Lecture 3:  Exploration of the Oceans
Focus Question:  What are the major events in the exploration of the ocean?

This is a text version of the notes presented in class

Feel free to email the instructor (knamjesn@kent.edu) with any comments about the format and ease of use of these online notes

Reading for this class includes important information in the Appendices.  Note the reading assignment:  Chapter 1, Appendices 3 and 4.  This reading will help you get familiar with general facts about the ocean-
The ocean basins:  note especially figure 4 in appendix 4.  Can you locate on a world map the Atlantic, Pacific, Indian, Arctic, and Southern Oceans?  Can you find the Mediterranean Sea and the Caribbean Sea?

  Latitude, Longitude, Maps note especially figure 2 in appendix 4

Historical Events in a Timeline:  Please note the Timeline in Chapter 1, table 1.1

We will consider 5 major events that marked major turning points in the exploration of the ocean.  They are
1.. Designing a seaworthy ship for the open ocean
2. Solving the Navigation Problem
3. Accurate Map Making
4. Measuring Bathymetry:  How far to the ocean floor?
5. Exploring Underwater:  Inventing diving technology and submarines

I..  Designing a seaworthy ship for the open ocean

First use of oceans for travel and trade

1.  Ancient history records the designs of many types of small boats used along coasts and rivers.  They were marked by a shallow draft (the depth of water into which a ship will sink when fully loaded), a long oar for steering, mounted or controlled from the side of the ship (origin of term starboard (steerboard, or right side of the ship), and single sails that were either center mounted square sails, or lateen sails (triangular sail extended by a long yardarm).

2. Egyptian paintings of ships on the Nile show features such as a single sail, and steering with long oars.  These ships were in use about 4,000 B.C.  By 1200 B.C.  Phoenician trading ships ranged over the Mediterranean Sea, and out into the Atlantic to Great Britain. Evidence indicates that Phoenician sailors circumnavigated Africa.

3. Polynesian Islanders in the Pacific Ocean colonized islands beginning about 1,000 B.C., traveling from island to island in catamaran and outrigger style boats, with single lateen sails.  By 500 A.D., Hawaii was colonized by the Polynesians.

Early scientific discovery and exploration

A note on the first circumnavigation of the continent of Africa by Phoenicians at orders of Pharoah Necho.

4. Ship design developed quickly in the Mediterranean Region, with the rise of the Greeks and later during the Roman Empire.  Galleys, which were long, narrow, shallow draft ships that relied primarily on oarsmen and secondarily on sail, were the common vessel of the ancient Mediterranean world.  There were many designs, some built for cargo, others for speed and ramming power during battle.  All relied on the relatively calm waters of the Mediterranean and were used primarily during the summer months only-galleys were not stable on the open ocean of the Atlantic.

Exploration, discovery, and colonization

5. The Vikings designed successful ships for crossing the Atlantic that were oar and sail powered.  Originally designed with shallow drafts for traveling up rivers, modifications in the hull made it possible to use them in the open ocean.  In such ships the Vikings successfully and repeatedly crossed the Atlantic, from Oslo to Iceland, Greenland, and the east coast of North America, the Newfoundland coast.  Most of their raiding and conquest activities occurred from about 780 to 1000 A.D.

6. From 1405 to 1433, during the Ming Dynasty in China, a fleet of 317 ships went on seven missions to explore the Indian Ocean, Indonesia, and the southern coast of Africa.  The purpose of the missions was to display the wealth and power of the Ming dynasty, and this included gift giving.  The largest ship in the fleet was a treasure ship, about 440 feet long with nine masts.  These were sail powered ships, with trapezoidal or triangular shaped sails designed like venetian blinds that could be run up or down quickly.  The Chinese were the first to develop a centralized rudder, the use of the magnetic compass, and complex sails on multiple masts.  Their designs were quickly picked up by other cultures.

7. Rapid development of sail power led to a general move from galleys, to galleasses, to carracks and galleons.  Prince Henry the Navigator of Portugal founded the Center for Navigation in 1451.  By the 16th century, all types were seen in use in the Mediterranean and north Atlantic.  Major maritime events during that time included Magellan’s circumnavigation of the globe (1522), and the defeat of the Spanish Armada (1588) by the British.

Modern Age of Oceanography

8. Further development of sail power through the 17th  and 18th centuries produced efficient and powerful ships, such as the U.S.S. Constitution, launched in 1797, and culminating in the “greyhounds of the sea”, the clipper ships of the 19th century.  The clipper ships sacrificed cargo space for sleek ship design, and the combination of a narrow, streamlined hull and tremendous sail power led to the fastest sailing ships the world had known.

II..  Navigation & Map Making

 1. Navigation in ancient times relied on a knowledge of one’s position relative to the stars, “dead reckoning”, and a trained eye for wave behavior.
Pacific Islanders- models of island positions called stick charts, showing wave refraction
  Local pilots- that knew the coastline in detail
  Maps that showed compass directions and exaggerated coastal features

2. Eratosthenes of Cyrene-3rd century B.C., Greek librarian in the Library of Alexandria, Egypt
 Measured diameter of the Earth and came within 8% of true value.
 Introduced the map concepts of longitude and latitude

3. Hipparchus, 2nd century B.C., another Greek librarian in the Library of Alexandria
 Introduced the map concepts of degrees for longitude and latitude
 Longitude extending from 0 to 360 degrees
 Latitude extending from 0 (equator) to 90 degrees North or 90 degrees South

Latitude can be determined with a knowledge of position relative to the stars.

4. Longitude is a function of time, and requires an accurate clock.  This problem was not solved until 1760 by John Harrison, who invented the chronometer.   International agreement in the 19th century set the zero line of longitude (prime meridian) as passing through Greenwich, England.

5. All maps have some distortion, because they are 2 dimensional flat representations of  the 3 dimensional Earth.  The type of distortion varies with the kind of map.  Two common map views are the Mercator Projection and the Equal Area Projection.

6. Important mapping expeditions of discovery include
Voyages of Captain James Cook – late 18th century
Voyage of the H.M.S. Beagle (Charles Darwin was the on-board naturalist) early 19th century
The H.M.S. Challenger Expedition – 1870s
Nansen’s Voyage in Fram – 1893-1896, and the Meteor in 1925

III.  Bathymetry-measuring the depth to the ocean floor.  Early measurements were done with baling wire and cannonballs-the late 19th century invention of steel cable improved the situation.
The H.M.S. Challenger Expedition – mapping with weights on cable
The Meteor Expedition – 1920’s  mapping with an echo sounder
  Use of Sonar to map the ocean floor
Modern Bathymetry Maps

IV.  Exploring Underwater

1.First submarines-built & designed for warfare-Bushnell’s “Turtle” used in the American Revolution against British warships

2.  Auguste Piccard’s Trieste-first submarine to travel to the deepest part of the ocean, the Marianas Trench, almost 6 miles down, in 1960

3.  Modern research submarines include small submersible vehicles and robot subs.

4.  Diving technology has changed tremendously over the 20th century, from the 1930’s tethered divers to the modern divers using SCUBA (developed by Jacques Costeau and a colleague in the 1940’s)

Next Lecture:  The Ocean Floor
Focus Question:  What are the topographic features of the ocean floor?
Readings:  Ch. 4, pgs 97-122, Ch. 5, pgs 128-150, (Ch. 4, pgs 86-114, and chapter 5, pgs 115-136).