Term
Abraham Ortelius (1596) and Sir Francis
Bacon (1620): |
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Definition
– Noted how coastlines of some continents
appeared to fit together like jigsaw puzzle |
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Term
| Eduard Suess (late nineteenth century |
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Definition
Postulated that southern continents were once
part of a giant continent called Gondwanaland |
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Term
| Alfred Wegener (early twentieth century |
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Definition
Fitted together separate continents, including
Gondwanaland, to form giant supercontinent of
Pangaea |
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Term
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Definition
when assembling
continents into the
supercontinent Pangaea……the mountain
belts aligned |
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Term
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Definition
First proposed his continental drift
hypothesis in 1915
– Hypothesis states that continents are not
stationary, but rather ‘drifted’ across
Earth’s surface over time
– Published his ideas in The Origin of
Continents and Oceans |
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Term
| Glacial deposits found in |
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Definition
South America,
Africa, India and Australia: |
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Term
| Grooves in Bedrock Indicate |
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Definition
| Weird Ice Flow Directions |
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Term
| But Ice Flows Make Sense If Continents Were |
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Definition
Assembled As
They Appeared 300 Million Years Ago |
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Term
| Glaciers appear to have radiated |
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Definition
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Term
| Coal deposits in ancient rocks that |
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Definition
now occur in Antarctica and the
Sahara desert |
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Term
Ancient deposits of desert sand and
evaporites in presently |
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Definition
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Definition
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Term
Similar fossils of ancient land
animals are found in |
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Definition
Africa, South
America and other southern
continents now separated by oceans |
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Term
| Continental Drift Hypothesis |
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Definition
Observations of Wegener and others led
to the hypothesis of continental drift. |
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Term
In the 1960s, the technologies of WWII
finally provided the evidence for a viable
mechanism: |
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Definition
mechanism:
– Mantle convection and seafloor spreading. |
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Term
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Definition
| Bathymetry of the ocean floor |
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Term
Mid-Ocean Ridges and Deep-Sea
Trenches Discovered Using |
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Definition
Echo
Sounders and Sonar After World
War II |
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Term
Mid-ocean Ridges
Are Sites Of |
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Definition
Undersea
Volcanoes And
High Heat Flow |
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Term
| Trenches And Undersea Volcanoes |
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Definition
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Term
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Definition
Discovered by Chinese (13th century)
floating a lodestone on a piece of
wood – it pointed north. |
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Term
Compass directions define two
components of magnetism |
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Definition
Inclination – Tilt of magnetization.
– Declination – Horizontal swing |
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Term
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Definition
Compass direction
presently points to the
magnetic north pole
Magnetic inclination
a function of latitude |
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Term
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Definition
By examining volcanic rock layers
spanning millions of years, geophysicists
found that some older layers exhibited
polarity opposite from Earth’s present
magnetic field: |
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Term
Evidence suggests that Earth’s magnetic
field |
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Definition
flipped from normal to reverse
polarity, then back again, many times in
the past |
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Term
Magnetic field has
also weakened by |
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Definition
~10% over the last
century |
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Term
| Marine Magnetic Anomalies |
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Definition
During WWII, technology was
developed to detect submarines by
magnetism (they’re made of iron) and
to chart the magnetism on the ocean
floor to aid submarine navigation |
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Term
| Mid-ocean ridges are sites where |
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Definition
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Spreading along the ridge pushes
older rocks aside as new crust
forms: |
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Definition
– This would occur in conjunction with
occasional flips in Earth’s magnetic
field |
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Term
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Definition
volcanic rocks
on land and in oceans were
isotopically dated |
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Term
| The Geomagnetic Time Scale |
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Definition
Based on dating
rocks of different
ages and magnetic
polarities from the
oceans and
continents |
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Term
Seafloor was dated using fossils from
overlying sediments and correlating
magnetic stripes with the Geomagnetic Time
Scale: |
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Definition
– Seafloor spreading occurs at rates ranging from
1-18 centimeters per year
– Youngest oceanic crust occurs along mid-ocean
ridges
– Oceanic crust becomes progressively older away
from ridges
– Oldest oceanic crust only Late Jurassic (~180
m.y. old) in age |
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Term
But Where Does All This New
Oceanic Crust Go |
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Definition
The distribution of earthquakes and
volcanoes provide clues |
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Term
Shallow earthquakes recorded over
time match the |
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Definition
trends of mid-ocean
ridges |
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Term
