chapter 9-1, 2 Flashcards
(13 cards)
what did alfred wegener believe?
that all continents joined together.
what is continental drift?
a process that started with all the continents merging together
what is pangaea?
large land mass (“all lands”)/ supercontinent when all continents were joined together
what are the evidences of continental drift? explain.
matching fossils - traces of ancient organisms in rock, areas covered in similar climate
rock types - edges of continents fit together
ancient climates - fossils of warm climates are in cold climates, drifted through ocean floor
how are glaciers evidence?
Glacial clues of glacial deposits found in areas near equator which is too warm for glaciers. Continents at one time were covered with glaciers.
where is ocean with lots of life?
Where ocean water is heated by hot mantle and sea-floor is spread
what is sonar?
sound navigation and ranging. Used to make maps of the ocean floor
what are deep-ocean trenches and mid-ocean ridges?
Deep-ocean trenches: long, steep valleys that form in deep parts of the ocean
Mid-ocean ridges: system of ridges through center of all the oceans
what is seafloor spreading? explain.
molten material rises at mid-ocean ridges and turns/flows sideways carrying sea floor from the ridge. Spreads in both directions and magma rises through cracks and cools, so new seafloor is created in the middle
what did the alvin submersible discover?
discovered pillow lava, when molten material is cooled quickly underwater
what is subduction and what is the process?
when ocean floor sinks beneath a deep-ocean trench and back into the mantle.
crust moves away from mid-ocean ridge and toward the deep-ocean trench. New oceanic crust moves away and rises from the ridge toward the trench. Sinks down beneath the trench and melts.
how are magnetic stripes evidence for seafloor spreading?
iron minerals in rock align themselves according to magnetic orientation at the time that they formed. Magnetic alignment of the rocks are reversed back and forth in strips and they alternate patterns in both directions. Shows that new rock was being formed at the mid-ocean ridges
what did the glomar challenger research ship find?
found that the youngest seafloor rocks were near mid-ocean ridges and no ocean rocks were older because they were recycled back in the mantle at subduction zones. Age becomes older farther from ridges on both sides, seafloor spreading took place
