GEOL 101 Section 004
• Text: Essentials of Geology, by Marshak
• You must take the lab, and pass it, to pass this course.
• Labs do meet this week. If you already missed your lab:
http://www.agiweb.org/workforce/video/index.html
• Grades – calculated as on syllabus.
• Grades posted on MyUNLV:
http://aboutmyunlv.unlv.edu/
• Department and UNLV classroom policies – participation
(quizzes), attendance (no makeup exams), misconduct and the
learning environment (laptops, cellphones, etc.), administrative
drops, children, etc…
• How to succeed in this class?
For Powerpoint Lectures:
http://geoscience.unlv.edu/terrylspell.htm
Click on “GEOL 101…” under Teaching
What is Geology?
• Geology = Geo (Earth) and Logia (study or
science).
• Geoscience perhaps a more modern term.
• Geology is a science of it’s own, but it also
includes chemistry, physics, math, biology,
engineering, economics and more.
• There are many areas of study in geology
and they are so diverse that one geologist
may not know much about what another is
doing.
Examples of Different Areas of Geology
• Volcanology – study of volcanoes
• Geochronology – study of the age of rocks
• Geophysics – study of earthquakes and the
interior of the Earth
• Paleontology – study of fossils and evolution of life
• Structural Geology – study of how rocks deform,
e.g. during mountain building events
• Hydrology – study of surface and ground water
• Petroleum and Mining Geology – study of
petroleum, natural gas and ore (metal) deposits
Why Study Geology?
• Understanding Volcanic Eruptions:
• In 1883, the biggest explosion the inhabited world has ever
known occurred. Indonesia's Krakatoa volcano erupted. It
did so with the force of 13,000 Hiroshima atom bombs,
propelled a trillion cubic feet of rock, pumice and ash into
the air, and made a noise loud enough to be heard 1,930
miles away in Perth. The explosions, fallout and resulting
tsunami (130 feet high in places) killed 36,417 people in
Java and Sumatra, destroyed 165 villages and towns, and
two-thirds of the island. Wind streams blew the fine ash as
far away as New York; sea levels were raised in the
English Channel, and over the following year, global
temperatures were reduced by 1.2 oC.
• Krakatoa was a relatively small eruption! (~17 km3 erupted
magma)
Jemez Volcanic Field, west-central U.S.
Ash layers 2 cm thick found in
drillcores in the Atlantic ocean.
1.85 Ma – 15 km3
1.65 Ma – 400 km3
1.22 Ma – 250 km3
60 ka – 2 km3
Mt. Ranier Looms Ominously Over The Seattle Area….
How would you
like to wake up
and see this out
your window?
What do we know
about predicting
such events?
Eruption Over Santiago, Chile
Why study Geology?
• Earth interacts with
humanity via:
– Earthquakes
– Floods
– Volcanoes
– Landslides
Why study Geology?
• Earth materials are
the source of most
energy used on the
planet.
–
–
–
–
Petroleum
Natural gas
Coal
Uranium
Why study Geology?
Is our use of fossil fuels the cause?
Why study Geology?
• Earth’s surface is covered with soil that
supports natural and agricultural plants.
• Soil is made largely of decomposed rock.
Fig 1.2c
Basic vs Applied Geologic Research
• Basic research is curiosity driven, plain and
simple, we just want to know.
Example: How did a metallic ore deposit form?
• Applied research is need driven only.
Example: How do we find metallic ore deposits?
The two are not completely disconnected. Someone studying
how ore deposits form (basic research) may discover that
they form by processes occurring only in specific places on
Earth. Thus, someone wanting to know how to find them
(applied research) will benefit… and perhaps get rich!
What are rates of geologic processes?
Fig 1.4
This figure shows the difference in the rates of Earth processes as
compared to processes we can normally observe.
Some Earth processes are fast, but most are… very very slow.
Many important processes are much slower than fingernail growth.
Must remember geologic time, millions and billions of years are available.
Changes in Geology – Past 100 years
• Geology began as an observational science.
• Geologists looked at the Earth and tried to explain
what they saw.
• Analytical instruments began to be rapidly
developed in the early 1900’s.
• By 1950’s we basically had the instruments we
have today, but they have been continually refined
and developed.
• Past 10-20 years have seen dramatic new
developments in analytical capabilities.
• Result is that geology has become an analytically
based science, laboratory data is very important.
Piston-cylinder
device used to
reproduce T and
P in the deep Earth
Ion Microprobe used for U-Pb dating
Scientific Method?
Scientific Method?
A Continuous, Dynamic Process
Geologists use the Scientific Method
1) Make observations, collect data.
2) Develop idea(s) to explain what is seen,
this is a hypothesis.
3) Come up with ways to test the hypothesis.
4) If well designed the test(s) will validate, or
refute, the hypothesis.
5) A hypothesis that has been tested
repeatedly, often for many years, and has
continued to be supported as new data
becomes available, is called a theory.
Scientific Method ???
You are driving home when
suddenly…
your car stops running.
1) Observations – collect
data (information)
• Car sputtered to a stop
• Starter cranks engine over, but car
won’t run
• Gas gauge sitting on empty
2) Hypothesis – idea(s)
• Your car is out of gas ($10 fix).
• You need a new engine ($1000 fix).
3) Test Hypothesis – by
prediction and experiment
• Put some gas in the tank, if out of gas then it
should now run.
• Take car to shop and have new engine
installed, if engine was bad it should now run.
• Which would you do first?
(Occam’s Razor)
4) Accept or reject hypothesis
• Car runs after gas is put into tank – accept
they hypothesis that it was out of gas.
• Car does not run after gas put into tank –
reject hypothesis that it was out of gas.
• Return to step 2 (different hypothesis) or
perhaps even step 1 (more observations).
5) Theory
• You are not a genius, and forget to put gas in the
car every week.
• The car quits running on the way home at the end
of each week. This happens over and over and
over and over…
• Putting gas in the tank always fixes the problem.
• Your theory? Whenever the car quits running it
needs gas.
• A theory is a hypothesis that has not yet been
proven wrong – one day your car may truly need
a new engine instead of gas!
Next: Formation and Structure of the Earth