P39. 1-15
1. Early Mediterranean cultures saw their world as land (Europe, Asia,
Africa) surrounding a central sea (Mediterranean). They envisioned these
landmasses as being surrounded by narrow oceans. Thus, in their world, there
was more land (or earth) than ocean.
2. An Ocean is generally considered to be larger and deeper than a Sea,
unless of course you’re referring to the ocean as The Sea. Most seas are
bounded by land (e.g., Mediterranean Sea) although one, the Sargasso Sea, is
bound by no land at all and is simply the central gyre surrounded by the
clockwise currents in the North Atlantic. Oceans and seas both contain salty
water (although some large lakes, e.g., Caspian Sea, are called seas). The
book says the “seven seas” are North and South Pacific, North and South
Atlantic, Indian, Arctic, and Antarctic, but also explains how that term has meant
different hings to different cultures throughout history.
3. Many early seafaring peoples navigated in the open ocean by using the
heavenly bodies, that is, the Sun, the Moon, and the stars at night. Polynesians
supplemented celestial navigation by understanding wave patterns. In the 18th
century the development of a marine chronometer (John Harrison) provided
measurements of accurate time in Greenwich, England. Longitude was
determined by comparing the time in Greenwich with noon local time of the ship
at sea. In the 20th century, earth encircling satellites emit radio signals that are
picked up by ships at sea. Today, a computer (usu a GPS receiver) accurately
determines a ship’s position by comparing the travel times of radio signals
from at least three satellites to a ship at sea.
4. Timelines may have any combination of the following:
• Herodotus maps Greek world
• Pytheas determines latitude
• Eratosthenes determines circumference of Earth
• Ptolemy maps Roman world
• Cosmas maps southern Europe (a view of the world during the Middle
Ages)
• Arabs dominate Mediterranean region and Vikings explore North Atlantic
• Constantinople falls
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• Bartholomeu Diaz reaches Cape of Good Hope
• Columbus discovers the New World
• Vasco da Gama sails around Africa to reach India
• Ferdinand Magellan and Sebastian del Caño circumnavigate Earth
• Vasco Nunez de Balboa discovers Pacific Ocean
• Captain James Cook conducts three major voyages of discovery
• Cook proves the value of the chronometer developed by John Harrison
• Benjamin Franklin publishes map of Gulf Stream
• Sir John Ross recovers life from Arctic
• Charles Darwin sails aboard Beagle
• Edward Forbes studies distribution of life in oceans
• Sir James Clark Ross recovered life from Antarctic deep ocean bottom
• Matthew Fontaine Maury publishes Physical Geography of the Sea
• HMS Challenger expedition
• Dittmar’s salt water analysis, from HMS Challenger expedition (1884)
• Fram and Nansen
• Scripps Institute of Oceanography founded (1903)
• Meteor voyage (1925)
• Woods Hole Oceanographic Institution founded (1930)
• Cousteau/Gagnan invent aqualung (SCUBA) 1942-43
• Lamont-Doherty Geological Observatory founded (1949)
• Trieste dive to 10,915 m (1960)
• Deep Sea Drilling Project
• Geochemical Ocean Sections Project
• Alvin
• Seasat A satellite launched
5. (See Fig 1-6 on p16) Eratosthenes Earth Circumgerence measurement, c.
200 BCE. A straight line crossing two parallel lines will create two pairs of
corresponding and equal angles (see Figure 1-6). We can then compare the
number of degrees associated with a lateral distance of 800 km (distance from
Syene or Aswan to Alexandria) with the number of degrees (360) associated with
the circumference of Earth.
7.2˚/360˚ = 800km/ CE
OR
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7.2˚/800km = 360˚/CE
NOTE: Eratosthanes used a unit of measure called the stadion (Greek)
stadium (Latin) stade (Anglicized), which was 600 feet. HOWEVER, the “foot”
was different things in different regions, and one stade could have been anything
from 157m to 209m.
6. In northern Europe the Vikings explored the North Atlantic Ocean from
Iceland to Greenland to the shores of North America (Baffin Island,
Newfoundland).
