GEO 101 UA Flashcards

Terms Definitions
What is Geology?
The study of the Earth, including our planet's composition, behavior, and history.
What is Physical Geology?
The study of physical features of the earth's surface.
What is uniformitarianism?
The belief that Earth's past geological changes can be fully explained by processes taking place now.
What is the concept of uniformitarianism and why is it important ?
The present is the key to the past. Uniformitarianism is important because it helps geologists understand how earth worked in the past
Geologic Time
The span of time since the formation of the Earth.
How old is the Earth?
4.57 Billion years-old
How is the age of earth determined?
By the decay of long-lived radioactive isotopes of elements that occur naturally in rocks and minerals and that decay with half lives of 700 million to more than 100 billion years to stable isotopes of other elements.
Magnitude of Geologic Time
Involves vast times- millions or billions of years (Geologic process may be gradual or rapid)
The Nature of Scientific Inquiry
Science assumes the natural world is consistent and predictable, goal of science is to discover patters in nature and use the knowledge to make predictions, scientists collect data through observation and measurements.
Hypothesis
A proposal intended to explain certain facts or observations
Theory
a well-substantiated explanation of some aspect of the natural world
Scientific Methods
a series of steps followed to solve problems, including collecting data, formulating a hypothesis, testing the hypothesis, and stating conclusions
Subsystems of the Earth
The Atmosphere, The Crust, The Mantle, The Core, The Lithosphere and Asthenosphere
Geology and its effects on our lives
Global Warming, Tsunamis, Earthquakes, Economy, Resources
Origin of Planet Earth
The Big Bang Theory
Nebular theory
theory that the sun and the planets condensed out of a spinning cloud of gas and dust
Solar Nebular Hypothesis
a giant cloud of dust and gas collapsed (about 5 billion years ago this happened and created our solar system)
Origin of the Solar System
Solar Nebular Hypothesis
Inner Core
Depth of 5,155 km to 6,371 km, is a solid iron-nickel alloy that may reach a temperature of over 4,700 degrees Celsius
Outer Core
Depth of 2,900 km and 5,155 km deep, is a liquid iron alloy (because of high temperature), a layer of molten iron and nickel that surrounds the inner core of Earth
The Mantle
2,885-km-thick layer surrounding the core, It is the intermediate layer. The outermost part is solid and the deepest one is formed by molten rocks
Upper Mantle
depth of 400 km, layer of the earth that is a plastic like solid yet flows under pressure
Lower mantle
Extends to core; does not melt b/c of high pressure
Asthenosphere
The solid, plastic layer of the mantle beneath the lithosphere; made of mantle rock that flows very slowly, which allows tectonic plates to move on top of it
Lithosphere
the solid, outer layer of the earth that consists of the crust and the rigid upper part of the mantle
Crust
the thin and solid outermost layer of the Earth above the mantle
Oceanic Crust
7 to 10 km thick
Continental Crust
35 to 40 km thick
Plate Tectonics Theory
Theory that great slabs or plates of Earth's outer layer float on a hot, semi-molten mantle. All plates are moving slowly and have rafted continents to new positions over time.
Divergent Boundaries
(a.k.a. normal faulting) is a place where 2 plates move apart. Most of these types of boundaries occur at the mid-ocean ridge. On land, this boundary is called a rift valley, such as the Great Rift Valley in East Africa and the Rio Grande in Texas.
Convergent Boundaries
(a.k.a. reverse fault) is a place where 2 plates come together. At places where oceanic crust converges, the denser oceanic crust will dive under the other (subduction). At places where oceanic crust and continental crust converge, the denser oceanic crust will dive under (subduction) the less dense continental crust. At places where 2 continental crusts converge, subduction does not take place. Rather, the plates crash and squeeze rock up into mountains!!!
