Geology Study Guide

What geologic feature is formed at a convergent subduction boundary?

Trench

What eon do we live in today?

Phanerozoic Eon

What is geologic time?

A system to organize Earth’s history into smaller and understandable parts

What happened at the end of the Cretaceous Period and how did it affect life on Earth?

Mass extinction of dinosaurs, made life easier for mammals

How many eras are in the Phanerozoic Eon divided into and what are they called?

3, Paleozoic, Mesozoic, Cenozoic

How many periods are in the Mesozoic Era and what are they called?

3, Triassic, Jurassic, Cretaceous

What is chemical weathering?

A process that breaks down rock through chemical changes

What two geologic features are formed at a divergent boundary between two pieces of oceanic crust?

Mid-ocean ridge and rift valleys

On which layer of Earth do tectonic plates float?

Asthenosphere, the upper layer of the Earth’s mantle

What is crystallization in igneous rocks and how is it different in extrusive and intrusive rocks?

As magma or lava cools, different crystals form at different temperatures. The rate of cooling determines how much time the crystals will have to form. Slow cooling produces larger crystals and fast cooling produces smaller crystals. Since extrusive rocks are cooled quickly, they have smaller crystals and since intrusive rocks are cooled slowly, they have larger crystals.

Explain how the law of conservation applies to rocks, be sure to talk about ‘new rock being formed’ at divergent boundaries and ‘old rock being destroyed’ at convergent subduction boundaries.

The law of conservation states that mass cannot be created or destroyed but is cycled between different forms. At divergent boundaries, magma rises to the surface and eventually cools and hardens, which creates an igneous rock. At convergent subduction boundaries, a trench is created and old rock is destroyed.