Geology Exam #2

Mantle how many kilometers deep and what is it made up of?

(8 km/s)(peridotite)

Normal faults

- extension, hanging wall down.

geothermometer

because different minerals crystallize and remain stable at different temperatures, we can use a rock's mineral composition as a kind of geothermometer to gauge the temperature at which it formed

P- wave shadow zone

between 105 degrees and 142 degrees

basic intervals of geologic time scale are the ___

eras; -the Precambrian -the Paleozoic -the Mesozoic -the Cenozoic

Foliated

exhibits foliation, which are parallel (or nearly parallel) layers of flat minerals (or cleavage planes) that have been realigned as a result of pressure and re-crystallizatoin

S-wave shadow zone

extends from 105 degrees to 180 degrees

upper continental crust

felsic rocks (granite): 6 km/s = rough values for P-wave velocities in igneous rocks

Ductile deformation causes ____?

folding

Plunging folds

folds rarely stay horizontal, so if the fold dies out or appears to plunge into the ground. if a folds axis is not horizontal it is called a plunging fold with a dipping axis.

faults

fractures with movement along fracture (fault plane).

Which mineral is commonly used to determine a metamorphic P-T path?

garnet

beta decay:

neutron to proton e.g., 87Rb decays to 87Sr

fault types

normal, reverse, strike-slip, thrust

On August 3, 2004 the first new mission to Mercury in 30 years was launched successfully. After 7 years in Space, _____ arrived on March 18, 2011, and entered a mapping orbit.

Messenger

stress

-force applied to rock

The Wilson Cycle

1. rifting during the breakup of a supercontinent 2. passive margin cooling and sediment accumulation during seafloor spreading and ocean opening 3. active margin volcanism and terrain accretion during subduction and ocean closure 4. orogen during the continent-continent collision that forms the next supercontinent

The volume of the continents has increased by about ____

2 km3/year for the past 4 Ga

the focal depth of most earthquakes occurring in continental crust range from about __ to __ km

2 to 20 km

Average geothermal gradient:

20 - 30°C/km

What is the average rate at which temperature increases with depth in the Earth's crust?

30°C/km

The center of the Earth is about ___ km below us ... the deepest well is

6,400; < 15 km.

Largest earthquake measured was a magnitude of?

9.5- Chile

Appalachians extend from ____ to ______

Alabama to Newfoundland.

deep sea drilling vessels such as the ____ _____ have taken cores from sedimentary beds around the worlds oceans. Geologists can use the carbon-14 method to estimate when the shells recovered from these sediments were formed, and they can measure the stable isotopes of oxygen to estimate temperature of the seawater in which the shell-producing organisms lived.

JOIDES RESOLUTION

GRAVITY

Newton: Force of gravitational attraction (F) between 2 masses (m1 and m2) is proportional to the products of their mass and inversely proportional to the square of the distance (D) between their centers of mass: F = G (m1 x m2) / D2 where G = gravity constant

major radioactive elements used in isotopic dating

Parent: Daughter: Uranium-238 Lead-206 Uranium-235 Lead-207 Potassium-40 Argon-40 Rubidium-87 Strontium-87 Carbon-14 Nitrogen-14

Types of Metamorphism

Regional Contact Seafloor Burial Shock (impact) Ultra-high Pressure

Temperature Increases with Depth:

The Geotherm Curve

TORRES DEL PAINE (Patagonia), 4000ft,1300.

The door to the ANDES

HUASCARAN (Peru): (22,204 feet, 6,768 m),

The highest point in the Cordillera Blanca. In 1962 a hanging glacier broke from the mountain's northern flank, killing 6,000 people in the village of Ranrahirca

CHIMBORAZO (ECU): 20,700', 6310 m.

The summit of Chimborazo constitutes the furthest point from the center of the Earth because of the high elevation, the location of the mountain at the equator and the oblateness of the Earth

Seismic tomography can detect relatively warm regions of the mantle because seismic waves?

Travel more slowly through these regions

Metamorphic rocks result from the recrystallization of existing rocks while they are still in a solid state.

True

confining pressure

a general force applied equally in all directions. just as a swimmer feels greater confining pressure when diving to greater depths, a rock descending to greater depths in earth's interior is subjected to progressively increasing confining pressure

glassy texture

a homogenous texture with no visible grains, resembling glass

sedimentary sequence

a series of beds bounded above and below unconformities.

aftershocks

almost all large earthquakes trigger smaller earthquakes called aftershocks. they follow the mainshock, and their foci are distributed in and around the rupture plane of the mainshock. -aftershock sequences can't be described by the simple elastic rebound theory -although fault slipping during mainshock decreases the stress along most of the rupture surface it can increase the stress on parts of the fault surface that did not slip or where the slip was incomplete, as well as in the surrounding regions. -they occur where that stress exceeds the rock strength

Types of Radioactive Decay

alpha decay beta decay electron capture

The pyroxene-bearing granulites are the products of high-grade metamorphism in which the temperature is high and the pressure is moderate. The opposition condition, in which pressure is high, and temperature is moderate, produces rock of the ___grade

blueschist grade -comes from parent rocks or various starting compositions, from mafic volcanic rocks to shaley sedimentary rocks

Earthquakes occur when

brittle rocks being stressed suddenly break along faults

Domes -

circular anticlines

micro-crystalline

composed of medium to coarse grade textures, crystals are fine grained or barely visible

crystalline

composed of medium to coarse grade textures, visible crystals

Reverse faults

compression, hanging wall up

the largest earthquakes occur at

convergent boundaries

unconformities are classified according to the relationships between the layers above and below them. types of unconformities:

disconformity, nonconformity, and angular unconformity

syncline

down-arched fold into troughs (youngest strata in middle).

The Late Heavy Bombardment explains why so few rocks on Earth have ages ______ than _____ billion years. It is this event that marks the end of the _____ eon and the beginning of the ____ eon

greater than 3.9 billion years, Hadean eon and the beginning of the Archean eon

MOUNTAINS are located at ____ and _____

hot spots and plate boundaries

Relative dating (fossils, structure, cross-cutting relationships):

how old a rock is compared to surrounding rocks

the two gases that form nebulae clouds are

hydrogen and helium, the two elements that make up all but a small fraction of our sun.

the travel times and paths of P and S waves an be used to contrast models of Earth's ____ ____

internal layers

Intensity

is a measure of the damage done by an earthquake.

foreshock

is a small earthquake that occurs near but before a mainshock. -One or more foreshocks have proceeded many large earthquakes.

epicenter

is the geographic point on Earth's surface directly above the focus

the moons materials are _____ than Earths, probably because the _____ matter of the giant impacting body _____ _____ in Earth. The lunar core is therefore ____, compromising only about ___ percent of the lunar mass

materials are lighter, heavier matter, remained embedded, lunar core is therefore small, compromising only about 20 percent of the lunar mass

electron capture:

proton to neutron e.g., 40K decays to 40Ar

Two Ways to Date Geologic Events

relative and absolute dating

the longer the fault ____, the greater the fault ___

rupture, slip

faults are classified by their

slip direction

Accretion by continental collision/rifting

time 1: a plate carrying a continent sub ducts beneath another continental plate time 2: the continent is not subducted, so two continents are welded together along a set of trust faults time 3: later, rifting and seafloor spreading carry the continental plates apart, leaving a fragment of one continent welded to the other

Accretion of island arcs

time 1: a plate carrying a continent subducts beneath an oceanic island arc time 2: the continental crust is more buoyant than the subducting lithosphere and is not subducted with it time 3: the island arc crust becomes welded to the island continent

phyllitic texture

wavy foliation of fine-grained material, exhibiting a shiny or glossy luster. -common rock is phyllite, a product of low-grade metamorphism

The stable interior platform of North America is bounded on the ___ by a younger complex of mountain ranges and deformation belts. This region is part of the ___ ___ ____, a mountain belt that extends the length of North America from ____ to _____. Across its middle section, between San Francisco and Denver, the Cordilleran system is about 1600 km wide and includes several different tectonic provinces: the ____ ____ along the Pacific Ocean; the lofty ____ ____; the ___ and ____ province; the high tableland of the _____ ____; and the rugged ____ _____, which end abruptly at the edge of the ___ ____ on the stable interior platform

west, North American Cordillera, Alaska to Guatemala, Coast Ranges along the Pacific Ocean, the lofty Sierra Nevada, the Basin and Range province; the high tableland of the Colorado Plateau, and the rugged Rocky Mountains, which end abruptly at the of the Great Plains on the stable interior platform.

oblique-slip fault

when blocks of rock move along the strike and simultaneously up or down the dip -caused by shearing in combination with either compression or tension

Density of core

10-13 g/cm3

Which of the following rocks represents the highest metamorphic grade?

Gneiss

Principle of Superposition:

In a sequence of undisturbed layered rocks, the oldest rocks are on the bottom and the youngest layers at the top

Structures built on what suffer the most damage in an earthquake?

Wet mud or sand

Monocline -

a bend in flat or uniformly dipping layers.

stratigraphic succession

a chronologically ordered set of star

Evidence from astronomy tells us that the universe began with the Big Bang:

a cosmic explosion of matter and energy that expanded from a single densely packed point

scarp

a fault may form this, it is a cliff that marks the position where the fault surface intersects the ground surface.

