standard”
standard” of geology
Seasonal processes
Instrumental/laboratory work
Computer simulations
Geology is unique because of the scale and
nature of its “natural laboratory”!
1.3 How do we know … How to study Earth?
The scientific method integrates inquiry,
explanation, and testability in understanding
natural phenomena.
Geologists use laboratory studies less often
than some scientists due to the rates and
scales of some Earth processes.
1.4 Uniformitarianism
The evidence seems to support the premise
1.3 How do we know … How to study Earth?
The “Big Picture”
Picture”
– Theories and Laws of Nature
Principles (aka “Laws”
Laws”) – universally applicable
generalizations that do not necessarily offer
explanation
Theories – widely accepted explanations of
natural phenomena that explain all relevant data
e.g. Theory of Plate Tectonics, Theory of Evolution by
natural selection, Quantum theory etc
Theory – An explanatory system of propositions, general principles or
laws, inferred from the phenomena and linking known facts and
observations; held to be true until contradicted or amended by new facts
or observations (from the Glossary of Geology, 2005)
1.4 Uniformitarianism
What is it? What does it mean?
– Uniformity of natural processes as old as the Greek
philosophers
Means that the current processes on Earth obey the
same basic physical laws they did “then”
then” allowing us to
backback-calculate some prior condition.
– James Hutton and Charles Lyell (Principles of
Geology v1–
v1–3, 1830–
1830–35) formalized concept.
1.4 Uniformitarianism
A modern earthquake mirrors events past that built
mountains like those in the distance.
At left - an active
Atlantic beach in
South Carolina
with ripple marks.
At right fossilized ripples
of a beach
millions of years
past based on
age estimates
from radiometric
dating.
Fig 1.8 top
Fig 1.8 bottom
Fig 1.9
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1.4 Uniformitarianism
1.5 What is the Theory of Plate Tectonics?
Current perspectives
– Not taken literally
Early conditions likely differed (temperature, chemistry)
Conditions affect rates of processes
Early Earth processes likely occurred at different rates
than today, although the same physical principles limited
them…
them…
– Is Uniformitarianism predictive? Sort of …
Sure: in the future, mountains will wear down and oceans
will open and close cause they have before...
However, it is less likely that we can predict where and
when an earthquake will occur.
1.5 What is the Theory of Plate Tectonics?
A “new”
new” theory (c. 1960s)
The solid lithosphere of Earth is composed of
a number of plates.
Over time these plates move (processes
described later in book)
Some plates grow while others shrink,
maintaining a balance of forces and area
across Earth’
Earth’s surface.
1.5 What is the Theory of Plate Tectonics?
Divergent boundary
–
–
–
–
–
contain both
continental
Others are mainly
oceanic crust
New crust
Crust becoming wider
Shallow earthquakes
Extrusive volcanism
MidMid-ocean ridge system
Some plates
and oceanic crust
Fig 1.10
1.5 What is the Theory of Plate Tectonics?
Convergent boundary
–
–
–
–
–
Subducting zone
Plate is consumed
Deep earthquakes
Volcanic chain above
Ocean trenches
Fig 1.11b
Fig 1.11a
1.5 What is the Theory of Plate Tectonics?
Transform boundary
–
–
–
–
Shearing zone
Lots of earthquakes
Little/no volcanism
E.g., California (San Andreas system)
Fig 1.11c
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1.5 What is the Theory of Plate Tectonics?
1.5 What is the Theory of Plate Tectonics?
Hot spots
– Fixed (sort of) spot of
rising mantle plume
– Plate moves across
– Builds island chain in
passing
Island chain from hot spots
Measurements of plate motions
using gps and other geodetic
techniques supports the amount
of uplift and movement through
geologic time measured via
radiometric age estimates for
rocks.
Fig 1.12
1.5 What is the Theory of Plate Tectonics?
The theory of plate tectonics = Earth’
Earth’s
lithosphere is divided into a number of plates.
These plates move, either towards or away
from one another, or past each other…
other…
The interaction of plates along their contact
boundaries accounts for the distribution of
earthquakes, volcanoes, and mountain belts—
belts—
and provides a basis for examining most Earth
processes and products.
1.6 How does … work
apply to Earth?
Work requires energy
Energy on Earth takes
various forms
– Stored
deep ocean trenches
earthquakes
volcanoes
Fig 1.10
The best evidence for plate
tectonics is that it explains
so many observations.
1.6 How does … work apply to Earth?
Earth is full of active processes
– Water flowing in streams
– Plate motion
– MountainMountain-building … for example
These processes involve movement of Earth
materials.
Thus, by definition, Earth processes are forms
of work.
1.6 How does … work apply to Earth?
Three modes of heat
transfer
Only convection causes
motion
Position
Form (e.g., stress,
petroleum)
– Transformed
Motion
Heat
Fig 1.13
Fig 1.14
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1.6 How does … work apply to Earth?
Sunlight heats the
ground.
1.6 How does … work apply to Earth?
Within Earth’
Earth’s crust
– Cold dense rock sinks
in subduction zones.
Warmer, molten
matter inside rises
and convection
occurs.
– Again, transferring
heat and moving
mass.
– Causes air to rise
– Cooler air replaces
the rising warm air
– Convection occurs,
transferring heat and
moving mass.
Fig 1.15c
Fig 1.15b
1.6 How does … work apply to Earth?
Potential energy of landscapes
ConvectionConvection-driven processes create “high spots”
spots” (mountains)
Mountains are high relative to the rest of the landscape. This is
is
potential energy.
Water flowing down the mountain, or dislodged rocks or
particles, realize this potential as motion.
This gradual flattening, erosion, is a powerful force explored
(along with others) in Part IV.
1.6 How does … work apply to Earth?
Movement of mass within and on Earth’
Earth’s surface is
evidence of work.
Work requires energy.
On Earth, sunlight and internal heat from radioactive
decay are the most prevalent sources of energy.
Heat is transferred by radiation, conduction, and
convection—
convection—the last of which is most important in
Earth processes.
Potential energy is a form of stored energy based on
physical position with respect to gravity. When mass
falls, flows, or goes downhill, this energy is realized.
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