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biological oceanography
the study of life in the oceans
geological oceanography
the study of the ocean floor
chemical oceanography
the study of the composition of seawater
physical oceanography
study of the motion of water in the ocean
ocean engineering
study of how to design/build things at sea
what is one major challenge of oceanic research?
it is very expensive
why is earth called the blue planet?
due to the abundant amount of water on its surface
how much of the earth’s surface is ocean water?
about 70%
what is the “water sphere”?
the southern hemisphere because it is mostly water
the world’s oceans
Atlantic, Pacific, Indian, Arctic
What is the largest ocean?
Pacific
What is the shallowest ocean?
Arctic
What is the smallest ocean?
Arctic
observation
the act of knowing and recording something
hypothesis
an educated guess as to what will happen during your experiment
theory
a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment
law
a statement that describes an observable occurrence in nature that appears to always be true
what is the difference between a theory and a law?
a law is the description of an event, while theory is the explanation for that event
What were early oceanographers classed as?
explorers
Why were oceans important to early civilizations?
They were essential for livelihood (transportation, knowing rain helps maintain crops and food)
Phoenicians
the first explorers, middle eastern society (lebanon, syria, etc), understand currents and water approaching land
Arab traders
1500-500 BC, traded all across Indian Ocean, East Africa, India, etc., learned about sea faring through traveling
Polynesians
1500 BC, originated from South Asia, India, over to Australia, begin to strike out across South Pacific ~1000 BC, courageous, hoping to run into land. boats made out of local materials, exploring and learning how to fish across Pacific Ocean. star structures using sticks, shells, rocks
Why did explorers need to stay close to land?
in order to see where they are navigating and to be closer to supply, know where you are and tell people how to get there, orally share information
The use of stars for navigation
ancient Polynesians used star maps for navigation, use how the seasons change as a guide
Aristotle’s discoveries
studies of the currents, determined that we have a hydrologic cycle (water is evaporated from oceans, then will condensate, and later precipitate), first to start thinking about the ocean as a science (cataloged animals and plants, figured out that oceans occupy the deepest parts of the Earth’s surface
Eratosthenes’ contribution
: Egyptian scientist, used geometry to determine the actual size of the Earth and the fact that it was spherical
Pliny the Elder’s contribution
(23-79 AD) proposed that the phases of the moon were related to the ocean/tides, detailed the currents moving through the Straits of Gibraltar (passageway between Spain & Morocco)
Ptolemy
(127-151 AD) drew detailed maps of known world, put latitudes and longitudes on the map, published the first atlas, and the flaw in his map = he used the wrong radius of the Earth (made locations too close together). later consequence = Columbus (1492) thought he was in indigenous but was actually in San Salvador Island
Middle Ages
dark time for science, little discovery, but advances in ship building, use of compasses (aid navigation), Vikings came to Greenland and Newfoundland from Norway, Denmark, Iceland, Sweden – didn’t stay but settled in eastern part of North America but left because of changing climatic conditions. Arab explorers continue and describe winds and currents during monsoons, established more efficient trade routes throughout the Indian Ocean. Dark Ages was a bad time for science, but Black Death proved its importance and influenced Renaissance, Enlightenment (Europe/China), Age of Exploration (1400s)
Ming Dynasty
Emperor Zheng sent fleet of 300 ships across Pacific and Indian Oceans = largest expedition ever, perhaps reached North America but not a lot of permanent remnants
Who were European explorers funded by? (15th/16th century)
the governments
Dias
sailed around tip of Africa, Indian Ocean
Columbus
(1492) sailed through the Bahamas from Spain (thought that he was in India but was actually San Salvador Island)
Vespucci
: new world named for Americo Vespucci, Italian explorer, sailed to Americas and recognized South America as separate continent
Balboa
1500s, from Spain, crossed the Isthmus of Panama, named Pacific Ocean
Magellan
1519, first circumnavigation of the globe, sets out from Portugal and goes all the way around, ended up in conflict with locals (internal warfare), Magellan killed in Malaysia, but his expedition fleet/ships made it back to Portugal
Charts and navigation
allowed people to know where they were going, break maps up into latitude and longitude (latitude runs east/west, longitude runs north/south)
Harrison’'s contribution
developed time at sea, time plot to develop latitude/longitude, determine where you are in the world by what time it was (angle of sun). however, time pieces at sea were not completely accurate, ships misjudged and ran into reefs etc. British gov (1700s) gave grant Harrison for developing accurate sea time piece (coronagraph). determine longitude and help accurate calculations.
