Transcript welcome to gg 101 physical geology

WELCOME TO GG 103
GEOLOGY of the
HAWAIIAN ISLANDS
My name is Patty Lee.
We meet Monday , Wednesday
and Friday from 12:30 to 1:20.
Let’s have some fun!
GOOD INFO
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Office:
POST 713 B
Phone:
956-8489
email:
[email protected]
Office
Wed 11:15 - 12:15
Hours:
and by appointment
• Lecture Power Points will be available at
the following WEB SITE:
• <www.soest.hawaii.edu/GG/FACULTY/PLEE/gg103/index.html>
GG 103 text:
ESSENTIAL GEOLOGY
custom edition
• Course Objectives:
• Learn about the PHYSICAL characteristics or
the GEOLOGY of our planet, EARTH
• Learn about physical features of Hawaiian
Islands, their origin and how human activities
affect them
• To be better citizens & guardians of our planet!
GG 103 Goals
• To present knowledge that will be useful for life,
whether forming opinions on environmental
issues, selecting a home site or other property,
evaluating a business, or deciding on a
candidate, or understanding how our Earth
works, or just appreciating our beautiful Earth.
• To prepare you to consider many environmental
issues facing society and Hawaii, such as
resource utilization, water use and conservation,
and land-use planning.
• *** Use the CD. It is very good!!***
Scientific principle:
The universe is sensible and
governed by unchangeable
rules.
Think about what this means!
WHAT IS GEOLOGY?
• logia (study) of the geo
(earth)
HOW DO WE STUDY IT?
• directly & indirectly using
the scientific method
What are the tools used in Geology?
Observational (DIRECT):
maps
rock types, distributions, structures
microscopic investigations
Experimental (INDIRECT):
chemical
geophysical
The problem of experiments
Since geologists are interested in systems that are
very big (hundreds of km) and that have evolved
over long periods of time (millions of years), they
cannot conduct controlled experiments. They
must observe the results of Nature’s experiments
that are already complete or “in the works”.
The scientific method
1) Make an observation about
the sensible world.
2) Develop an explanation
(hypothesis) that predicts the
outcome of other observations
or experiments.
The scientific method (cont.)
3a) Make new
experiments.
3b) Make new
observations.
The scientific method (cont.)
return to
step 2
return to
step 3
Reject the
hypothesis
no
4) Do the
results match the predictions of the
hypothesis ?
yes
Hypothesis -> Theory -> Law
A hypothesis is an explanation initially
offered for a set of observations.
When a hypothesis withstands many tests it
may be called a theory.
A theory for which there seem to be no
sensible reasons to challenge is called a
law.
We study Earth to figure out how
it works!
• resources
• environment
• hazards
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RESOURCES
HAZARDS
BEAUTY
ENVIRONMENT
Geology in the News
Earthquakes in Iran
Mud slides in California
Just on O`ahu: rain problems
Mudslides
Sewage spills
Runoff (flooding)
Falling rocks
Geology of the Hawaiian
Islands
Concentrate on volcanic geology
Plenty of terminology, but we need it to
communicate
Introduced to Physical Geology
as applied to the Hawaiian Islands “+”
including natural & human-induced hazards
2 MAJOR CONCERNS
• GEOLOGIC TIME
• ENERGY
TIME
Geology is a science......just like
chemistry and physics!
But geologists face the special
challenge of not being able to do
experiments in the sense that
chemists and physicists do.
TIME
The big difference between geology and other
sciences is that not much happens geologically
in a human lifetime!
Rates of geologic processes: ~ cm/year
Big earthquakes may displace the ground several
meters in a few seconds, but they occur only
every 500 years or so.
TIME
The rates of geologic processes are almost always
slower than the rates of human effects on the
environment.
Geologists use millions of years as the standard
unit of time:
Ma = million years ago
m.y. = an interval of time (million years)
MAN & GEOLOGIC TIME
(ARISTOTLE - EARTH CENTERED)

FAST TIME

BISHOP USSHER


CATASTROPHISM
WORLD-WIDE &
SUDDEN DISASTERS

SLOW TIME

JAMES HUTTON

UNIFORMITARIANISM

THE PRESENT IS THE
KEY TO PAST
Siccar Point, Scotland
Some geologic
features take
millions of
years to form.
Carr Clifton
Others take
seconds!
John Sanford/Photo Researchers
Scientific principle:
The universe is sensible and
governed by unchangeable
rules.
What does this mean?
IT MEANS
James Hutton’s
Uniformitarianism
“The present is the key to the
past”
i.e.
Natural laws do not change —
however, rates and intensity of
processes do.
Geologic Time Scale
Geologic
Time
Scale
ENERGY


