OCS 1005

ocean exploration and voyaging
The early history of oceanography/marine
science is closely related to the history of
Polynesian migration in the Pacific Ocean
First demonstration of ability and knowledge to navigate transoceanic voyages
The Polynesians
are one of the four cultures that inhabited some 1,000 islands in the central and eastern Pacific.
Polynesian triangle
Polynesia is generally defined as the islands within the
Hawaii, New Zealand and Easter Island
Geographically, Polynesia may be described as a triangle with its corners at
many islands
The term “Polynesia” means
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Library of Alexandria
Systematic study of the ocean began at the
The Library of Alexandria, in Egypt
was founded in the third century B.C. became a repository of maritime records describing the Mediterranean coast
celestial navigation
The principles of_________ were invented at the Library of Alexandria.
Eratosthenes of Cyrene
was the second librarian at Alexandria.
Eratosthenes of Cyrene
He was the first to calculate the circumference of Earth. He also invented a system of longitude and latitude.
Pytheas
was a notable Greek sea adventurer
Vikings
periodically raided various parts of Europe. By 1000 A. D. Colonized Vinland in Newfoundland (North America), though the colony was later abandoned.
Chinese navigators
set out in the 1400s to explore the Indian Ocean, Indonesia, Africa and the Atlantic.
wealth and degree of civilization
Chinese navigator’s ships were laden with gifts designed to show China’s _____ and ________.
The central rudder, Water-tight compartments, Sails on multiple masts, and Magnetic compass
The Chinese invented:
Chinese Ocean Exploration
The largest peacetime ocean exploration ever mounted which was made up of 7 voyages that lasted from 1405-1433
Arabs
controlled the trading route to Asia (silk, spices)
Marco Polo
from Venice, wrote a book (known in Italy as the “Book Million about miracles of the world”) about his journey with his father and uncle to China via Silk Route (Great Silk Road)
Portugal’s Prince Henry the Navigator
Established a center for seafaring in order to mount expeditions to open a new trading route to Asia
Vasco Da Gama
reached India by sailing around the tip of Africa
Europeans
explored the world by sea during the Renaissance
Henry the Navigator
Explorers under his patronage compiled detailed charts and explored the west coast of Africa.
Christopher Columbus
“discovered” the new world in 1492. Although in reality he never saw the mainland of North America, his stories inspired other explorers to follow.
Ferdinand Magellan
a Portuguese sailor
The journey of the Magellan expedition
the first voyage around the world
18 out of 260
Only ___ out of ______ sailors managed to return after three years of dangerous travel
John Harrison’s Chronometer
needed to find longitude at sea
magnetic compass and an accurate clock
you can find your location at sea with a ______ and _______
James Cook
a commander in the British Royal Navy – his cruises are considered to be the first scientific ocean exploration and greatly contributed to scientific oceanography
• Initiation of friendly relations with many native populations • Sampling marine life, land plants and animals
• Verification of calculations of planetary orbits
• Charting of New Zealand and the Great Barrier Reef, Tonga and Easter Islands
• Recording data concerning the ocean floor and geological formations
Some of the accomplishments of James Cook and his scientists include:
Governments
The First Scientific Expeditions Were Undertaken by
The United States Exploring Expedition
launched in 1838 was a naval and scientific expedition
The HMS Beagle
where Charles Darwin served as a naturalist, voyaged to South America and some Pacific Islands (“On the Origin of Species”).
HMS Challenger
expedition of 1872-1876 was the first oceanic expedition dedicated to scientific research. It was sponsored by Royal Society of London. It started Marine Biology
Benjamin Franklin
published the first map of the Gulf Stream (a swift current circulating clockwise in the North Atlantic Ocean) in 1770.
