Plate Tectonics

Continental Drift

Alfred ______(1912)

•German ______

•______moved slowly to their current locations.

•______- the single landmass of Earth that broke apart about 200mya . “All Land”

Evidence

______-like Fit

•______s of continents fit together like puzzle pieces.

•Examples: S.America & ______

Fossil Clues

•Certain ______of ancient animals & plants are found on distant landmasses.

•Freshwater/land-dwelling reptile Mesosaurus fossils have been found on ______& Africa.

______of the ancient plant Glossopteris were found in ______, South America, Australia, India, & Antarctica.

______Clues

-Fossils of warm climate plants were found in present-day cold climates. (______

-Rocks deposited by ______from the ice ages have been found in present-day warm climates.

Rock Clues

•Similar rock structures are found on different continents separated by ______.

-Appalachian mountains of the USA are similar to mountains found in ______& western Europe

-Rocks of South America match those in ______

  • Main ______to Wegener’s hypothesis was its inability to provide a ______for the movement of the continents.

______Spreading

Hypothesis

  • ______waves were used to map the ocean floor.
  • Mid-ocean Ridges- ______mtn ranges

Less dense ______flows sideways dragging the seafloor along.

As the seafloor spread apart, magma flows up through ______in at the ridge forming new rock.

Evidence

• ______- Ocean floor rock samples show that the age of the rock gets older the further the rock is from the mid-ocean ridge

•______-Changes in the magnetic alignment of the Earth are found in ______bands in the seafloor rock.

Theory of Plate Tectonics

  • Combined theory of ______Drift & Seafloor Spreading.
  • Earth’s crust & upper mantle (______) are broken into plates and move around on a ______-like layer of the mantle (______.)

Seven major plates:

______(largest) N. American

S. American African

Eurasian______

Antarctic

  • Plate Boundaries

______Boundaries

  • Two plates spread apart.
  • Where ______spreading occurs.
  • ______crust is formed.Ex: Mid-Atlantic Ridge

•______Boundaries

–Two plates come together (______

–Oceanic plate will sink under a continental plate (______) producing a deep ______. Ex: ______& Cascades

–Two oceanic plates will converge resulting in a ______island arc.Ex: ______Islands

•______Fault Boundary

– Two plates slide past each other.

– Move at ______rates.

– Also known as ______slip faults.Ex: San Andreas Fault

Causes (______)

•______Currents

–Hot magma rises in the ______.

–Magma hits the ______& cools.

–Cooling magma sinks dragging the ______plate with it (centimeters.)

–Magma sinks into the mantle & ______.

Features Formed by Tectonics

•______

– Cracks in the tectonic plates caused by ______.

– Plate ______are also faults.

– Movement along faults cause ______.

•Volcanoes-Magma produced by friction during ______oozes up through the crust, ______, & forms volcanoes.

______

• Convergent & Divergent boundariesform ______.

• Process of mountain building is called ______.

-Volcanic Mountains

•______Mountains

  • Horizontal rock layers are squeezed from opposite sides, causing them to ______& fold.EX: ______& Appalachians

•______-block Mountains: Huge, tilted blocks of rock that are separated by ______. EX: Sierra Nevada

•______Mountains- blocks of Earth’s crust are pushed up by ______inside the Earth. (______) EX: ______Mountains