cook’s contribution
(1768-1779) sailed Pacific using Harrison’s clock and maps lat/long of coastline to make accurate maps of area for the first time, measures depths, winds, currents, temperatures. one of the first oceanographers
Franklin and the North Atlantic current
trades, science research, studies currents, credited with first proper map of the Gulf Stream (fast moving stream that goes over to Europe and then comes back)
Maury’s contributions
(19th Century) US Navy, founded naval depot, collected data from ships from all over world to make charts of currents and winds. used this info to cut down sailing times. published first oceanography book (1855), many say he was one of the first oceanographers
Darwin
cataloging ocean organisms, become basis of his evolution theories
Forbes
catalogs marine organisms in England and Mediterranean Sea, collects samples and different depths and proposes diff groups of animals live at diff depths of the ocean
Ross’ contributions
finds there in fact is life at depths of ocean (contradicts Forbes), similar creatures at different parts of the oceans
Muller’s contributions
microscopic plants & animals under the microscope (later named plankton)
Challenger expedition
first true oceanographic cruise, 3 ½ year expedition, sparked public interest by putting strange looking creatures on board to spark interest in funding, collected deep water samples, investigated deep water motion, measured temperatures, collected biological and geological samples, lead to an interest in the exploration of the ocean. uses data to describe why and how the ocean works
Nansen’s experiment with the Fram
(late 1800’s) investigated how certain ocean currents moved in the Arctic, had his ship (Fram) reinforced and frozen into the ice, drilled into ice to make temperature and depth measurements, made advances in technology that improved ocean order
Kelvin’s contribution
(late 1800s) invents time predicting machine and timetables that combined astronomical predictions with tidal theory
Amundsen’s contributions
Norwegian explorer, works his way through Northwest Passage, confirms location of the magnetic pole, becomes first to reach the North Pole, (1910) starts putting thermometers in a nonsense bottle (water sample bottle that was put below the ocean to get a sample contaminated by surrounding water)
eco sounding
sending sound signal to the bottom of the ocean and bouncing it back up (know how long it takes for water to travel through sound)
Why did oceanographic exploration take hold again in the 1940s?
due to WWII and need to get to remote locations quickly, needed to predict conditions for amphibious landing in WWII and chart beaches and harbors from the air, need to know how explosives behave and find enemy submarines, many oceanographers work for gov instead of private research
What technological advances came from the 1940s exploration?
radar, better sonar, temperature & depth records, money for more research and education
What the Glomar Challengere was for in the 1960s
(now JOIDES ship does the same): deep sea drilling into the sea floor to see what it was composed of and how deep they could get, used computers so data can be analyzed while still at sea and modify sampling based on trends in data
The significance of satellites
(since 1970s) aided exploration, measure surface height, wind speeds, ice cover, cloud cover, oil spill, abundances, and temperatures remotely. different satellites take different amounts of time and money, can also be put on ISS (space)
contribution of submarines
can go to depths of the ocean that humans cannot. most famous: alvin (35000 ft deep been to bottom of marianas trench)
ROVs
remotely operated vehicle, can stay at bottom of the ocean because no humans requiring oxygen. can gather data, collect samples, etc. can be used to find things & send down subs
What are “water reservoirs”?
the hydrologic cycle
What percentage of earth’s water is in the oceans?
71%
What is the second water largest reservoir, and about what percentage of earth's water is in it
Atlantic Ocean, 2%
What is the third largest water reservoir?
Indian Ocean
Basics of the hydrologic cycle
evaporation, condensation, precipitation
What is the source of energy for the hydrologic cycle?
the sun
radiometric dating
establishing how old something is based on the presence of a radioactive isotope within it
half-life
the amount of time it takes for half of the atomic nuclei of a radioactive sample to decay
geological timescale
way to subdivide time, tied to what lived during that time period (eon, era, period, epic/age)
What do scientists consider the age of the earth to be?
about 4.5 billion years
Precambrian eon
Precambrian is the time period before complex life forms
Phanerozoic eon
the time period with visible life forms (only 10% of history with complex life forms)
Phanerozoic divisions
Paleozoic (old life), Mesozoic (middle life), Cenozoic (recent life)
origins of planets & earth
started as a cloud of dust and gas that contained all the elements, asteroids and comets formed other planets, over time particles grow and collide with space debris to become planets
What are the four factors that affect the evolution of earth?
