Chapter GEO307 1
I. What is oceanography? a. Interdisciplinary Earth Science that studies the oceans & seas b. 4 major sub-disciplines i. Marine Geology & Geophysics 1. Shape & origin of ocean basins, seafloor features 2. Plate tectonics 3. Geology of oceanic crust 4. Origin & distribution of sediments 5. Marine sediments as archives of climate & tectonic history ii. Chemical Oceanography 1. Composition of seawater 2. Oceans & Earth's chemical cycles 3. Chemical tracers of ocean circulation 4. Chemical nutrients & the regulation of biological production 5. Relationship b/w seawater chemistry & changes in atmospheric CO2 iii. Physical Oceanography 1. Study of ocean circulation (wind-drive surface currents, densitydriven deep water movement, & connections to climate) 2. Waves 3. Tides iv. Biological Oceanography & Marine Biology 1. Distribution of marine organisms & the relationship of their distributions to the environment (physical, chemical, & geological) 2. Influence of biology on environment 3. Interactions b/w organisms (ecology) 4. Biology of marine organisms, biological adaptations to the marine environment Earliest Interests in the Ocean a. Copper age metal tools such as copper fish hooks were developed by 5000 BC b. Egyptians developed early vessels (1st recorded voyage in 3200 BC) c. Phoenicians were excellent sailors & navigators (traded throughout Mediterranean & had own navy) d. Figures of Ancient Greece i. Alexander the Great reached the deserts of the Mekran Coast in 325 BC ii. Aristotle knew why the sea is salty & catalogued marine organisms
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iii. Eratosthenes mapped the known world & calculated an accurate circumference of the Earth iv. Ptolemy produced the 1st world atlas & underestimated Earth's circumference (responsible for the mistake of Columbus concluding that he'd landed in Asia) Middle Ages a. Scientific interest dwindled after the Greeks progress slowed & knowledge lost b. Emphasis of interest in the oceans was on trade & navigation c. Shipbuilding improved & longer voyages were made d. Scholarship about the sea remained primitive but knowledge about navigation increased e. Harbor charts became available f. With the introduction of the magnetic compass to Europe from Asia, compass directions were added Voyages of Discovery a. Increasing interest was driven largely by economic forces (currents & trade routes, bathymetry & cable-laying) b. Improvements in technology were key developments c. Chinese admiral Zheng He conducted 7 voyages i. 300 ships, including 62 treasure ships that were much larger than European ships ii. China w/drew w/in its borders for 400 years of isolation d. Amerigo Vespucci made several trips to New World for Spain & Portugal (America named after him) e. Ferdinand Magellan left Spain in 1519 w/ 5 vessels & 270 men in search of a westward passage to the Spice Islands i. Killed in Philippines ii. One ship & 18 crew members made it back to Spain in 1522 in 1st circumnavigation of Earth f. Francis Drake from England also circumnavigated the Earth in 1579-80 & returned home w/ a cargo of Spanish gold & was knighted by Queen Elizabeth I Beginnings of Earth Science - In the 17th century, interest in experimental science increased & curiosity about Earth flourished a. Edmund Hailey (1656-1742), astronomer, suggested that the age of the oceans could be calculated by how fast rivers deliver salts to ocean b. John Joly, physicist, calculated an age of 90-100 million years (far too young because sea-salt losses were not accounted for) c. Captain James Cook
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i. Made 3 voyages to chart the Pacific Ocean b/w 1768 & 1779 ii. Prevented vitamin C deficiency & scurvy by controlling sailors' diets iii. Made soundings to depths of 400 m & accurately observed winds, currents, & water temps iv. One of the founders of Oceanography v. Killed by natives in Hawaii in 1779 d. Benjamin Franklin (1706-1790) w/ cousin Captain Timothy Folger, he constructed the 1769 Franklin-Folger Chart of the Gulf Stream current to improve the efficiency of shipping routes Importance of Chart & Navigational Information a. Importance of relationship b/w time & longitude was recognized since 1500s but clocks for ships were not available b. In 1700s, awareness increased in developing accurate charts & navigational techniques c. Spain & England offered awards for development of accurate sea-going clocks d. John Harrison (Yorkshire) received an award for developing accurate chronometer (high accuracy clock) in 1760s e. Captain James Cook used Harrison's chronometer produce to accurate charts in 