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.