GEOSCIENCE is the scientific study of the Earth. More specifically, it is the scientific
study of the processes, events, and consequences of the Earth through time.
When we refer to the Earth
in this course, we are referring to the:
We
may also refer to Planetary Geology from time to time, by which we mean the
study of other planets in our solar system. Mars has been of particular
interest these days!
Geologic processes form Landscapes,
processes such as:
-
volcanoes,
-
wind,
-
rivers,
-
mountain building,
-
glaciers,
-
waves.
Understanding geologic
processes will minimize unexpected and unwanted Environmental Change:
e.g.
- Air Pollution: e.g. oil refining, copper smelting
Global Warming is
a Scientific Fact! Its cause(s) and
consequences, however, remains far less clear!
B.
What is Science and How Does it Work?
The nature of
scientific inquiry often uses both inductive and deductive reasoning:
One Scientific Method
uses the approach described below:
An
observation that has been repeatedly confirmed is considered a scientific
fact.
An
example: In 1887, the famous
The experiment actually demolished the ether theory when it gave the wrong kind of result. (Engines of Our Ingenuity, 1/22/04)
A Theory is: A well tested and widely
accepted view that scientists agree best explain certain observational facts.Ó
Like the hypotheses from which it grew, it must
also be testable and falsifiable! Therefore, all
theories are considered provisional. Nonetheless, theories are the end points
of science.
There is no scientific statement stronger or more widely accepted
than a theory!
Scientific
Revolutions (ala Kuhn, 1960's)
We no longer believe in
some scientific theories, e.g.:
In the 17th and 18th century,
most people believed in ___________________ (an early ruling paradigm),
which stated that all geologic features were the result of a few sudden,
catastrophic events which have occurred over a relatively short time period
In
addition, many believed these events occurred relatively recently (to fit with
biblical chronology), and were the direct result of GodÕs will.
In the late 1700's,most
people were either:
In1795,
_________________ published his book, Theory of the Earth, which
revolutionized the way we look at the earth! This book represents the beginning
of Geology as a modern science. Two major contributions were:
The
Principle of __________________: The processes that have shaped the
earth in the geologic past are essentially the same as those operating today.
It is sometimes simplified as "the present is the key to the past".
The
concept of the _____________ recognizes that rocks have a variety of
origins, including igneous, sedimentary, and metamorphic, and that rocks may be
transformed from one rock type to another through a variety of processes, all
of which continue to occur to the present.
(figure 1.21)
_______________
Rocks: rocks formed from
the crystallization of magma
a) ______________________
rocks form by the crystallization of lava extruded at the surface of the
earth.
b) _______________________rocks
form by the crystallization of magma intruded below the earthÕs surface
(figure
8.19)
Rocks exposed at the
surface of the earth are subjected to:
*
________________________: the in-situ alteration of rocks at or near the
surface;
* ______________ &
______________: the removal of material by mobile agents (running water, wind,
waves, glaciers, etc)
* ________________ or
___________________ as sediments.
Sediments become
Sedimentary Rocks by the combined processes of:
a)
__________________________
c)
__________________________
that together are
referred to as ___________________.
_____________________Rocks:
formed at the surface of the earth, derived from pre-existing rocks.
a)
__________________________Rocks Ð formed from the deposition of solid particles
(e.g. sand, clay)
b)
_________________________Rocks Ð formed from the precipitation of dissolved
material (e.g. carbonate)
_____________________ Rocks:
formed from the solid-state alteration of pre-existing rocks due to:
a) increased
_____________,
b) increased
_____________, or
c)
_______________________________
Regional
mountain building can form
______________________ rocks.
Contact
metamorphism by heating of
intruding magmas can form ___________________ rocks, for exampleÉ
(fig. 8.19)
Note that the Rock
ÒCycleÓ might better be thought of a a ÒRock WebÓ, much as the food ÒchainÓ is
better thought of as the food ÒwebÓ.
Perhaps
the greatest contribution of Hutton was to free us from the constraints of an
earth only a few thousand years old, and allow us to recognize the immense age
of the earth (and Universe). Without this contribution, modern Physics,
Astronomy, Geology, Biology, Anthropology, Archeology, etc could not exist.
The earth is VERY old ~
_________ years give or take a
few!
The first 88% of
earthÕs history is referred to as the ________________
(figure 1.7 Ð The Geologic Time Scale)
(figure 1.13)
According to the ____________________
Hypothesis, the early history of our solar system started when:
a) Dust and gases
started to ______________________
b) The nebula
contracted into a rotating disk, heated by the conversion of _________________
to ______________ energy.
c) The nebula cloud
cooled, causing condensation of _________________________.
d) Repeated collisions
caused dust particles to coalesce into asteroid particles called
_______________________
e)
Bodies accreted into planets within a few ______________ years.
Q. What is the most
recent hypothesis for when and how the moon formed?
A.
Large-scale melting led
to the differentiation of the planet, where more dense elements (e.g. Iron) sank
to the center and lighter elements (e.g. Silicon and Oxygen)ÒfloatedÓ to the
top
This lead to the differentiation of
major compositional zones of the earth as we see them today.
De-gassing of the
earthÕs interior led to the formation of the earthÕs atmosphere and
hydrosphere.
All this happened when?
The most recent 12% of
earth history is referred to as the __________________ Eon.
Q. What event marks to
base of this Eon?
A.
This Eon is further
subdivided into three Eras. They are the:
a)
b)
c)
Q. What type of event
marks the base of the two youngest Eras?
A.
And, the earth is
LAYERED
EarthÕs
internal layers
defined by composition are:
(figure 1.14a)
The Mohorovicic Discontinuity (MOHO) separates the _____________ from the _______________.
EarthÕs
internal layers
defined by physical properties are:
a) ____________________ (rigid, ~150 km thick)
b) ___________________ (plastic ~ 500 km thick)
c) __________________ (semi-plastic)
d) __________________ (fluid)
e) __________________ (solid)
Q. What is the outermost solid layer of the earth called? (this is a trick question)
A.
(figure 1.14b)
How do we know what the interior of the earth looks like???
What is a system?
What are some examples of Earth Systems? (e.g. figure 1.11, 1.21)
-A _______________________ converts thermal energy into kinetic energy (motion) Ð e.g. your car.
-The
EarthÕs ___________________ is powered by the
________, and drives the earthÕs fluid envelopes (the atmosphere and
hydrosphere)