History and Plate Tectonics Flashcards
Early Explorers and Trade:
- Focused on shipbuilding and coastal piloting _____?
- North Africa, excellent sailors; explored the Mediterranean, traded with Britain and they may have circumnavigated Africa around 600 BC_____?
- Explored the Indian Ocean ___?
- Explored the Pacific Ocean ____?
Egyptians, Phoenicians, Arabs, Polynesians
- Colonized islands in the Pacific Ocean (Hawaii, Tahiti, Easter Islands, etc.)
- Navigated with stars, sun, moon, behavior of marine organisms, ocean properties.
- Sailed in large canoes
- Made “stick charts” from bamboo and wood to diagram islands
Polynesians
_____ were first real European explorers. They could identify where they were by the type of seaweed floating, types of seabirds flying, presence of whales and other sea animals.
Vikings
- First maps were made of this sea
several civilizations navigated here - Greeks were the first to sail out of sea into ocean; they observed currents
- Systematic study of ocean began at Library of Alexandria
- _____? determined Earth’s circumference to be 25,000 miles; became chief librarian
Mediterranean Sea, Eratosthenes
- Stimulated by the lust for resources and better trade routes.
Age of Discovery (1400s-1800s)
1487: Who rounded Cape of Good Hope? He is a Portugese explorer, first European to reach Indian Ocean from Atlantic Ocean
Bartholomeu Dias
1498: Who continued route of Dias and mapped route to Indian Ocean?
Vasco de Gama
1451-1506: Who made voyages across Atlantic Ocean and thought he found islands in Asia? He is Italian but citizen of Spain.
Christopher Columbus
1513: Who found the Pacific Ocean?
Balboa
1519: ____?, led by Portuguese _____?, circumnavigates the world; 3 of 5 ships are lost on voyage; _____? is killed in Philippines, then del Cano takes over
Victoria, Ferdinand Magellan
1768: English _____? charts Australia region aboard Endeavor; prevents scurvy by getting sailors enough Vitamin C. Has 3 major voyages mapped South Pacific, coasts of New Zealand, Australia and N America, “discovered” Hawaiian Islands
James Cook
1772: Cook charts islands of Pacific with ship _____?; killed by natives of Hawaii
Resolution and Adventure
1728: _____? made a ______, a timepiece that is precise and accurate enough to be used as a portable time standard; it can therefore be used to determine longitude by means of celestial navigation which allowed navigators to determine longitude on ships.
John Harrison, Marine Chronometer
1769: ______ and ______ map the Gulf Stream
Ben Franklin, Tim Folger
1800s German naturalist, contributions in geophysics, meteorology, and oceanography.
Humboldt
1842: _______? dubbed the “Father of Oceanography”, systematically collected wind and current data; charted North Atlantic. In 1847, he produced first bathymetric, wind and current chart
of the North Atlantic.
Matthew Fontaine Maury
1831: _____? sails aboard HMS Beagle as the naturalist; accurately described atoll formation. Created the Subsidence theory of coral reef formation (atolls) & origin of species. He is a English naturalist, geologist and biologist, best known for his contributions to the science of evolution. His theory of evolution states the principle by which each slight variation [of a trait], if useful, is preserved” called _____?
Charles Darwin, Natural Selection
- First true oceanographic research expedition
- Renovated a British corvette, a small warship
- Discovered Mariana Trench; deepest spot was later given the name ____?
- Discovered mid-ocean ridge and collected water data
- Led by ______? and _____?
HMS Challenger, Challenger Deep, Charles Wyville Thomson and John Murray
- Comprehensive scientific expedition
- Ship refitted with laboratories, winches, and sounding scope
The Challenger Expedition
Other explorations after Challenger:
(6)
- Norway – explored North Atlantic with Voringen (1876-78)
- Germany – studied Baltic and North Sea in SS Pomerania (1871-72) and Crache (1881-1884)
- France – financed cruises by Travailleur and Talisman (1880s)
- Austria – worked in Mediterranean and Red Seas in Pola (1890s)
- US – circumnavigated earth with US Enterprise (1883 and 1886)
- Italy and Russia – also circumnavigated (1886 & 1889)
Oceanography Pioneers
- Victor Hensen (1800s): plankton studies
- Alexander Agassiz (1800s): studied corals aboard the Albatross
- Fridjtof Nansen (1800s): drifted in ice with the Fram near the North Pole
- Walfrid Ekman (1900s): Scandinavian who studied physical oceanography
- Robert Peary (1909) reaches North Pole
- Roald Amundsen (1911) reaches South Pole
This expedition introduced modern optical and electronic equipment (echo sounder)
Meteor Expedition (1925)
This expedition collected data about sea floor; started with Glomar Challenger (1968-83), then JOIDES Resolution and Chikyu (“Planet Earth”)
Ocean Drilling Program
15 year expedition to Mid-Atlantic Ridge between South America and Africa drilling core samples
Deep Sea Drilling Program
This expedition was drilling for deep sea sediments and confirmed Alfred Wegener’s theory of continental drift.
