GeoLogy Lecture Outline

IntroDuction, Earth Origins and Anatomy

And UnifomitariAnism (CH 1)


I. Lecture Content

What is Geology?

Observing Nature: Consciousness and the Act of Perception

Earth from a Scientific Perspective - A Systems Approach

Geology and Human Civilization

Geologic Studies, the Scientific Method & Theory

Origin of Earth and our Solar System

Why is Earth a Dynamic Planet?

Overview of Plate Tectonic Theory

The Hydrologic and Rock Cycles

Geologic Time and the Principle of Uniformatarianism

II. What is Geology?

A. Word comes from Greek: geo = earth; logos = study


B. The Scientific Study of Planet Earth


1. A very broad field of study:


    The earth's internal structure and composition, its dynamic character (earthquakes, volcanoes, plate tectonics), and the processes that occur within it


    The processes that shape the surface of the Earth, and the materials that constitute its surface layers


    The origin, occurrence, extraction and conservation of the Earth's natural resources - minerals, fossil fuels, soils, water


    Earth's place within the Solar System


    The history of life on Earth



2. Geologic study is divided into two major areas:


      Physical = materials and processes

      Historical = origin and evolution


C. The Discipline of Geology is Very Broad and Diverse

1. Geochronology

2. Planetary Geology

3. Paleontology

4. Economic Geology

5. Environmental Geology

6. Geochemistry

7. Hydrogeology

8. Mineralogy

9. Petrology

10. Geophysics

11. Structural Geology

12. Seismology

13. Geomorphology

14. Oceanography (marine geology)

15. Paleogeography

16. Stratigraphy/ Sedimentology

17. Tectonics

18. Volcanology

19. Engineering Geology


D. Geological Science Research - "Pure" Versus "Practical"

1. "Pure" = sake of curiosity and scientific knowledge

Examples: Studies of Trilobites; Age of the Earth


2. "Practical" = solving human-related problems or concern

Examples: Oil Exploration; Geologic Hazards; Mining


E. Economical & Environmental Aspects of Geology

1. Economical = Geology impacts local & global economies

Examples: Mineral & Energy Resources; Engineering


2. Environmental = Geology affects local & global ecosystems

Examples: Geologic Hazards; Pollution; Development


F. Interesting & Rewarding Careers in Geology



III. Observing Nature Through the Human Experience

A. Making Sense of Mother Nature and the Universe

1. Humans have an amazing capacity for exploring and

understanding nature and the Universe.


2. Humans take great efforts in searching for and defining

the order and relationships between matter, energy, and

life amidst a mind-boggling backdrop of cosmic chaos.



B. The Tricky Thing We Call (Human) Perception

1. Identification, evaluation and categorization of objects


2. Complex process of comparing different objects & events


3. Prioritizing sensory (experiential) input (objects & events)


4. Constantly creating a "perceived" reality (occurring now) based

on a "remembered" reality (the past)


5. Personal and societal perceptions of Life on Earth are

based on popularly-held belief systems

C. The Means of Understanding the Nature of Things

1. Human Senses - Input of Information


2. Human Mind - Information processing (Thinking)

    "Mapping" how everything is connected together

    Finding out How and why things change the way they do

    Making explanations and predictions of phenomena's behavior


3. Technology - Extension of input and processing abilities

         Input - Sensitive, sophisticated instruments

         Process - Computers


IV. Systems Approach To Understanding the Earth

A. The Science Perspective of Earth

1. Rational, analytical approach to studying the Earth


2. Based upon empirical, reproducible evidence (facts)


3. Testable interpretations (hypotheses & theories)


4. Always open to debate and modification


B. The System-Subsystem Conceptualization of Earth

1. The Concept of a System - Combination of related parts

(subsystems) that interact in an organized fashion.


2. Individual Systems are characterized by the dynamic

transfer of energy, matter, and information:


       Input = into the system from outside (the system)

       Output = out of the system to outside (the system)

       Process = transfer within/between subsystems


3. Very useful for understanding complex things such as

Earth or a human body


4. The Earth can be described as being a limited System

having a virtually limitless set of Sub-systems


C. The Principle Subsystems of Earth

1. Core

2. Mantle

3. Lithosphere

4. Biosphere

5. Hydrosphere

6. Atmosphere

D. Complex Interactions Among Earth's Subsystems

1. The Rock Cycle

2. The Hydrologic Cycle

3. The Biological Cycle

4. Plate Tectonics - the "Supercontinent Cycle"


V. Geology and Human Civilization

A. The Human Experience Has Been Shaped by Geology

1. Every human society, past & present, developed their

unique character and perceptions through daily interaction with

their surrounding dynamic environment (land, sea, air & life)

