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GEO110 EXAM 1
GEO
70
Geology
Undergraduate 4
10/04/2011

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Term
List the physical properties of minerals?
Definition
luster, streak, hardness, cleavage, fracture, crystal shape, color, effervesece (reaction to acid)
Term
All silicate minerals contain which two elements?
Definition
Silicon and Oxygen
Term
What is the term for the tendency of a mineral to break along flat surfaces or planes of weak bonds?
Definition
Cleavage
Term
Which mineral reacts readily with cool, dilute hydrochloric acid to produce visible bubbles of carbon dioxide gas?
Definition
Calcite
Term
What is the name of the most common mineral group?
Definition
Silicates
Term
How are igneous rocks classified?
Definition
texture and composition
Term
List at least 3 common igneous rock textures.
Definition
Coarse grained, fine grained, porphyritic, glassy, vesicular
Term
What is the composition of a felsic rock?
Definition
High in Si, Al, Na, K - low in Fe, Mg,Ca - minerals such as quartz, kspar
Term
What is the composition of a mafic rock?
Definition
High in Fe, Mg, Ca - low in Si, Al, K - contains minerals such as olivine, pyroxene, Ca plagioclase
Term
Produces a magma made of the lowest melting temperature minerals, which are higher in silica than the original rock.
Definition
partial melting
Term
Name one type of igneous intrusion and describe it.
Definition

sill, dike, batholith

Sill = nearly horizontal, concordant bodies that form when magma exploits weakness btwn sedimentary beds

-generally stores magma

Dike = discordant bodies that cut across bedding surfaces or other sturcture in the host rock

-serve as tabular conduits that transport magma

Term
Shield volcanoes are composed of what type of lava?
Definition
basaltic
Term
Composite volcanoes are generally composed of?
Definition
alternating layers of pyroclastic materials and lava of intermediate composition
Term
What type of magma is required to have explosive volcanic conditions?
Definition
felsic, gas rich
Term
What is the main volcanic hazard from a composite volcano (ex. Mt. St. Helens)?
Definition
Pyroclastic flows, mudflows, nuee ardentes
Term
What is the definition of a theory?
Definition
rigorously tested and generally accepted by the scientific community
Term
How are earth's layers arranged?
Definition
increasing density with depth
Term
List the layers of the earth in order from inside out and describe their physical state.
Definition
DRAW the chart: inner solid core, outer liquid core, solid mantle, solid crust
Term
Where in the Earth's subsurface do we find convection currents, and why are they important?
Definition
mantle--mechanism for plate motion
Term
Imagine yourself standing in a universe exhibiting blue shift, what does that tell you about the universe?
Definition
It is collapsing instead of expanding like it does when exhibiting red shift
Term
Describe 3 conditions that cause rock to melt?
Definition
1. temperature, 2. composition of the rock, 3. volatiles in the rock
Term
How did the Earth and other planets in our solar system originate?
Definition
According to Big Bang theory a huge explosion occurred which sent all matter of the of the universe flying outward at incredible speeds. Then once the debris from this explosion (mostly hydrogen and helium) began to cool and condense the galaxies formed
Term
Sketch a cross section of the Earth & include a table that describes the composition and physical make-up of earth's layers
Definition
Term
Theory of Plate Tectonics
Definition
Earth’s surface is divided into plates that are slowly moving and changing in size
Term
what are the three types of plate boundaries?
Definition
Transform, convergent, divergent
Term
Transform
Definition
plates move side to side in relative motion
•conservative
•2 plates grind past eachother without production or destruction of lithosphere
•shallow earthquakes
Term
Convergent plate boundary
Definition
coming together (destructive)
•2 plates move together resulting in oceanic lithosphere descending (subducting) beneath an overriding plates, eventually to be reabsorbed into mantle or possibly in the collision of 2 continental blocks to create a mountain system
•subduction occurs because the density of descending tectonic plate is greater than density of underlying asthenosphere
•deep sea trenches
Term
Divergent plate boundary
Definition
plates moving away from eachother (constructive)
•2 plates move apart resulting in upwelling of hot material from the mantle to create new seafloor
•ocean ridges
Term
Describe how density has played a part in the development of a) our solar system and b) planet.
Definition
Term
7. Describe how red shift works, and how it is used to support the Big Bang Theory.
Definition
Redshift is essentially just the Doppler effect for light. Red light has lower frequency, so if the light source is moving away from you, its light will be slightly redder, and if it moves towards you, it is bluer.
Term
Describe the steps leading to the formation of our solar system, including the observations used to interpret that history (Solar Nebula Theory).
Definition
Big bang happened. The nonce everything started cooling galaxies formed and so did our solar system. Earth and other planets formed at roughly the same time and from the same primordial material as the sun. The bodies of our solar system evolved from an enormous rotating cloud called the solar nebula.
Term
9. What is the scientifically accepted age of the Earth? Age of the Universe? Describe how these numbers have been determined
Definition
Earth = 4.6 Ga, Universe = 13.7 billion
determined by finding out the age of Earth's rocks b/c we can use D = r x t since we know the velocity of the objects and distance between most of them
Term
What are minerals, and how are they different from rocks?
Definition
Chemical formula-definable chemical composition
Orderly crystalline structure
Inorganic
Naturally occuring
Solid

