Types of plate boundary Flashcards
What are the 4 types of boundary
Constructive
Destructive
Conservative
Collisional
What happens at a constructive plate boundary
Convention currents from the mantle
Drive plates apart
Magma wells up through the gap
What landforms and events can occur at a constructive
Volcanoes
Ocean Ridges
Rift valleys
Earthquakes
e.g. of constructives
North American and Eurasian
Formation of an Ocean ridge
A low mountainous ridge in the ocean Convection currents push up Force plates apart Basaltic lava wells up Marks sea floor spreading Often the location of submarine volcanoes
e.g. of ocean ridge
Mid-Atlantic Ridge
Formation of a rift valley
A lowland region with parallel blocks (called horsts) On continental areas (not the sea) Convection currents push up Forces plates apart Causes areas of crust to drop down Causes stepped appearance Crust fractures so areas drop
E.g. of rift valley
African Rift Valley
Baikal Rift Valley, Siberia
What happens at a Conservative boundary
Convention currents push plates in any direction
This means plates could move alongside eachother, at different rates, directions and angles
Events at a conservative plate boundary
Earthquakes
E.g of conservative faultline
Pacific and North American
San Andreas Faultline - causing the Loma Prieta 1989 earthquake
What happens at a destructive boundary
Convection currents push plates together
Oceanic under continental crust (because its more dense)
Forms a subduction zone
Friction melts the oceanic crust
Landforms and events at a destructive boundary
Earthquakes Volcanoes Fold mountains Island Arcs Ocean Trenches
E.g. of destructive
Nazca and South American
Formation of fold mountains
Sedimentary rocks form a geosyncline when plates forced together
Rivers carry sediment into the depression
Its compressed into sandstone
Forced up by plate movement
Upfolds are called anticlines
Downfolds are called synclines