       Weather and Climate

       Natural Disasters

       Habitation & Resources

       Cultural Behaviors & Belief Systems

       Religions & Spirituality


2. Humans are quickly becoming a major geologic force

B. Geology Affects Every Person's Everyday Life

1. Same factors as defined above


C. Important Global, Regional and Local Geologic Issues

1. Volcanic eruptions

2. Earthquakes

3. Tsunamis

4. Flooding

5. Mining and Oil Drilling

6. Dams Building

7. Environmental Degradation

8. Urban Development

9. Water Conservation

10. Climate Change


VI. Geologic Studies, the Scientific Method & Theory

A. Geologic Research is Conducted in a Scientific Manner

1. Clear stated purpose


2. Well thought out & carefully planned


3. Follows a set of logical and rational guidelines outlined

in a step-by-step method called the Scientific Method


4. Collaboration, review, and debate with fellow geologists


5. Always open to scrutiny, challenge, and modification

from the scientific community and the world at large

B. The Scientific Method - A Set-by-Step Research Plan


1. Observation - Observe something in nature, using your

bodily senses or sensing instruments. 


2. Question - Ask a question about what you observe.


3. Hypothesis - Predict what you think the answer to your question

might be. (Hypothesis = an interpretation or model)


4. Method - Figure out a way to test whether or not your hypothesis

is correct. Note that the outcome must be measurable,

i.e. quantifiable and reproducible.


5. Result - Perform the experiment using the method you came up with,

and record the results. Repeat the experiment to confirm you



6. Conclusion - You state whether your prediction was confirmed or not

and try to explain your results.


7. Follow up - Repeat above steps (modify research plan) until your

hypothesis confirms your results.


C. The Development of Hypotheses and Theories


1. A hypothesis becomes an acceptable model after repeated tests that

repeatedly confirm the hypothesis's prediction.


2. A hypothesis becomes elevated to a theory only after years of rigorous,

exhaustive tests and scrutiny by the world scientific community.


VII. Origin of Our Earth and Solar System

A. Solar System Formed from Interstellar Gas & Dust


1. Material came from two sources

      Original primordial gases left over from Big Bang

    Mostly Hydrogen & Helium


      Secondary material from exploded star(s)

    All sorts of elements from H to Uranium

    Both gases and solid matter


2. Coalescing of cold matter caused by gravitational fields

       Gravity waves through interstellar space

       Increasing gravity force of condensing matter


B. Earth Accreted from the Rotating Solar Nebula Disc


1. Condensing Solar nebula cloud began rotating


2. Increasing angular momentum caused nebula to flatten

from an irregular mass into a spinning disc-like form


3. Central mass condensed into the "proto" Sun


4. Outer mass coalesced into many planetisimals, which

eventually lumped together to form "proto" planets


5. Over time, the "proto" planets swept up the remaining

planetisimals to become the nine known planets


6. Inner planets, including Earth, formed mainly from the

cold accretion of solid materials (heavier elements)

      Metals (mostly iron, magnesium & nickel)

      Silicates (rich in oxygen, silicone, and aluminum)

7. Outer planets, like Jupiter, formed mainly from volatiles

and gases (lighter elements)

      Hydrogen & Helium

      Water & Carbon Dioxide

      Ammonia & Methane

8. Accretion process probably took 1 BY to 500 MY


C. Age of Earth & Solar System is about 4.6 Billion Years


    Age come from the dating of meteorite & Moon samples


D. Infant Earth Underwent Further Differentiation


1. Extreme heating of Early Earth, due to released energy from

gravitational collapse, causes Earth to become molten


3. Segregation of Core and Mantle (facilitated by molten condition)


4. Theorized collision of a Mars-sized planet with Earth to

form the Earth-Moon system - Extremely violent event


5. Intense period of planetisimal bombardment (~ 3.5 BYA)


6. Sufficient cooling to create a solid, thin, & very mobile

lithosphere made up of many fast-moving micro plates


7. Earth's atmosphere underwent drastic changes (~ 2.5 BYA)


VIII. Why is Earth Dynamic and Constantly Changing?

A. Evidence of Continual Change Since Accretion


1. Profound differences in character of the Earth's rock

record for different periods of geologic time


    Unique rock types; their abundance & occurrence

Examples: Komatiites

Sedimentary iron beds



Glacial tillites

    Unique fossils; their abundance & occurrence

Examples: Trilobites




    Distinctive tectonic terranes and their locations

Examples: Wrangalia


Southern California & Baja

Mount Everest & the Himalayas

2. Present-day geologic activities and events

    Earthquakes; Volcanic eruptions; Uplift & Erosion


B. Powerful Driving Forces Sustain Earth's Dynamism

1. Internal Forces


    Gravity - Increases with accretion of matter


    Radioactive decay - Release massive amounts of heat


    Rotational momentum - Coriolis effect; other effects


    Organic Life - Biochemical terra-forming


2. External Forces


    Solar Wind - Sunshine, EMR and nuclear particles


    Heavenly body gravitational fields


    Bolides (comet and meteor impacts)


