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
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?
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?
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?
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 ________.
A typical rate of seafloor spreading in the Atlantic Ocean is ________.
Which type of convergence will result in a volcanic island arc?
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?
Which factor contributes the most toward plate motion?
deep ocean trenches
the subduction of lithosphere into the asthenosphere form..
Definite chemical composition
Orderly crystalline structure
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 _____.
rocks are formed by the cooling and crystallization of molten rock.
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 __________.
The igneous rock exhibits mineral crystals too small to see with the naked eye.
Ultramafic rocks contain __________ and are commonly found in __________.
A mineral that makes up a relatively small portion of the total rock composition
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 _____.
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 __________.
volcano fed by silica rich magma; volcano fed by water rich magma
volcano fed by mafic magma;volcano fed by low amounts of dissolved gasses; volcano fed by high temperature magma
glow in sheets; 90% of lava on earth; fast lava flow
intermediate lava flow
1% of lava on earth;silica-rich lava; slow lava flow
lava landform with rough,broken surface caused by rapidly moving basalt that cools quickly
lava landform with smooth, billowy surface caused by slowly moving basalt that are still hot
lava landform which results from a relatively fluid lava cooling and forming an outer shell through which the flow continues to flow
lava landform with rough surface of smooth-sided fragments formed by viscous lava cooling quickly.
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?
What drives melting at divergent boundaries?
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?
cinder cones are made of ____.
In general, how often do most cinder cones erupt?
What are shield volcanoes generally made of?
What is the range of shield volcano height?
What are composite volcanoes made of?
What type of magma erupts out of dome complexes?
What type of volcanoes are the highest?
What is the range of dome complex height?
Lavas erupting from composite cones are generally ________-rich, making them very viscous.
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.
What changes are occurring in the igneous pluton that would result in sheeting?
__________ is when various geologic materials exposed to the same environmental conditions will weather differently depending on their composition.
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)
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
thicker, less dense, and more silica rich (granitic) 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
below the mantle, liquid// generates earth’s magnetic field
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
1 to 10 cm/yr
east african rift
example of early rifting
red sea rift
example of intermediate rifting
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…
ocean ocean, ocean continent, continent continent are examples of…
lesser antillas, marianas
a cylindrically shaped upwelling of hot rock. located beneath hawaii
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)
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
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?
when confined pressure drops significantly, _____ is triggered.
water content that affects melting is called..
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)
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
steepest, small, pyroclastics
steep, viscous, plug vent
(lava flows) at shields, common eruption type
(pyroclastics) at com-
posite, cinder cones, & domes, common eruption type
the rounding of rock due to more rapid weathering of corners and edges
results in expansion of cracks in rocks due to freeze/thaw cylces; frost heaving lifts rock and soil vertically through free/thaw cycles.
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
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