Download Crustal Features

Crustal Features
8.9B relate plate
tectonics to the
formation of crustal
features
What is Earth’s crust?
• Earth’s crust
covers the
mantle.
• The crust is the
outermost layer
surface layer.
– 25 miles thick
under continents
– 6.5 miles thick
under oceans
What makes up the crust?
• Oceanic crust – Rocks that make up the
oceanic crust are relatively young compared
to the rocks that make up the continental
crust. It is mostly basalt rock.
• Continental crust – Continental crust is older
than oceanic crust. It has two layers, mostly
igneous rock. The upper crust is mostly
granite. The lower crust is mostly basalt and
diorite.
Moving crust
• The crust is part of the lithosphere, the
outermost layer of the crust.
• Plates are part of the crust. (continental
crust/plate and oceanic crust/plate)
• The convection currents in the mantle layer
below and perhaps also gravity cause the
plates to move.
What happens when plates move?
• When the plates move, the surface of the
crusts change.
• Earthquakes, volcanoes, ocean ridges, and
mountains are all crustal features that form
when plates move.
How do plates move?
When two
boundaries
converge
(come
together),
volcanoes and
mountain
building is
common.
When two boundaries diverge (move
away) from one another, this is
common in oceans to form rifts.
When two boundaries transform (slide
past) one another, earthquakes are
common.
Crustal plate boundaries is where you
would expect to find the most activity.
Look at where most earthquakes
occur, along plate boundaries.
Look at where most volcanoes are
found, also along boundaries.