melting, volcanos, distance from the sun, presence or absence of a plane
melting
caused differences between crust and earth as a whole
chemical composition of the mantle and crust
heavier elements (iron and magnesium) in the mantle and lighter elements (silicon and oxygen) in the crust
volcanoes
radioactive decay of elements emits heat, which allows volcanoes to form. gasses get released during volcanic eruptions, water vapor in the atmosphere eventually condenses and falls to earth, resulting in rivers/lakes/oceans
Where is earth wider?
Earth is wider around the equator than around poles
time zones
formed due to light and darkness at different times (distance from sun & equator)
distance from the sun
controls the state of the water present (liquid, gas, etc.), Know the true “reason for the seasons”: rotation & revolution, tilt of the earth’s axis, angle of sunlight
tropic of cancer
23 ½ degrees north latitude, vertical rays hit on June solstice
tropic of capricorn
23 ½ degrees south latitude
Arctic and Antarctic Circles
24hrs of dark (eternal night/new moon)
Equator
imaginary line equally distant from both poles, divides the northern and southern hemisphere
Summer and Winter solstices
December and June
Fall and Spring Equinoxes
March and September
Why and how length of day changes between seasons
tropic of Capricorn and tropic of cancer, summer and winter solstice
How did plants change Earth’s atmosphere?
through photosynthesis, they take up carbon dioxide and then release oxygen into the atmosphere
Prime Meridian
line drawn from north to south at 0 degrees longitude
Where is the equator?
0 degrees latitude
lines of latitude and longitude
equator is at zero, latitude and longitude lines are drawn horizontally and vertically on globe. longitude is measured through the prime meridian
globes vs. maps
maps were not re-producible for a long time, globe is totally accurate, maps have distortion but are more practical
What do earthquake waves tell us about the interior of the earth?
show that the earth’s interior consists of a series of concentric shells with a crust, mantle, liquid outer core, and a solid inner core
Alfred Wegener’s idea
Wegener came up with the continental drift and his idea was that the continents were not in the places had always been (they had moved)
evidence for Wegener’s idea
fit of coastlines (particularly Africa and South America, coastlines all fit together, they split apart during Pangea)
fossil similarities (Mesosaurus and Glossopteris: fossils from around the same time period were found in lands that were once together, same rocks were found all across South America, India, Antarctica, Australia, and Africa)
glacial evidence (till, straitions: large bundles of ice and parts of glaciers that make grooves on the rock’s surface. usual for Antarctica but not for South America and Africa, proves that continents were together at the time)
mountain ranges (rocks & mountains from different sides of earth were still similar)
Why was Wegener’s idea criticized?
no mechanism, no evidence of actual motion
How did new data revive Wegener’s ideas?
deep sea data from WW2, and by 1968 the theory of plate tectonics was accepted
What were the new lines of evidence for Wegener’s ideas?
mid-ocean ridges: where seafloor spreading occurred
ages of sea floor: mid ocean ridges are the youngest part of the sea floor
thickness of seafloor sediments: the thickest sediments were found at the edges of the contents, thinnest in the middle because it had not been around as long
magnetic reversals: geomagnetic pole was pointing to the South Pole, when a rock cools it records the geomagnetic field at that time, allowing us to see seafloor spreading
polar “wandering”: seemed two magnetic poles flipped from north to south and wandered all over the globe (European and North American paths), but the continents were moving not the poles
earthquake and volcano patterns (pacific ring of fire): follow the plate boundaries
hydrothermal vents and black smokers: hot water minerals are coming out into cold water causing them to solidify at the mid ocean ridge (evidence of heat flow at the mid-ocean ridge)
hot spots: a mantle plume, plate moves over top of the hotspot and get increasingly older/younger
hot spots
a mantle plume, plate moves over top of the hotspot and get increasingly older/younger, comes from underneath up to the sea surface
asthenosphere
the upper layer of the earth's mantle, below the lithosphere, in which there is relatively low resistance to plastic flow and convection is thought to occur
lithosphere
the rigid outer part of the earth, consisting of the crust and upper mantle
mantle
the region of the earth's interior between the crust and the core, believed to consist of hot, dense silicate rocks