Earth Crust And Volcanoes – Geology Test 1

Earth Crust And Volcanoes – Geology Test 1

The topics include in this chapter are earth crust and volcanoes, layers of earth, lithosphere and asthenosphere, nebular theory, physical geology, minerals, bowen’s theory, divergent and convergent – Geology Test 1


largest division of time on the geologic time scale

phanerozoic eon

presence of organisms with hard parts and the rapid increase in biodiversity.


the jurassic period lies in the _____ era.


We _____ live in the Holocene Epoch of the Quaternary Period, which is part of the Cenzoic Era and Phanerozoic Eon

chemical composition and physical properties

the layers of earth are based on what two sets of characteristics?

D” layer

A partially molten layer above the outer core at the base of the mantle.

lithosphere and asthenosphere

the upper mantle is made up of the…


the layer of the upper mantle that is solid, but mobile


the layer of the upper mantle that is solid and relatively rigid

oceanic and continental

what are the two types of crust?

atmosphere thins

what happens as move away from the earth’s surface?


molten rock located below the surface


molten rock erupted above the ground

high heat and pressure

What are the two most important driving forces of metamorphism?


_____ igneous rocks are those that cool below the surface.

cementation and compaction

What are the two important processes involved in lithification of sedimentary rocks?

metamorphic and sedimentary

An igneous rock becomes buried, is subject to high heat and pressure, and recrystallizes. This rock then is eroded, transported, deposited and subsequently lithified. Which rock types—in order—did the original igneous rock develop into?

Canadian Shield, Appalachians, North American Cordillera

the order in which major features of North America were formed?

continental shield

very old, stable regions composed of igneous and metamorphic rocks

age and degree of erosion

What main characteristics are used to distinguish the two types of mountain belts?

wegner’s continental drift

Continents were formerly in different positions on the Earth and have shifted to their present locations over time.

warm, humid climate near equator

Late Paleozoic sedimentary rocks often contain extensive coal seams that were used to support the existence of Pangaea. What would the climate have been at that time and at the location where the coal deposits were formed, and what would it indicate about the continent’s past latitude?


What evidence supports that the glaciers on the southern continents were once part of a single, massive ice sheet?

crust; upper mantle

The lithosphere is composed of material from the ________ and the rigid part of the ________.

east african rift valley

A location where continental rifting is occurring today is ________.

2 cm/yr

A typical rate of seafloor spreading in the Atlantic Ocean is ________.

oceanic oceanic

Which type of convergence will result in a volcanic island arc?

ocean floor

Where are the majority of transform faults located?

distance from the rift and age of seafloor sample

What two pieces of information would researchers need to have in order to calculate the rate of plate motion for seafloor spreading?

slab pull

Which factor contributes the most toward plate motion?

deep ocean trenches

the subduction of lithosphere into the asthenosphere form..


Naturally occurring
Definite chemical composition
Orderly crystalline structure

ionic bond

Complete transfer of electrons between atoms





oxygen and silicon

what are the two most abundant elements in earth’s crust?


what minerals make up half of earth’s crust?

silicon oxygen tetrahedron

four-sided figure with a silicon atom in the middle bonded to four neighboring oxygen atoms.


The micas (biotite and muscovite) exhibit what type of silicate structure?

different numbers of neutrons

Two isotopes differ from one another because they have _____.


An ion with a surplus of electrons _____.

igneous rocks

rocks are formed by the cooling and crystallization of molten rock.

fine-grained texture

the product of rapid cooling and crystallization of lava.

intrusive; below the surface

A phaneritic texture is characteristic of a(n) __________ igneous rock that cooled __________.

aphanitic texture

The igneous rock exhibits mineral crystals too small to see with the naked eye.

olivine; mantle

Ultramafic rocks contain __________ and are commonly found in __________.

accessory mineral

A mineral that makes up a relatively small portion of the total rock composition

Andesite porphyry

What is the rock name of an intermediate rock with two distinct grain sizes?

introduction of water

At a subduction zone, melting is triggered by _____.

geothermal gradient

What is the term used to describe increased temperature with depth in the Earth?

