Transcript GeologyIntroduction - University of Hawaii

GG 103 Aloha and Welcome to
Geology of the Hawaiian Islands
Nasir Gazdar, PhD, MPH
1. Course Website:
//www2.hawaii.edu/~nasir
2. Announcements, Lecture
notes and Study Guide Files,
Extra credit, Geology Events at
//myuhportal.hawaii.edu at GG
103 Course Site
3. Hawaii Atlas, Plate Tectonics,
Geology Text, CDs, DVDs at
The Library Reserve GG 103
4. Email for any help. Mahalo
for excellence.
GG 103 Exams and Grading
1st term exam
Midterm
3rd term
Final exam
Presentation
Total
150 points
150 points
150 points
400 points
150 points
1000 points
Extra credit – to be announced in the
class - may be emailed
Grade
A
B
C
D
900+
800+
700+
600+
• Geology is vital in human civilization
• Geology in Today’s World
• Geology - The scientific study of the Earth
– Physical Geology is the study of Earth’s materials,
changes of the surface and interior of the Earth, and the
forces that cause those changes
• Practical Aspects of Geology
– Natural resources
– Geological hazards
– Environmental protection
– Sea level Rise, Climate Change, Global Warming
Geology and Other Sciences
Physics
•Geophysics
•Seismology
Astronomy
•Planetary Geology
•Helioseismology
Chemistry
•Mineralogy
•Petrology
•Geochemistry
Biology
•Paleontology
•Paleoecology
•Economic Geology
•Historical Geology
•Hydrology
•Geomorphology
•Engineering
Geology
•Oceanography
•Petroleum Geology
•Volcanology
•Structural Geology
Natural Resources
All manufactured objects depend on Earth’s resources
Localized concentrations of useful geological resources are
mined or extracted
If it can’t be grown, it must be mined
Most resources are limited in quantity and non-renewable
Earth Science: The science of Geology
Earth System Science
• Geology is the science that pursues an
understanding of planet Earth
• Physical Geology - examines the materials
composing Earth and seeks to understand the
Internal Processes that operate beneath, and
External Processes upon its surface.
• Historical Geology - seeks an understanding of the
origin of Earth and its development through time
What Do Geologists Do?
• Seek to understand all processes that operate on and
inside the Earth and on the Hawaiian Islands
• Study:
– Our planet’s long history and origin of Hawaiian islands
and their place on the earth in the ocean
– Landforms: volcanoes, reefs, water bodies (ocean, rivers
and groundwater), mountains, valleys, glaciers, dunes
– Hazardous processes such as earthquakes, volcanic
eruptions, tsunamis, floods, and landslides
– Rocks, minerals, water, geothermal resources of the
Hawaiian Islands
Geology Involves Study of:
• Earth Materials (rocks, minerals, soils)
– formation, effects on health, as resource or waste
• Natural Hazards
– Volcanoes and volcanic eruptions, earthquakes, tsunamis,
floods, landslides, rockfalls
• minimize loss of life
• Natural Resources – Volcanoes, Reefs, Beaches,
Geothermal energy
• Hydrologic Processes of surface/ground water
– Water resources, pollution
• Geologic Process
– Atmospheric, hydrologic, and lithospheric
North
America
Asia
Europe
South
America
Africa
Antarctica
Australia
Hawaii
Pacific Ocean
Pacific Ocean
Mahukona
North
America
Asia
Hawaii
Pacific Ocean
Indian
Ocean
Australia
Atlantic
Ocean
South
America
Subduction crack on the
Pacific Oceanic crust
Earthquakes
Oceanic crust is forced
below the fracture because
oceanic crust is denser than
the one composing the
fracture. Magma is created
at the subduction wedge
Magma Chamber
Hotspot
Origin of Planet Earth, Sun and Solar System
The Nebular Hypothesis claims that 5
billion years ago, for reasons
unknown, a huge nebular cloud began
to contract under its own gravitational
influence. As it contracted it also had
some rotational motion. The more it
contracted the faster the cloud
rotated, causing the nebular cloud to
take on a disk shape. As the cloud
collapsed, the temperature of the
central mass continued to increase
and most of the material was
gravitationally pulled toward the
center, producing the Sun. However,
because of the rotational motion,
some dust and gases remained
orbiting the Sun, forming planets.