Glomar Challenger
This expedition was designed to study wave height, acoustic signals (e.g. marine mammal research), collect meteorological data.
FLIP (Floating Instrument Platform)
Bathyscaphe that still holds the deepest dive to 11,000 m in Challenger Deep; designed by Auguste Piccard
Trieste
(max: _____?): manned DSV; discovered hydrothermal vents, recovered missing bomb
Alvin (Max:4000m)
(max: ____?): went deeper than Alvin
_____: pair of ROVs attached to each other
Sea Cliff II (max: 6000m), Jason/Medea
(self-contained underwater breathing apparatus, 1943): initially developed by Jacques-Yves Cousteau and Emile Gagnon
SCUBA
Invented SCUBA during
World War II, most famous oceanographer of the 20th century
Jacques Costeau
Navy officer, explorer, film maker. Discovered hydrothermal vents, RMS Titanic, battleship BiSMARK, 11 warships from lost fleet of Guadalcanal, WWII aircraft carrier Yorktown; Exploration of Lusitania and hospital ship Britannic
Bob Ballard (1942)
short-lived satellite; pioneer in oceanography remote sensing
SEASAT (1978)
satellite that measured sea surface height to reveal info about circulation; successful mission
TOPEX/Poseidon
Is an indicator of the heat content of the upper ocean. The image of the Pacific Ocean was produced using sea-surface height measurements taken by the U.S.-French _____? satellite.
Sea-surface Height, Jason
Forces or conditions within the earth that cause movement of the crust.
Plate Tectonics
Continental and Oceanic Crusts make up the _____?. The distance of the crust from core is _____?
Lithosphere, 8840 km
- Continents and oceans are really like plates
- Thin blocks move horizontally
- Interactions of plates build major features of Earth’s crust
- A very recent idea (1950s-1960s)
Theory of Plate Tectonics
- German meteorologist & geophysicist
- 1880-1930
- Proposed one large continent called ____? about 200 my ago.
- Also proposed one large ocean called ____?
- Also proposed smaller sea (Greek sea Goddess)
Alfred Wegener, Pangaea, Panthalassa, Tethys
Wegener envisioned that the continents were slowly drifting across the globe – called his idea ____?
Continental Drift
The supercontinent of Pangea began to break apart in the Middle Jurassic. In the Late Jurassic the Central Atlantic Ocean was a narrow ocean separating Africa from eastern North America. Eastern Gondwana had begun to separate from Western Gondwana
Late Jurassic Period
During the ____? the South Atlantic Ocean opened. India separated from Madagascar and raced northward on a collision course with Eurasia. Notice that North America was connected to Europe, and that Australia was still joined to Antarctica.
Cretaceous Period
The bull’s eye marks the location of the Chicxulub impact site. The impact of a 10 mile (16km) wide comet caused global climate changes that killed the dinosaurs and many other forms of life. By the Late Cretaceous the oceans had widened, and India approached the southern margin of Asia
K/T Extinction Period
50 - 55 million years ago India began to collide with Asia forming the Tibetan plateau and Himalayas. Australia, which was attached to Antarctica, began to move rapidly northward.
Eocene Period
20 million years ago, Antarctica was covered by ice and the northern continents were cooling rapidly. The world has taken on a “modern” look, but notice that Florida and parts of Asia were flooded by the sea.
Miocene Period
When the Earth is in its “Ice House” climate mode, there is ice at the poles. The polar ice sheet expands and contracts because of variations in the Earth’s orbit (Milankovitch cycles). The last expansion of the polar ice sheets took place about 18,000 years ago.
Last “Ice Age” Period
We are entering a new phase of continental collision that will ultimately result in the formation of a new Pangea supercontinent in the future. Global climate is warming because we are leaving an Ice Age and because we are adding greenhouse gases to the atmosphere.
Modern Period
Evidence for Continental Drift:
- Fit of continents
- Matching sequences of rocks and mountain chains
- Distribution of glacial deposits
- Distribution of fossils
____?, the earliest proponent of plate tectonics, argued partly on the basis of the coastline matching of _____ and _____.
