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Title: CHAPTER%201%20Introduction%20to%20Planet%20


1
CHAPTER 1 Introduction to Planet Earth

2
Overview
  • 70.8 Earth covered by ocean
  • Interconnected global or world ocean
  • Oceans contain 97.2 of surface water
  • 99 of earths biosphere is in the ocean!!

3
Introduction
  • Oceanography the description of the oceans
  • Interdisciplinary
  • Geological
  • Chemical
  • Physical
  • Biological

4
Global Ocean4 principal oceans plus one
  • Pacific
  • Largest, deepest
  • Atlantic
  • Second largest
  • Indian
  • Mainly in Southern Hemisphere
  • Arctic
  • Smallest, shallowest, ice-covered
  • Often consider only a sea
  • Antarctic or Southern Ocean
  • Connects Pacific, Atlantic, and Indian
  • South of about 50o S latitude

5
The Seven Seas
  • Smaller and shallower than oceans
  • Salt water
  • Usually enclosed by land
  • Sargasso Sea defined by surrounding ocean currents

http//www.jimloy.com/biology/sargasso.gif
6
The Seven Seas
  • Before 15th Century
  • Red Sea
  • Mediterranean Sea
  • Persian Gulf
  • Black Sea
  • Adriatic Sea
  • Caspian Sea
  • Indian Ocean
  • Current list also includes
  • North Pacific
  • South Pacific
  • North Atlantic
  • South Atlantic
  • Indian
  • Arctic
  • Southern

7
Comparison of elevation and depth
  • Average depth 3729 m (12,234 ft)
  • Average elevation of land is 840 m (2756 ft)
  • Deepest ocean area is Mariana Trench 11,022 m
    (36,161 ft)
  • Highest continental mountain Mt. Everest 8850 m
    (29,935 ft)

8
History of Oceanography
  • http//www.divediscover.whoi.edu/history-ocean/ind
    ex.html

9
Journey to the bottom of the ocean
  • Alexander the Great
  • Supposedly went down in sealed container in 332
    BC
  • William Bebe - 1934
  • Bathyshpere heavy steel ball with windows
  • Went about 923m (3028 ft)
  • US Navys Trieste
  • took 3 people down 9906m (32,500 ft!) in Mariana
    Trench, heard cracking sound
  • Submersible Alvin
  • Began dives in 1964
  • Can go down 4000m (13,120 ft)
  • Submersible Shinkai
  • Japanese submersible that can dive over 21,000ft
  • James Cameron 2012 (National Geographic)
  • http//www.youtube.com/watch?vDO6_jKN-1hwfeature
    player_embedded

10
Nature of scientific inquiry
  • Natural phenomena governed by physical processes
  • Physical processes similar today as in the past
  • Scientists discover these processes
  • Make predictions and test them
  • Leads to better understanding and prediction of
    future events that rely on natural processes

11
Scientific method
  • Observations and questions
  • Develop falsifiable, testable hypotheses
  • Science can only deal with hypotheses that are
    testable!
  • Predictions based on hypotheses
  • Test predictions
  • Comparative studies
  • Controlled manipulative experiments
  • Field and lab experiments
  • Lot of trial and error! And retesting!
  • Gather data and analyze results
  • Accept or reject (falsify) hypothesis
  • Modification of hypotheses

12
Scientific method
Fig. 1.9
13
Scientific method
  • Theory
  • Well-substantiated by large body of data
  • Many facts, supported by testing of many
    scientists
  • Probably true versus absolutely true
  • Always possible that additional data cannot be
    fully explained by current theory
  • The public often thinks that scientists really
    dont know because of the word theory
  • However, in biology the word theory is a close to
    a law as you will come!
  • Science is continually developing because of new
    observations and new technology

14
Formation of Solar System and Earth
  • Big Bang formed universe over 15 billion years
    ago
  • Earth formed from gases dust
  • 4.6 5 bya
  • How do we know that? Scientists use radiometric
    dating

15
Formation of Solar System and Earth
  • Nebular hypothesis
  • Nebula cloud of gases space dust
  • Mainly hydrogen and helium
  • Gravity concentrates material at center of cloud
    (Sun)
  • Protoplanets from smaller concentrations of
    matter (eddies)

