12. Drifting Continents: Plate Tectonics Flashcards
pangaea
the supercontinent formed about 300 million years ago by the fusion of all continents
panthalassic ocean
the single large ocean that surrounded Pangaea 300 million years ago
Laurasia
a landmass that resulted when Pangaea split about 200 million years ago, which consisted of modern day North America, Greenland, and Eurasia
Gondwana
a landmass that resulted when Pangaea split about 200 million years ago, which consisted of modern day South America, Australia, Africa, India, and Antarctica
continental drift
a theory proposed by Alfred Wegener stating that continents move slowly across earth’s surface
plate tectonics
a theory addressing the origin, movement, and recycling of lithospheric plates and the landforms that result
subduction
the process in which oceanic lithosphere bends and dives into the mantle beneath another lithospheric plate
plate boundary
the margin of a lithospheric plate
ridge push
the process by which magma rising along a mid-ocean ridge forces oceanic crust of two seperate plates apart
mantle drag
the dragging force between the asthenosphere and the overlying lithosphere
slab pull
the process by which the weight of subducting oceanic lithosphere accelerates plate movement by pulling the plate deeper into the mantle
divergent plate boundary
a region where two lithospheric plates move apart
convergent plate boundary
a region where two lithospheric plates move toward each other
transform plate boundary
a plate boundary where one lithospheric plate slips laterally past another
rift
a region where continental crust is stretched and splitting
rift valley
a linear valley with volcanoes formed by rifting of continental crust, sometimes filled with freshwater to form a deep lake
Wadati-Benioff zone
a sloping pattern of increasingly deep earthquake foci found in a subduction zone
continental volcanic arc
a long chain of volcanoes formed on the margin of a continent above a subducting plate
volcanic island arc
a chain of islands formed where oceanic lithosphere of one plate is subducting beneath oceanic lithosphere of another plate
Pacific Ring of Fire
a zone of volcanically active mountain chains resulting from subduction on the margins of the Pacific Ocean
collision
convergence of the continental crust of two different plates
accreted terrane
a mass of crust that is transported by plate movement and fused onto the margin of a continent
active continental margin
a margin of a continent that follows a plate boundary, typically characterized by a deep-sea trench and a narrow continental shelf
passive continental margin
a margin of a continent that does not coincide with a plate boundary, typically characterized by a broad, sloping continental shelf