Taylor, Eastern South America, Western Africa
Glacial deposits in the ____? and ____? at high latitudes
Tropics, Corals
It is a type of sedimentory rock formed from the remains of plants. It probably began accumulating when plants first appeared 425 millions ago, but most was laid down in the carboniferous period. Decaying trees in swampy areas formed peat marshes. As the peat became more deeply buried, it turned into ignite, then bitumenous ___ and then anthracite- the best quality ____.
Coal
Fossil remains of ___?, an extinct freshwater reptile that lived 250 million yrs ago, located in S America and W Africa.
Mesosaurus
- Wegener’s Book: Proposed driving mechanism – gravitational attraction of earth’s equatorial bulge and tidal forces
- Continents couldn’t possibly move through the rocks of the seafloor (like an icebreaker)
The Origins of Continents and Oceans (1915)
- Harry Hess (Princeton) and Robert Dietz (Scripps) (1960)
- Mid-ocean ridge site of new ocean crust
- Oceanic trenches site of crust destruction (subduction)
Seafloor Spreading
- Unites concepts of continental drift and sea floor spreading
- Lithospheric plates “float” on the asthenosphere (isostasy)
- Different plate boundaries and large scale geologic features occur at plate boundaries
Plate Tectonics Theory
Two major tectonic forces causing plate movement:
- Plates form and slide off raised ridges of spreading centers
- Plates are pulled downward into the mantle by cool, dense leading edges
Good quantitative evidence of Plate Tectonics. Earth’s magnetic field generates invisible lines of magnetic force similar to a large bar magnet with opposite polarities – cause magnetic objects to align parallel to magnetic field.
Paleomagnetism
- Magnetite in magma (igneous rock) orients to the Earth’s magnetic field when cooled.
- Magnetic pole reversals.
Parallel ____? record changes in Earth’s magnetic polarity as sea floor created. Locked in as rock cools. Think ‘magnetic zebra stripes’
Sea floor Stripes, Magnetic Anomalies
Sequence of polarity changes on one side of an oceanic ridge is ____? to the sequence of reversals on the opposite side of the ridge. Rocks became older with _____? from the ridge axis.
Identical, Increasing Distance
Apparent ____? states that there can only be 1 magnetic North Pole at any given time. Implies that magnetic north remained stationary while N America and Eurasia (continents) moved
Apparent Polar Wandering
Sets up stresses within the lithosphere as plates move. First clues as to location of the plates is that most tectonic events such as earthquakes and volcanic activity confined to the _____?
Seafloor Spreading, Linear Belts
7 Major Plates:
- Pacific
- North American
- Eurasian
- African
- Antarctic
- Indo-Australian
- South American Plate
Types of Boundaries
- Convergent
- Divergent
- Transform
- Plates move apart
- Mid-ocean ridge
- Rift valley
- New ocean floor created
- Shallow earthquakes
Divergent Boundary
Part of longest mountain range in the world
Mid-atlantic Ridge
Two stages of ocean basin development. First rift valleys are pulled apart. Red Sea is at the ____?, it has rifted apart so far that the land has dropped below sea level. Gulf of California in Mexico is another ____?.
Linear Sea Stage/Linear Sea
Types of Spreading Centers:
- Fast-spreading, Gentle slopes
- Slow-spreading, Steep slopes
- Deep rift valley, Widely scattered volcanoes
Oceanic Rise, Oceanic Ridge, Ultra-slow
- Plates move toward each other
- One plate is destroyed in the subduction zone
- Deep earthquakes
Convergent Boundary
- Ocean plate subducted
- Continental arc (coastal mountains, Andes, S. America) and corresponding oceanic trench (Peru-Chile Trench)
- Deep earthquakes (strongest ever near Peru-Chile Trench at magnitude 9.5)
Oceanic-continental convergence
- Older oceanic plate denser so it subducts
- Produce deep oceanic trench (Mariana Trench)
- Island Arc
- Deep Earthquakes
Oceanic-oceanic convergence
- Ex. collision of India with Asia (45M yrs ago) – created uplifted mountain ranges
Himalayas (include Mt. Everest) - Deep earthquakes
Continental-continental convergence
- Plates sliding past each other; no creation or destruction
- Shallow but strong earthquakes
Transform boundary faults
Types of Transform Boundary:
- Wholly in ocean floor
- Extends from mid-ocean ridge across continent
- Oceanic
- Continental
_____? caused by presence of mantle plumes (related to position of convection cells in mantle).
Hotspots
Columnar areas of hot molten rock that rises from the deep within the mantle.
Plumes/Mantle Plumes
Largest reef system in the world (150 km widtth, >2000 km length).
Great Barrier Reef
Stages in Coral Reef Development
- 1st Stage
- 2nd Stage
- 3rd Stage
- Fringing Reef
- Barrier Reef
- Atoll