Absolute dating (isotopic, tree rings, etc.):

actual number of years since the rock was formed

Basins -

circular synclines

Which layer in the Earth does not transmit S waves?

outer core

accretion

the integration of crustal material previously differentiated from mantle material into continual massed by horizontal transport during plate movement. examples: on the active margins of North America.

a fault system

the zone of deformation between two moving plates is usually made up of a network of interacting faults -fault system in So Cal is an example

Symmetrical folds -

vertical axial planes with limbs dipping symmetrically away from the axis, and a horizontal fold axis

Overturned Folds

when the deformation is so intense that one limb has been tilted beyond the vertical it is called an overturned fault -both limbs dip the same direction, but the older layers in the bottom limb is precisely the reverse of their original sequence, aka-- older rocks are on top of younger rocks

Shear

which push two sides of a rock formation in opposite directions, dominate at transform-fault boundaries, where plates slide past each other

CRUST/MANTLE BOUNDARY =

"MOHO" (Mohorovicic) -composed primarily peridotite, composed of olivine and pyroxene -the layering of the upper mantle is caused by the effects of increasing pressure and temperature on peridotite

Earth's crust

molten materials that were less dense than iron and nickel floated toward the surface of the magma ocean. There they cooled to form Earth's solid crust -ranges in thickness from about 7 km in oceans to 40 km on continents. -continental crust began to accumulate early in earth's history from silicates of relatively low density with a felsic composition and low melting temperatures -oceanic crust is constantly being recycled and generated because it is more dense than the continental crust which drives it into subduction zones and not continental crust.

slaty cleavage

nearly perfect, planar parallel foliation of very fine grained minerals. - Common metamorphic rock is slate, a product of low-grade metamorphism

granoblastic rocks are _______ metamorphic rocks composed mainly of crystals that grow in equant (equidimensional) shapes, such as cubes and spheres, rather than in _____ or _____ shapes

nonfoliated, platy or elongate shapes. -these rocks result from metamorphic processes, such as contact metamorphism, in which directed pressure is absent, so foliation does not silicate minerals.

a dip-slip fault is called a _____ if the rock's hanging wall moves downward relative to the foot wall, extending the structure horizontally

normal fault

contact metamorphism

occurs locally, adjacent to igneous intrusions, and along fractures that are in contact with hot fluids -high temperatures -low stress environment -little change in bulk composition of the rock -limited to very thin zones because lavas cool quickly at the surface and their heat has little time to penetrate deep into the surrounding rocks and cause metamorphic changes

shock metamorphism

occurs when a meteorite collides with earth. upon impact, the energy represented by the meteorites mass and velocity is transformed into heat and shock waves that pass through the impacted country rock. -the country rock can be shattered and partially melted to produce tektites -rare on earth

regional metamorphism

occurs where both high temperatures and high pressures are imposed over very large areas, such as deep within the cores or rising mountain ranges, and it is accompanied by folding of rock layers -the different stresses result from the type of tectonic forces at convergent boundaries - it occurs in volcanic mountain belts, such as the Andes, where subducted plates sink deep into the mantle. and it occurs in the cores of mountain chains produced by continent continent collisions, such as the Himalayas

On the edges of these ____ tectonic provinces are ____ metamorphic belts where most of the present-day ____ ____ are formed. These ___ ____ formed elongated topographic features near the margins of the continent.

older, younger, mountain chains, mountain chains

in the regional metamorphism of basalt, for example:

parent rock: basalt diagnesis: zeolites low grade: greenschists intermediate grade: amphibolites high grade: granulates

As a parent rock is metamorphosed, it changes from a low-grade rock to high-grade rock. example:

parent rock: shale low grade: slate low-intermediate grade: phyllite intermediate grade: schist intermediate-high grade: gneiss high grade: migmatite

ASTHENOSPHERE

part of mantle -because partial melting allows peridotite to flow more easily, geologists identified the LVZ with the top part of the asthenosphere Discovered by Low Velocity Zone (LVZ) Weak, partially molten 75-250 km deep.

the ____ margins of continents--- those that are attached to oceanic crust as part of the same plate and thus not near plate boundaries-- are zones of ___ crust, ___ during the rifting the broke older continents apart and initiated ____ ____. This rifting often occurred along older mountain belts such as the _____ ____ ___

passive, extended, stretching, seafloor spreading, Appalachian fold belt

the eras are subdivided into ____

periods; usually named for the geographic locality in which the formations representing them were first or best described, or for some distinguishing characteristic of the formations.

Many features within rock bodies are either ____ or _____

planar or linear; Minerals Foliation

Most earthquakes occur at

plate boundaries

Continents are made and deformed by

plate tectonic processes

most large earthquakes are caused by ruptures of ____ faults, where past earthquakes have already weakened the rocks on the fault surface. The two blocks of rock on either side of the fault slip sudden, releasing energy in the form of ____ ___, which we feel as the ground shaking. When the fault slips, the stress is ____, dropping to a value ____ the rock strength. After the earthquake, the stress begins to ___ again, eventually leading to another large earthquake. The faults involved in this repeated cycle are called _____ faults, and they are concentrated in the zones that form ___ ____, where most of the stress and strain caused by plate movement is concentrated

preexisting faults, seismic waves, reduced, below, increase, active, plate boundaries

rocks produced by high pressure and ultra high pressure metamorphism are ____ because they form at ____ depths

rare; great most high pressure metamorphic rocks form in subduction zones as sediments scraped from subducting oceanic plates are plunged to depth over 30 km

Metamorphic Grade - the intensity of metamorphism

reflects the temperatures and pressures it was subjected to during metamorphism -High grade: High temperature and high pressure at deeper zones of the crust -Low grade: Low temperature and low pressure at shallower crustal regions

what is Elastic rebound?

return of rocks to original shape after an earthquake

Elastic stress:

return to original shape. -temporary change in shape or size of a body that is recovered when the stress is removed

Seismic Tomography Uses Travel Times to Create 3-D Images of Earth's Interior

reveals hot and cold rocks because seismic waves slow down in hot rocks

a dip-slip fault is called a ______ if the hanging wall moves upward relative to the foot wall, causing a shortening of the structure

reverse fault

Metamorphic rock:

rock that has undergone changes in texture, mineralogical, or/and chemical composition in the solid state

stromatolites

rocks with distinctive thin layers formed by microbial communities as matted sheets and domes in lakes and tidal flats. -some of the best evidence for life in the early Archean comes from stromatolites -common in Precambrian continental cratons and have been identified in sedimentary rocks of early Archean age.

The parent rock of a quartzite is __________.

sandstone

Earth's interior is explored by using information from _____ and their passage through the body of the Earth

seismic waves

Which set(s) of waves is/are most likely surface waves?

set C

rocks subjected to differential stress may be ...

severely distorted, becoming flattened in the direction the force is applied and elongated in the direction perpendicular to the force.

seismic waves can also be used to probe the ___ parts of Earth's crust. this technique, called ___ ___, has a number of practical applications. Seismic waves generated by artificial sources, such as dynamite explosions, are reflected by _____ ____ at ____ depths in the crust. Recording these reflections has proved to be the most successful method for finding deeply buried ____ and ___ ____. Reflected seismic waves are also used to measure the depth of water tables and the thickness of ____. As sea, ___ waves can be generated, and oceanographic sips routinely use the underwater sound they produce the measure the depth of the ocean and the thickness of sediments on the seafloor

shallow, seismic profiling, geologic structures, shallow depths, oil and gas reservoirs, compressional waves

shearing tectonics

sharing of continental crust occurs on a nearly vertical strike-slip fault. -a transform-fault is a strike-slip fault that forms a plate boundary. -transform faults such as the San Andreas can offset geologic formations by long distances, but as long as they stay aligned with the direction of relative plate motion, the blocks on either side can slide past each other without much internal deformation. - Long transform faults are rarely straight, however, so deformation patterns along these faults can be much more complicated

the absence of ____ waves on seismograms recorded at large distances from earthquake foci revealed the ___ state of Earth's core

shear, liquid

Strike-slip faults-

shear, slide sideways. -a fault on which the movement has been horizontal, parallel to the strike of the plane -caused by shearing forces

many of the major boundaries in the geologic time scale represent mass extinctions-

short intervals during which a large proportion of the species living at the time simply disappeared from the fossil record, followed by the blossoming of many new species.

isograd

show where one mineral zone containing rocks of one metamorphic grade, changes to another

A seismogram

shows the varying amplitude of ground oscillations beneath the seismograph Determine time, location, and magnitude

microbes

single-celled microorganism were flourishing 3.5 billion years ago. They must have been composed of carbon-rich compounds, and they must have contained genes- molecules with instructions for growth and reproduction.

the movement of the block of rock on one side of the fault with respect to that on the other side can be described by a ____ _____ and by the _____ ______, or _____

slip direction and by the total displacement, or offset

Inner Core is

solid

When waves move from one type of material to another, they change ___ and ____

speed and direction

Compressional

squeeze and shorten rock formations, dominate at convergent boundaries, where plates move toward each other

Continental shields and platforms make up the most ____ parts of the continental lithosphere, called ___, and contain the eroded remnants of ancient deformed rocks.

stable, cratons

Smith's principle of faunal succession

states that the sedimentary strata in an outcrop contain fossils in a definite sequence. The same sequence can be found in outcrops at other locations, so strata in one location can be matched to strata in another location

deformation=

strain

tectonic stress leads to _____

strain

metamorphic recrystallization may align minerals in a particular direction depending on the type of ___ applied to the rock

stress

plate tectonic processes such as ____ and _____, are the mechanisms that form most metamorphic rocks

subduction and continent-continent collision (which transports rocks and sediments into the hot depths of the crust)