Nebular Hypothesis
Explains Origin of
Sun’s Solar System
8 Planets, Moons,
Comets, Asteroids
Rocky Planets
Mercury
Venus
Earth
Mars
Gaseous Planets
Jupiter
Saturn
Uranus
Neptune
Dwarf Planet Pluto
As these
fragments
began to
condense
and collide,
they joined
together
into larger
objects
which
eventually
became the
planets
which
continued
to orbit the
Sun
• Earth formed as a planet in the Sun’s Solar system
from a nebula: 4,600,000,000 years ago, 4.6 billion
years, 4,600 million years
• Life on Earth began: 3,800,000,000 years
• Geology: Science of processes related to:
– Composition, structure, history and life of Earth
– Processes on the earth, landforms and islands
• Geology of Hawaiian Islands:
• Studies entire spectrum of Hawaiian Islands physical
environment, Birth and Life of the Isles
• It is geology applied to:
• Islands origin, volcanic formation and life stages
• Awareness of unique geologic environment
• Understand the geologic processes on the islands
Origin and evolution of Earth
• Origin of planet Earth 4,600,000,000 years before
present
• Nebular hypothesis – Sun and Solar System
• While this theory incorporates more basic physics,
there are several unsolved problems. For example,
a majority of the angular momentum in the Solar
System is held by the outer planets. For
comparison, 99% of the Solar System's mass is in
the Sun, but 99% of its angular momentum is in
the planets. Another flaw is the mechanism from
which the disk turns into individual planets
• Layered structure developed by chemical
segregation early in the formation of Earth
Earth is Unique
• No other planet in the solar system
currently has the right chemical and
physical mix needed to support life
• No conclusive evidence of life existing
elsewhere in the universe has yet been
discovered as far as we know
A view of Earth Planetary System
• Earth is a planet that is rocky and self-contained
– Earth System and Spheres
• Earth’s spheres
• Hydrosphere – water, oceans, lakes, rivers
• Atmosphere - air
• Biosphere – life and environment, ecosystem
• Lithosphere - Solid Earth
• Pedosphere – soil
– Cryosphere – ice sheets, Antarctica, Greenland
– Anthrosphere – Human built environment
Our Planet’s “Five Spheres” or
Subsystems
• The Atmosphere:
– Nitrogen, oxygen, argon, carbon dioxide, and water vapor
• The Hydrosphere:
– Oceans, lakes, streams, underground water, snow, and ice
• The Biosphere: Ecosphere, Sphere of Life
– All of Earth’s organisms, as well as any organic matter not
yet decomposed, Anthrosphere is Human Living
Environment
• The Geosphere – Crust, Lithosphere, Mantle and
Core
– The solid Earth from core to surface crust– Crust composed principally of rock, minerals, sediments,
ores and soils
– Soils are in Pedosphere
The science of Geology
• Some historical notes about geology
• The nature of Earth has been a focus of study for
centuries
• Catastrophism
• Uniformitarianism and the birth of modern
geology
Uniformitarianism
The Rock Cycle
Uniformitarianism
Continuity of Cause and Effect
• Apply Cause and Effect to Future Prediction
• Apply Cause and Effect to Present Technology
• Apply Cause and Effect to Past Uniformitarianism
Uniformitarianism does not
mean:
• Catastrophes never occur
• Physical Conditions on Earth never
Change
• Earth has always been the same
• Physical processes always occur at the
same rate or intensity
• Laws of Physics have always been the
same
Uniformitarianism does mean:
Using our knowledge of physical laws, we can test:
• Whether catastrophes have occurred
• Whether physical conditions on earth have changed,
and if so, how (climate change, ice ages, warm
periods, high or low sea level, etc.)
• Whether physical laws themselves have changed in
time, or elsewhere in the universe.