Felsic magma and mafic residue

Once a source rock partially melts, what does it produce?


According to Bowen’s Reaction Series, __________ is one of the first minerals to melt, but last to crystallize.

basaltic magma transformed into felsic magma

Basaltic magma partially melts the continental crust, which is more felsic in composition.

Decompression melting of the mantle

What causes an elevated geothermal gradient in a divergent plate setting?

the melting temperature of mantle rocks to decrease

In a subduction zone, water driven from subducted oceanic crust causes __________.

explosive eruption

volcano fed by silica rich magma; volcano fed by water rich magma

nonexplosive eruption

volcano fed by mafic magma;volcano fed by low amounts of dissolved gasses; volcano fed by high temperature magma

balsatic composition

glow in sheets; 90% of lava on earth; fast lava flow

andesitic composition

intermediate lava flow

rhyolitic composition

1% of lava on earth;silica-rich lava; slow lava flow

aa flow

lava landform with rough,broken surface caused by rapidly moving basalt that cools quickly

pahoehoe flow

lava landform with smooth, billowy surface caused by slowly moving basalt that are still hot

lava tube

lava landform which results from a relatively fluid lava cooling and forming an outer shell through which the flow continues to flow

block lava

lava landform with rough surface of smooth-sided fragments formed by viscous lava cooling quickly.

pillow lava

lava landform of solid, bubble-like masses caused by lava quenching extremely quickly

ring of fire

volcanism caused by convergent oceanic-oceanic boundaries
volcanism caused by convergent oceanic-continental boundaries

divergent oceanic oceanic

What type of boundary is present along the eastern boundary of the North American plate?

oceanic hot spot

At what tectonic setting is Hawaii located?

decompression melting

What drives melting at divergent boundaries?

transform boundary

tectonic settings that does not produce volcanism


In order to cover such large expanses of seafloor, shield volcanoes erupt ________ lava.

more gas than shield volcanoes

Based on the structure of the cone and the rock making it up, what interpretations can be made about the gas content of eruptions from cinder cone volcanoes compared to those of shield volcanoes?

shape and type of deposits

What information do geologists use to classify volcanoes?

pyroclastic deposits

cinder cones are made of ____.


In general, how often do most cinder cones erupt?

basalt flows

What are shield volcanoes generally made of?

300-1000 m

What is the range of shield volcano height?

pyroclastic deposits

What are composite volcanoes made of?

felsic magma

What type of magma erupts out of dome complexes?

shield volcanoes

What type of volcanoes are the highest?

500-2000 m

What is the range of dome complex height?


Lavas erupting from composite cones are generally ________-rich, making them very viscous.

physical weathering

Mechanical processes break substances into smaller pieces.


Which of the following rocks would most likely experience sheeting?


When sheeting develops in an igneous pluton, fractures will develop in an orientation __________ to the direction of expansion.

volume increase

What changes are occurring in the igneous pluton that would result in sheeting?

differential weathering

__________ is when various geologic materials exposed to the same environmental conditions will weather differently depending on their composition.

physical geology

the materials composing earth and seeks to understand the many processes that operate beneath and upon its surface.


earth’s landscapes were shaped primarily by great catastrophe. (Ussher)


the physical, chemical, and biological laws that operate today have also operated in the geologic past. (Hutton)

nebular theory

the bodies of our solar system evolved from an enormous rotating cloud


The geological process by which the Earth came to have its present interior structure


earth’s relatively think, rocky outer skin

continental crust

thicker, less dense, and more silica rich (granitic) crust

oceanic crust

thinner, more dense, and more mafic (basaltic) crust


below the crust, omprised of ultramafic rocks (rich in iron & magnesium, poor in silica)// the largest part of the earth

outer core

below the mantle, liquid// generates earth’s magnetic field

inner core

solid iron, below outer core


rock that forms from crystallization of magma or lava


rock that forms from accumulation of sediments produced by weathering and erosion