Continental-continental convergent plate boundaries
areas of great compression and mountain building
Continental-oceanic plate convergent boundaries
Denser oceanic slab sinks into asthenosphere, along descending plate partial melting of mantle rock generates magma
Oceanic-oceanic convergent plate boundaries
When two oceanic slabs converge, one descends beneath other, Often forms volcanoes on ocean floor
Divergent plate boundaries
occur when two oceanic plates move apart from one another. Results in oceanic ridges. Magma flows into the resulting cracks oceanic ridges under the surface of the ocean.
Mid-oceanic ridge
The longest mountain range in the world; all along the center of the Atlantic Ocean; formed by active volcanoes through sea floor spreading
Rock Types
sedimentary, igneous, metamorphic
Rock Cycle
sequence of events in which rocks are formed, destroyed, altered, and reformed by geological processes
Igneous Rocks
rocks formed by the cooling of molten rock (either magma or lava)
Sedimentary Rocks
Rocks formed from the weathering, erosion, deposition, and compaction of other rocks
Metamorphic Rocks
formed from preexisting rock subjected to heat and pressure (rock is solid, but minerals break down, form, change shape)
Wegner's hypothesis of continental drift
suggested a super continent (Pangaea) existed until the Mesozoic era, then broke apart to form the continents we see today- these continents drifted from each other
Evidence for Continental Drift
the fit of the continents, locations of past glaciations, the distribution of equatorial climatic belts, the distribution of fossils, and matching geologic units
Paleomagnetism
The study of the alignment of magnetic minerals in rock,specifically as it relates to the reversal of Earth's magnetic poles; also the magnetic properties that rock requires during formation.
The Earth's magnetic field
is believed to arise from currents in the Earth's core.
Seafloor Spreading (the beginning of a revolution)
The process that creates new sea floor as plates move away from each other at the mid-ocean ridges
Evidence for new crust
Magnetic Anomalies
Plate Boundaries
the edge of a tectonic plate
Plate tectonics
the theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle
Hot spots
areas of volcanic activities that result from plumes of hot solid material that have risen from deep inside earths mantle
Birth and death of plates
Continental Rifting and collision
Mantle convection
The driving force of plate tectonics
What is matter?
anything that has mass and takes up space
What is matter composed of?
All matter is composed of mass
Types of matter
Solids, liquids, gas, plasmas.
How do we know if something is a mineral?
Is it a solid? Is it inorganic? Is it formed in nature? Does it have a crystalline structure?
What is a rock?
A mixture of minerals, rock fragments, volcanic glass, or other natural materials.
Crystalline
consisting of or containing or of the nature of crystals
What is amorphous?
No definite structure
What is an element?
many of the SAME kind of atom
What is an atom?
the smallest particle of an element
Structure of atoms
Neutrons, Electrons, Protons
Neutrons
the particles of the nucleus that have no charge
Electrons
negatively charged particles
Protons
Positively charged particles
How is an atom's identity determined?
by number of protons in atom's nucleus
Atomic Number
Number of Protons
Atomic Mass Number
Number of Neutrons and Electrons
Types of Chemical Bonds
Ionic, Covalent, Metallic, van der Waals bonding
Ionic bonds
formed when one or more electrons are transferred from one atom to another
Covalent bonds
form when electrons are shared between atoms
Metallic bonds
consist of the attraction of the free-floating valence electrons for the positively charged metal ions
van der Waals bonding
sheets of covalently bonded atoms held together by weak electrostatic electrical forces, very weak bonds
Isotopes
atoms of the same element that have different numbers of neutrons
Mineral Structure
naturally formed, inorganic, solid, definate crystalline structure
Polymorph
One of two or more alternative possible crystal structures for a single chemical compound; for example, the minerals quartz and cristobalite are polymorphs of silica (SiO2).
Does internal structure determine the external shape?
yes
Halite structure
isometric
Properties of minerals
color, luster, hardness, streak, density, crystal shape, cleavage and fracture, and special properties (such as magnetism & smell)
Is color a good diagnostic feature?
