History of Oceanography

History of Oceanography

  • Herodotus’s map of the world ~ 450 B.C. (ancient Greek)

  • Ptolemy’s map of the world ~ 150 A.D. (Roman)

Post-Roman World

  • Roman Empire collapses

  • Western knowledge of Greek and Roman world largely dies with the Roman Empire in Middle Ages - “Dark Ages”

  • Middle Ages - Arabs become maritime traders using knowledge of Greeks and Romans

    • Trade with India and southeast Asia for silks and spices

      • Sold for huge profits, making them rich

      • European buyers

    • Become accomplished celestial navigators

    • Developed powerful army from riches and triumphed many areas

    • European monarchs decide to pioneer the trade routes and goods themselves

Age of Discovery (1487-1522)

  • Could be retitled: Revenge of the Europeans/Revenge of the Monarchs

  • Sailed in large groups to try to obtain great riches for the European monarchs

  • Western European monarchs seek trade routes and riches

    • Columbus - essentially built Spanish empire

    • Balboa

    • Magellan

  • Spanish became rich, English and Dutch became accomplished pirates

England Becomes Ruler of the Seas

  • England defeats Spanish Armada in 1588

    • Spain lost its navy

  • English knows that in order to project power in the world and maintain world trade, they need to understand the oceans

Advances in Scientific Understanding

  • Kepler (1571-1630): planetary motion

    • moon’s connection to the tides

  • Galileo (1564-1642): mass and acceleration

    • allowed us to study air and water motion

  • Newton (1642-1721): unifying law of gravity, later used to explain tides

Challenger

  • England’s effort to understand the world’s ocean

  • Floating laboratory

  • Largely a sailing vessel

  • Built floating labs

  • Pulled nets behind it to study the ocean life

    • Discovered new living organisms basically every time they pulled up the net

  • Used an anchor and a cable to measure the depth of different areas of the ocean

    • Deepest water they found was ~11,000m deep (called the Challenger Deep) → Mariana Trench!

    • Made ~300 of these around the world

    • Depth varied widely

Voyage of the Meteor (1925-1927)

  • German ship

    • Period between the World Wars

  • First use of SONAR

    • SOund NAvigation Ranging

  • Two-Way Travel Time: the time it takes the sound wave to hit the sea floor and return to the ship

    • Distance/time = velocity

      • distance = velocity * time

        • ex: 60 = v * 6

          • v = 10 ft/s

      • 2 depth = v t

        • depth = v * t/2

          • ex: d (2 seconds) = 10 ft/s * 2s/2

            • d = 10 ft

          • ex: d (4 seconds) = 10 ft/s * 4s/2

            • d = 20 ft

      • Inconsistent velocity

        • Speed of sound is not constant

          • Function of the “stuff” it goes through

            • Higher the density of a material, the faster a sound wave can move through it

            • Water pressure doesn’t have much to do with density

              • Water density in the oceans is NOT consistent

              • Soundwaves speed up as they get deeper in the ocean

3 Star Concept:

  • CORK CONCEPT: high density things want to sink, low density things want to float

Glomar Challenger (1968-83)

  • Scientific drill rig

    • Drilled holes into the sea floor to recover sea cores

      • If you know what the sea floor is made of, you can figure out how it’s made

      • Age of the seafloor is important because it goes towards the validity of the plate tectonics theory

        • Important because they are repositories that help us understand global climate change

Franklin Folger Map

  • Studied ship logs and floated along with the currents and recorded navigational hazards

  • Gulf Stream: takes water out of the Gulf of Mexico