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
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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
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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

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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
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Earths internal structure

• Highest density material at center (core)
• Lowest density material at surface (crust)
• Earth layered
• Chemical composition
• Physical properties

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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)

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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)

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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

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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

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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

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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

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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

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Photosynthesis and respiration
Fig. 1.19
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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

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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.

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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.

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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.

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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.