flashcards

Welborn Continental drift/plate tectonics

Question Answer
what is pangaea? theory that the continents had once been joined in one supercontinent and have slowly drifted to their present day locations
who proposed the claim of a supercontinent? Wegener
What was his claim on continental drift? that all continents had once been joined in one supercontinent that he liked to call pangea and have slowly drifted to their present day location.
which ocean separates south america from africa atlantic ocean
in wha type of climate do glaciers form extremely cold climates
why did wegener suggest that continents in the southern hemisphere had a colder climate long ago glacier evidence found in s am and africa
what was glossopteris tropical plant fossil
where was glossopteris found antarctic
what was mesosaurus freshwater reptile
what is significant about the fossils of mesosaurus that were found fossil found on South America and Africa but could not swim in ocean
based on the map, which fossil alone supports the idea that all continents were once joined Glossopteris
Why did scientists argue with Wegener’s Continental drift hypothesis he couldn't show "how" the continents moved.
when did scientists begin to explore the seafloor? world war 2, mid 1950's
what did they use to explore the seafloor sonar
how does sonar work it bounces sound waves off underwater objects and then records the echoes of these sounds
who began studying the seafloor harry hess
what is the mid ocean ridge long underwater mountain range where magma rises up the mantle
where is the mid ocean ridge located mid-atlantic, plate boundaries
what is seafloor spreading the process that continually adds new material to the ocean floor; pushing the continents
how does the sediment near the ridge compare to the sediment farther from the ridge? near-younger; farther-older
where was the first evidence used to support seafloor spreading found? mid-atlantic ridge
what creates earth's magnetic fields spinning of the inner core
what is normal polarity a state in which magnetized objects, such as compass needless, will orient themselves to point north
what is reversed polarity a state in which magnetized objects would reverse direction and orient themselves to point south
how does the basalt that forms during seafloor spreading record a magnetic signature whichever way the magnetic field is arranged when new crust forms the magnetic particles in basalt will align in that direction
name the 2 types of evidence scientists use to support the theory of seafloor spreading magnetic stripes and the age of ocean rocks
how does seafloor spreading help explain the continental drift hypothesis this gave a mechanism of how continents moved
what 3 forces drive plate movement gravity, pressure, and convection current
what is a subduction zone one plate is being pushed under another and will melt back into the mantle
name the 2 types of crust & characteristics oceanic (thinner, more dense, & younger) & continental (thicker, less dense, & older)
what is the lithosphere made up of the crust and top part of mantle "plates"
what is the asthenosphere mad up of upper portion of mantle
which sphere moves the plate asthenosphere
where is the oldest ocean crust found as far as possible from the mid ocean ridge
what is formed at a subduction zone trenches
which factor is found at all plate boundaries earthquakes
what happens at a convergent boundary plates collide with eachother
what happens at a divergent boundary plates move apart from eachother (divide)
what is formed at a transform boundary plates slide past eachother
what is a hotspot volcanically active spot that is not at a boundary
where are most volcanoes and earthquakes found pacific plate
what is this place known as ring of fire
what two things increase the deeper you go in earth and/or ocean pressure and temp
what is the theory of plate tectonics theory that explains how earth's plates move and what happens when they interact
which plate do we live on north American plate
what is seafloor spreading process of the seafloor slowly growing outward from mid ocean ridges as new crust is formed
what is tectonic plate theory theory describing how earth's plates move and what happens when they interact with eachother
explain how gravity and convection currents drive seafloor spreading and plate tectonics gravity pulls the plates downward and convection currents pushes the plates along in the direction of the current
what was Pangaea? how does continental drift support the existence of Pangaea? ancient supercontinent; continental drift supports Pangaea because the separation and movement of the continents have formed today's seven continents
what is a convection current hot material heating-rising-cooling-sinking

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