16
Protoearth
  • Larger than Earth today
  • Homogeneous composition
  • Bombarded by meteorites
  • Moon formed from a chunk of protoearth after
    collision with large asteroid
  • Heat from solar radiation
  • Initial atmosphere boiled away
  • Ionized particles (solar wind) swept away nebular
    gases

17
Protoearth
  • Denser materials started to move to center
  • density stratification (layered Earth)

http//instruct1.cit.cornell.edu/Courses/biog105/p
ages/demos/106/unit08/media/interior-of-earth.jpg
18
Earths internal structure
  • Highest density material at center (core)
  • Lowest density material at surface (crust)
  • Earth layered
  • Chemical composition
  • Physical properties

19
Chemical composition
  • Crust
  • Low-density, mainly silicate minerals
  • Oceanic and continental crust
  • Mantle
  • Mainly Fe (iron) and Mg (mangnesium) silicate
    minerals
  • Core
  • High-density, mainly Fe and Ni (nickel)

20
Physical properties
  • Lithosphere
  • Asthenosphere
  • Mesosphere
  • Outer core
  • Inner core
  • Rock 'behavior' determined by temperature,
    density and stress
  • ranges from brittle to plastic ("deformable") to
    elastic

21
Physical properties
  • Core
  • 90 iron with nickel
  • 5,500-6,600O C (9900-12000O F)
  • Solid inner core and viscous liquid outer core
  • Differential spin of inner/outer cores ?
    Earth's magnetism

22
Physical properties
  • Mantle
  • Iron and magnesium silicates
  • 2500O C (4500O F)
  • Inner mantle -mesosphere
  • rigid
  • 'Upper' mantle
  • Asthenosphere - partially molten ? plastic
  • Lithosphere rigid (part of crust)

23
Physical properties
  • Upper Mantle
  • Asthenosphere
  • Plastic deforms by flowing
  • High viscosity able to flow slowly
  • From 100 km to 700 km (430 miles)

24
Physical properties
  • Upper Mantle and Crust
  • Lithosphere
  • Cool, rigid, brittle
  • (500O C, 900O F)
  • Surface (crust) fused to uppermost mantle, to
    about 100 km (62 miles)

25
Two types of crust
  • Oceanic crust
  • Underlies ocean basins
  • Igneous rock basalt
  • Dark colored
  • Average thickness 8 km (5 miles)
  • Relatively higher density
  • 3.0 g/cm3
  • Continental crust thicker but LESS dense
  • Underlies continents
  • Igneous rock granite
  • Average thickness 35 km (22 miles)
  • Lower density
  • 2.7 g/cm3

26
Isostatic adjustment (isostasy)
  • Buoyancy less dense floats higher than more
    dense
  • Continental crust floats higher than oceanic
    crust on plastic asthenosphere
  • As we will see, when oceanic and continental
    crust meet, the oceanic crust is forced below the
    continental crust

27
Origin of Earths atmosphere
  • Partial melting resulted in out-gassing about 4
    billion years ago
  • Similar to gases emitted from volcanoes
  • Mainly water vapor (steam)
  • Carbon dioxide, hydrogen
  • Other gases such as methane and ammonia
  • Living organisms had dramatic effect

28
Origin of Earths oceans
  • Water vapor released by outgassing
  • Condensed as rain (acidic)
  • Accumulated in ocean basins
  • About 4 billion years ago
  • Ice Comets may have contributed to ocean waters,
    but much, much less than outgassing

29
Origin of Ocean Salinity
  • Rain dissolves rocks
  • Acidic due to CO2 and H2S gas levels in the
    atmosphere at that time
  • Dissolved compounds (ions) accumulate in ocean
    basins
  • Ocean salinity based on balance between input and
    output of ions
  • Ocean salinity nearly constant over past 4
    billion years

30
Life in oceans
  • Life originated in the oceans
  • Originated as prokaryotic life
  • Ocean water gave protection against harmful UV
    rays from sun (ozone layer was not yet well
    established)
  • Earliest life forms fossilized bacteria in rocks
    about 3.5 billion years old
  • Found in marine rocks

