Tectonic Activity and Plate Tectonics Flashcards
Define Pangaea
its a real theory that claims that the earths continents were once connected into one large landmass
define continental drift
its the separating of earths continents by drifting across the earths surface
what was Wegener’s 1st proof on continental drift (Pangaea)
the continents seemed to fit together like a jigsaw
what was Wegener’s 2nd proof on continental drift (Pangaea)
the fossils of the same species were found on continents that were a long way apart
what is sonar and what is it used for
echo sounding. to locate underwater navigation
what is a rift
a large crack in the ground or in rock
define seafloor spreading
tectonic plates—large slabs of Earth’s lithosphere—split apart from each other under water
what is an ocean trench
is like the shape V on the seafloor and goes deep down
what is subduction
when an oceanic plate runs into a continental plate and slides beneath it.
what was the 3 proofs of harry hess theory ( sea floor spreading)
1-magnetic spreading
2-age of sea floor
3-sediment thickness
what a tectonic plate
it is large slabs of rock that divide the earths crust
define lithosphere
it is lowest part of the erths crust and top part of the matle.is rigid (not flexible)
define the athenosphere
it is the layer beneath the lithosphere and behaives like melted slightly heated plastic meaning flows very slowly.the tectonic plates “float” on which helps them move slowly across the earth
define the core and its character
its the center of our earth and the outer core is liquid while the inner core is solid
why do plates move? give two main theories
1-dragged along when the hot magma in the athenospere rises
2- gravity
a-slab pull-gravity pulls the heavier part of the plate downwards.
b-ridge push- new ocean crust formed at ridges upove others which cause the older crust to go below
what is rifting
when continents break up and allow water to fill the empty space in between
geological features that form at divergent plate boundaries.
rift valleys, ocean ridges, fissure volcanoes, and underwater mountain
geological features that form at convergent plate boundaries.
trenches, volcanoes, and mountains
what is the other name for divergent bounndries and why
contructive boundries because new crust forms in between from when the plates seperate and magma fills in the gap and solidifies
what is the other name for covergent boundries and why
destructive boundries because rock (crust) is destroyed at converging boundries because they collide head-on
why do some converging plate boundries sink under eachother
its when oceanic crust and continental crust collide and so the denser plate (oceanic plate) sinks under the lighter plate (continental plate. and this is subduction