The North American Cordillera was formed during the ______ of the _____ Plate beneath the ____ ____ continent.

subduction, Farallon Plate, North American continent

Earthquakes outline ?

tectonic plates

the four inner planets are known as _____ planets. In contrast to the outer planets, they are ____ and made up of rocks and metals. They formed closed to the Sun, where conditions were so hot that most of the ___ materials (materials that most easily become gases) boiled away. Radiation and matter streaming from the Sun--the solar wind--blew away most of the hydrogen, helium, water and other light gases and liquids on these planets. Thus, the inner planets were formed mostly from the _____ matter that was left behind, which included the rock-forming _____ as well as metals such as ____ and ____.

terrestrial planets, small, volatile materials, dense matter, silicates, iron and nickel

Foliated Rocks Classification is based on:

texture mainly, metamorphic grade, grain (crystal) size, type of foliation, banding

Continental rocks are generally older ____

than oceanic rocks

the heavily cratered lunar surface we see today is that of a very old, geologically dead body, dating back to a period early in the history of the solar system known as

the Heavy Bombardment, when crater-forming impacts were very frequent.

ex of craton

the North American crayon, comprises the Canadian Shield and the interior platform

Magnitude

the amount of energy released by an earthquake. -earthquakes magnitude is the main factor that determines the intensity of the seismic waves it produces and thus the earthquake's potential destructiveness

Fault Slip -

the amount of ground displacement in an earthquake

hanging wall

the block of rock above a dipping fault plane

foot wall

the block of rock below a dipping fault plane

ex of directed pressure

the compressive force exerted where lithospheric plates converge, and it results in deformation of the rocks near the plate boundary. heat reduces the strength of a rock, so directed pressure is likely to cause severe folding and other forms of ductile deformation, as well as metamorphism in mountain belts where temperatures are high.

Heat inside the Earth drives the _______ and ______

the core's geodynamo and the mantle convection.

Smith book, "General Map of Strata in England and Wales"

the first geologic map of an entire country

a major cause of foliation?

the formation of minerals with a platy crystal habit, chiefly the micas and chlorite, under directed pressure.

Northern Lights are produced by

the interaction of solar radiation and the Earth's magnetic field

fold axis

the line made by the lengthwise intersection of the axial plane with the rock layers

Where is the Earth's magnetic field produced?

the liquid outer core

burial metamorphism

the most common type of metamorphism and occurs on a regional scale as rocks form and get buried -caused by confining pressure -caused by increase in temperatures and pressures as sediments are gradually buried deeper in the crust -low grade metamorphism

oblique-sip, strike-slip, and dip-slip require further classification because

the movement can be up or down or right of left. To describe these movement, geologists call the block of rock above a dipping fault plane the handing wall and the block of rock below it the foot wall

nebular hypothesis

the origin of the solar system could be traced to a rotating cloud of gas and fine dust.

the original atom is called

the parent

fault mechanism

the pattern of ground shaking also depends on the orientation of the fault rupture and the direction of slipping, which together specify the fault mechanism of an earthquake. -the fault mechanism tells us whether the rupture was on a strike-slip fault, normal, or reverse fault. it also tells us whether the motion was right-lateral or left-lateral.

focus

the point at which fault slipping begins

"protolith"/parent rock

the rock type or source before it was metamorphosed to its present state

moment magnitude

the seismic moment of an earthquake is defined as a number proportional to the product of the area of faulting and the average fault slip. the corresponding moment magnitude increases by about one unit for every 10-fold increase in the area of faulting.

outcrop

the solid rock that underlies the ground surface--the bedrock--is exposed

SEISMOLOGY

the study of earthquakes

recurrence interval

the time required to accumulate the strain that will be released by fault slipping in a future earthquake-- can be calculated from the rate of relative plate movement and the expected fault slip, as estimated from the displacements observed in past earthquakes

gravitational differentiation:

the transformation of random chunks of primordial matter into a body whose interior is divided into concentric layers that differ from one another both physically and chemically. this occurred in early earths history, when the planet got hot enough to melt

Seismic velocity depends on

the type of material (composition), temperature, and pressure

Folding of Rocks is influenced by?

the type of rock and the compressive forces

nonconformity

the upper sedimentary beds overlie metamorphic or igneous rocks

Within the interior platform are broad sedimentary basins, roughly circular or oval depressions where the sediments are _____ than in the surrounding areas. Most of these features are____ _____ ___, that is, regions that subsided when heated portions of the lithosphere cooled and contorted.

thicker, thermal subsidence basins,

a _____ is a low-angled reverse fault, that is, one with a dip of less than 45 degrees, so the movement is more horizontal than vertical

thrust fault

Accretion of continental fragments

time 1: a buoyant oceanic or continental fragment is carried into a plate collision zone time 2: the fragment is more buoyant than the subducting lithosphere time 3: the fragment becomes welded to the overriding plate

Accretion along transform faults

time 1: two plates slide past each other along a transform fault time 2: a terrane fragment on plate B is carried along the margin of plate A time 3: when the fault becomes inactive, the fragment becomes welded to plate A in a position distant from its original position

upper mantle

ultramafic rocks (peridotite): 8 km/s

formation of the sun:

under the pull of gravity, matter began to drift toward the center of the nebulae cloud accumulating into a pro-star, the precursor of our present Sun. Compressed under its own weight, the material in the proto-Sun became dense and hot. The internal temperature rose to millions of degreases, at which point nuclear fusion began.

The principle of superposition states that _______________.

undisturbed sedimentary layers get progressively younger from bottom to top

anticline

up-arched fold (oldest strata in middle).

metamorphic rocks, even those exposed at earths surface, are mainly the products of processes acting on rocks at deaths ranging from the ____ to the ____ ____

upper to the lower crust

intensity scales

used for estimating the intensity of shaking directly from an earthquake's destructive effects. Scale most used today is called the modified Mercalli intensity scale

Stable Platforms

• Shields covered with horizontal sedimentary rocks • Sandstones, limestones, and shales deposited in ancient shallow seas

SOUTHERN APPALACHIANS AND THE GROWTH OF THE CONTINENTS

• Wilson Cycle • Continental accretion • Arc - continent collision • Continental collision • Continental rifting • Failed rifts • CAMP volcanics

Hot Spots

- Mid plate - Hawaii - Plate boundary - Iceland

Historical Geology

- branch of Geosciences that deals with the Earth's past.

Fossils

- comes from the Latin, fossilus, meaning "something dug up." -Consist of the remains of ancient organisms, or other evidence of their existence. -Found primarily in sedimentary rocks.

P-waves (Primary waves)

- fastest, compressional, like sound waves, can travel through solid, liquid, or gaseous materials. -"push pull waves"- they push or pull particles of matter in the direction of their path of travel

Metamorphic Facies

- grouping of rocks of various mineral compositions formed under different grades of metamorphism from different parent rocks. Each facies has certain minerals that are indicative of pressure and temperature. The minerals in a rock can therefore be clues to the (pressure and temperature) history of the rock

Canadian Shield

- oldest rocks of N. America

S-waves (Secondary waves)

- shear waves, can not travel through liquids or gases, only solid materials, half the speed velocity of P waves. -shear waves that displace material at right angles to their path of travel.

Geochronology

- the study of time in relation to the Earth.

lower mantle

--Below the transition zone, the seismic wave velocities increase gradually and do not show any more unusual features until close to the core-mantle boundary. This relatively homogenous region, more than 2000 km thick, is called the lower mantle

Convergent boundaries

--Ocean - ocean boundaries - Island arcs - Japan, Philippines, Carolina slate belt. --Ocean - continent boundaries. Volcanic arc - Andes. --Continent - continent collision - Himalayan Mountains & Tibet plateau. Appalachian Mountains. ***worlds largest earthquakes, such as the Tohuko -fault mechanisms were caused by horizontal compression along megathrusts, the huge thrust faults that form the boundaries where one plate is subducted beneath another. Generates deadly tsunamis -ruptures of descending plates in subduction zones causes Earth's deepest earthquakes

Divergent boundaries

--Oceanic spreading centers - world's longest mountain ranges. - Continental rifts - E. African Rift, Basin & Range - US -the narrow belts of shallow earthquakes that run through ocean basins coincide with mid ocean ride crests and their offsets on transform faults. ****Tensional forces at divergent boundaries cause normal faulting

Tohoku (Japan), 2011

-11 March 2011 -Magnitude 9.0 -$309 billion in damage -15,700 fatalities, 4,670 missing -Subduction zone

San Francisco, 1906

-18 April 1906, Magnitude 8.3 ->700 fatalities, San Andreas Fault

Seismic date show that Earth's crust is thin (about __ km) under ____, thicker (about __ km) under the ____, ___ ____ ____, and thickest (as must as ___km) under ___ ___

-7 km, under oceans -33 km, under the stable, flat-lying continents 70 km, under high mountains

Orogeny

-A general term for mountain-building processes • Folding and thrusting of rock layers • Often accompanied by magmatic activity and metamorphism -most periods of mountain building resulted from plate convergence

Strength

-Ability of an object to resist deformation -Compressive or tensile

Direct Measurement of the Rates of Geologic Processes

-Absolute ages give real numbers to Earth's history -Dating precision decreases with increasing geologic time -Global Positioning System (GPS) allows measurements of processes, such as plate motion, ± 1 mm/year

Absolute Geochronology

-Add numbers to the stratigraphic column which was originally based on fossils and correlation -Based on the regular radioactive decay of some chemical elements

2 types of Crust (6.75 km/s) how many kilometers deep and what are they made up of?