Shallow and deep earthquakes match
the trends |
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Definition
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Term
The distribution of volcanoes also
show definite trends: |
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Definition
– Active undersea volcanism occurs along
mid-ocean ridges
– Lines of volcanoes on continents and
oceans parallel ocean trenches
– Volcanic islands and seamounts in the
oceans also follow linear trends |
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Term
The plates are separated by three types of
boundaries |
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Definition
Divergent (mid-ocean ridges) where plates pull
apart
– Convergent (subduction zones) where plates
come together
– Transform boundaries where plates slide
laterally past one another |
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Definition
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Definition
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Move horizontally
past one another: |
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Definition
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Term
| Transform Fault Boundaries |
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Definition
Plates slide laterally past one another:
– Lithosphere is neither created nor destroyed |
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Term
| – Lithosphere is neither created nor destroyed |
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Definition
Most join two segments of a mid-ocean
ridge along breaks in the oceanic crust
known as fracture zones
– A few (the San Andreas fault and the Alpine
fault of New Zealand) cut through
continental crust |
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Term
| Convergent Plate Boundaries |
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Definition
Two plates come together with one
plate (usually oceanic) subducting
(sinking) beneath another along an
oceanic trench
– Subducting lithosphere destroyed |
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Definition
Parallel To
Nearby Volcanic Arcs |
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Definition
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Definition
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Definition
Linear chains of volcanoes also
occur in ocean basins far removed
from plate boundaries |
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Term
These volcanoes are generated by
rising mantle plumes that impinge
upon the base of the overlying plate
to produce hot spots: |
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Definition
| Hawaiian islands is an example |
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Term
| Rising Mantle Plume Impinges Upon The |
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Definition
Base Of The
Lithosphere To Form A Hot Spot |
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Term
| Hot Spot Beneath Hawaii Produced |
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Definition
Linear Chain Of
Volcanoes Over 70 Million Years |
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Term
| New Oceanic Lithosphere Formed At Mid-ocean Ridge Is |
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Definition
| Ultimately Destroyed Along Convergent Plate Boundary |
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Term
| The Plate Tectonics Cycle Is Driven By |
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Definition
Mantle
Convection And Powered By Earth’s Internal Heat |
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Term
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Definition
Opening of an Ocean
Crustal
doming
Riftin
linear sea
Mature
Ocean |
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Term
| Mediterranean Sea Is A Remnant Of The |
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Definition
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| Wegener assembled the continents like pieces of a jigsaw puzzle into a giant supercontinent called... |
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Definition
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Term
| Weird ice-flow directions of ancient glaciers, as evidenced today on the continents of South America, Africa, India, and Australia, make sense if we... |
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Definition
| Assemble these continents into a giant supercontinent. |
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Term
| which of the following does NOT constitute evidence for continental drift? |
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Definition
| A cooling, shrinking Earth. |
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Term
| Which of the following statements regarding mid-ocean ridges is FALSE? |
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Definition
| lithospheric plates converge along mid-ocean ridges. |
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Term
| Which of the following statements regarding reversals in Earth's magnetic field is TRUE? |
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Definition
Correctc.
The Geomagnetic Time Scale indicates numerous reversals in Earth's magnetic field over the last 5 million years. |
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Term
| Which of the following statements is FALSE? |
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Definition
Correctc.
Polarity reversals in Earth's magnetic field only affect the magnetic inclination, but not the declination, of ancient rocks. |
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Term
| Studies of the ocean floor indicate that oceanic crust varies in age from place to place. Which of the following statements is FALSE? |
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Definition
| Oceanic crust becomes progressively older as we approach a mid-ocean ridge |
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Term
| Where would you least expect to find active volcanoes? |
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Definition
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| What constitutes the plates of plate tectonics? |
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Definition
| Crust and solid upper portion of the mantle directly above the asthenosphere |
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Term
| Which of the following is LEAST likely to be a plate boundary? |
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Definition
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| Which of the following statements regarding convergent plate boundaries is FALSE? |
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Definition
| Only occurs where a continental plate meets an oceanic plate |
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Term
| A principle driving force for the movement of lithospheric plates is/are... |
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Definition
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| Which of the following statements is TRUE? |
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| Plate tectonics is a process by which lithospheric plates are created along mid-ocean ridges and afterwards recycled back into the mantle along subduction zones. |
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Term
| With regard to the Wilson Cycle, which of the following is an example of opening of an ocean basin? |
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