GIANT MACHINE (EARTH) DRIVEN BY
2 HEAT ENGINES:
EXTERNAL ENGINE
INTERNAL ENGINE
[CD: External Processes, external v.
internal]
EXTERNAL ENGINE - SUN
60% OF SOLAR
ENERGY IS USED TO
DRIVE WEATHER
SYSTEM BY VARIABLE
HEATING
 HYDROLOGIC CYCLE
-> EVAPORATION

JOB IS TO FLATTEN THE
SURFACE OF EARTH BY
WEATHERING,
EROSION &
DEPOSITION!
INTERNAL ENGINE



HEAT FLOWS FROM
HIGH TO LOW
TEMPERATURE
FROM INSIDE TO
OUTSIDE OF EARTH
JOB IS TO BUILD
VOLCANOES &
MOUNTAINS, MOVES
PLATES -> PLATE
TECTONICS
HOW HEAT WORKS



WORKS IN 2 WAYS -> CONDUCTION & CONVECTION
ROCKS BEHAVE PLASTICALLY (wax, soft tar)
GEOTHERMAL GRADIENT -> ~1deg.C/40M
THE
UNIVERSE
BIG BANG
 UNIVERSE
COMPOSED OF
 HYDROGEN (76%)
 HELIUM (23%)
 ALL ELSE (1%)
THE SOLAR SYSTEM
 SOLAR NEBULAR




FORMED 4.55 BILLION
YEARS AGO AS
PLANETESIMALS
COALESCED INTO
PLANETS
4 INNER ROCKY
PLANETS AND 4 GAS
GIANTS + PLUTO
HEATED BY IMPACTS
OF NUBULAR DEBRIS
CAUSING PLANETS TO
DIFFERENTIATE
The origin of the solar system.
A catastrophic impact between the proto-Earth and a
Mars-sized impactor made the moon.
Heating and
differentiation
of the early
Earth.
EARTH - OUR ISLAND HOME
The
Three
States of
Water
(Why Earth is
so special)
STRUCTURE OF EARTH
[CD: A 1-2]
OK!
SO WHAT?
WE HAVE ALL THIS
INFORMATION
BUT
HOW DOES EARTH WORK?
PLATE TECTONICS!!!
PLATE TECTONICS
• UNIFYING THEORY of plate motion
• PLATES (same as lithosphere) - 7 major
plates & many minor plates
• MOVE with respect to each other as fast as
finger nails grow
• **remember that crust rides in lithosphere
over the asthenosphere**
• Three (3) kinds of PLATE MARGINS
• [CD: INTERNAL, PLATE TECTONICS]
DIVERGENT MARGIN
<-SPREADING->
• Plates move apart leaving a gap that is filled by
magma/lava making new sea floor & new plate
• Occurs at Divergent Margins (MOR)
• Mid-Ocean Ridges (MOR) are elevated sub-marine
volcanic mountains
SUBDUCTION &
COLLISION
MARGINS
where subducting
plates move into
Earth’s interior.
Oceanic crust is
SUBDUCTED
& destroyed.
Continental crust
COLLIDES and
builds mountains.
SUBDUCTION
QuickTime™ and a
GIF decompressor
are needed to see this picture.
TRANSFORM MARGINS
•Plates slide horizontally past each other at great vertical faults
•Plates scrape & deform margins as they move
•Crust is neither created nor destroyed
SYSTEMS - Run by energy & made of
matter
1.
Definition: ANY PORTION OF THE UNIVERSE
SEPERATED FROM THE REST OF THE
UNIVERSE FOR THE PURPOSE OF OBSERVING
CHANGES

It is implied that all systems have boundaries

The amount of matter in a closed system is fixed!

Systems are composed of SUBSYSTEMS which
are in DYNAMIC BALANCE
Kinds of Systems
Earth is a
Closed
System
with 4
subsystems
CYCLES - Group of processes that
move matter and energy between
subsystems
HYDROLOGIC CYCLE - driven by Sun and works on surface
ROCK CYCLE - 3 families defined by formation processes
IGNEOUS ROCKS - “born of fire”; melted rock-> MAGMA
SEDIMENTARY ROCKS - formed at surface from rock
fragments
METAMORPHIC ROCKS - altered preexisting rock material
TECTONIC CYCLE - moves rock material between surface &
Earth’s interior by interaction of tectonic plates; run by
internal heat
Assignment: Read V1