Fossil cyanobacteria, 850 MYA
http//www.ucmp.berkeley.edu/bacteria
31
  • Bacteria are microscopic organisms
  • How can scientists say they have found
    cyanobacteria fossils that are 3.5 billion years
    old?
  • Mats of cyanobacteria can form stromatolites
  • Trapped sediment and secreted calcium carbonate

32
Stanley Millers experiment 1953
  • Experiment replicated Earths early atmospheric
    conditions
  • They put molecules/gases that were present,
    water, exposed UV light, electrical sparks
    (atmosphere was very dynamic, lightening)
  • Organic molecules started to form by ultraviolet
    light, electrical spark (lightning), and mixture
    of water, carbon dioxide, hydrogen, methane, and
    ammonia
  • Organics combined to form more complex molecules
  • These molecules are needed for life

http//fig.cox.miami.edu/cmallery/150/life/Stanle
y_Miller_large.jpg
33
Evolution and natural selection Darwins On
the Origin of Species 1859
  • Populations of organisms adapt and change through
    time ? evolve
  • Advantageous traits are naturally selected
  • Individuals with better traits for environment
    tend to survive and reproduce better than others
  • Advantageous traits passed on to offspring ?
    inherited
  • Produces organisms that
  • are adapted to environments
  • Organisms change environments

34
Types of life forms
  • Heterotrophs
  • Most bacteria and animals and fungi
  • Must get energy from others
  • Autotrophs
  • Chemosynthetic autotrophs
  • Bacteria that chemosynthesize, fairly recently
    discovered
  • Photosynthetic autotrophs
  • Photosynthetic bacteria, algae, and plants
  • Chlorophyll captures solar energy
  • ? produces excess O2 as by-product released

35
Photosynthesis and respiration
Fig. 1.19
36
Oxygen
  • Photosynthetic anaerobic bacteria released oxygen
    (O2) to atmosphere
  • About 2 billion years ago, sufficient O2 in
    atmosphere to oxidize (rust) rocks
  • Ozone (O3) built up in atmosphere
  • Protects Earths surface from ultraviolet solar
    radiation
  • Oxygen and ozone in atmosphere resulted in
    aerobic organisms to evolve and allowed life to
    move to land
  • Aerobic organisms (including us) need oxygen for
    cellular respiration

37
Age of Earth
  • Radiometric age dating
  • Spontaneous change/decay
  • Half-life
  • Can determine age of rocks and organisms
  • http//www.youtube.com/watch?v2io5opwhQMQ
  • Earth is about 4.6 billion years old

38
Geologic time scale
39
MisconceptionsWhat have we learned that make
these statements false?
  • Science is just a collection of facts just to be
    memorized.
  • Scientific ideas are absolute and unchanging.
  • Scientists have already studied all the Earths
    systems so there will not be any new discoveries.
  • All theories are permanent.
  • Science and technology can solve all of our
    problems.
  • Not everyone can love science and get something
    out of it.
  • Science always has exact answers.
  • All radioactivity is dangerous.
  • The Earth is younger than 4.6 billion years old.
  • All rocks are more or less the same.
  • The Earth has always been pretty much the same it
    is now.
  • There is significant disagreement about Earths
    age among scientists.
  • Evolution has never been observed.
  • Evolution is a theory on the origin of life.
  • Life does not continually change.
  • Fossils are man made.

40
Ocean Literacy Principles
  • 1.a - The ocean is the dominant physical feature
    on our planet Earthcovering approximately 70 of
    the planets surface. There is one ocean with
    many ocean basins, such as the North Pacific,
    South Pacific, North Atlantic, South Atlantic,
    Indian and Arctic.
  • 1.b - An ocean basins size, shape and features
    (islands, trenches, mid-ocean ridges, rift
    valleys) vary due to the movement of Earths
    lithospheric plates. Earths highest peaks,
    deepest valleys and flattest vast plains are all
    in the ocean.
  • 1.h - Although the ocean is large, it is finite
    and resources are limited.
  • 5.a - Ocean life ranges in size from the smallest
    virus to the largest animal that has lived on
    Earth, the blue whale.
  • 5.e - The ocean is three-dimensional, offering
    vast living space and diverse habitats from the
    surface through the water column to the seafloor.
    Most of the living space on Earth is in the
    ocean.

