Last Test Flashcards
magma
metled or molten rock material beaneath Earth’s surface
mid-ocean ridge
an underwater mountain system/chain, including ranges and valleys formed by plate tectonics
seafloor spreading
a phenomenon by which magma from earth’s mantle comes up at the mid-ocean ridges and creates new oceanic crust
what is the first step of seafloor spreading
convection currents bring magma up towards the mid-ocean ridge
what is the third step of seafloor spreading
the lava flows outward and cools, creating new seafloor
what is the second step of seafloor spreading
the magma flows out of the ocean ridge as lava
what is the fourth step of seafloor spreading
finally, the seafloor moves sideways, away from the center of the ridge
what is the action of older rocks being pushed down into the mantle for new rocks
subduction
where does heat eascape the earth most than any other oceanic locations?
mid ocean ridges
addition of new seafloor makes the ocean ____?
wider
what happens to the continents as the ocean grows
they drift apart
earth’s magnetic field has not always had the same _____
orientation
what rocks record reversals in earth’s magnetic field?
igneous rocks
how did seafloor spreading help scientists find evidence to support the seafloor-spreading hypothesis?
seafloor drillings showed that the oldest rocks were farthest away from the mid-ocean ridge and that the youngest rocks were found in the center of the mid-ocean ridge.
what method technology did they use in world war 2 to map the topography of the seafloor?
sonar tech