-Continent (35 km, granodiorite) -Ocean (7 km, basalt/gabbro)

Charleston, South Carolina, August 31, 1886 Charleston intraplate earthquake produced

-Damage all over the eastern US. "sand blows" volcanoes and fissures. Can be used to identify paleo-earthquakes.

How do we know about the interior of earth?

-Deep Drilling -Seismic Waves --Waves move out in a sphere from the source. --Seismic waves are refracted (bent) like light from air to water. --Waves are reflected. Useful for exploration.

ELASTIC REBOUND THEORY

-Energy is stored in rocks as they bend. -When rock strength is exceeded, they break and snap back or "rebound" = earthquake. -some of this elastic energy is radiated as seismic waves, which can cause violent shaking many kilometers away -implies that there should be a periodic buildup and release of elastic energy at faults. --however, most active faults, including the San Andreas, rarely exhibit this simple behavior. For instance, all of the strain accumulated since the last earthquake may not be released in the next, that is, the rebound may be incomplete, or the stress on one fault may change because of earthquakes on nearby faults. this irregularity is one reason why earthquakes are so difficult to predict

Role of Pressure in Metamorphism

-Greater pressure (burial, collision, etc.) - confining pressure tends to decrease the space available for mineral growth; density -Stress causes preferred orientation of minerals - differential stress (directed pressure)

Two of the largest "intraplate" (away from plate boundaries) earthquakes:

-New Madrid, Missouri, 1811-1812 -Charleston, South Carolina, August 31, 1886 - largest reported earthquake in the eastern U.S.

Correlation

-No single area records a complete record of Earth history. -Record must be correlated from one area to another. -Fossils play a key role. -Correlation across the Atlantic Ocean played a pivotal role in the advent of plate tectonics.

Steno's Laws Nicholas Steno (1669):

-Principle of Superposition -Principle of Original Horizontality

LITHOSPHERE

-Rigid plates -Includes crust & upper mantle 75 - 150 km thick -mantle, just below the MOHO, is cold. It is part of the lithosphere like the crust. -lithosphere on average is about 100 km, highly variable though, ranging from about no thickness near spreading centers, to over 200 km beneath the cold, stable continent cratons

ex of monoclines:

-San Rafael Mountain, Utah monocline -Roxborough State Park

Earthquake Prediction

-Seismic risk maps - based on distribution and intensity of past earthquakes. -Long-range prediction - regulate zoning and building codes - saves lives and money-- emergency response (plan ahead and have emergency supplies, rescue teams, evacuation procedures) -Short-term prediction --Precursor earthquakes --Land deformation --Water level in wells --Magnetic field --Electrical resistance of ground --Animal behavior --Radon gas --Low frequency radio waves **Very few successful short-term predictions have been made.

Locating Earthquakes

-Seismic waves from an earthquake move out concentrically from the focus and arrive at distant seismographic stations at different times. -At least 3 recording stations are necessary to determine the location of an epicenter

John Drayton

-South Carolina geologist John Drayton was one of the first to correlate sedimentary beds regionally using fossils. -Drayton was Governor of South Carolina when he founded the University of South Carolina in 1801. USC Department of Geology (now Earth & Ocean Sciences) is the second oldest in the United States.

Half-life

-The half-life of a radioactive isotope is defined as the time required for half of it to decay to the daughter product -The half-life is CONSTANT and does not vary with time, temperature, pressure, etc.

How Do Rocks Metamorphose?

-Through partial or complete recrystallization of minerals in the rocks over long periods of time -Rocks remain in solid state during metamorphism

How to locate earthquakes:

-Use P & S wave arrival times to calculate distance -With 3 seismograph stations, locate epicenter (place on earth's surface above the focus or hypocenter).

How do waves move in the Interior of the Earth?

-Waves move out in a sphere from the source. -Seismic waves are refracted (bent) like light from air to water. -Waves are reflected. Useful for exploration. -Primary wave (P-wave) = pressure -Secondary wave (S-wave) = shear. Can not travel in liquids.

Magnetization

-When hot magma cools below Curie temperature, magnetic minerals (magnetite) are frozen in the direction of the earth's field. -Magnetic minerals in sediments line up with the earth's field.

core/mantle boundary

-about 2890 km below the surface, we encounter the most extreme change in properties. -here the material changes abruptly from a solid silicate rock to a liquid iron alloy. -because of the loss of rigidity, the S-wave velocity drops from about 7.5 km/s to 0 and the P-wave velocity drops from more than 13 km/s to about 8 km/s, causing the core shadow zones -density, increases by about 4.5 g/cm^3 -this large density difference, keeps the core-mantle boundary very flat and prevents any large-scale mixing of the mantle and core -heat conducted out of the core increases the temperatures at the base of the mantle as much as 1000 degrees C -some geologists believe this hot region to be the source of mantle plumes that rise all the way to Earth's surface, creating hot spots

SARA L. SAMSON

1981 - SARA L. SAMSON, a graduate student in geology at the USC, on a field trip near Batesburg, S.C., found a trilobite - from an ancient sea 400 million years ago, was thrust up onto this continent and stayed behind when the sea opened again to form the modern Atlantic Ocean. -CONTINENTAL DRIFT: LATEST FOSSIL FINDS LINK ANCIENT AFRICA TO THE CAROLINAS

continental earthquakes below __ km are rare, because under the ___ temperatures and pressures found at those ____ depths, continental crust behaves as ____ rather than a ____ material.

20 km, high, greater, ductile, brittle material

when subjected to horizontal compression, brittle rocks of the continental crust usually break along thrust faults with dips of about ____ degrees or less, rather than along more _____ dipping reverse fault

30 degrees; steeply dipping

crystal minerals more than _______ years old have been dated using uranium isotopes

4 billion years

____ eons, based on the isotopic ages of terrestrial rocks and meteorites, are now recognized. They are called....

4 eons: -Hadean Eon -Archean Eon -Proterozoic Eon -Phanerozoic Eon

most of the volatile materials swept from the region of the terrestrial planets were carried to the ____ outer reaches of the Solar system to form the _____ outer planets and their satellites. These planets were ___ enough and their gravitational attraction ____ enough to enable them to hold onto the ____ nebular material. Thus, although they have ___ and ____ cores, they are composed mostly of ___ and _____ and the other ___ materials of the original nebula

cold, Giant, big enough, strong enough, lighter nebular material, rocky and metal-rich cores, hydrogen and helium and the other light materials

by increasing erosion rates, climate may help drive the flow of metamorphic rocks from _____ in the Earth's crust to earth's _____

deep, surface

seismologists have used seismic waves reflected by sharp boundaries between Earth's layers to estimate the ___ of the boundaries

depths

seismic risk

describes the damage that can be expected over the long term in a specified region, such as a country or state, usually measured in terms of casualties and dollar losses per year

seismic hazard

describes the frequency and intensity of earthquake shaking and ground disruption that can be expected over the ling term at some specified location.

geologic cross sections

diagrams showing the features that would be visible if vertical slices were made through part of the crust

geologic time scale

divides earth's history into intervals marked by distinctive sets f fossils, and it places the boundaries of those intervals at times when those sets of fossils changed abruptly

transform fault boundaries

earthquake activity is even greater along the transform-fault boundaries that offset mid-ocean ridge segments -these earthquakes have strike-slip fault mechanisms, just as one would elect where plates slide past each other in opposite directions. -for earthquakes along these transform faults, the slip direction indicated by the fault mechanisms is left-lateral where the ridge crest steps right and right-lateral where it steps left. These directions are the opposite of what would be needed to create the offsets of the ridge crest but are consistent with the direction of slip predicted by seafloor spreading

Moving _____, we encounter regions of increasing deformation. The folded and faulted _____ sedimentary rocks of the ____ ___ ____ ____. The eroded mountains of the ___ ___ ___, composed of highly metamorphosed ____ and ____ rocks, which were thrust as sheets over the sedimentary rocks of the ___ and _____ _____. The hilly ____, containing ____ and _____ metamorphosed sedimentary and volcanic rocks, intruded by granite and thrust over ___ ___ rocks. The modern ___ ___, made up of relatively undisturbed sediments of ____ age and _____, underlain by rocks similar to those of the _____

eastward, Paleozoic rocks, Valley and Ridge Province, Blue Ridge province, Precambrian and Cambrian rocks, Valley and Ridge Province, Piedmont, Precambrian and Paleozoic, Blue Ridge rocks, coastal plain, Jurassic age, and younger, Piedmont

another metamorphic rock formed at extremely high pressures and moderate to high temperatures is

eclogite, which is rich in garnet and pyroxene

unusual metamorphic rocks once located at the base of Earth's crust can sometimes be found at Earth's surface. These rocks are called

eclogites; indicating depths over 80 km. in some cases these rocks contain microscopic diamonds, indicative of depths greater than 120 km

Around these cartons are ______ ____ ___ that were formed by later episodes of ______ deformation. The youngest orogenic, such as the ___ ____ ____, are found along the ____ margins of continents, where tectonic activity caused by relative plate movement continues to deform the continental curst.

elongated mountain belts, compressive deformation, North American Cordillera, active margins

to represent the rich history of the Precambrian, a division of the geologic time scale longer than the era, called the ____, was introduced.

eon

some periods are further subdivided into ___

epochs

tensional tectonics

extension of continental crust produces normal faults with high dip angles in the upper crust that flatten with depth, forming curved fault surfaces. -produces a rift valley bounded by normal faults

Brittle Deformation causes ___?

faults

Brittle (rupture) stress:

fracture, break, upper crust rocks, earthquakes -the body undergoes little change under the stress, until it breaks suddenly (earthquakes) ---marble behaves as a brittle material at low confining pressures --more likely with lower temperatures and pressures, harder rock types, more rapid deformation, and tensional rather than compressive forces

What mountain chain runs along the eastern margin of North America?