Geologic time
• Geologists are now able to assign fairly accurate
dates to events in Earth history
• Relative dating and the geologic time scale
• Relative dating means that dates are placed in their
proper sequence or order without knowing their
age in years
Geologic time
• The magnitude of geologic time
• Involves vast times – millions or billions of years
• An appreciation for the magnitude of geologic time
is important because many processes are very
gradual
The nature of scientific inquiry
• Science assumes the natural world is consistent
and predictable
• Goal of science is to discover patterns in nature
and use the knowledge to make predictions
• Scientists collect “facts” through observation and
measurements
The nature of scientific inquiry
• How or why things happen are explained using a
• Hypothesis – a tentative (or untested) explanation
• Theory – a well-tested and widely accepted view
that the scientific community agrees best explains
certain observable facts
The nature of scientific inquiry
• Scientific methods
• Scientific method involves gathering facts
through observations and formulation of
hypotheses and theories
• There is no fixed path that scientists follow
that leads to scientific knowledge
Earth as a system
• Earth is a dynamic planet with many interacting
parts or spheres
• Parts of the Earth system are linked
• Characterized by processes that
• Vary on spatial scales from fractions of millimeter
to thousands of kilometers
• Have time scales that range from milliseconds to
billions of years
Earth as a system
• The Earth system is powered by the Sun that
drives external processes in the
• Atmosphere
• Hydrosphere
• At Earth’s surface
Earth as a system
• The Earth system is also powered by the Earth’s
interior, Internal Processes.
• Heat remaining from the formation and heat that is
continuously generated by radioactive decay
powers the internal processes that produce
volcanoes, earthquakes, and mountains
The rock cycle: part of the Earth
system
• The loop that involves
the processes by which one
rock changes to another
• Illustrates the various processes and paths as
earth materials change both on the surface and
inside the Earth
The face of Earth
• Earth’s surface has two principal divisions
• Continents
• Ocean basins
• Significant difference between the continents and
ocean basins is their relative levels
The face of Earth
• Continents
• Most prominent features are linear mountain belts
• Shields
• Ocean basins
• Ocean ridge system – the most prominent
topographic feature on Earth
• Deep-ocean trenches
Early evolution of Earth
• Origin of planet Earth
• Most researchers believe that Earth and the other
planets formed at essentially the same time from
the same primordial material as the Sun
• Nebular hypothesis
• Layered structure developed by chemical
segregation early in the formation of Earth
Earth’s internal structure
• Earth’s internal layers can be defined by
• Chemical composition
• Physical properties
• Layers defined by composition
• Lithosphere, Crust
• Mantle
• Core
Structure of the Earth
The Earth is made up of three main layers:
The core is at the center of the Earth
The outer core is a mobile semi-molten layer around the inner
core
The mantle is a solid, rigid layer around the outer core; the top of
mantle gets internal heat.
The outer-shell of the Earth is called the LITHOSPHERE - crust.
it's the part we're on now
Dynamic Earth – Plate Tectonics
• Theory of Plate Tectonics
• Involves understanding the workings of our
dynamic planet
• Began in the early part of the twentieth century
with a proposal called continental drift – the idea
that continents moved about the face of the planet
• Seafloor Spreading
Dynamic Earth
• The theory of plate tectonics
• Theory, called plate tectonics, has now emerged
that provides geologists with the first
comprehensive model of Earth’s internal workings
• Plate boundaries
• All major interactions among individual plates
occurs along their boundaries
8 Major Tectonic Plates of the Lithosphere
Ring of Fire
Ring of Fire
Dynamic Earth
• Plate boundaries
• Divergent boundary – two plates move apart, resulting
in upwelling of material from the mantle to create new
seafloor
• Convergent boundary – two plates move together with
subduction of oceanic plates or collision of two
continental plates
Dynamic Earth
• Plate boundaries
• Transform boundaries - located where plates grind
past each other without either generating new
lithosphere or consuming old lithosphere
• Changing boundaries - new plate boundaries are
created in response to changes in the forces acting on
the lithosphere