41
Sunshine State Standards
  • SC.6.N.1.2 - Explain why scientific
    investigations should be replicable.
  • SC.6.N.1.5 - Recognize that science involves
    creativity, not just in designing experiments,
    but also in creating explanations that fit
    evidence.
  • SC.6.N.2.2 - Explain that scientific knowledge is
    durable because it is open to change as new
    evidence or interpretations are encountered.
  • SC.6.N.2.3 - Recognize that scientists who make
    contributions to scientific knowledge come from
    all kinds of backgrounds and possess varied
    talents, interests, and goals.
  • SC.6.N.3.1 - Recognize and explain that a
    scientific theory is a well-supported and widely
    accepted explanation of nature and is not simply
    a claim posed by an individual. Thus, the use of
    the term theory in science is very different than
    how it is used in everyday life.
  • SC.6.E.7.9 - Describe how the composition and
    structure of the atmosphere protects life and
    insulates the planet.
  • SC.7.N.1.5 - Describe the methods used in the
    pursuit of a scientific explanation as seen in
    different fields of science such as biology,
    geology, and physics.
  • SC.7.N.1.7 - Explain that scientific knowledge is
    the result of a great deal of debate and
    confirmation within the science community.
  • SC.7.E.6.1 - Describe the layers of the solid
    Earth, including the lithosphere, the hot
    convecting mantle, and the dense metallic liquid
    and solid cores.
  • SC.7.E.6.4 - Explain and give examples of how
    physical evidence supports scientific theories
    that Earth has evolved over geologic time due to
    natural processes.
  • SC.7.E.6.5 - Explore the scientific theory of
    plate tectonics by describing how the movement of
    Earth's crustal plates causes both slow and rapid
    changes in Earth's surface, including volcanic
    eruptions, earthquakes, and mountain building.
  • SC.8.N.1.3 - Use phrases such as "results
    support" or "fail to support" in science,
    understanding that science does not offer
    conclusive 'proof' of a knowledge claim.
  • SC.8.N.1.4 - Explain how hypotheses are valuable
    if they lead to further investigations, even if
    they turn out not to be supported by the data.
  • SC.8.N.3.2 - Explain why theories may be modified
    but are rarely discarded.

42
Sunshine State Standards (cont)
  • SC.912.N.1.3 Recognize that the strength or
    usefulness of a scientific claim is evaluated
    through scientific argumentation, which depends
    on critical and logical thinking, and the active
    consideration of alternative scientific
    explanations to explain the data presented.
  • SC.912.N.1.7 Recognize the role of creativity in
    constructing scientific questions, methods and
    explanations.
  • SC.912.N.2.2 Identify which questions can be
    answered through science and which questions are
    outside the boundaries of scientific
    investigation, such as questions addressed by
    other ways of knowing, such as art, philosophy,
    and religion.
  • SC.912.N.2.4 Explain that scientific knowledge
    is both durable and robust and open to change.
    Scientific knowledge can change because it is
    often examined and re-examined by new
    investigations and scientific argumentation.
    Because of these frequent examinations,
    scientific knowledge becomes stronger, leading to
    its durability.
  • SC.912.N.3.1 Explain that a scientific theory is
    the culmination of many scientific investigations
    drawing together all the current evidence
    concerning a substantial range of phenomena
    thus, a scientific theory represents the most
    powerful explanation scientists have to offer.
  • SC.912.E.5.1 Cite evidence used to develop and
    verify the scientific theory of the Big Bang
    (also known as the Big Bang Theory) of the origin
    of the universe.
  • SC.912.E.5.5 Explain the formation of planetary
    systems based on our knowledge of our Solar
    System and apply this knowledge to newly
    discovered planetary systems.
  • SC.912.E.6.1 Describe and differentiate the
    layers of Earth and the interactions among them.
  • SC.912.E.6.3 Analyze the scientific theory of
    plate tectonics and identify related major
    processes and features as a result of moving
    plates.
  • SC.912.E.6.5 Describe the geologic development
    of the present day oceans and identify commonly
    found features.
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