C. Driving Forces Produce Heat and Density Gradients


1. Gravity and radioactive decay generate internal Earth heat


    Gravitational heat left over form accretionary event


    Sustained nuclear "barbeque" in mantle and crust


2. Internal Gravity and Thermal energy generate density

contrasts in the solid Earth = Internal layering






3. Solar radiation generates thermal and density contrasts in

the hydrosphere and atmosphere

    Dynamic Layering and Circulation Patterns

4. Gravity of the Moon and Sun generate tidal forces on Earth

    Ocean tides


IX. The Plate Tectonic Theory A simple Overview

A. Earth's Outermost Solid Layer is called Lithosphere


1. Consists of two parts (sub-layers)

       Crust (top part)

       Uppermost mantle (bottom part)


2. Two major types of Lithosphere

       Continental lithosphere

       Oceanic lithosphere


3. The lithosphere "floats" on top of the partially melted



4. The lithosphere is made-up of a number of separate,

irregular segments called tectonic plates

      Six major plates

      Six or so minor plates


B. The Lithospheric Plates are Mobile


1. The plates move over the underlying mantle


2. Each plate has a separate and unique plate motion


3. The tectonic plates jostle with one another


4. Plates interact with one another in three different ways


C. There are Three Types of Plate Boundaries


1. Divergent - plates move away from each other


2. Convergent - plates toward each other


3. Transform - plates slide past each other

D. Plate Boundaries are the Primary Site of Present-day

Mountain Building Events (Orogenies)


1. Major Earthquakes

2. Volcanism

3. Crustal Uplift

4. Folding & Faulting


E. Seafloor Spreading Occurs at Divergent Boundaries

1. New oceanic lithosphere is created where two plates are

actively pulling away from one another


2. Predominant regional tensional forces at work


3. Site of the spectacular mid-ocean ridge system


4. Examples: Mid Atlantic Ridge & East Pacific Rise


F. Subduction Occurs at Convergent Boundaries


1. Old, dense oceanic lithosphere plunges back into the

underlying mantle


2. Predominant regional compressional forces at work

3. The site of a paired oceanic trench/ volcanic arc system


4. Examples: Cascades, the Andes, the Alps, & Himalayas


G. The Plate Tectonic Theory is a Unifying Principle


1. Best explains the relationships between many different

and seemingly unrelated geologic phenomena


2. Provides a sort of predictive "map" for explaining, past, present

and future geologic phenomena & events


X. The Rock and Hydrologic Cycles

A. The Rock Cycle

1. A multi-process recycling (creation & destruction) of

one rock type into another


2. Three major rock types (material reservoirs)





3. Several major multi-step rock-forming processes

      Partial melting (magma), cooling & crystallization


      Weathering, erosion, deposition, compaction, &

cementation and/or crystallization


      Recrystallization & neocystallization of solid rock

under elevated temperature and/or pressure


4. The various rock reservoirs and related processes are

all interconnected under the title: Rock Cycle


B. The Hydrologic Cycle

1. A multi-process (re)cycling of water between the

hydrosphere, atmosphere, and lithosphere


2. Several major water reservoirs




      Lakes and Rivers




3. Several water-transforming & moving processes






XI. Geologic Time and Uniformatarianism

A. The Geologic Time Scale

1. Defined: A hierarchical time-rock scale in which the 4.6 billion-year

geological/biological history of the Earth is divided into time units of

varying duration and subdivisions.

2. Development of timescale was a long, evolutionary process made

by a great number of individuals working on outcrops scattered far

and wide across the entire globe.


3. Illustration of the Geologic Timescale (Figure 8.1)


B. Principle of Uniformatarianism

1) Defined: the view that all geological processes that are

occurring today (the rock cycle) were operating in the past,

and produced similar results throughout Earth's history.


2) "The" guiding fundamental principle in geology


3) Important implications for historical geology


XII. Vocabulary Terms


Cold Accretion theory



Convergent plate boundary

Core (inner and outer)

Crust (continental and oceanic)



Divergent plate boundary

Geologic time scale



Historical geology

Hydrologic cycle



Igneous rock



Metamorphic rock


Physical geology


Plate tectonic theory

Principle of Uniformatarianism

Radioactive decay


Rock cycle

Scientific method

Seafloor spreading center

Solar nebula

Subduction zone



Transform plate boundary