No
Moh's hardness scale
a scale ranking ten minerals from softest to hardest; used in testing the hardness of minerals
mineral fracture
tendency of some minerals to break unevenly along curved or irregular surfaces
mineral cleavage
determined by a minerals structure is the tendency to split along definite planes
Specific Gravity
ratio of a mineral's weight compared with the weight of an equal volume of water
Rock Forming Minerals
Minerals that make up most of the rock's crust. 20 minerals make up the earth's crust. Ex.: Granite is made of quartz, feldspar, hornbelnde, and mica.
Silicates
rocks made of compounds of silicon and oxygen
Most abundant elements in the continental crust
silicates
Silicon-oxygen tetrahedron
a structure composed of four oxygen atoms surrounding a silicon atom that constitutes the basic building block of silicate minerals
Silica groups
Independent tetrahedra, single chains, double chains, sheet silicates
Common silicates
Quartz and feldspar
Silica tetrahedron
Basic building block of silicate minerals, made up of four oxygen atoms and 1 silicon aton
Ferromagnesian
subgroup of silicate minerals that form rocks; based on presence of iron, magnesium, calcium etc. Olivine
Nonferromagnesian
do not have iron and magnesium, feldspar
Non-silicate mineral groups
Carbonate, Halite, native, oxides, sulfates, and sulfides
Types of Igneous rocks
intrusive extrusive
Intrusive Igneous rocks
rocks formed from the cooling a magma beneath the earth's surface
Extrusive Igneous rocks
rocks formed from molten lava that hardens on the earth's surface
What is Magma?
Magma is molten, hot, liquid rock under the Earth's surface.
Properties of igneous rocks
Magmatic consolidation, both crystalline and non-crystalline, non-porous, poorly eroded, no fossils 40-80% silica
Aphanitic
Rapid cooling at earth's surface results in tiny mineral crystals that can only be seen under a microscope.
Phaneritic
coarse-grained, crystals are large enough to be seen w/out a microscope, formed by slow cooling (intrusive)
How are crystal sizes related to cooling rates?
the slower they cool, the larger the crystals are
Volcanic Igneous rocks
created when rocks are melted through enormous amounts of heat and pressure and liquid magma is forced through other rocks to erupt on Earth's surface as lava
Glassy texture
a term used to describe the texture of certain igneous rocks, such as obsidian, that contain no crystals
Pyroclastic texture
an igneous rock texture resulting from the consolidation of individual rock fragments that are ejected during a violent eruption
Pegmatitic
Very large crystals formed by extremely slow cooling, or in the presence of water.
Felsic
Describes magma or igneous rock that is rich in feldspars and silica and that is generally light in color.
Intermediate igneous rocks
midway between felsic and mafic ends of the scale.
mafic
describes magma or igneous rock that is rich in magnesium and iron and that is generally dark in color
ultramafic
Igneous rocks with low silica content and very high levels of magnesium
How does silica content vary from Felsic to Ultramafic?
Felsic- highest silica content, Ultramafic- lowest silica content
Felsic viscosity
highest viscosity
Ultramafic viscosity
lowest viscosity
How does silica content affect viscosity?
The more silica is in a magma the more viscous the magma will
mafic basalts
fine grained, pyroclastic, vesicular, Amygdaloidal
felsic rhyolites
SiO2=70%, Fe-Mg poor, low temp, high viscosity, formed at hot spots, continental rifts
viscosity
a liquid's resistance to flow
explosivity
rate of volcanic explosion. high rates= more dangerous
What types of magma are more viscous?
Felsic rhyolites
Origin of Magma
melting of preexisiting rock
What is the geothermal gradient?
The gradual increase in temp. with depth in the crust--know relation to magma
evolution of magmas
Felsic magma can evolve from mafic magma.
Progressive removal of mafics depletes Fe, Mg, and Ca. Remaining melt becomes enriched in Na, K, Al, and Si.
Bowen's Reaction Series
the simplified pattern that illustrates the order in which minerals crystallize from cooling magma according to their chemical composition and melting point
Changing Magma Compositions
1.filter pressing
leave mafic minerals behind
2.Assimilation
melt another rock & mix!!