B) the Appalachians

One important type of mineral deposit occurs in distinctive geologic units called "_____ ____", where _____-age island arcs were stitched together to form vast volcanic terrains composited dominantly of ____ _____ rocks. The ____ are composed of minerals with a ___ hue, such as chlorite, actinolite, and other ___ amphiboles.

greenstone belts, Archean-age, metamorphosed mafic rocks, greenstones, green, green

As a result of the tremendous impact energy absorbed during Earth's formation, its entire interior was heated to a "soft" state in which its components could move around. ____ materials sank to the core, releasing gravitational energy and causing ____ _____, and _____ materials floated to the surface and formed ______. The rising ____ matter brought interior heat to the surface, where it could radiate into space. In this way, Earth differentiated into a _____ planet with _____ main layers. A _____, a _____, and an ____ ____

heavier materials, more melting, and lighter materials, formed the crust, rising lighter matter, zoned planet, with 3 main layers, a central core, a mantle, and an outer curst

What does NOT hold up mountain belts?

high density "roots"

Gneiss are _____ grade, ____ grained rocks in which the ratio of granular to platy minerals is ____ than it is in slate of schist. the result is ____ foliation and thus ____ tendency to split

high grade, coarse grained, poor foliation, little tendency. gneiss, is a coarser foliation of light colored rocks with coarse bands of light and dark minerals throughout the rock. Under high pressures and temperatures, the mineral assemblages of the lower-grade rocks containing micas and chlorite are transformed into new assemblages dominated by quartz and feldspars, with lesser amounts of micas and amphiboles.

temperatures ____ than those necessary to produce gneiss may begin to ____ the country rock. The result is a mixture of igneous and metamorphic rock called ____?

higher, melt, migmatite.

phyllites are rocks of a slightly ___ grade than the slates but are similar in character and origin

higher. they tend to have a more glossy sheen resulting from crystals of mica and chlorite that have grown a little larger than those of slates. they tend to split into think sheets, but split less perfectly than slates

metasomatism

hydrothermal fluids carry dissolved carbon dioxide as well as chemical substances that are soluble in hot water under pressure. As hydrothermal solutions percolate up to the shallower parts of the crust, they react with the rocks they penetrate, changing their chemical and mineral compositions and sometimes completely replacing one mineral with another without changing the rock's texture. this kind of change in a rock's composition by fluid transport of chemical substances into or out of the rock is called metasomatism

limited metamorphism may occur where rocks are subjected to elevated temperatures near _____ _____

igneous intrusions. The heat is locally intense but does not penetrate deeply; thus the intrusions can metamorphose the surrounding country rock, but the effect is localized

Charles Darwin studied paleontology as a young scientist, and he collected many unusual fossils on his famous voyage aboard the ____

Beagle (1831-1836) -Darwin proposed his theory of evolution by natural selection which provided framework for paleontology: if organisms evolve progressively over time, then the fossils in each sedimentary bed must represent the organisms living when that bed was deposited.

Seismic waves 3 types:

Body waves: -Primary-Pressure Waves (P-Waves) -Secondary-Shear Waves (S-Waves) Surface Waves: -Rayleigh waves -Love waves

FLEXURE

But lithosphere has elastic strength (like ice on a frozen lake) so it bends (flexure) under the weight of the mountains. Isostasy is regional.

The size of a magnitude 8 earthquake is how much larger than that of a magnitude 6 earthquake?

C) 100x

earliest period of geologic history recorded by faunal successions was the _____, when animal life, in the form of shelly fossils, suddenly appeared in the geologic record

Cambrian

Divisions in the worldwide stratigraphic column based on variations in preserved fossils Examples?

Cambrian - Cambria, England Devonian - Devon, England Jurassic - Jura Mountains, Switzerland

many rock formations were clearly older than the ____ period because they occurred below the ____ rocks in the stratigraphic successions. But these formations contained no recognizable fossils, so there was no way to determine their relative ages, and all such rocks were lumped into the general category _____

Cambrian, Cambrian, Precambrian

The oldest parts of North America's crust, built during the most ancient episodes of deformation, tend to be found in the northern interior of the continent. This huge region was named the ____ _____ because the crystalline rocks that form the upper crust emerge from the surrounding sediments like a _____ partially buried in the dirt of a ____.

Canadian Shield, shield, battlefield

schists, which are ______ grade rocks, are among the most abundant metamorphic rock types.

intermediate. they contain more than 50 percent platy material, ,saintly the micas muscovite and biotite. they may contain thin layers of quartz, feldspar, or both, depending on the quartz content of the parent shell

axial plane

is an imaginary surfaces that divides a fold as symmetrically as possible, with one limb on either side of the plane.

directed pressure

is force exerted in a particular direction, as when you squeeze a ball of clay between your thumb and forefinger. Directed pressure, also called differential stress, is usually concentrated within particular zones or along discrete planes.

Earth's Magnetic Field

is like the field that would be produced by a giant bar magnet placed at the Earth's center -Earth has a dipole (N&S poles) magnetic field. -Field produced by convective electrical currents in the outer core at core/mantle boundary. --Inclination = deviation from horizontal. --Declination = angle between geographic N & magnetic N.

angular unconformity

is one in which the upper beds overlie lower beds that have been folded by tectonic processes and then eroded to more or less even planes. -the two sequences have bedding planes that are not parallel

geothermal gradient

is the increase in temperature with increasing depth in earth's interior

When magnetic field weakens ....?

it may reverse

____ earthquakes occur less often than ____ ones. The number of quakes per year decreases by a factor of ___ with each magnitude unit.

large, smaller, 10

Principle of Original Horizontality:

layered strata are deposited horizontally or nearly horizontally (parallel to the Earth's surface) under the influence of gravity

Many rocks occur naturally in ____

layers; Sedimentary rocks Lava flows Metamorphic rocks (foliated)

Isostasy

Deflection of plumb line in India survey less than expected Because Himalayas have a "low density root" - The mountains float like icebergs = isostasy.

Ductile (plastic) stress:

Ductile flow, keep deformed shape. lower crust and mantle rocks. -permanent change in shape or size of a body that is not recovered when the stress is removed ---marble behaves as a ductile material at the high confining pressures found deep in the crust

Types of Deformation

Elastic Ductile (plastic) Brittle (rupture)

Elastic Rebound:

Explains Why Earthquakes Occur on active faults in Earth's crusts -stressed rocks are strained elastically (by elastically, we mean that the blocks would spring back and return to their undeformed, stress-free shape if the fault were suddenly to unlock), so that when a fault breaks, the rocks on either side of the fault returnn to their uniformed, stress-free shape

Role of Fluids in Metamorphism

Fluids (H2O): act as a catalyst during metamorphism - aids the exchange of ions between growing crystals

Destructive effects of earthquakes

Ground shaking: -Structures built on solid bedrock suffer less damage. -Structures on soft wet mud or sand suffer most. Ground may behave like liquid = liquifaction. -Adobe and mud-walled structures - weakest. -Steel and wood frame structures flexible and strong. Fire: -Earthquakes break electric, gas, and water lines. Tsunami: -Seismic sea waves - "Tidal Waves" -Travel at several hundred km/hr in open ocean. -Wave height ~ 1 meter -Wave length - several hundred kilometers -Slow down and pile up at shorelines Ground Failure: -Landslides and liquifaction

____ eon is the earliest eon, who's named comes from ____, began with the formation of Earth 4.56 billion years and ended about 3.9 billion years ago. During its first 660 million years, Earths was bombarded by chunks of materials from the early solar system. Although very few rock formations survived this violent period, individual ___ grains 4.4 billion years old have been found, indicating that earth had a ____ crust within 160 million years of its formations

Hadean, Hades (greek word for hell), zircon grains, felsic crust

Role of Temperature in Metamorphism

Heat: greatly affects a rock's mineralogy and texture; increases mobility of elements Geothermal gradient: measure of variation of temperature with depth (average 30°C/km)

Extensive flat-laying (platform) sediments have been deposited on stable continental crust around the periphery of the Canadian Shield and also near its center, beneath ____ ___. The vast, low-lying, sediment-covered region south and west of the Canadian Shield, which includes the ____ ___ of Canada and the United States, is called the ____ _____. The _____ basement rocks of the _____ ____ are a continuation of the Canadian shield, although here they lie under nearly flat layers of _____ sedimentary rocks, typically less than 2 km thick.

Hudson Bay, Great Plains, Interior Platform, Precambrian basement rocks, Interior Platform, Paleozoic sedimentary rocks.

Mercalli Scale:

I X (Not felt) (Damage total) Small Large earthquake Far Near Deep Shallow Well-built Poorly built structures Bed rock Alluvium or mud

Low Density Root

In fact, continental crust under the Himalayas, Tibet, and the Altiplano can be up to 70 km thick

the two sides of a fold are called its

limbs

The Carolina Piedmont is made of

Island arc rocks accreted to North America

the _____ and ____ periods of the _____ era, have together accounted for almost 60% of the worlds petroleum production.

