Plate Movement Flashcards
define thermal convection
believed to be responsible for plate movemen
what do you call the upper part of the Earth’s mantle?
asthenosphere
cooler,denser material descends carried by _______________
convection current
how is an ocean ridge formed?
two convection cells meet and move upward
TRUE/FALSE:
Warm, less dense material of the lower mantle rises very slowly in the regions of oceanic ridges
TRUE
The _________________ have revealed that the flow of material in the mantle is very complex
availability of new technologies and modern research techniques
plate movement occurs because of two processes called ____________ AND _________
slab-pull and ridge push
the subducting cold and denser slab of lithosphere pulls the rest of the plate as it moves down-ward into the asthenosphere
slab-pull
a German meteorologist, proposed the continental drift hypothesis
Alfred Wegener, 1912
the theory where all landmasses were originally united in a single supercontinent
continental drift theory
a Greek word meaning “all land.
Pangea
What evidence did Wegener have that the continents were joined together in a gigantic landmass?
the matching of the shorelines of two continents, South America and Africa
similarity of rock types and structures on both sides of the Atlantic Ocean
The fossil remains of animals like the ___________
Mesosaurus
The fossil remains of the _____________ flora found in South America, Africa, India, Antarctica, and Australia
Glossopteris
where was the Glossopteris found?
South America, Africa, India, Antarctica, and Australia
a scientist who used sonar to map the ocean floor as a US Navy officer during World War II tied his knowledge of the then newly discovered Mid-Atlantic Ridge to the continental drift theory
Harry Hess, 1950
He proposed the theory of seafloor spreading to explain the moving continents.
Harry Hess
the newly formed crust moved laterally away from the ridge, known as the _____________
spreading center
the residual magnetism in ancient rocks, which records the direction and intensity of Earth’s magnetic poles at the time the rock was formed
paleomagnetism
define paleo
old or ancient
define paleontology
refers to the study of fossil animals and plants
define paleoclimate
refers to the ancient climate
It is the result of the changing speed of rotation of the mantle and the outer core.
Earth’s magnetic field
the complete reversal of the north and south magnetic poles
magnetic reversal
These _______________ stripes on the seafloor occur symmetrically on either side of a spreading center, confirming Hess’ theory of seafloor spreading
zebra-like magnetic
theory that the continents were joined into a single landmass that broke apart and were moving over Earth’s surface
Continental DriftTheory
phenomenon involving the complete reversal of the north and south magnetic poles
magnetic reversal
residual magnetism in rocks, studied to determine the direction and intensity of Earth’s magnetic field in the past
paleomagnetism
theory that the seafloor moves away from spreading centers or ocean ridges and it is eventually destroyed at deep-ocean trenches
Seafloor SpreadingTheory
What makes the tectonic plates move?
mantle con-vection, ridge-push, and slab-pul
What are the lines of evidence about the Continental Drift Theory
a) the continental shelves of South America and Africa fit together like a jigsaw puzzle
(b) the similarity of rock types and structures
(c) glacial deposits and striations; and (d) fossil remains of animals and plants
what are the lines of evidence support tectonic plate movement.
a) continental drift
(b) seafloor spreading
(c) paleomagnetism
(d) geomagnetic reversal
TRUE/FALSE:
The development of the Seafloor SpreadingTheory is credited to Alfred Wegener
FALSE: Continental Drift Theory
TRUE/FALSE:
Most scientists believe that a kind of thermal convection is the driving force for plate movement
TRUE
TRUE/FALSE:
Warm, less dense material of the lower mantle rises very slowly in the regions of oceanic ridges
FALSE: Upper
