What are the major plate tectonic boundaries?
Video lecture on divergent, transform, and convergent types of plate boundaries. Recorded during a 2007 teacher workshop on earthquakes and tectonics. Speaker is Dr. Robert Butler, University of Portland Oregon
Three main types of plate boundaries:
Conceptual model of the relative thicknesses of the Lithosphere relative to the diameter of the Earth uses a hard-boiled egg to gain understanding about the scale of the lithospheric plates.
New oceanic crust is created at this boundary when basalt magma, formed in the mantle, rises into fractures in the crust and solidifies. Spreading ridges are high elevation because the young oceanic plate at the ridge crest is hot and less dense than the older, colder and more dense plate on the flanks of the ridge.
The subduction zone iswhere two tectonic (lithospheric) plates come together, one subducting (diving) beneath the other. The plates are locked together and periodically overcome the friction causing the leading edge of the overlying plate to surge back, lifting a wall of water producting a tsunami.
A transform fault is a type of strike-slip fault wherein the relative horizontal slip is accommodating the movement between two ocean ridges or other tectonic boundaries. They are connected on both ends to other faults.
In a normal fault, the block above the fault moves down relative to the block below the fault. This fault motion is caused by tensional forces and results in extension. Other names: normal-slip fault, tensional fault or gravity fault. Examples: Sierra Nevada/Owens Valley; Basin & Range faults.
In a reverse fault, the block above the fault moves up relative to the block below the fault. This fault motion is caused by compressional forces and results in shortening. A reverse fault is called a thrust fault if the dip of the fault plane is small. Other names: thrust fault, reverse-slip fault or compressional fault]. Examples: Rocky Mountains, Himalayas.
In a strike-slip fault, the movement of blocks along a fault is horizontal. The fault motion of a strike-slip fault is caused by shearing forces. Other names: transcurrent fault, lateral fault, tear fault or wrench fault. Examples: San Andreas Fault, California; Anatolian Fault, Turkey.
The Earth has 3 main layers based on chemical composition: crust, mantle, and core. Other layers are defined by physical characteristics due to pressure and temperature changes. This animation tells how the layers were discovered, what the layers are, and a bit about how the crust differs from the tectonic (lithospheric) plates, a distinction confused by many.
Fault types and rock deformation. The faults and folds in rocks provide evidence that the rocks are subjected to compressional, tensional, and/or shear stress. Silly Putty™ allows students to discover that the structure we see in rocks provides evidence for they type of stress that formed. Students apply this idea by examining images of faults and folds experimentation with sponge models.
Interactive map of tectonic plates from the US Geological Survey plate tectonic map reveals the plate names when you scroll over the plate. Scrolling over green button shows relative motions.
How are the tectonic plates related to earthquakes and volcanoes?
Interactive relief and bathymetric map reveals tectonic plates, as well as world-wide earthquakes and volcanoes.