EARTH AND PLANETARY SCIENCES 101 Fall, 2002

THE WAY THE EARTH WORKS

GENERAL INTRODUCTION AND WELCOME/OVERVIEW

I. Usual “STUFF”

Text and associated materials, course outline, handouts, exams and “paper” for the course, office hours, questions; note possibility that I will miss a lecture or two because of job-related travel (more on this).

II. EPS105 Laboratory---Encourage!!!!

III. Introduction to Physical Geology

A. Why important?

1. Short‑lived concerns(hazards)(e.g., Pinatubo, Mt. St.Helens, Northridge EQ, Kobe EQ, Montserrat, etc.

2. Future short-lived concerns (Jemez Mountains, Yellowstone, Wasatch Fault system, Teton fault system, dams filling up!!)

3. Long‑term concerns

a. ENVIRONMENT, global warming, etc.

b. EARTH RESOURCES; a timely question, considering the Persian Gulf, the demise of the Soviet Union, a new president’s “energy policy”

c. PLANET EARTH, our home

4. Our setting, Rio Grande Rift, southernmost Rocky Mountains

a. water?????? (floating on Lake Superior, ha!)

b. water quality

c. Jemez Mountains

B. Our focus and objectives in EPS101

1. WHY AND HOW OF THE DYNAMICS of a LIVING planet, that operates as a COMPLEX SYSTEM

2. development of thought concerning geologic processes

3. importance of surface processes (long term)

3a. importance of catastrophic processes (short term)

4. relations to our environment, climate, earth resources

5. what does the future hold? (e.g., should we worry about greenhouse gas emissions, or simply adapt to a changing climate?????)

C. Learning by association/experiences

1. Earth Science as a career??? Good grief!?!?

a. Industry (exploration, mainly overseas; site remediation, groundwater, etc.)

b. government (although science does not appear to be a favorite of the Contract ON America)

c. Academia (what, and end up teaching at a place like UNM?????)

2. What do I do???

a. Geophysicist (paleomagnetist--concerned with the fossil magnetism in rocks)

b. typical routine

‑‑teach classes (graduate to field geology to Physical Geology)

‑‑research (combination of field and laboratory work; all over the world, from the Albuquerque volcanoes to the Lancaing Jaing and the Junggar Basin of western China and the Burma Road area of Yunnan and easternmost Tibet)

‑‑support/maintain quality research laboratories (B22, 219).

‑‑write scientific manuscripts (why?)

--escape, listen to Grateful Dead, every now and then

‑‑educate, support, pacify, and placate graduate students

‑‑Editor, Bulletin of the Geological Society of America, a society of over 17,000 members.

-review manuscripts for geological journals, serve on editorial boards, give lectures elsewhere

-Editor, weekly newsletter Eos, for the American Geophysical Union

-Faculty Senate President for the past year and a half

‑‑summers, ah----- a time to live for. Teach field courses, field work, enjoy life, for a change

IV. DEVELOPMENT OF THOUGHT IN THE EARTH SCIENCES

A. Inspection of earth materials (rocks of all sorts)

B. Observations with implications for time and the age or our planet (Herodotus, Greek, observing the Nile‑continuum)--

C. Biblical dictum (creation “science”) vs. geologic observation (scientific thought—use of reason and rational thinking, without faith)

General idea of the scientific method—hypothesis (or model) is proposed, tests are devised, phenomena are tested, observations and data are evaluated, theory is generated……

D. Uniformitarianism—merger of the scientific method and geology

1. Hutton in late 1700's, early 1800's by Sir Charles Lyell

2. Present is the key to the past

3. Siccar Point, Scotland; visit by Hutton in 1788.

"No vestige of a beginning, no prospect of an end" Hutton's Theory of the earth 1785.

E. Discovery of Radioactivity

1. Late 1800's.

2. Rethinking of the origin, thermal history of Earth

3. Implications for internal processes

F. A. Wegener, continental drift hypothesis

1. Most interesting hypothesis, but without a viable, provable mechanism

2. Met with very little support

G. A Revolution!!! : Plate Tectonics, late 50's and early 60's.

1. Began, actually, during World War II when we started to learn about the ocean floor, in particular its topography and magnetism.

2. Rethinking of Wegener's hypothesis. 1963 F. Vine and D. Matthews, suggest a model for ocean floor "production" that accounted for the majority of present observations.

3. Debate!!

4. General acceptance, by Summer, 1967. Historic "vote" at the Spring Meeting of the American Geophysical Union, Washington.

H. A New Revolution (?)

1. Earth as a complex system, most if not all processes closely related

2. “punctuated” uniformitarianism--recognition of “unusual” causes to great earth disasters (e.g. mass extinctions over very short lived periods of time).

3. Recognition that climate of Earth may vary considerably, over short time periods.

V. General Earth Processes

A. Earth Materials

1. Rocks---igneous, sedimentary, metamorphic; origins and differences.....

2. Composed of minerals--inorganic, naturally occurring, solids, regular internal structure, and definite/limited range of chemical compositions

a. mineral properties--density, melting temperature, composition, ductility, etc.

b. mineral reactions

B. Rock cycle

1. simple but useful view of how geologic materials form (and change!!!).

2. devised without any context/concept of “plate tectonics” or internal stratification to the planet

3. therefore, limited in its utility, but still emphasizes the incredibly slow rate of most geologic processes

C. Internal Structure of Earth

1. Chemical layers

a. crust--light, composed of relatively low density elements and by implication low density earth materials, also of relatively low melting temperature at surrounding pressures

b. mantle--heavy, composed of relatively high density elements, and by implication high density earth materials, also of relatively high melting temperature at surrounding pressures.

c. core (inner solid and outer liquid)

2. Physical layers

a. lithosphere

b. asthenosphere

c. mesosphere

d. lower mantle

e. core (inner solid and outer liquid)

3. Convection and Conduction

a. convection--transfer of heat by physical movement of hot material to a colder area

b. conduction-transfer of heat without physical movement--hot object placed next to a cold object, and the cold one gets warmer!!!

D. A new Paradigm---setting the stage

E. Current “tenets” and relation of Plate Tectonics to previous concepts.

1. Lithosphere “slabs” or plates move over the surface of the planet, just like low melting temperature scum in a pot of your favorite green chile stew.

2. lithosphere plates interact in different ways--constructive, destructive, and “non-committal”

3. Style and rate of interaction dictates processes that can have incredible social impact