Jurassic and Cretaceous periods ( the age of the dinosaurs) of the Mesozoic era -abundant in marine life that helped provide a lot of the organic matter that was buried in the sediments. This carbon-rich material has been cooked up and transported into the oil reservoirs

two types of strike-slip faults

Left-lateral - opposite block moves left. Right-lateral - opposite block moves right (San Andreas fault).

ex of reverse fault

Lewis thrust fault in Glacier National Park

How Continents Grow

Magmatic differentiation Continental accretion Accretion of island arcs Accretion of continental fragments Accretion along transform faults Accretion by continental collision/rifting

not all the material from the solar nebula ended up in planets. some planetesimals collected between the orbits of ____ and ____ to form the _____ ______. This region now contains more than 10,000 _____ with diameters larger than 10 km.

Mars and Jupiter, form the asteroid belt, asteroids

____ surface is most similar to Earths. It has features suggesting that liquid water once flowed across its surface, and liquid water may still exist in its deep subsurface. Parts of the surface consists of ______ _____ terrain, but other parts are covered with ____ and ____. ______ ____, at 25 km high, is a giant, recently active volcano--- the tallest mouton in the solar system. The ___ ____ canyon, 4000 km long and averaging 8 km deep, is five times deeper than the Grand Canyon and stretches the distance from New York to LA

Mars, ancient cratered terrain, lavas and sediments, Olympus Mons, The Vallis Marineris Canyon

Mariner 10 was the first and only spacecraft to visit _____ when it flew by the planet in March 1974. It mapped less than half the planet, and we have little idea of what is on the other side. It confirmed that this planet has a geologically dormant, _____ crated surface. It is the _____ surface of all the terrestrial planets. It shows very few features that are due to ___ ____ having reshaped its surface.

Mercury, heavily crated, oldest surface, tectonic forces

An example of of an interior platform is the _____ ____, a circular area of about 200,000 km^2 that covers most of the _____ ____ of _____. This basin subsided throughout much of the _____ era and received sediments more than 5 km thick in its central, deepest parts. The sandstones and other sedimentary rocks of these basins, laid down under tectonically quiet conditions, have remained unmetamorphosed to this day. The interior platform basins contain important deposits of ____, ___, ____, and ___ ___

Michigan Basin, Lower Peninsula of Michigan, Paleozoic era, uranium, coal, oil, and natural gas.

alpha decay:

loss of a 4He (2n, 2p) e.g., 147Sm decays to 143Nd

slate are the ____ grade of foliated rocks

lowest. commonly produced by the metamorphism of shales or, less frequently, volcanic ash deposits.

oceanic crust or the lower continental crust

mafic rocks (gabbro): 7 km/s

Non-foliated

metamorphic rocks that do not have obvious layering of platy minerals. They are usually characterized by granular texture of cataclastic texture (fracturing and crushing). -Examples of granular rocks are marble, quartzite, and anthracite coal

greenstones

metamorphosed mafic volcanic rocks. -many of these low-grade metamorphic rocks form when mafic lavas and ash deposits react with percolating seawater of other solutions. -large areas of seafloor are covered with basalts that have been slightly or extensively altered in this way at mid-ocean ridges -chlorite gives these rocks their greenish cast

the start of the _____ eon is marked by the first appearance of _____ fossils at the beginning of the _____ period, now dated at 542 million years ago. The name of this eon-- from the Greek ____ and ____-- certainly fits, because it comprises all three eras recognized in the fossil record: The ____ (542 million to 251 million years ago), ______(251 million to 65 million years ago), and the _____(65 million years ago to present)

Phanerozoic Eon, shelly fossils, Cambrian period, phaneros and zoi (visible life), Paleozoic, Mesozoic, Cenozoic

all major groups of animals on earth today originated in the beginning of the ____ eon, the _____ era, and the early _____ period during a rapid evolutionary radiation called the _____ _____

Phanerozoic eon, Paleozoic era, Cambrian period, Cambrian explosion

the record from deep sea drilling shows a cooling trend beginning about 3.5 million years ago and the subsequent development of rapid climate cycles that became especially large during the _____ epoch. The low temperatures during these cycles, which were as much as 8 degrees Celsius below the present-day temperature of Earth's surface correspond to this epochs "____ ___" when ____ covered large areas of North America, Europe, and Asia

Pleistocene epoch, "Ice Ages", glaciers

the last part of the Precambrian is the _____ eon (from the Greek words ___ and ___, meaning "earlier life", which spans the time interval from 2.5 billion to 542 million years ago. By the beginning of this eon, the plate tectonics and climate systems were operating like they do today. Organisms that produced ____ as a waste product (as ____do today) increased the amount of ____ in the atmosphere. Although life remained soft-bodied, some organisms evolved into sophisticated creatures with____ _____ _____. The increase in atmospheric _____ to nearly present day concentrations toward the end of tis eon may have encouraged single-celled organisms to evolve into _____ ____ and _____, which are preserved in the late _____ fossil record

Proterozoic Eon, Greek words proteros and zoi, organisms that produced oxygen as a waste product, like plants do today, cells containing nuclei, increase in oxygen, encouraged the growth multicellular algae and animals, which are preserved in the Proterozoic fossil record

Changes in Texture are Due to ______

Recrystallization -Grain size -Shape of grains -Directed stress will orient minerals in two ways: --Lineation --Foliation (a set of flat or wavy parallel planes produced by deformation)

Which of the following is the best statement of the principle of original horizontality?

Sediments are deposited as horizontal layers

The Mars Exploration Rovers, named ___ and ____ went to mars in June 2003, accompanied by the ____ ____, an orbiter equipped with geologic remote sensing tools. Another new orbiter, ____ _____ ____, which started in 2006, has collected a vast set of observations that show evidence of aqueous processes over broad regions of the planet. The ____ lander conducted operations in the polar region of Mars and confirmed the presence of water ice just a few centimeters below the dusty surface. The largest rover ever built, named _____, will search for environments that might have been habitable for microorganisms

Spirt, Opportunity, Mars Express, Mars Reconnaissance Orbiter, The Phoenix, Curiosity

continental components:

Stable cratons: - Shields - Platforms • Folded mountain belts (orogens)

Sequence Stratigraphy

Stratigraphic analysis in which the major geologic units are bound by unconformities Used widely with seismic data, especially in petroleum exploration

The study of the layers in sedimentary rock is known as _________.

Stratigraphy

Unconformities

Surface between two beds that were laid down with a time gap between them--the boundary along which the two existing formations meet-- is called an unconformity. -surfaces where erosion has removed rock layers. "Missing time"

Cross-cutting Relationships

The geometry of rock bodies, and their relationship with adjacent bodies, allows geologists to place rock units in relative chronological order Used for relative dating of igneous intrusions, faults, and sedimentary strata -because the deformation or intrusion events must have taken places after the affected sedimentary beds were deposited, those structures must be younger than the rocks they cut. -if the intrusions or fault displacements are eroded and planed off at an unconformity and then overlaid by younger sedimentary beds we know those structures are older than the younger strata

The Amount of Change During Metamorphism Depends on:

The grade of metamorphism The duration of metamorphism The composition of the rock

Paleontology

The study of life in the past based on the fossil remains of plants and animals -most common fossils they founds were the shells of invertebrate animals -Fossils that are preserved in sedimentary rocks are used to determine: 1) relative age 2) the environment of deposition

____ is a geologically active planet with a ______ mantle like Earths. Its surface shows evidence of tectonic activity, especially _____. The _____ was the spacecraft that used radar to show high-resolution pictures of this planets surface. It is also called the _______ Planet.

Venus, convecting mantle, volcanoes, Magellan, Volcano Planet.

Ions

When an atom loses or gains an electron to or from another atom it is called an ion -Positively charged ions (loss of electron) - cations -Negatively charged ions (gain of electron) - anions

Planets form

although most of the matter in the original nebula was concentrated in the proto-Sun, a disk of gas and dust, called the solar nebula, remained to envelop it. The temperature of the solar nebula rose as it flattened into a disk. It became hotter in the inter region. Once formed, the disk began to cool, and many of the gases condensed. Gravitational attraction caused the dust and condensing material to clump together (accrete) into small chunks, or planetesimals. In turn, the planetesimals collided and stuck together, forming larger, moon-sized bodies. In a final stage of cataclysmic impacts, a few of the larger bodies, swept up the others to form the planets in their present orbits. This happened rapidly.

disconformity

an unconformity in which the upper sedimentary sequence overlies an erosional surface developed on an underformed, still horizontal lower sedimentary sequence. -Sea levels drop and broad tectonic uplifts often create disconformities

Dip

angle of steepest descent of the bed from the horizontal; max. angle between inclined plane & horizontal.

Most of world's petroleum and natural gas production comes from ____?

anticlinal traps.

An up-arched fold with the oldest strata in the middle is:

anticline

five types of folds:

anticline and syncline and plunging folds and monocline and overturned folds

Earthquakes

are vibrations of the Earth caused by the sudden release of energy as rocks move along fractures or faults.

Lithosphere floats on a viscous layer below the continents, known as the ____, within the Earth's mantle

asthenosphere

Strike

at right angles to the dip direction; direction of line formed by intersection of a horizontal plane & an inclined plane.

