Name (in ink)_________________________________________ # _____ period _____
2.1 Continental Drift
Plate Tectonics
 the outermost portion of Earth is made up of thin, ________ lithospheric plates
--lithospheric plate (def)-a large section of Earth’s outermost shell composed of _________
and the _________ portion of the mantle; also called a tectonic plate
 according to the theory of plate tectonics, these plates can shift ________________ causing
the continents to move
 plate tectonics (def)-the geologic theory that Earth’s lithosphere is divided into a small
number of plates that float on, and _________ independently _______ the less rigid mantle
rocks below
--this is a relatively ______ theory
--until a few decades ago continents were believed to be ______________ over geologic time
 plate tectonics helps to ___________ a variety of phenomena and surface features on Earth
including:
1) the global distribution of earthquakes, _________, volcanoes and mountain building
2) why mountains haven’t all been __________
Fig. 2.2 page 37: Reconstruction of Pangaea
away
caption:
3) the origin of most ________________ and
ocean floor features
4) how the continents and ocean floor
__________, and why they are different
5) the continuing _________________ of
Earth’s surface
6) the distribution of present and past
_______ on Earth
Continental Drift
 the current theory of plate tectonics
________ with an idea called continental drift
 continental drift (def)-a hypothesis proposed
by Alfred ___________ in 1912, stating that
the Earth's continents were once joined
together and have moved away from each
other at different times in the Earth's history
 ---Wegner was a __________ physicist and
meteorologist (1880-1930)
 he suggested that ______ million years ago
the continents were combined into ______
land mass (Pangaea) surrounded by a
__________ large ocean (Panthalassa)
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Evidence: Fit of the Continents
 the continents seem to ______ together like puzzle
pieces
 this was first noted by Sir Francis Bacon in ______
 the fit _____________ if continental margins are
included (see fig. 2.3 page 37--- which extends the
continental edge out, to a depth of _______ m)
--the continental margin is the ___________,
submerged edge of a continent
Evidence: Matching Rock and Mountain Sequences
 rock sequences of _____________ age and
composition are found on __________ side of the
Atlantic Ocean
--rocks from the Karroo strata in South Africa
_________ Santa Catarina rocks in Brazil
--this suggests that current transatlantic rock
sequences were once a _______________ body
of rock
 mountain sequences also _________ up across the
Atlantic
--the Appalachian Mountains in North America are
____________ in composition, age and structure
with the Caledonian Mountains in the British Isles
and Europe (see fig. 2.4 page 38)
--this suggests that at one time they formed one
_______________ mountain belt
Fig. 2.3 page 37: An early computer fit of the
continents
caption:
Evidence: Climate Evidence and Glacial Age
 climate is controlled by
_____________
 evidence of ___________ glaciation
is found in areas that are ______
tropical
--this indicates these regions were
once located ___________ south, in
polar zones
 a variety of fossils have been found
at latitudes where they could not
have _____________
 coal deposits in North America and
Color the polar zones blue; the temperate zones
Europe were created by ancient
orange; and the tropical zone green (use colored
tropical __________
pencils)
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--this indicates these regions were once ____________ much closer to the equator
 as glaciers flow, they leave __________ behind in the underlying rock
--these grooves indicate the ______________ of glacial flow
--_____ million years ago glaciers flowed northward from Antarctica
--tracks from this _______ are found on many continents today
--backward tracking brings each set of grooves together, _____________ the original icecovered position of the continents
--reconstruction suggests that 300 million years ago the southern portion of a single,
supercontinent (Pangaea) was covered in slowly moving ______ (see fig. 2.5 page 39)
Evidence: Distribution of Organisms
 the __________ record supports the hypothesis of continental drift
--fossilized remains of ______________ species are found on each side of adjacent
continents
--many of these are freshwater species that could ______ have __________ed across vast
oceans
 the _________________ of present day organisms also supports continental drift
--Australian marsupials and the North American opossum have similar ______________
--it appears that each branch continued to evolve in ______________ after the separation of
the continents
Objections to Continental Drift
 Wegner did not live long enough to see his ideas accepted (1880-________)
 his hypothesis was ______________ and criticized by other scientists during his lifetime
 the major obstacle for acceptance was his inability to come up with a ______________
explanation for how the continents moved
 new scientific discoveries in the 1940s, 50s and 60s would ______________, and eventually
confirm the idea of continental drift
Fig. 2.5 page 39: Ice Age on Pangaea
caption:
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