Shared Flashcard Set


Earth and Environment Systems
5. Igneous Rocks
Undergraduate 1

Additional Engineering Flashcards




Know what to call liquid hot rock underground versus on the surface.

underground - magma

surface - lava


 Know what to call an igneous rock that cooled and crystallized underground and what to call one that formed on the surface and what their relative crystal sizes are.


intrusive igneous rocks (plutonic rock) - larger crystal and underground

extrusive igneous rocks (volcanic rock) - smaller crystal and surface, cools faster

Know the five principal igneous rock textures and their definitions.

glassy - no crystals

aphanitic - crystals too small to see

phaneritic - crystals visible

pegmatitic - crystals are larger than 1 in across

porphyritic - large crystals surrounded by small crystals

What are the two most common gasses dissolved in magma, and what implications do they have for the Earth’s early atmosphere?

80% of gases are water and CO2

largest gas ouput from volcaones is water, 2nd is CO2, no O

oceans and atmospheric water was low to begin with and increased overtime

Co2 increased over time, there was no oxygen


Know the names of the phaneritic, aphanitic, and glassy igneous rocks which form from each magma type.

basaltic(mafic)/phanetic(largest crystal) - gabbro

basaltic(mafic)/apanitic(smallest crystal) - basalt

basaltic(mafic)/glassy(no crystal) - obsidian

andestic(inter)/phanetic(largest crystal) - diorite

andestic(inter)/apanitic(smallest crystal) - andesite

andestic(inter)/glassy(no crystal) - obsidian

rhyolitic (felsic)/phanetic(largest crystal) - granite

rhyolitic (felsic)/apanitic(smallest crystal) - rhyolite

rhyolitic (felsic)/glassy(no crystal) - obsidian

What are the three main pieces of information we can get from Bowen’s reaction series?

- can tell us the order in which minerals crystallize form a melt

- can tell us the order in which minerals will melt when heated

- can tell us which minerals are most likely to be stable at the surface


Know how to tell the difference between an igneous sill and a lava flow that has been buried.


sill - burn the land above and below

lava - only the botom


Know the definition of the following terms and be able to identify them in a picture/illustration: country rock, plug (a.k.a. volcanic neck), sill, dike, baked zone, xenolith.


Country rock is a geological term meaning the rock native to an area

A volcanic plug, also called a volcanic neck or lava neck, is a volcanic landform created when magma hardens within a vent on an active volcano

A sill is a tabular pluton that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or even along the direction of foliation in metamorphic rock.

A dike in geology is a type of sheet intrusion referring to any geologic body that cuts discordantly across

  • planar wall rock structures, such as bedding or foliation
  • massive rock formations, like igneous/magmatic intrusions and salt diapirs.

A xenolith is a rock fragment which becomes enveloped in a larger rock during the latter's development and hardening.

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