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


epoch

largest division of time on the geologic time scale


phanerozoic eon

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


mesozoic

the jurassic period lies in the _____ era.


current

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…


asthenosphere

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


lithosphere

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?


magma

molten rock located below the surface


lava

molten rock erupted above the ground


high heat and pressure

What are the two most important driving forces of metamorphism?


intrusive

_____ 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?


striations

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..


mineral

Naturally occurring
Definite chemical composition
Orderly crystalline structure


ionic bond

Complete transfer of electrons between atoms


carbonates

CO32-


silicates

SiO24-


oxygen and silicon

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


feldspars

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.


sheet

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


different numbers of neutrons

Two isotopes differ from one another because they have _____.


negative

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?


quartz

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


basaltic

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 ____.


once

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?


silica

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


physical weathering

Mechanical processes break substances into smaller pieces.


granite

Which of the following rocks would most likely experience sheeting?


perpendicular

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.


catastrophism

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


uniformitarianism

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


differentiation

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


crust

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


mantle

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


igneous

rock that forms from crystallization of magma or lava


sedimentary

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


metamorphic

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


divergent

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


convergent

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


transform

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


isotopes

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


ions

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


covalent bond

form through sharing of outer (valence) electrons between atoms


oxygen

most abundant element in earths crust


silicon

second most abundant element in earth’s crust


feldspars & quartz

important silicate rock forming minerals


calcite

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)


cleavage

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


aphanitic

fine grained igneous rock texture


phaneritic

coarse grained igneous rock texture


extrusive

faster cooling near the surface creates fine grained called..


intrusive

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


felsic

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


mafic

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


differentiation

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.


shields

largest, gentle slopes, basaltic lava flows


composite

large, steep, lava flows and pyroclastics


cinder cones

steepest, small, pyroclastics


domes

steep, viscous, plug vent


effusive

(lava flows) at shields, common eruption type


explosive

(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


oxidation

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


hydrolysis

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


quartz

mineral not susceptiable to chemical weathering


humid

climates generally lead to more rapid chemical weathering


temperature

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


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