7. Age of Discovery: Columbus voyages to New World (Bahamas, Caribbean
islands, Central and South America, 1492-1502; Cabot lands in North America,
1497; Balboa names Pacific Ocean, 1513; Magellan and del Caño
circumnavigate Earth, 1519-1522.
8. Captain James Cook (1728-1779), British navy, 1768 and 1779 (ships:
Endeavour, Resolution, and Adventure)
a. Searched for hypothesized Antarctica
b. Accurately mapped many islands in Pacific
c. Systematically measured seawater temperature, winds, currents, depth,
and so on
d. Used the marine chronograph (Harrison’s H4) to determine
longitude. NOTE: Chronograph and chronometer both refer to
clocks/timers/stopwatches, but technically a timepiece is not a chronometer until
it has been certified to a particular standard of accuracy by the COSC (Contrôle
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Officiel Suisse des Chronomètres) the Official Swiss Chronometer Testing
Institute.
9. The major achievements of the HMS Challenger can be summarized as
the collection and analysis of water samples, marine life, and bottom
sediments from the Atlantic and Pacific Oceans. (The list might include
specific references to 492 deep sea soundings, 133 bottom dredges, 151 open
water trawls, 263 serial water temperature observations, netting and classifying
4717 new species of marine life, measurement of 8183 m depth in the Mariana
Trench, collection and later analysis by William Dittmar of 77 seawater samples.
Dittmar’s work was instrumental in understanding what controls salinity.)
10. Nansen’s ship Fram was designed to withstand entrapment in Arctic sea
ice. The trapped ship and its crew drifted slowly with pack ice in the Arctic for
nearly three years. Fram drifted, unimpeded by land, for 1658 km to within 394
km of the North Pole. Depth soundings determined that the Arctic Ocean is
deeper than 3000 m.
11. As U.S. Postmaster General Ben Franklin wanted mail to travel as
quickly as possible across the North Atlantic. (Fig 8-16, p246) The Gulf
Stream quickened the travel time for ships going from North America to Europe
and impeded the travel time for ships going the other way. With a map of the
Gulf Stream, ship captains could know where to “catch” the current and where to
avoid it.
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12. Matthew F. Maury’s main contributions to oceanography were the
collection and interpretation of data. Maury established international standards
in the collection of data. He synthesized these data in the first oceanographic
textbook, The Physical Geography of the Sea, in 1855.
13. Echo sounding used in World War I to find submarines led to mapping
of the ocean floor topography by using sound waves. During World War II the
military performed and funded many studies of topography, currents, waves, and
so on to understand the oceans. As a result of World War II many geophysical
techniques were applied to the study of the oceans (e.g., study of gravity and
magnetism over ocean floors).
14. Remote sensing (i.e. satellite surveillance) of the oceans can reveal info
about:
• surface temperature
• amount of ice cover
• topography* of ocean surface
• topography of seafloor
• coastal geomorphology (the shape and character of coastlines)
• color
• phytoplankton populations
• waves and wave patterns
* Topography (topo- “place,” -graph “writing”) usually refers to “the lay of the
land” especially in topographic maps. (Countour lines indicate a topographic
map) In this contoext, “topography of the ocean surface” means the shape of it,
how it is affected by variations in earth’s gravity, etc. Topgraphic maps of the
seafoor are nearly indistinguishable from continental maps, except the contour
lines often have negative numbers, indicating depths below sea level.
15. Diving underwater can raise issues concerning:
• lack of air
• cold temperature
• darkness (lack of visibility)
• enormous pressure while deep in water
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- decompression when surfacing (the bends)
- Nitrogen narcosis
The Bends: Air is 80% N2 and great pressures at depth force a lot of this N2 into
your bloodstream (the same way soda companies use pressure to dissolve CO2 in
water to make soft drinks.) When you resurface and pressure lessens, N2
“outgasses.” (…as CO2 does when you open a carbonated beverage.) If you
surface too quickly it outgasses fast enough to form bubbles, which in your
bloodstream can wreak all kinds of havoc.
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