3.6 Geomorphic processes Flashcards
Tectonic, erosion/weathering, soil (48 cards)
Tectonic forces are caused by
Earth’s internal energy
What is the lithosphere
Solid, outer portion of Earth’s rigid upper mantle
T or F the lithosphere is broken up into section
T
What do tectonic plates move around on?
Asthenosphere
Continental drift is
The movement of tectonic plates
When did Alfred Wegener theorise continental drift
1915
New land is created under…
The ocean (investigations of mid-Atlantic ocean showed sediments near the ridge are thin and relatively young)
When oceanic and continental plates converge, which is forced under the other?
Oceanic (more dense)
Almost all surface tectonic and volcanic activity occurs at plate boundaries T or F
T
Diverging plate boundaries
Plates separate and new crust is created by molten material
What landform created by diverging plates
Mid-ocean ridge
Converging plate boundaries
2 plates collide (due to process of seafloor spreading)
What happens when oceanic and continental converge
Dense ocean floor is subducted beneath less dense continental plate > deep trench > descending slab of sea floor melts, erupts in chain of volcanoes along edge of continental
What happens when 2 oceanic plates converge
The older, colder, denser plate subducts under other > forms trench > movement weakens crust, molten rock escapes to surface forming volcanic mountains (e.g. many in Pacific basin)
Transform/conservative boundary?
2 plates move horizontally past each other on a single vertical fault line
Which boundary do earthquakes occur on
Transform- when built-up pressure is released due to plates sliding horizontally
Where are mountains formed?
At advancing edges of continental plates- when they collide, crust thickens to absorb impact. Pressure exerted, layers of rock are compressed.
What are folds
Wave like patterns in Earth’s crust. As continental movements are very slow, mountain chains they produce are dominated by folded rock strata (layers of rock)
What are faults?
Fractures in rock structure. On large-scale, faulting creates landforms like rift valley
Define earthquake
Series of rapid vibrations caused by sudden movements in the crust. The energy released by these sudden movements travels through the ground in waves.
Difference between earthquake focus and epicentre?
Focus= point earthquake began
Epicentre= point on surface directly above focus
Why do volcanoes happen?
Eruptions occur when molten rock reaches Earth’s surface, through cracks or rocks in underlying rock structures.
Where are the world’s most active volcanoes?
Volcanic belts coinciding with zones where plates collide and fracture
Gradational processes disturb the land, making the surface uneven and creating new landscapes
F- that defines tectonic
Gradational smooth out surfaces
