Plate Tectonics Lecture Notes

30 fill-in-the-blank flashcards covering Earth’s layers, discontinuities, plate boundaries, driving forces, and key examples from the Plate Tectonics lecture.

The compositional layers of Earth, in order from outside to inside, are __, mantle, and core.

crust

The mechanical layer directly beneath the lithosphere is the __.

asthenosphere

The rigid, brittle outer shell composed of crust and upper mantle is called the __.

lithosphere

Continental crust is primarily __ in composition.

granitic

Oceanic crust is primarily __ in composition.

basaltic

The average density of continental crust is about __ g/cm³.

2.7

The average thickness of oceanic crust is roughly __ km.

7–10

Oceanic crust is constantly renewed and is generally less than __ million years old.

200

The discontinuity that separates the crust from the mantle is called the __ discontinuity.

Moho

The German scientist who proposed Continental Drift was .

Alfred Wegener

Wegener’s 1915 book proposing Continental Drift was titled “The __ of Continents and Oceans.”

Origin

According to Plate Tectonics Theory, the lithosphere is divided into large __ that move.

plates

Plates that lie below sea level and are mostly basaltic are called __ plates.

oceanic

The boundary where two plates spread apart is known as a __ boundary.

divergent

A continental divergent boundary forms a feature known as a .

rift valley

The East African Rift is an example of a __ boundary on land.

divergent

The Mid-Atlantic Ridge is formed at an oceanic __ boundary.

divergent

The boundary where plates slide past one another horizontally is called a __ boundary.

transform

The San Andreas Fault is a classic example of a __ boundary.

transform

The boundary where two plates move toward each other is a __ boundary.

convergent

When an oceanic plate meets a continental plate, the denser oceanic plate __ beneath the other.

subducts

The deepest part of the world’s oceans, the Mariana Trench, was created at an - convergent boundary.

oceanic-continental

Convergence of two oceanic plates can generate a curved chain of volcanoes called a(n) __.

volcanic island arc

Collision between two continental plates builds large mountain ranges such as the __.

Himalayas

Circular movement of mantle material driven by temperature and density differences is called __.

convection

The force produced by gravity pulling newly formed lithosphere down and away from a mid-ocean ridge is called .

ridge push

The downward force exerted by a sinking, cold, dense slab at a subduction zone is known as .

slab pull

A long, narrow depression on the ocean floor where subduction occurs is called a __.

trench

The elevated underwater mountain chain formed at a divergent plate boundary is abbreviated as __.

MOR

The two main gravity-driven forces, along with convection, that drive plate motions are push and pull.

ridge; slab