Earth Energy, Structure, and
the Rock Cycle
GPH 111
Earth Time, Energy, Structure,
and the Rock Cycle
1)
2)
3)
4)
5)
6)
7)
Where are we going?
Geologic Time Scale
Earth energy from isotopic decay
Earth in Cross Section
Magnetic Field
Major Rock Types
Rock Cycle
Game plan: Learn the Rock Cycle and
Hydrologic Cycle so we can talk about the
Geomorphic Cycle!
Pale Blue Dot
A view of earth
from Voyager 1
from beyond the
orbit of Neptune,
1990 (NASA)
Earth Time
Roughly 4.6
Billion years old
If all of earth time
was compressed
into one year; then
the dinosaurs died
off on Christmas
Eve; and humans
started running
around 8:30 pm on
New Year’s Eve.
Earth Energy: Isotopic Decay
 Big Bang, Stars, and Supernova generate
the matter package (atoms) on our planet
 Some of that matter is unstable and breaks
down over time, known as Isotopes
 They change from one element into another
element, releasing a electron, proton, or
neutron and energy in the process.
 Using these elements to date rock is known
as Radiometric Dating
Earth Energy: Isotopic Decay
Big Bang (up to Lithium)
Stars
(Helium
to Iron)
Supernova (up to plutonium)
Earth Energy: Isotopic Decay
Earth Energy: Isotopic Decay
Atoms: Consist of protons (positive)
and neutrons (no charge) in the nucleus
and surrounded by orbiting electrons
(negative)
Isotopes: Unstable atoms
that decay protons,
neutrons, and / or electrons
at specific rates over time
–- and ENERGY.
Earth Energy:
Isotopic Decay
Half Lives!!!
Uranium-238 decays to Lead206 (4.5 billion years)
Potassium-40 to Argon-40
(1.3 billion years)
Carbon-14 to Nitrogen-14
(5,730 years)
A neutron decays into an electron and a
proton, changing the carbon atom into a
nitrogen atom
Earth in Cross Section:
Inner Core - Solid
Outer Core – Liquid (Magnetic Field)
Mantle - Solid
Asthenosphere - Plastic
Lithosphere - Brittle
Earth in Cross
Section:
Earth in Cross
Section:
Earth in Cross Section:
The distance to the center of the earth is roughly 2,900
miles (15,312,000 feet).
How deep do you think we have ever sampled?
Earth in Cross Section:
Kola Superdeep
Borehole:
Penetrated 42,000 feet
1/3 of the Baltic Crust
Reached 356 degrees
Missed the center of the
Earth by 15,270,000 feet or
2,890 miles
How deep is the ocean?
Earth in Cross Section:
Kola Superdeep
Borehole:
Penetrated 42,000 feet
1/3 of the Baltic Crust
Reached 356 degrees F
Missed the center of the
Earth by 15,270,000 feet or
2,890 miles
How deep is the ocean?
16,000 pounds per square inch
Earth in Cross Section:
We figured out the
cross section of the
Earth through
earthquake waves.
- P waves travel
longitudinal - push
and pull (faster)
- S waves travel
transverse - side to
side (slower)
Slinky!
Earth’s Magnetic Field:
A liquid outer
core of iron
and nickel
generates
Earth’s strong
magnetic field!
The magnetic
poles wander
over time…
Earth’s Magnetic Field:
Earth’s Magnetic Field:
Some think our
magnetic field is
undergoing a reversal
from north polarity to
south polarity
Evidence for past
pole reversals
come from the
ocean floor
Earth’s Rock Cycle
 What is a Mineral and a Rock?
 Major Rock Type: Igneous
 Major Rock Type: Sedimentary
 Major Rock Type: Metamorphic
 Rock Cycle as a whole
What is a Mineral?
 An elemental or chemical compound
with crystalline structure and formed as
a result of geological processes.
What is a Rock?
 An object that resulted from geological
processes and consists of a mixture of
minerals.
What is a Mineral?
What is a Rock?
Rock Cycle:
Igneous
Intrusive
or
Extrusive
Rock Cycle:
Igneous
Extrusive
small crystals
(Basalt)
Rock Cycle:
Igneous
Extrusive
small crystals
(Basalt)
Rock Cycle:
Igneous Intrusive BIG crystals (Granite)
Rock Cycle:
Igneous Intrusive BIG crystals (Granite)
Granite forms deep in the earth, how did it get
to the top of Mt Whitney (el. 14,464ft)?
Rock Cycle: Sedimentary
Clastic (sandstone)
Consists of pieces (clasts)
of eroded rock and
ranges in grain size from
conglomerate, sand, silt,
and clay.
Chemical
(limestone)
Consists of mineral
crystals precipitated from
saturated water.
Rock Cycle: Metamorphic
Foliated (gneiss)
Consists of rocks highly
cooked that such minerals
of similar composition
merge with each other
generating banded rocks.
Non-Foliated
(quartzite)
Consists of rocks not as
highly cooked where
minerals undergo some
change but similar
mineral types to not band
together.
Rock Cycle:
Major Rock Types:
Igneous
Sedimentary
Metamorphic
Things to Know:
 Big bang, super nova, and stars responsible
for all elements on the planet
 Earth energy from isotopic decay
 Different layers of the earth and whether they
are solid or liquid/plastic
 Spinning inner solid core within liquid outer
core responsible for magnetic field
 Difference between a mineral and a rock
 Three major rock types and breakdown within
each major rock type (like igneous extrusive
vs. igneous intrusive)
 How the three major rock types interact to
generate the Rock Cycle
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