Continental accretion:

buoyant fragments of crust attached to continents as the result of plate motions - amalgamation or accretion of terranes - exotic terranes (seem out-of-place)

measure the orientation of a fault how?

by its strike and dip

Magnetometers

can be used to detect magnetic ore bodies.

Metamorphism:

change affected by pressure, heat, and water that results in a more compact and more highly crystalline condition

deform

change volume or shape of rock by Stress

must meteorites, ______(def)____, are tiny pieces of asteroids ejected from the asteroid belt during collisions with one another

chunks of material from outer space that strike earth

in subduction zones, where ___ oceanic lithosphere plunges into the mantle, earthquakes can originate at depths greater than ___ km.

cold, 600 km

Texture types of foliated rocks:

-slaty cleavage -phyllitic texture -schistosity -gneissic texture

Tensional

-stretch and pull rock formations apart, dominate at divergent boundaries where plates move away from each other

transition zone

-about 400 km below the surface, S-wave velocity increased by about 10 percent within a narrow zone less than 20 km thick. -This jump in S-wave velocity can be explained by a phase change in olivine, the major mineral constituent of the upper mantle, whose ordinary crystal structure is transformed into a denser, more closely packed structure at high pressures. -in the region from 410 to 660 km below the surface, mantle properties change slowly as depth increases. -near 660 km, the S-wave velocity abruptly increases again, indicating a second major phase change in olivine to an even more closely packed crystalline structure. -because it contains two major phase changes, the layer between 400 and 700 km is called the transition zone.

quartzites

-are hard, white rocks derived from quartz-rich sandstones. - some are homogenous, unbroken by preserved bedding or foliation. -others contain thin bands of slate or schist, relics of former interceded layers of clay or shale

marble

-are the metamorphic products of heat and pressure acting on limestones and dolomites -some show a smooth, even texture of interlocked calcite crystals of uniform size -others show irregular banding or mottling form silicate and other mineral impurities in the original limestone

earths mantle

-between the core and the crust lies the mantle, the layer that forms the bulk of the solid Earth - it is made up of the material left in the middle zone after most of the denser material sank and the less denser material rose toward the surface - it is about 2900 km thick and consists of ultramafic silicate rocks containing more magnesium and iron the crustal silicates do. -convection in the mantle removes heat from earth's interior -because the mantle was hotter early in Earth's history, it was probably convecting more vigorously than it does today. Some tectonic activity may have been operating by the "plates" were much smaller and thinner, and the tectonic features were probably very different from the linear mountain belts and long mid-oceann ridges we now see on Earth's surface.

Folds -

-common form of deformation observed in layered rocks. -occurs when an originally planar structure, such as a sedimentary berm is bent into a curved structure. the bending can be produced by either horizontally or vertically directed forces in the crust. -come in all sizes -the bending can be gentle or severe, depending on the magnitude of the applied forces, the length of time they were applied, and the resistance of the rocks to deformation -caused by compression - permanent, plastic deformation.

relative time scale for the formation of lunar surfaces principles:

-craters are absent on new geologic surface, older surfaces have more craters than younger surface -impacts by small bodies are more frequent than impacts by large bodies; thus, older surfaces have larger craters -more recent impact craters cross-cut or cover older craters

descriptors of non-foliated textures

-crystalline -micro-crystalline -sandy texture -glassy texture

Asymmetrical folds -

-folds don't remain symmetrical always. -if they have one limb that dips more steeply than the other it is asymmetrical. -these have inclined axial planes -occurs when the direction of the deformation forces is oblique to the layering of the beds. -these are common

Formation of cratons

-formed in the Archean by the accretion of smaller rafts of lithosphere -the first continental crust with long-term stability began to form around 3.3 to 3.0 billion years ago. -In North America, the oldest surviving example is the central Slave province in northwestern Canada where the Acasta gneiss is founds. - granite-greenstone terrains - high-grade metamorphic terrains

hornfels

-granular texture over all even though it commonly contains pyroxene, which makes elongate crystals and some micas -not foliated, and its platy of elongate crystals are organized randomly

granulite

-high grade metamorphic rock that is also referred to as granofels, has a homogenous granular texture -it is medium-to-coarse-grained rock in which the crystals are equant and show only faint foliation. -formed by the metamorphism of shale, impure sandstone, and many kinds of igneous rocks

Metamorphic Textures from low grade to high grade:

-increasing intensity of metamorphism -increasing grain or crystal size -increasing coarseness of foliation

Seismograph

-instrument that records and measures earthquake vibrations.

Main factors driving metamorphism:

-internal heat of the Earth -Earth's pressure -Earth's fluids

Earths core

-iron accounted for 1/3 of the primitive planet's materials -the iron and nickel, sank to form a central core, which begins at a depth of about 2890 km. -molten on the outside -but solid in a region called the inner core, which extends from a depth of about 5150 km to Earth's center at about 6370 km. The inner core is solid because the pressures at the center are too high for iron to melt

dip-slip fault

-is one on which there has been relative movement of blocks of rock up or down the dip of the fault plane -caused by compressive or tensional forces

Surface waves

-last waves to come, slow -travel around Earth's surface -damage structures Rayleigh waves - like water waves Love waves - shear waves

where do these chemically reactive fluids originate?

-most rocks contain water in minute pores (the space between the grains) -this water comes from chemically bound water in clays. -water forms part of the crustal structures of metamorphic minerals such as micas and amphiboles. -the carbon dioxide dissolved in these high-tempeature fluids is derived largely from sedimentary carbonated: limestones and dolostones

type of texture classification: porphyroblasts

-newly formed metamorphic minerals that may grow into large crystals surrounded by a much finer grained matrix of other minerals -found in rocks formed by contact and regional metamorphism -vary in size, ranging from a few millimeters to several centimeters in diameter -garnet and staurolite are two common minerals that for porphyroblasts

two types of terrain on moon

-rough areas that appear light-colored with lots of big craters - and smooth, dark areas, usually circular in shape, where craters are small or nearly absent. light-colored regions are the mountainous LUNAR HIGHLANDS, which cover about 80% of the surface the dark regions are low-lying plains called LUNAR MARIA, because they looked like seas to early Earth-bound observers

Earth's ocean and atmosphere form

-the planetesimals that aggregated into our planted contained ice, water, and other volatiles such as nitrogen and carbon. -originally, these volatiles were locked up in minerals carried by the aggregating planetesimals. -as Earth differentiated, water vapor and other gases were freed from these minerals, and released through volcanic activity. -almost all the hydrogen escaped to outer space, while the heavier gases enveloped the planet. -some of the air and water may have come from volatile-rich bodies, such as comets, that struck the planet after it had formed. -the comets, for example, are composed largely of frozen water plus frozen carbon dioxide and other gases. -countless comets may have bombarded Earth early in its history, contributing water and gases to the early oceans and atmosphere.

Magmatic differentiation (addition):

-the process of magmatic differentiation of low-density, silica rich magma in Earth's mantle and vertical transport of this buoyant, felsic material from the mantle to the crust is called magmatic addition. -most new continental crust is born in subduction zones from magmas formed by fluid-induced melting of the subducting lithospheric slab and the mantle wedge above the slab. These magmas, which are of basaltic to andesitic composition, migrate toward the surface, pooling in magma chambers near the ace of the crust.

Isotopic Dating

-the use of naturally occurring radioactive elements to determine the ages of rocks -Radioactive elements (parents) decay to stable, non-radioactive elements (daughters) The rate at which this decay occurs is constant and known If we know the rate of decay and the amount present of parent and daughter we can calculate how long this reaction has been occurring

Exhumation -

-transported back to earth;s surface -Subducted light metamorphic rocks are driven upward by buoyancy

Richter Magnitude Scale

-two earthquakes at the same distance from a seismograph differ by one magnitude if the size of their ground motions differ by a factor of 10 -the ground movement of an earthquake of magnitude 6, therefore, is 10 times that of an earthquake of magnitude 5 -a magnitude 7 earthquake produces ground motions that are 100 times greater than those of a magnitude 5 earthquake. -the energy released as seismic waves increases even more strongly with earthquake magnitude, by a factor of about 32 for each Richter unit. -A magnitude 7 earthquake released 32 x 32, or about 1000, times the energy of a magnitude 5 earthquake. Logarithmic scale: -Amplitude of magnitude 6 wave is 10 X larger than a magnitude 5. -Energy released by a magnitude 6 is 30 X larger than by magnitude 5. -So seismic waves of magnitude 6 are 100 X larger than magnitude 4 waves and 900 X more powerful.

The dip of a layer in a geologic formation can vary between ___________.

0-90 degrees

the four outer plants in order of closeness to the sun are

1. Jupiter 2. Saturn 3. Uranus 4. Neptune

the four inner planets in order of closeness to the Sun are

1. Mercury 2. Venus 3.Earth 4. Mars

Earth's Core causes shadow zones for?

1. P-waves between 2. S-waves because outer core is liquid.

two essential points that characterize the concept of metamorphic facies

1. given the same metamorphic grade, different kinds of metamorphic rocks form from the parent rocks of different composition 2. given parents rocks of the same composition, different kinds of metamorphic rocks form at different metamorphic grades

a fault must be _____ than the youngest rock its cuts and ____ than the oldest disrupted formation that covers it

1.younger 2. older

most metamorphic rocks are formed at depth of __to__ km

10 to 30 km, in the middle to lower half of the crust but they can also occur at the earths surface

continents are made up of:

A. Ancient granitic cratons B. Island arcs accreted to the edges of the cratons C. Exotic terranes (microplates) D. All of the above Answer: D, all of the above

The ____ greenstone belt, one of the worlds largest, contains an enormous volcanic caldera complex about 2.7 billion years old.