3.Mixing
4.Partial melting
Only melts felsic minerals
Crystal settling
during the crystallization of magma, the earlier formed minerals are denser than the liquid portion and settle to the bottom of the magma chamber
Magma Mixing
altering the composition of a magma through the mixing of material from another magma body
Igneous features
dikes, sills, plutons, batholiths, laccoliths
Weathering
The breaking down of rocks and other materials on the Earth's surface.
Differential Weathering
the process by which softer, less weather resistant rocks wear away and leave harder, more weather resistant rocks behind
Types of weathering
mechanical weathering, chemical weathering
Mechanical weathering
The type of weathering in which rock is physically broken into smaller pieces
Chemical weathering
the process in which rock is broken down by changes in its chemical makeup
Types of mechanical weathering
frost wedging, unloaded/loaded pressure release, thermal expansion, biological activity and abrasion
Types of chemical weathering
dissolution, hydrolysis, oxidation, hydration
Rates of weathering
depend on climate, elevation, and makeup of the rock
Factors affecting weathering
chemical weathering affected by water and temperature. mechanical affected by water, temperature and slope.
Factors Controlling Soil Formation
Parent material and time
Soil horizons
horizontal layers that reveal a soil's history, characteristics, and usefulness
erosion
(geology) the mechanical process of wearing or grinding something down (as by particles washing over it)
rates of erosion
The rate in years at which rock wears away by natural processes, such as a stream eroding its bed. Only practical for features that formed within the last 10000-20000 years.
What controls the rate of erosion?
human activities that remove natural vegetation such as farming, logging and construction.
origin of sedimentary rocks
deposited at earth's surface, temp cool, pressure low, transported by wind, water, ice, typically deposited as LAYERS or STRATA
diagenesis
a collective term for all the chemical, physical, and biological changes that take place after sediments are deposited and during and after lithification
How does diagenesis change sediment into a sedimentary rock?
by lithification
Detrital
sedimentary rocks made from the broken fragments of other rocks that are compacted and cemented together
Chemical sedimentary rocks
form when minerals are precipitated from a solution or left behind when a solution evaporates
detrital example
clay minerals and quartz
Breccia
a rudaceous rock consisting of sharp fragments embedded in clay or sand
conglomerate
a composite rock made up of particles of varying size
Chemical sedimentary rock example
limestone, rock salt
Stages of coal formation and grades
1. peat 2. soft coal 3. hard coal
Sedimentary environments
Dunes, beaches, streams, glacier deposits, etc., a geographic location characterized by environmental conditions and geological processes
Sedimentary textures
clastic, non-clastic
Clastic
texture which results when fragments of rock are lithified, discrete fragments and particles can be identified
Non-clastic
other textures including crystalline, amorphous, and biochemical; crystalline rocks have pattern on interlocking crystals. Discrete particles can not be seen when looking at a rock in your hand
Explosivity factors
the more explosive volcanoes are depends on how frequently the tectonic plates move.
Factors affecting viscosity
Chemical composition of magmas (more silica content=more viscous), temperature (hotter temperature=less viscous), amount of dissolved gases
Types of Volcanic eruptions
magmatic eruptions, Phreatomagmatic eruptions , Phreatic eruption
Pahoehoe
fast-moving, hot lava that has low viscosity
Aa lava
Slow moving, rough lava. (high viscosity)
Lava tubes
A natural conduit through which lava travels beneath the surface of a lava flow, they form by the crusting over of lava channels and pahoehoe flows
Pillow Lavas
lava that solidifies in an underwater environment and develops into a structure like a pillow
Pyroclastic Materials
the volcanic rock ejected during an eruption including ash, bombs, and blocks
Ash
the smallest lava fragment produced by a volcano.
lapilli
pebble like bits of magma that cool in the air
Volcanic bombs
A projectile of hot magma or rock that is blown from the vent during a volcanic eruption. These solidify in flight and frequently form an elongated rock of streamlined shape.
