Chap 2 – Facts & Origins
I. Ocean facts II. Science &
scl. method
I. Ocean facts
The "world ocean" is:
A. BIG
Area: 140,000,000 mi2 ("miles squared" = square
miles)
Mass: 150,000,000,000,000,000,000 tons (=150 billion
billion tons)
Stats:
97% of all water on Early is in ocean FI 1.2
71 % of Earth surf covered by ocean
B. DEEP
Avg depth --12,500 ft (below sea level)
Deepest spot: Marianas Trench (Philippines) --36,000 ft
C. COLD
Avg ten.p (OF) is_ ...what? Look I U
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Hawaii (tallest mt on Earth) =+33,476 ft from base sea floor
E. OLD
At least 3.5 (poss 4) billion yrs old based on age-dated
fossils - may nave formed soon after Earth itself formed
1(2)
B. Hypotheses, theories, & laws
If hypothesis appears valid and is consistently supported by
experiments & observations, it's status is elevated to a theory (eg,
theory of plate tectonics).
If theory is NEVER found to vary, it's status is elevated to a
law (eg, law of gravity).
C. Disclaimer
Sci method does not necessarily prove that things are
absolutely true - theories & laws may change as powers of
observation or knowledge increases.
EXAMPLE OF SCI METHOD
1. Ask question - Will ice float in water?
2. Poss answer (hypothesis) - "No, because ice is a solid, and
because solids are more dense than liquids, a solid will sink like a
rock."
3. Test hypothesis with an experiment - put some ice in water
(CAUTION -PROFESSIONAL SCIENTIST UNDER
CLOSELY MONITORED CONDITIONS-DO NOT TRY THIS AT
HOME!)
Hypothesis wrong - ice floats ......
OK, let's cycle through the pro^Pss again
....
1. Ask question- Why does ice float?
2. Hypothesis - something about crystal structure causes solid ice
to be less dense than liquid water
1(3) 3.
Experiment using high power, scanning electron microscope to
observe crystal struc as water changes from liquid to solid find
that H-0-H bond angle opens up when change of state occurs,
causing solid crystal struc to become less dense than liquid
crystal struc.
Impor pt hers-doesn't matter that initial hypothesis was wrong what's important is that the sci method gives us an iterative
process we can use to continue to search for scientific truth
III. Origins of universe, earth, ocean, llfe
A. Origin of universe
• - h 15 billion yrs ago
• From a point source ("Big Bang" theory)
• Universe continues to expand (things moving are v from
each other)
• Expansion may eventually slow down & stop due to grav
attract on trying to pull things back together ...will universe th
en contract, collapse on itself, heat up & explode outward all
over again?
B. Galaxies
• Definition: "huge rotating aggregate of stars, dust. as"
Fits 1.7
Origin:
- -1 million yrs after Big Bang, hydrogen (H) atoms
began to form from subatomic particles (gravity pulling things
together) _ 1 billion yrs after Big Bang, H atoms start to congeal
w/ one another to form first galaxies & stars (again, grav pulling
things together)
1 (a)
C. Stars
• Definition: "massive sphere of incandescent ("makes it's
own light" gases"
ngin :Condensation Theory"
1. A certain portion of a nebula (an area of cold clouds
of dust and gas) starts to shrink into a cloud-like sphere
("protostar") due to weak gravitational attraction
2. Protostar further contracts due to gravity, and
temperature starts to rise due to increased compression
(pressure).
(PS-This temp rise is mandated by Ideal Gas Law:
PV=nRT
(Pressure x Volume= n (no of moles) x Rate (gas constant) x
Temp).
If there is an increase in either pressure or volume,
*temperature must rise.)
3. When temp reaches 10 million ° C (1 S million' F),
nuclear fusion begins, star becomes incandescent (during
nuclear fusion rxn H+H = Helium, energy released as heat &
light).
• Life of a star- dependent upon mass (= weight)
-1 ass mass, burns cooler, longer life; Carbon (C) &
Oxygen (O) heaviest elements produced
- -More mass, burns hotter, shorter life; heavy elements
uptolron (Fe) produced due to higherTemp
-Star burns H & other elements in core until fuel is
depleted
1 (5)
&Death of a star
-When fuel is depleted, star's core collapses on itself
-Collapse causes rapid compression, which in turn
causes increased Temp (PV=nRT again, as at beginning of
star's life)
-When Temp is high & compression is high, star
explodes as a ~su
-During
explosion, elements heavier than Fe
(eg, gold, uranium) are formed
-All elements, light and heavy, are blown
into space
Me
Me
D. Our solar system (Sun & planets)
• Origin: indirect result of supernova
-Original solar nebula here may have been struck by
shock wave and matter from supernova
-Shock wave imparted spin to our nebula
-Supernova matter "seeded" our nebula w/ heavy
elements created during explosion of supernova
• Sequence of formation, arrangement of planets. Fi 1.10
-Original solar nebula (=5 toy. ago) compose 23% He,
2% other
-As nebula condensed, it spun faster. Material near
center became protosun; outer material became planets
-Planets nearest young Sun formed from metals and
minerals w/ high melting points. These materials can exist in solid
form under conditions of very high Temp before they melt (hence
term "high melting point"); they are also the first minerals to
crystallize out of a rock "melt" as it cools
Analogy - Bowen's rxn series for rocks crystallizing
High Temp ---_------------- ---------------- Low Temp
Olivine>Pyroxene>Amphibole>Biotite>K-felspar>Quartz
High Mg,Fe
---------------------------------- High Si02
1 (s)
• Examples of different planetary composition: Fia 1. f0
-Inner planet-Mercury: predom iron ( Fe can stay
solid at very high Temp)
iddl
net-Earth a mixture of elements that are
solid onl at cooler Tem (Silicon, Oxygen,etc)
-Outer planets- Jupiter,Saturn, Uranus,
Neptune-mostly materials that are solid only at very cold Temp
(eg, ammonia, methane; these are gases at warmer art
temperature)
a
• Notice similarities between Bowen's rxn series on
earth and processes operating on solar system-wide basis
-Process is the same; only the scale is
different
(This theme repeated over & over again in many aspects
of geology specifically & science in general)
E. Earth
• Origin:
-May have accreted cold, but then became heated
by "cosmic debris" &/or radioactive decay
-Heating caused melting; melting allowed
density stratification to occur
-Earth became stratified due to gravity pulling
denser elements toward center leg, Iron) while Ii Inter ones
mi rated toward surface (eg, Silicon, Aluminum,
magnesium), ~including gases
-You can view density stratification as less
dense layers "floating" on denser layers, likes oil
floating on water.
(I need a density experiment here ....tequila sunrise? oil
on water?)
1 (7)
F. Ocean
• Origin:
-Outgassing from inside earth to atmosphere occurred
via volcanism (think of it as Earth burping)
-As gases cooled, water formed (= 4.5 b.y. ago), rains
fell, ocean developed over millions of years
G. Life
• Origin:
-Stanley Miller's 1953 experiment He passed an
electric spark, simulating lightning, through WHAT?
(Look it up & know it ....)
• Possible sites for early life Fla 1.15
-Tidal pools ("organic sop")
-Hydrothermal vents on ocean floor
• Earliest life FI 1.16
-3.5 Billion yes, Billion) year old fossil bacteria from
Australia
Bacteria appears somewhat complex, suggesting that
life may have formed even earlier
-Closer to home - 2.2 billion yr old algal stromatolite in
the Randville Dolomite, just south of the Marquette State Prison!
(Don't ask me HOW I know .... )