unit 2 test Flashcards
whats happening to the distance between south america and africa
slowly drifting (2-3 cm per year)
in what way is mt everest changing
getting taller
what observation did early mapmakers make when looking at the continents that made them wonder if they were connected
south america and Africa seemed to fit suggesting they were connected
scientist that proposed continental drift
Alfred wegener
what does pangaea mean
all earth
how long ago did he think pangea began to break up
200 million years ago
what was his hypothesis called
continental drift
3 features on adjacent continents that match
fossil evidence
geological similarities
fits together like a puzzle
why was wegeners theory rejected at first
no evidense
what did people think the bottom of the ocean look like
flat
2 types of ocean features scientists found using sonar
mid Atlantic ridge
trenches
how does the Mariana trench compare in size of the grand canyon
trench 36000 canyon 6000
trench is 30000 deeper
what did scientists notice about the age of the rocks nearest the Mid Atlantic ridge compared with the age of the rocks farthest from the ridge
ones near the ridge are younger than the ones farther from the ridge are older and thicker
what did wegener notice about the depth of the sediment on either side of the ridge
increased with distance from the ridge
what fills gap and creates new rock when plates seperate at the mid atlantic ridge
magma
how do we know the the earths magnetic field has reversed in the past
studying patterns of minerals in the rock
what causes earths magnetic field?
movement of molten iron and nickel
what happens that makes the field reverse from time to time
change in flow in the iron
how many major plates are there
7
which plate in the us on
north american
what the the pacific ring of fire
horseshoe shaped area in the pacific ocean of volcanoes and earthuakes
divergent boundary
plates move apart
mid atlantic ridge
convergent boundary
plates collide
Himalayans
transform boundary
plates slide past each other
san andreas fault
cont/cont
make mountains: collide into weird mountain shapes
cont/oceanic
trench more dense goes under less dense
oceanic/oceanic
trench
what a hot spot? which islands are located over a hotspot
fixed area of volcanoes
hawaiian islands created ny the hotspot
layers of earth and their meterial
crust- solid rock
mantle- semi solid rock
outer core- semi solid iron and nickel
inner core- solid iron and nickel
where is asthenoshpere locateed
upper mantle
what causes plates to move along the surfa e of the earth
currents in the asthenoshpere