Abitibi Greenstone Belt

the ____-____ ___. the breakup of Pangaea sent Africa, Arabia, and India northward, causing the ___ Ocean to close as its lithosphere was subducted beneath _____. The ____, are the most spectacular result of ____-____ collision. They were firmed from overthrust slices of the old northern portion of ____ stacked one atop the other. The horizontal compression and formation of fold and thrust belts also thickened the crust north of ___, causing the uplift of the huge ___ ___, which now has a crustal thickness of 60 to 70 km. Further compression has pushed China and Mongolia ___, out of ___ way. Most of this sideways movement has taken place along the major ___-___ faults. The mountains, plateaus, faults, and great earthquakes of ____, extending thousands of kilometers from the ___-____ suture, are all results of the ___-___ orogeny

Alpine-Himalayan Belt, Tethys Ocean, Eurasia, Himalayas, continent-continent collision, India, India, Tibetan Plateau, eastward, India's ways, strike-slip faults, Asia, Indian-Eurasian suture, Alpine-Himalayan Orogeny

strain

Any change in original shape or size of an object in response to stress acting on the object

the second earliest eon, the _____ eon, its name comes from _____. Rocks of the ____ age range from 3.9 to 2.5 billion years old. The_____ and the _____ were established during this eon, and ____crust accumulated to form the first stable continental masses. The process of plate tectonics were probably operating. Life, in the form of primitive _____-_____ ______, became established.

Archean, archaios (greek word for ancient), Archean age, geodynamo and the climate system, felsic, single-celled microorganisms

Isotopes

Are atoms of the same element with different numbers of neutrons. -most are stable but the nucleus of a radioactive isotope can spontaneously disintegrate, or decay, emitting particles and transporting the atom into an atom of a different element --Example: the carbon atom (C) typically has 6 neutrons and 6 protons (called C12), but there are also small amounts of C13 and C14

OJOS DEL SALADO (CHILE):

At 6885 m, this is the world's highest active volcano, although the edifice itself is not large -- its basement is at about 4500 m

The ____ ___ ___ and continental shelf were areas of ____ during the breakup of Pangaea and have since _____

Atlantic Coastal Plain, rifting, subsided

The Canadian Shield, which includes most of ____ and the closely connected landmass of ____, is _____ _____. In other words, it has remained largely undisturbed by rifting, continental drift, or continent-continent collision throughout the ________, but it has been eroded nearly flat. It consists primarily of _______ granitic and metamorphic rocks, such as ____, together with highly deformed and metamorphosed sedimentary and volcanic rocks, and it contains major deposits of ____, ___, ____, _____, and ____. Large portions of the shield were formed during the _____ eon, representing one of the oldest records of Earth's history.

Canda, Greenland, is tectonically stable, Phanerozoic, Precambrian, gneisses, iron, gold, copper, diamond, and nickel, during the Archean eon.

Continental Shields

Central, oldest rocks in continents (up to 3.96 byo) • Low elevation and relatively flat • "Crystalline basement" metamorphic and igneous rocks • once tectonically active

the biggest asteroid is ____, which has a diameter of 930 km.

Ceres

The types of faults and folds we see depend on the main tectonic focus in the upper crust, which are produced mostly by horizontal movements of plates. The tectonic forces that act at plate boundaries are thus predominantly horizontally directed. Horizontal plate movements exert three types of tectonic forces:

Compressional -squeezed Tensional - pull apart rock, Shear - sideways slip on parallel planes.

ISOSTATIC REBOUND:

Continents rebound after the ice sheets melt. Up to 300 m in 10,000 years.

The two main examples are the ____, which runs down the ____ edge of North America and includes the ___ Mountains, and the ____ ___ ___, which runs ____ to _____ on the continents ___ margin from ____ to ____

Cordillera, western, Rocky Mountains, Appalachian fold belt, southwest to northeast, eastern margin, from Alabama to Newfoundland

Core is made up mostly of

Core is mostly iron - (based on density and meteorites) with some nickel (inner core) & sulfur (outer core).

ex of mass extinction: at the end of the _______, which killed off 75 percent of the living species, including all ______, was almost certainly the result of a large meteorite impact that darkened and poisoned the atmosphere and plunged Earth's climate into many years of bitter cold. This disaster marks the ends of the ____ era and the beginning of the ____ era

Cretaceous, dinosaurs, end of Mesozoic, beginning of the Cenozoic

Gravity used for mineral and Gas Exploration

Mining - valuable minerals associated with high density igneous rocks Oil Exploration - oil found with low density salt domes

collision with a Mars-sized body ejected debris that formed the ____ and ____ the outer part of the Earth

Moon, melted

Stability of Minerals

Most minerals are stable over a relatively narrow range of pressure and temperature (e.g., ice unstable above 0°C) The stability range of different minerals sometimes overlap and provide insights into the metamorphic history of rocks

HEAT FLOW

Most of Earth's heat is generated by radioactive decay. The Earth is cooling off.

each metamorphic rock has a distinctive history of changing conditions of temperature and pressure that is reflected in its texture and mineral composition. This history is called a metamorphic ________

P-T path. -this path can be a sensitive recorder of many important factors that influence metamorphism--such as sources of heat, which change temperatures, and rates of tectonic transport (burial and exhumation), which change pressure. Thus, P-t Paths are characteristic of particular plate tectonic settings

ex of mass extinction: the mass extinction at the ____-____ boundary (55 million years ago) was not one of the largest of such event but it is significant in the evolution of life because it paved the way for ____, including the ____, to radiate into an important group. It was the result of abrupt ____ ____. The end of the ____ epoch occurred when suddenly the ocean belched an enormous amount of ____ into the atmosphere that caused temperatures to rise dramatically.

Paleocene-Eocene boundary, mammals, primates, global warming, Paleocene epoch, methane

KIMBERLITE PIPES

Peridotite - inclusions from mantle Coesite - high pressure quartz - less than 300 km depth. Diamonds - high pressure carbon - more than 100 km depth. Diamonds - high pressure carbon - more than 100 km depth.

ex of mass extinction: the largest mass extinction, at the end of the _____ period, which defines the _____-_____ boundary, eliminated nearly 95& of all living species.

Permian Period, Paleozoic-Mesozoic boundary

comets

aggregations of dust and ice that condensed in the cooler outer reaches of the solar nebula. Most comets orbit the Sun far beyond the outer planets, forming concentric "halos" around the solar system

sandy texture

a medium to coarse grained aggregate of fused sand-sized grains that resembles sandstone

schistosity

a parallel to sub-parallel foliation of medium to coarse-grained minerals. -common rock is schist, product of intermediate to high-grade metamorphism

gneissic texture

a parallel to subparallel foliation of medium to coarse grained minerals. It is usually distinctly banded, alternating bands of ferromagnesian and quartz, feldspars, or carbonate minerals. -common rock is gneiss, a product of high-grade metamorphism

foliation

a set of flat or wavy parallel cleavage planes produced by deformation under direct pressure. -foliation places may cut through the bedding of the original sedimentary rock at any angle or be parallel to the bedding

intraplate earthquakes

a small percentage of global seismic activity originates within plate interiors. the foci of there are relatively shallow, and most occur on continents. ex: New Madrid Missouri, The Charleston, SC, and the Cape Ann, near Boston, Massachusetts. -many occur on old faults that were once part of ancient plate boundaries. these faults no longer form plate boundaries but remain zones of crustal weakness that concentrate and release intraplate stresses. ex: one of the deadliest intraplate earthquakes occurred near Bhuj in the state of Gujarat, in western India

Joints

a type of fracture -a crack along which there has been no appreciable movement -found in almost every outcrop, and they create surfaces that are more vulnerable to weathering.

The Fish Bowl Experiment

a way to show how seismic waves move to help explain Earth's interior

compressive tectonics

compression of continental crust occurs on low-angled thrust faults -in subduction zones, oceanic lithosphere slips beneath an overriding plate along a huge thrust fault, or megathrust. -words largest earthquakes are caused by sudden slips on megathrusts -thrust faulting is the most common type of faulting within continents undergoing compressive compression. -sheets of crust may glide over one another for tens of kilometers along nearly horizontal thrusts faults, creating overthrust structures -when two continents collide, the crust can be compressed across a wide zone, resulting in mountain building; during such collisions, the brittle basement rocks ride over one another by thrust faulting while the more ductile overlying sedimentary rocks compress into a series of great folds, forming a fold and thrust belt -large earthquakes are common in fold and thrust belts

The rock assemblages and structures of the old, eroded Appalachian Mountains resulted from the ______-_____ collisions that formed the supercontinent ____ 470 million years ago. The ____ side of the Appalachians is bounded by the ____ ____, a region of slightly uplifted, middy deformed sediments that is rich in coal and oil.

continent-continent collision, Pangaea, western, Allegheny Plateau

Earthquakes that originate at depths greater than 100 km are associated with ______ plate boundaries.

convergent

by applying these principles and by mapping the number and sizes of craters--- a procedure known as ____ ____--geologists show that the ___ ____ are older than the ____ ____

crater counting, Lunar Highlands are older than the Lunar Maria

the product of decay is its

daughter