Structure of Volcanoes
molten rock in the asthenosphere finds weakness in the crust, creating a central vent. Secondary branches will form
Volcano Features
magma chamber, fissures and vents, craters, calderas
magma chamber
the pocket beneath a volcano where magma collects
fissures and vents
conduit from the magma chamber to surface; makes linear tear form magma to erupt
volcanic craters
a bowl-shaped opening at the top of a volcano
caldera
a large crater caused by the violent explosion of a volcano that collapses into a depression
Fumarole
a vent in a volcanic area from which fumes or gases escape
Types of Volcanoes
Shield; Composite Cone; Cinder Cone
Shield Volcano
A low, flat, gently sloping volcano built from many flows of fluid, low-viscosity basaltic lava
Composite Volcano
a tall, cone-shaped mountain in which layers of lava alternate with layers of ash and other volcanic materials
Volcanoes impact on humans/ environment
Dormant- rich soil from chemicals of past explosions
Active volcanoes-ash, flying molten rocks, shockwave of sound, landslides, Nuee ardentes (huge cloud of gas)
Underwater volcanoes- can cause tsunamis after eruption
Pyroclastic flow
The expulsion of ash, cinders, bombs, and gases during an explosive volcanic eruption
Nuee ardentes
superheated ash/gasclouds that race down slope (about 60 mps) blast laterally from the side of cone, or collapse from a tall column of ash/gas in the atmosphere
Lahars
mudflows (water mixed with ash)
Caldera formation
formed when massive explosive eruption causes collapse of a volcano into its magma chamber
Fissure Eruptions
the eruption of lava from a crack in the lithosphere rather than from a central vent. columbia plateau, hawaii
Flood basalts
Hot spots under continents: Example: 50MA before now, vents opened near Kamploos and flood basalts accumulated in the valleys to the depth of 2400m
Lava Domes
inside other volcanoes, felsic magmas from melting of continental crust
Volcanic necks
Remains of cooled magma in the pipe of a volcano. They become exposed when the softer rock around the pipe wears away.
Volcanic pipes
brings magma from magma chamber towards the surface
Plutons
magma that stops moving before it reaches the surface and cools into mineral crystals
Dikes
Formed when magma squeezes across rock layers and cools (vertically).
Sills
Formed when magma squeezes between rock layers and cools (horizontally).
Batholith
large mass of intrusive igneous rock believed to have solidified deep within the earth
Intrusive igneous rock
rock formed from the cooling and solidification of magma beneath Earth's surface
laccolith
a hardened magma chamber
Concordant
an intrusive igneous mass that formed parallel to the bedding of the surrounding rock. Laccolith, Lopolith, Phacolith, Sill
discordant
an intrusive igneous mass that formed on top of the bedding or surrounding rock. batholith, dike, stock
Hot spot locations
above the hottest parts of the mantle
Hot spot magma
basaltic magma (continental hot spots also have rhyolitic debris)
Volcanic effects on climate
can trigger coolness in volcanic area
Mid-Oceanic Ridges
mountain ranges at divergent boundaries in oceanic crust, created by magma rising to Earth's surface and cooling (new lithosphere), example Mid-Atlantic Ridge
Type of Magma associated with divergent plate boundaries?
basaltic
felsic rock location
continental crust
circum-pacific belt (ring of fire)
belt around pacific ocean on which most composite volcanoes are located and where earthquakes occur
mafic rock location
derived from mantle
Location of Volcanoes
Most volcanoes occur along plate boundaries or at hot spots in the crust. Volcanoes can occur along a converging plate boundary where an oceanic plate is subducted into the mantle.
Convergent plate boundaries
Two plates colliding and creating either a mountain range (2 continental) or a subduction zone (2 oceanic), or trench (oceanic and continental)
Types of Magma
Basaltic magma
Andesitic magma
Rhyolitic magma
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