Mathew Fontaine Maury
“Father of Physical oceanography”
Mathew Fontaine Maury
Organized the vast amount of data on wind, current and
weather recorded in ships logbooks
24
Earth rotates once in every____ hours
east, west
Sun rises from the _____ and sets in the _____
Local noon time
defined as the time the sun is exactly over your head
geological, physical, chemical, and biological
the four marine processes of oceanography are:
ocean
Earth’s largest feature
70.78
_____% of the Earth is covered by water
Earth
also known as the “blue planet”
10, 1
Every ____ m in depth corresponds to
____ kg/cm2 (14.22 pounds/in2) in pressure
Mariana Trench
At the known deepest spot on the ocean bottom called ______ , pressure would be1.1ton/cm2 (7.82ton/in2)
James Cameron
Completes Record-Breaking Mariana Trench Dive, The first human to reach the 6.8-mile-deep (11-kilometer-deep) undersea valley solo
97
More than ____% of the water lies in the ocean. Of all water at Earth’s surface
1.7
ice on land contains about _____%
.8
groundwater ____%
.007
rivers and lakes ____%,
0.001
the atmosphere _____%.
30%
How much percentage of the Earth’s surface is covered by land?
3,796m or 12,451 ft.
average depth of the world oceans
Mariana Trench 11,022 m
deepest spot in the world oceans
Mt. Everest 8848m
Highest spot on land
3.9 degrees celcius
average temp for the world oceans
3.4
average salinity is about ____%
4 billion years
age of the world oceans is about
-transportation
-natural resources
-high concentration of human population in coastal region
-pollution
-naval power
what is the utilization of the ocean:
oceanography
Scientific study of the ocean
Highly interdisciplinary
a marine biologist who has to know currents to study movements of organisms.
marine biology
the study of the nature and distri- bution of marine organisms
marine geology
the study of Earth’s crust and composition
chemical oceanography
the study of the dissolved gases and solids in the ocean
physical oceanography
the study of waves, currents, and climate prediction
70.8
Ocean covers ____% of the earth’s surface
hurricanes
only form over warm water
heat capacity
______ of water is much larger than that of land and air
dominant role of ocean
atmosphere interaction in regulating the earth’s weather and climate (versus land-atmosphere interaction)
solar radiation
what drives the climate system?
Seafloor features
result from a combination of tectonic activity and the processes of erosion and deposition.
bathymetry
the ocean floor is mapped by____
Bathymetry
The discovery and study of ocean floor contours is called
Early bathymetric studies were often performed using a weighted line to measure the depth of the ocean floor
How did early scientists study the ocean floor?
-echo sounding
-multibeam systems
-satellite altimetry
advances in bathymetry include:
echo sounding
is a method of measuring seafloor depth using sound pulses. The accuracy can be affected by water conditions and bottom contours
multibeam systems
can provide more accurate measurements than echo sounders do. Collect data from as many as 121 beams to measure the contours of the ocean floor
satellites
can be used to map seabed contours
Satellite altimetry
measures the sea surface height from orbit
29.2
land covers ____% of the earth
A hypsographic curve
is a plot of the area of the Earth’s surface above any given elevation or depth above or below sea level
3,000
Note that more than half of Earth’s solid surface is at least_______ meters (10,000 feet) below sea level.
depth, elevation
The average _____ of the ocean (3,790 meters) is much greater than the average ______ of the continents (840 meters).
continental margins and ocean basin
what are the two classifications of ocean floor?
continental Margins
the submerged outer edge of a continent
Ocean Basin
the deep seafloor beyond the continental margin
Continental slope
has the steepest slope, and the abyssal plain is the flattest
passive and active margins
what are the 2 types of continental margins?
Passive margins
also called Atlantic-type margins, face the edges of diverging tectonic plates. Very little volcanic or earthquake activity
Active margins
known as Pacific-type margins, are located near the edges of converging plates.
– are the site of volcanic and earthquake activity
Continental shelf
the shallow,submerged edge of the continent.
continental slopes
the transition between the continental shelf and the deep- ocean floor, has the steepest slope
shelf break
the abrupt transition from continental shelf to the continental slope
continental rises
accumulated sediment found at the base of the continental slope
Submarine canyons
are a feature of some continental margins. They cut into the continental shelf and slope, often terminating on the deep-sea floor in a fan-shaped wedge of sediment
turbidity current
Avalanche-like sediment movement caused when turbulence mixes sediments into water above a sloping bottom are called
turbidity currents
flow down submarine canyons and deposit sediments as deep-sea fans
turbidity currents
are an underwater “avalanche” of sediments thought responsible for the sculpturing of submarine canyons and a means of sediment transport into abyssal plains.
