Transcript The scientific method and some basics

The scientific method
and the foundations of
Geology
Goals
• To understand the basic scientific method
as it applies to the Earth Sciences
• To cover some of the basic principals of
the Earth Sciences
Question?
Siccar Point, Scotland
The Scientific Method
QUESTION: We want to know how some part
of the Earth works.
DATA COLLECTION: Observe, measure,
describe, compile.
HYPOTHESIS: A logical but tentative
explanation that fits all the data collected
and is expected to account for future
observations.
It’s not “just a theory”
TESTING: Testing, testing, and more testing.
MODIFICATION: Hypotheses are modified to
include the results of testing (see #4).
THEORY: Our hypothesis now withstands
rigor of all the testing (see #4) and
consistently explains accumulating data.
It is now a theory: A generally accepted
explanation for a large set of diverse data
and observations.
If a theory is really special...
TESTING: Testing, testing, and more testing.
SCIENTIFIC LAW: If a theory meets rigorous
testing over a long period of time it may
become a Scientific Law, like The Law of
Gravity.
PRINCIPAL: Generally a scientific law is so
fundamental it provides the foundation of
science.
How we develop and test
hypotheses in the Earth
Sciences
Because we can’t fit the Earth in a test tube
or sit and take notes for 20 m.y we use:
• Case studies of ancient features
• Remote sensing of the Earth’s interior
• Numerical and analogue simulations
We have learned that the Earth is very
old (~4.5 billion years). So….
We have lots and lots and lots of time
to work with.
“The present
is the key to
the past”
Birth of modern Geology
Principle of Uniformitarianism: Processes
observed today have acted on the Earth
over very long periods of time.
So
Observations of current geological
processes can be used to interpret very
old geologic events.
Other Important Geologic
Principles
Superposition: In any
unaltered sequence
of rock layers, each
layer is younger than
the one beneath it
and older than the
one above it.
Other Important Geologic
Principles
Superposition: In any
unaltered sequence
of rock layers, each
layer is younger than
the one beneath it
and older than the
one above it.
Original Horizontality: Sediments are deposited
horizontally in layers that are parallel or
nearly parallel with the Earth’s surface.
Think-pair-share activity
1. Come up with an every day analogue for
the principal of original horizontality
(preferably incorporating unhealthy food).
2. Compare, discuss, and refine your
analogue with one or two of your
neighbors.
3. Write up your results and pass them in.
Cross-Cutting Relationships: An igneous
intrusion or geologic structure is always
younger than the rock that surrounds it.
Answer
Siccar Point, Scotland
1. Deposition
2. Tilting
3. Erosion
4. Deposition
5. Tilting
6. Erosion
Principle of Inclusion: Rock fragments
contained within a larger body of rock are
always older than the surrounding body of
rock.
Basic rock types
Igneous rocks: Crystallize (or freeze) from a
melt
Sedimentary rocks: Made up of particles
(gravel, sand, clay) glued and pressed
together
Metamorphic rocks: Rocks that have
recrystallized at high temperatures and
pressures, but not melted.
The rock cycle