Tectonic Plates Flashcards
What is the theory of continental drift?
-continents once formed a single landmass (Pangea) that broke into smaller continents
created by wegener
what are the main evidences presented for the theory of continental drift
1) Fit between the Atlantic coastlines
2)Fossil distribution
3)Traces of ancient glaciation
4)Matching geological structures
What does “Fit between the Atlantic coastlines”
the current continents fit together like puzzle pieces
Explain how fossil distribution helps prove continental drift
fossils that are found in Africa are also found in south America (which would have been impossible)
Explain how the traces of ancient glaciation proves
traces of ancient glaciation are found all over the world (in places that would have connected to Antarctica)
how do matching geological structures prove continental drift
in south America there are traces of the west African shield and the Tanzanian shield- this would only be possible if they were once connected
What are the 3 types of plate boundaries
1) Divergent plate boundary
2)Convergent plate boundary
3)Transform plate boundary
list mechanisms of Divergent Boundaries
-heat
-convection cells
-rising of hot mantle towards surface
-uplift and stretching of lithosphere +partial melting of mantle
-rising and eruption of magma @ surface
-new lithosphere
-new divergent plates
what are some characteristics of divergent boundaries
-zone of divergence
-opening of crust
-rising magma
-shallow earthquakes
explain oceanic ridges
giant undersea mountain ranges found along well developed divergent plate boundaries
formation of oceans
*took millions of years
-continental rift
what are some characteristics of convergent plate boundaries
-zone convergence
-subduction (plunging of lithospheric plate under another plate)
-production of lithosphere
-oceanic trench (> 11,000m)
what are the types of convergence collisions
- ocean to ocean
-ocean to continent
-continent to continent
describe ocean - ocean collisions
- Collision between 2 oceanic plates
- One subducts under the other
- Formation of island arcs (volcanic islands):
-Release of volatiles
-Partial melting of the asthenosphere
*Caribbean, kuril islands, japan (2011 earthquake/ tsunami)
Explain ocean- continent collisions
- Collision between an o.p and a c.p.
- O.p under c.p
- Age of c.c. vs. o.c
- Meteoric impacts on oceanic floors
- Moon
- Formation of continental volcanic arcs
Explain continent - continent collisions
- Collision between two continental plates after the
oceanic plate was completely consumed - Neither of the two c.p. dives under the other one
- Formation of important mountain belts by the
stacking of material (thrust sheets)
what is the ring of fire
a series of active volcanoes along convergent plate boundaries
explain the formation of mountain belts
-formed at convergent boundaries
-formed in the context of an active continental margin (@ subduction zone)