Grand Banks Earthquake
triggered the turbidity current that damaged underwater cables
-oceanic ridges
-hydrothermal vents
-abyssal plains and abyssal hills
-seamounts and guyots
-trenches and Island Arcs
what are some features of the deep-ocean floor?
oceanic ridge
is a mountainous chain of young, basaltic rock at an active spreading center of an ocean
Transform faults
are fractures along which lithospheric plates slide horizontally past one another. -Are the active part of fracture zones.
Hydrothermal vents
are sites where superheated water containing dissolved minerals and gases escapes through fissures, or vents
Seamounts
are volcanic projections from the ocean floor that do not rise above sea level.
guyots
Flat-topped seamounts eroded by wave action are called
Abyssal hills
are flat areas of sediment-covered ocean floor found between the
continental margins and oceanic ridges.
Abyssal hills
are small, extinct volcanoes or
rock intrusions near the oceanic ridges
Trenches
are arc-shaped depressions in the ocean floor caused by the subduction of a converging ocean plate
The Big Bang
is the term used to describe the beginning of the universe, probably about 14 billion years ago. As the universe expanded, it cooled, eventually allowing the formation of atoms, which then formed galaxies and stars
Most of the substance of Earth, its ocean, and all living things, was formed by stars. Every chemical element heavier than hydrogen was manufactured and released into space by stars.
What do stars have to do with the ocean?
nuclear fusion
Our sun, like all normal stars, is powered by
4.6 billion years ago
formation of the planets of the solar system was about
density
is a key concept for understanding the structure of Earth and measures the mass per unit volume of a substance
high density
something that is small but heavy is considered to have ____
low density
something that is light for its size has _____
sink, float
things that have density will _____, while things with low density will ______
Volcanic activity
is a major source of the Earth’s ocean and atmosphere
Outgassing
process releases water into Earth’s surface.
Comets
may have delivered some of Earth’s surface water
3.8
Intense bombardment of the early Earth by large bodies – comets and asteroids – probably lasted until about ____billion years ago.
photosynthesis
Single-cell plant organisms use ______
chemosynthesis
Bacteria in the absence of sunlight, using chemical compounds such as ammonia, methane, hydrogen sulfide to produce food (carbon dioxide fixation) this is called
our sun will begin to die in 5 billion years
-6 billion years from now the sun will enter the red giant phase and ingulf the inner planets
How long can Earth exist?
-europa
-mars
-titan
where have scientists found evidence of water?
titan
Saturn’s largest moon, may have an ocean of hydrocarbons
mantle
is thought to consist mainly of silicon, oxygen, iron, and magnesium
the outer and inner core
consist mainly of iron and nickel
lithosphere
which layer is least dense?
Continental crust:
granitic, less dense, thicker and older
Oceanic crust:
basaltic, denser, thinner and younger
lithosphere, asthenosphere
A cool, rigid, less dense layer the _____ floats on a hot, slowly-flowing, more dense layer the _________
Buoyancy
is the ability of an object to float in a fluid by displacing a volume of that fluid equal in weight to the floating object’s own weight.
Alfred Wegener
proposed ContinentalDrift (1915). He could not explain the source of energy to move continents.
Harry Hess
proposed Seafloor Spreading
Wegener
published “The origin of continents and oceans” and proposed the Continental Drift theory
Pangaea
-Shape of shorelines
-Mountains
-Fossil records
-characteristic features left by ancient glaciers
explained by the supercontinent called ______
Seismographs
revealed a pattern of volcanoes and earthquakes.
Radiometric dating
of rocks revealed a surprisingly young oceanic crust.