1772 Coastal Surveys a. In 1807, President Thomas Jefferson & the US Congress formed the Survey of the Coast, now known as the National Ocean Survey b. In 1842, Lt. Matthew F. Maury founded the Naval Depot of Charts & he began a systematic collection of wind & current data from ships' logs c. In 1855, Maury published The Physical Oceanography of the Sea (sometimes considered the 1st text book for oceanography) d. Maury's work allowed ships to sail safely & take days off their sailing times Ocean Science Begins a. Ocean became interesting to biologists & naturalists in 1800s b. Alexander von Humboldt studied currents west of South America c. Charles Darwin naturalist on the survey ship Beagle during 1831-36 who described, collected, & classified organisms from land & sea & described atoll formation d. Laying telegraph cables in the late 1800s made a greater knowledge of the deep sea necessary e. Charles Wyville Thompson at Edinburgh University published The Depths of the Sea in 1873 (an early book on oceanography) The Challenger Expedition
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1st oceanographic expedition an example of the sort of coordination required Lasted over 3 years (1872-1876) Organized & funded by the British government Led by Charles Wyville Thompson, a naturalist at the University of Edinburgh Covered nearly 70,000 nautical miles Made almost 500 deep ocean soundings i. Measured 8180 m in the Marianas Trench ii. The deepest spot in the ocean is very near this & is called the Challenger Deep g. 133 dredge samples h. Conducted biological & water (chemistry) sampling at 362 stations i. Organisms were recovered from all depths j. Produced 50 volumes of data k. Sediments were collected & described by Sir John Murray i. Described the major types of marine sediments ii. Delineated their geographic distributions iii. Recognized their relationship to phytoplankton productivity in surface waters Oceanography as Science a. The Challenger expedition set the stage for the development of modern oceanography in the 20th century b. During the late 19th & 20th century, oceanography changed from descriptive science to a quantitative one c. Theoretical models of ocean circulation & water movement were developed d. Oceanography cruises tested hypotheses by gathering data e. Fridjof Nansen studied currents of the polar seas i. Ship (Fram) was frozen in sea for 35 months to measure currents ii. Discovered that the Arctic Ocean was a deep basin iii. Water chemistry & biology also studied iv. Designed "Nansen bottle" f. Northwest Passage sea route through Arctic Ocean along the northern coast of North America via the waterways amidst the Canadian Arctic Archipelago, connecting the Atlantic & Pacific Oceans (Gjoa was the 1st vessel to transit it) Importance of New Instrumentation to Oceanography a. Lord Kelvin invented a machine in 1872 to combine tidal theory w/ astronomical predictions b. Nansen water-sampling bottles were combined w/ thermometers for deep-sea temperature measurements to study water circulations a. b. c. d. e. f.
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c. Accurate method for measuring salinity was devised d. Development of echo sounder for accurate measurement of ocean depths Oceanography in the 20th Century a. Albatross, commissioned by US Fish Commission in 1882, was the 1st ship built for scientific ocean exploration recovered more specimesn of deep-sea fishes in one haul than the Challenger collected in 3 years at sea b. 1903: San Diego citizens established the Marine Biological Association & the Scripps Institution of Oceanography c. 1930: Woods Hole Oceanographic Institution was established mostly via a grant from the Rockefeller Foundation d. Modern oceanography benefited tremendously from technological advances driven by WWII (major funding provided by national & international agencies) e. 1960s active years i. Indian Ocean Expedition (1963-1964) ii. Deep Sea Drilling Project f. 1970s i. National Oceanic & Atmospheric Administration (NOAA) was formed from several agencies ii. International Decade of Ocean Exploration multinational effort to survey mineral resources, improve environmental forecasting, & modernize the collection/analysis/use of marine data iii. More interdisciplinary research iv. Satellite studies began Satellite Oceanography a. Satellites are used to gather many kinds of data about the oceans, including (but not limited to) sea surface height, sea surface temperature, chlorophyll concentrations, winds, ice coverage, visual data b. These data are used to investigate ocean circulation, biological productivity, ocean bathymetry, climate, etc.