Chapter 9 Flashcards
(17 cards)
What is folding?
a process that bends and deforms beds of various rocks subjected to compressional forces
What is faulting?
the process where displacement and fracturing occur between two portions of earths crust, usually associated with earthquake activity
How are mountains and continents built?
erosion
What do ocean-continent collisions create?
occurs along the pacific coast–formed the Andes and Sierra of Central America
what do ocean-ocean collisions create?
plate convergence can produce either simple or more complex volcanic island arcs–in places such as Indonesia and Japan
what do continent-continent collisions create?
large masses of continental crust are subjected to intense folding, overthrusting, faulting and uplifting
How were the Himalayas formed?
continent-continent collision
What causes earthquakes?
crustal plates do not glide smoothly past one another, instead friction exists along plate boundaries. the stress of plate motion builds strain in the rocks until friction is overcome and the sides along plate boundaries or fault lines suddenly break loose.
What is the elastic rebound theory?
two sides of a fault appear locked despite the motion of adjoining pieces of crust, but with accumulating strain they rupture suddenly, snapping to new positions relative to each other generating an earthquake
where are earthquakes likely to occur?
plate boundaries
Where are effusive volcanoes found?
sea floor spreading
divergent boundaries
hotspots
Where are explosive volcanoes found?
subduction zones
Why do subduction zones produce explosive eruptions?
high aluminum block the magma conduit blocks, traps and compresses gases causing pressure to build
What are characteristics of effusive volcanoes?
Gentle eruptions, enormous volume of lava
What are characteristics of explosive volcanoes?
Violent eruptions, large amounts of rock and glass
How are explosive volcanoes formed?
Mountains formed from layering of ash, pyroclastics, and lava.
- cinder cones
- composite volcanoes
How are effusive volcanoes formed?
Massive gradually sloped mountains are formed
- shield volcanoes
- flood basalts