Echo sounders
revealed the shape of the Mid-Atlantic Ridge and sense the contour of the seafloor
German Meteor Expedition
Echo sounders were first used on the ______ in 1925 in the South Atlantic
radioactive decay
Age of various rocks can be dated by measuring _______
Harry Hess
postulated that oceanic crust is formed at mid-ocean ridges and moves toward trenches, where it is destroyed
spreading centers
where New seafloor is being formed at mid-ocean ridges is called _____
subduction zones
where Old seafloor is being destroyed at trenches is called ______
Mantle Convection
driven by the heat escaping from the Earth’s interior provides energy to maintain sea floor spreading
Paleomagnetism
Study of geological past by examining the Earth’s magnetic conditions recorded in the rock samples.
divergent
(spreading centers) Example: mid-ocean ridges
Characteristic: hydrothermal activity, pillow lavas, shallow earthquakes
convergent
(subduction zones)
Example: deep ocean trenches
Characteristic: volcanoes, island arcs, deep earthquakes
transform-fault
(two plates sliding past each other) Example: fracture zones, faults
black smoker
When hot water circulating near the mid-ocean ridges comes in contact with cold surrounding sea water, precipitation of sulfur-bearing minerals takes place.
chemosynthesis
Rich biological communities flourish near vents
-vent community based on ________
convergent plate boundaries
Regions where plates are pushing together
Oceanic crust toward continental crust
a convergent plate boundary for example, the west coast of South America.
Oceanic crust toward oceanic crust
a convergent plate boundary that occurring in the northern Pacific
Continental crust toward continental crust
a convergent plate boundary one example is the Himalayas.
A fracture zone
is an oceanic feature, resulting from the action of offset mid-ocean ridge axis segments
transform faults
are found on the ocean floor. They produce zig-zag plate margins, and are generally defined by shallow earthquakes.
sediment
is particles of organic or inorganic matter that accumulate in a loose, unconsolidated form. May be classified by grain size or by the origin of the majority of the particles.
sand, silt, and clay
Although boulders, cobbles, and peddles occur in the ocean, most marine sediments are made of finer particles:
boundary layer
Water flowing near a solid surface is slowed down by friction along the boundary, and the region of flow influenced by proximity to the surface is called the
A velocity gradient
a change of velocity with depth – exists near the boundary
low-energy conditions, high- energy conditions
Fine-grained sediments suggest ______ , while coarse sediments suggest ________.
well-sorted sediments
-Composed of particles of mostly one size.
-Where energy fluctuates within a narrow range.
-Deep-sea floor
poorly-sorted sediments
* Sediments with a mixture of sizes.
* Where energy fluctuates over a wide range. * Near submarine canyon by turbidity current
terrigenous
type of sediment that comes from land
biogenous
type of sediment hard parts of some marine organisms. (siliceous-silicon-containing) and (calcareous-calcium carbonate)
hydrogenous
type of sediment that precipitated directly from sea
water.
cosmogenous
type of sediment that comes from outer space
terrigenous and biogenous
Most sediment deposits are mixture of _______ and ________ particles.
ooze
a biogenous sediment that contains more than 30% of the hard parts (shells) of planktonic marine organisms is called ____
turbidites
sediment deposits formed by turbidity
neritic
of the shore or coast location of sediment deposits (contains mostly terrigenous material)
pelagic
of the open ocean of sediment deposits (contain a greater proportion of biogenies material)
turbidites
deposit laid down by turbidity currents. (more prevalent in Atlantic than Pacific. Trenches
in the Pacifc trap most of the turbidites)
clays
the smallest sediment category (<0.004 mm) -make up about About 38% of deep-sea sediments
oozes
sediments of at least 30% biological origin (Calcareous ooze, siliceous ooze).
-dominate in deep water
salt domes
in order to find oil you must find _____
mid-ocean ridges, continental rise
sediments are thinnest near the ______, and thickest near the _______
erosion from the continent
what is the origin of most abyssal plain sediments?
Rate of sedimentation
is almost always higher on continental shelves than in the deep ocean. Shelves are closer to terrigenous sources and usually high in biological productivity (source of biogenous sediments)
Deltas
are landforms that develop wherever a river enters a large body of water — whether ocean, lagoon, or even lake and deposits sediment more rapidly than can be eroded
mantle
atmosphere is a portion of the _____
meteor expedition
the first scientific expedition to use an echo sounder was ______