Any naturally occurring inorganic solid that possesses an orderly crystalline structure and can be represented by a chemical formula. Minerals make rocks
Term
What is the basic structure of an atom?
Definition
protons, neutrons, electrons; protons & neutrons make up the nucleus & the electrons form a cloud around
Term
How do atoms bond together?
Definition
Covalent bonds: electrons shared; diamond, nonmetal atoms that don't loose electrons easily = strongest
2.metallic bonds- electrons free to move from A to A, gold, silver, copper
3.ionic bond-electrons transferred, so neutral; weakest
Term
Sketch and describe the forces that drive plate motion (Figure 15.29 in book)?
Definition
Term
How are igneous rocks formed?
Definition
by the crystallization of molten magma. Magma erupts via volcano or fissures (crack) – molten rock cools and solidifies
Term
Extrusive/volcanic
Definition
Igneous rocks that form due to the crystallization of melts above the surface of the earth
Term
intrusive/plutonic
Definition
Form by the crystallization of melts beneath the surface of the Earth
Term
Magma vs. Lava
Definition
Magma = (interior)a body of molten rock found at depth, including any dissolved gases and crystals
Lava = (exterior)magma that reaches Earth’s surface
Term
How does the cooling rate of magma influence the crystal size of minerals in igneous rocks?
Definition
When magma cools so quickly that atoms don’t have time to arrange into a crystal lattice
-Fine grained = fast cooling
-Coarse grained = slow phenocrysts
Term
Bowmen's Reaction Series
Definition
a series of crystallization sequences that occur during magmatic cooling. This series shows the order in which minerals will crystallize first (olivine) and all the way down to quartz (SiO2) in the discontinued branch.
-rocks that are partially melted necome more mafic because the silica-rich felsic minerals are melted first
Term
How do granitic rocks differ from basaltic rocks?
Definition
Granitic (intrusive) phaneritic/coarse grained texture
Basaltic (extrusive) aphanitic/fine grained texture
Term
Aphanitic
Definition
mineral grains too small to be seen without a magnifying glass.
Term
Phaneritic
Definition
mineral grains large enough to be seen without a magnifying glass.
Term
felsic
Definition
-lighter color more silicates Si O2– quartz and feldspar-
-more viscous slower moving
-more explosive
-granitic
Term
mafic
Definition
darker color- increase in Fe and Mg
-less viscous so more runny
-basaltic
Term
ultramafic
Definition
- most dense, least viscous, moves the quickest
Term
glass texture of igneous rock
Definition
extrusive
-melt cooled so quickly that atoms don't have time to arragne into a crystal lattice
-fine grained = fast cooling
Term
phenocrysts
Definition
intrusive
-coarse grained = slow cooling
Term
pyroclastic texture
Definition
- form from the accumulation of igneous debris ex.) volcanic ash
-extrusive
-includes other rock fragments
-broken/fragmental = breccia or tuff
-frothy = pumice
Term
vesicular (texture)
Definition
has bubbles
Term
Porphyritic texture
Definition
igneous rock texture characterized by two distinctively different crystal sizes
1. the larger crystals called phenocrysts and the matrix of smaller crystals termed groundmass
Term
The former late Paleozoic super continent is known as
Definition
Pangea
Term
Give one example of an active, continent-continent collision.
Definition
India colliding with Eurasia to form the Himalayas
Term
A very long-lived magma source located deep in the mantle is called a ________.
Definition
hot spot

-does this differ from a mantle plume?
Term
The continental drift hypothesis was rejected primarily because Alfred Wegener could not ________.
Definition
identify a mechanism capable of moving continents
Term
What effects a magma or lava's viscosity?
Definition
-Temp (high temp = less viscosity)
-volatile content (more volatiles = less viscosous)
-silica content (more silica more viscous)
Term
fissure eruptions
Definition
-more mafic
-hot lava, less viscous or flows more quickly
-blankets land
-hot spots & mid atlantic ridges
-need mantle source
Term
shield eruptions
Definition
produced by accumulation of fluild basaltic lavas
-shape = broad slightly domed structure
-most begin on the ocean floor as seamounts
-Hawaiian Islands
-mafic high Fe & Mg
Term
Stratovolcanoes
Definition
-intermediate composition
-erupt more violently
-becomes calderas (giant hole in ground)
Term
pyroclastic flows
Definition
-hot volcanic ash, gas, rocks
-very hazardous materials
Term
cindercones
Definition
-small volcanoes
-composition varies
-typically flow out from bottom
Term
extrusive products of volcanic eruptions
Definition
-gases/aerosols (H2O, CO2, etc..)
-liquids (lava)
-solids (ash)
Hazards, acid rain in areas of V.Erupt
Term
type of lava depends on...
Definition
viscosity (function of temp) & dissolved gases
Hotter = lower viscosity = flows faster
felsic (silica rich) = slow & more viscous' maafic = runny & faster
-more gases = more explosive
Term
basaltic flow
Definition
-mafic
-runny hot
-shield volcano
Term
andesitic flow
Definition
intermediate more silican than mafic
Term
rhyolitic dome
Definition
doesn't flow far
felsic
typically stratovolcanoes
Term
aa vs. pahoehoe flows
Definition
aa = chunky,rough jagged blocks
pahoehoe=smooth surfaces, resemble the twisted braids of rope
Term
composite cones
Definition
-stratovolcanoes
-most picturesque & most dangerous
-cone is large, nearly symmetrical,
-consists of alternating layers of explosively erupted cinders and ash inbedded with lave flow
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