Chapter 2 -- Plate Tectonics Flashcards
A theory that the Earth’s surface is made up of large rigid plates that are continuously moving.
Interactions at plate boarders cause most major geologic activity.
Explains the phenomenon of continental drift.
Plate Tectonics
He postulated that all landmasses were originally united into a supercontinent named _______.
Alfred Wegener
Pangea
_____ ____ proposed the theory of seafloor spreading in 1962.
Harry Hess
Hess suggested that the seafloor separates at oceanic ridges, where…
New crust is formed by upwelling magma
Occurs when plates are separating
New lithosphere forms at the opening rift.
Rift valleys may lengthen and deepen, filling with sea water, basalts, and sediment to become a new sea.
Also present under continents during the early stages of continental breakup.
Divergent Plate Boundaries
Type of Convergent Boundary
A _________ __________ arc forms on the non subducted plate
An ________ ________ forms parallel to the volcanic island arc.
Volcanoes result from rising magma produced by the partial melting of the subducting plate.
Oceanic Oceanic
Volcanic Island
Oceanic Trench
Type of Convergent Boundary
The denser oceanic plate is subducted under the continental plate.
A ___________ __________ forms on the continent side of the trench.
Partial melting of the oceanic plate forms a chain of andesite volcanoes.
Oceanic - Continental
Subduction Complex
Type of Convergent Boundary
Continental crust is not subducted, but partially underlies the other continental plate
Huge mountain ranges are formed due to collision
i.e Himalayans, Alps and Appalachian Mountains.
Continental - Continental
Fractures in the crust where plates slide laterally past each other.
The San Andreas fault separates the Pacific plate from the North American plate.
Transform
Is a location on Earth’s surface where a stationary column of magma, originating deep within the earth, has risen to the surface and formed a volcano.
They leave a trail of extinct and progressively older volcanoes that record the movement of the plate.
Hot Spots
Most geologists agree that some type of ______ ______ _______ is the basic process responsible for plate motion.
Convective Heat System
some geologists think that movement may be aided by…
This is cold and dense and pulls the plate
Slab Pull
some geologists think that movement may be aided by…
Rising magma pushes the ridges up and gravity pushes the ocean floor toward the trench.
Ridge Rush
Many metallic __________ ___________ are related to igneous and associated hydrothermal activity.
Mineral Deposits
Plants and animals occupy biotic provinces controlled mostly by __________ and ______________ ___________
Climate and Geographic Barriers
