Geology of U.S. National Parks Exam 1

Convergent Boundary

Plates push towards each other, or collide

Divergent Boundary

Plates pull apart from each other

Subduction

One plate slides below another plate at a convergent boundary

Slab pull

A plate gets pulled/sinks into Earth’s mantle at a subduction zone

Ridge Push

Gravitational force causing hot, raised oceanic lithosphere to slide down the side of a mid ocean ridge

How did Earth begin?

As a ball of magma/lava, later cooled down

What kind of rocks first existed on earth?

Igneous rocks

Minerals must meet __ criteria

5

What type of minerals are most common?

Silicate minerals

What does Mafic stand for?

Magnesium and Iron

What does Felsic stand for?

Feldspar and silica

What do Mafic rocks often look like?

Dark and dense in color

Where are Mafic rocks typically found?

Oceanic lithosphere

What do Felsic rocks often look like?

Often white and pink, less dense

Where are Felsic rocks found?

Continental lithosphere

Earth’s mantle is extra _____

Mafic

Mafic and Felsic rocks form at _________ temperatures

Different

Mafic rocks are _____ viscosity

High

Felsic rocks are _____ viscosity

Low

How are volcano shapes determined?

By magma/lava viscosity

What is a caldera?

A large, bowl shaped volcanic depression forming when the ground collapses inward after an eruption, emptying the underlying magma chamber