rock that forms from heat and/or pressure applied to existing rocks


where plates move apart and new oceanic crust is formed — Mid-Ocean Ridges


where plates move toward each other and oceanic crust is “recycled” into the mantle ocean-ocean and ocean-continent subduction zones and continent-continent collision


where plates move past each other horizontally — strike-slip faults e.g., the San Andreas

average rates

1 to 10 cm/yr

east african rift

example of early rifting

red sea rift

example of intermediate rifting

transform boundaries

Basic types: ridge-ridge (most common) with earthquakes occurring between ridge segments and aseismic fracture zones outside , ridge-trench, trench-trench
b. San Andreas fault system – right-lateral (strike-slip) are examples of…

convergent boundaries

ocean ocean, ocean continent, continent continent are examples of…

ocean ocean

lesser antillas, marianas

ocean continent

Andes, Cascades

continent continent

himalayas, appalachians

mantle plume

a cylindrically shaped upwelling of hot rock. located beneath hawaii

hot spots

an area of volcanism, high heat flow, and crustal uplifting that is a few hundred kilometers across


atoms with the same number of protons (same element) but different numbers of neutrons and
therefore different atomic masses


positively (cation) or negatively (anion) charged atoms (protons and electrons are not balanced)

covalent bond

form through sharing of outer (valence) electrons between atoms


most abundant element in earths crust


second most abundant element in earth’s crust

feldspars & quartz

important silicate rock forming minerals


important non silicate rock forming minerals

chains, sheets, framework

common silicate structures

mohs scale

hardness scale consisting of 10 mineral arranged in order from 1 (softest) to 10 (hardest)


tendency of a mineral to break along planes of weak bonding.


fine grained igneous rock texture


coarse grained igneous rock texture


faster cooling near the surface creates fine grained called..


slower cooling at depth creates coarse grained called.. aka plutonic


Quartz, Potassium Feldspars, Na-rich plagioclase are what kind of minerals?


Olivine, Pyroxenes, Ca-rich plagioclase are what kind of minerals?

decompression melting

when confined pressure drops significantly, _____ is triggered.

flux melting

water content that affects melting is called..

bowen’s theory

Discontinuous branch – Olivine, Pyroxene, Amphibole, Biotite
Continuous branch – Ca-rich to Na-rich Plagioclase feldspar
Last to crystallize – Potassium feldspar and Quartz


removal of early formed crystals (e.g. through crystal settling) results in a change in the
composition of the remaining magma (becomes more felsic)

partial melting

felsic minerals melt at lower temps and thus will melt first, so if a rock undergoes partial
melting, it will tend to produce a magma enriched in silica, Al, Na, & K.


largest, gentle slopes, basaltic lava flows


large, steep, lava flows and pyroclastics

cinder cones

steepest, small, pyroclastics


steep, viscous, plug vent


(lava flows) at shields, common eruption type


(pyroclastics) at com-
posite, cinder cones, & domes, common eruption type

spheroidal weathering

the rounding of rock due to more rapid weathering of corners and edges

frost wedging

results in expansion of cracks in rocks due to freeze/thaw cylces; frost heaving lifts rock and soil vertically through free/thaw cycles.

thermal cycling

large temperature swings break up rocks through expansion and contraction


when oxygen from the atmosphere reacts with minerals – particularly iron bearing minerals like pyroxenes to produce iron oxides like hematite and limonite


acidic rain water and ground water react with feldspar minerals to produce clay minerals (hydrous aluminum sheet silicates)


mineral not susceptiable to chemical weathering


climates generally lead to more rapid chemical weathering


higher _____ generally lead to more rapid chemical weathering. Freeze/thaw cycles in temperate climates can lead to more rapid mechanical weather through frost action

soil horizons

from top down: O – organic matter; A – organic matter mixed with minerals; E – zone of leaching; B – zone of accumulation of clays/Fe oxides; C – fragmented bedrock