ML

2 OCE 3008_Ch1

Academic Activity

  • Quiz Reminder: Academic activity quiz on Webcourses due by 11:30 PM tomorrow (Friday, January 12th).

  • Sample Exam Questions: Available on Webcourses.

  • Practice Exam Questions Folder: Check for updates in Announcements.

Introduction to Planet Earth

  • Quote by Arthur C. Clarke: "How inappropriate to call this planet Earth, when clearly it is Ocean."

Key Concepts in Oceanography

  • Definition and Significance:

    • Explore the marine environment and its characteristics.

    • Oceanography is considered an interdisciplinary science encompassing various fields.

  • Topics Covered:

    • Characteristics of Earth’s oceans.

    • Scientific inquiry and the scientific method.

    • Understanding the Earth’s age.

    • Formation of the Earth and Solar System.

    • Development of Earth’s atmosphere and oceans.

    • Origin of life thought to be in the oceans.

What is Oceanography?

  • Overview:

    • Oceanography is studying the oceans' past, present, and future.

    • Synonymous with marine science.

  • Sub-disciplines:

    • Geological Oceanography/Marine Geology: Study of rocks, processes forming ocean basins, and seafloor structure.

    • Chemical Oceanography: Composition of seawater and element distribution, impacts of pollutants.

    • Physical Oceanography: Study of waves, tides, currents, and ocean-atmosphere interactions.

    • Biological Oceanography: Examination of life forms, their interactions, and adaptations to marine environments.

The World Ocean

  • Coverage:

    • Oceans cover 70.8% of Earth’s surface.

  • Connection to Life:

    • The origin and development of life are closely linked to the ocean.

  • Historical Significance:

    • Oceans have a long history on Earth.

Earth's Water Composition

  • Saltwater vs. Freshwater:

    • 97.2% of Earth's surface water is seawater; 2.8% is freshwater.

    • Breakdown of freshwater: 78% trapped in ice and glaciers, 11% in deep groundwater, 11% in surface groundwater.

    • Less than 1% of freshwater is in lakes and rivers (approx. 0.3%).

Major Oceans of Earth

  • Overview: The ocean is an interconnected body of water divided into four principal oceans plus the Southern Ocean:

    • Pacific Ocean: Largest and deepest (3940 m) covering 50.1% of the Earth's oceans.

    • Atlantic Ocean: 26% of Earth's ocean, shallower than the Pacific at 3844 m depth.

    • Indian Ocean: 20.5%, primarily in the Southern Hemisphere, similar depth to Atlantic.

    • Arctic Ocean: Smallest and shallowest (3.4% of Earth's ocean).

    • Southern Ocean: Circumnavigates Antarctica.

Ocean Zonation

  • Depth Zones:

    • Benthic: Seafloor.

    • Pelagic: Water column divided into zones (e.g., Epipelagic: 0-200 m; Mesopelagic: 200-1000 m).

    • Layers of the ocean vary greatly in depth and characteristics.

Comparisons of Ocean Depths

  • Average ocean depth ranges from 3682-3729 meters.

  • Key Features:

    • Mt. Everest (8850 m) compared to the Mariana Trench (11022 m).

Characteristics of Seas vs. Oceans

  • Definition of a Sea: Smaller, shallower, saltwater body, usually enclosed by land.

Latitude and Longitude Measurements

  • Latitude: Determined by the North Star (Polaris); Equator is 0 degrees.

  • Longitude: Measured from the Prime Meridian at Greenwich, England.

Historical Voyages for Science

  • Captain James Cook: Conducted significant scientific voyages, mapped Pacific islands, and measured ocean characteristics.

Advancements in Oceanography

  • Modern Tools:

    • Sonar, robotics, computers, satellites, and models are utilized for oceanographic study.

Nature of Scientific Inquiry

  • Scientific Method:

    • Does not claim absolute truth; relies on testing hypotheses.

    • Theories develop from extensive observation, experimentation, and provide explanations of natural phenomena.

Age of the Earth

  • Radiometric Dating: Earth is estimated to be approximately 4.6 billion years old.

Geologic Time Scale

  • Event Markers: Includes key extinctions and the Great Oxidation Event (~2.45 billion years ago).

Formation of Earth and Solar System

  • Nebular Hypothesis: Solar system bodies formed from a nebula cloud mainly composed of hydrogen and helium.

Structure of the Earth

  • Layers:

    • Crust, Mantle, Core defined by chemical composition and physical properties.

Isostatic Adjustment

  • Vertical Movements: Resulting from crustal buoyancy and glaciers' weight.

Origin of Earth’s Atmosphere and Oceans

  • Outgassing: Contributed to the formation of Earth’s second atmosphere, leading to the creation of oceans.

Did Life Begin in the Oceans?

  • Earliest Life Forms: 3.5 billion-year-old bacteria fossils suggest life originated in the ocean.

The Importance of Oxygen to Life

  • Current Atmosphere Composition: 78% Nitrogen, 21% Oxygen, and 0.9% Argon.

  • The lack of ozone might have facilitated the origins of life.

Evolution and Natural Selection

  • Adaptation Mechanism: Organisms adapt over time, and beneficial traits are naturally selected.

Photosynthesis and Respiration

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  • Photosynthetic Process: Allowed complex organisms to capture sunlight, leading to oxygen production.

Great Oxidation Event**:

  • Ventured a shift to an oxygen-rich atmosphere due to photosynthesis.

Changes in Earth’s Atmosphere**:

  • Impact of Fossil Fuels: Human activity currently alters atmospheric composition.