Plate boundaries

A big slab of crust that moves across the Earth, generally composed of both continental and oceanic lithosphere A tectonic plate can have land and water on it.

• Continental crust • Oceanic crust Continental crust is thick and low density, while oceanic crust is thin and high density.

Thick Low density Rocks (Flesic)

Thin High density Rocks (Mafic)

Divergent: Move away from each other Convergent: Move together Transform: Slide next to each other Transform boundaries can produce bigger earthquakes.

A tectonic plate made mostly of deep oceanic crust and lacks major landmasses. Has high density? Oceanic plates are high density and tend to sink downwards.

A tectonic plate made mostly of continental crust with shallow oceanic crust. Has low density. Continental plates are low density and tend to rise upwards.

A convergent plate boundary where one plate sinks below the other due to having higher density. It can happen between oceanic-oceanic, and ocenaic-continetal. Subduction can involve two oceanic plates or one oceanic plate and one continental plate.

Oceanic and a shallow Continental crust

Continental sediments Shale, Sandstone, Limestone

-Plates pull apart and create a low point in the crust -Ocean fills in and creates shale and limestone rocks -Underwater volcanoes form an underwater mountain range -Lava and magma cool to create basalt and gabbro rocks -On ocean basin forms as the plates continue to spread Underwater volcanoes form an underwater mountain range as lava and magma cool to create basalt and gabbro rocks.

• Gabbro • Andesite • Low-grade metamorphic rocks • Diorite • Basalt • High-grade metamorphic rocks • Medium-grade metamorphic rocks These rocks form as a result of the geological processes at divergent boundaries.

The plates are colliding and one is sinking below the other

Volcanic activity occurs in hotspots in the middle of a plate, NOT on a plate boundary. Plates slide over a magma plume

Earthquakes happen on a plate boundary

Density: The plate that is farther/older away from the center is more denser. Landforms: Makes mid-ocean ridges, underwater ocean ranges, creates magma Direction: Sperates Rocks formed: Mafic igneous

Density: Almost same density. Landforms: Rift valleys, cracks in canyons form diverging plates, and new oceans Direction: Seperates Rocks formed: Felsic and Mafic igneous, and sedimentary rock

Density: Almost the same density. Landforms: Mountains Direction: Toward each other Rocks formed: Foliated, regional metaphoric rocks

Density: The subducting oceanic plate is more dense Landforms: Volcanic mountains, deep ocean trenches, earthquakes, new islands Direction: Slides under each other Rocks formed: Regional and contact metaphoric, mafic igneous

Density: Oceanic plate is more dense Landforms: Deep ocean trenches, volcanic islands, earthquakes Direction: Ocean plate subucts Rocks formed: Regional and contact metaphoric, intermediate igneous

Density: The older heavier plate is more dense Landforms: Earthquakes and faults Direction: Strike/slip fault. Side to side Rocks formed: Limited rock formation, can cause regional metaphoric rocks

There are convergent plate boundaries

The coast, because it is surrounded by convergent plate boundaries. However, they can occur anywhere in the world