Geo1330 Exam 3 GEO GEO GEO

What is radioactivity? What types of atoms undergo radioactive decay?

An unstable isotope will radioactively decay into a more stable isotope.

Recumbent Fold

Axial plane becomes horizontal

How does increasing the confining pressure affect the way a rock deforms?

Brittle: More likely at shallower depths and lower confining pressures. Rocks deform by fracturing and faulting Ductile deformation: More likely to be at greater depths and higher confining pressure. Rocks flow and deform w/o fracturing

How does the focus (hypocenter) of an earthquake differ from the epicenter?

Epicenter: the point on the Earth's surface directly above the focus Hypocenter- the site of the earthquake ORHypocenter: the area on the fault plane where the slip is initiated. Epicenter: the point on the Earth's surface directly above the focus

Metamorphic Facies:

Grouping of rocks formed under different pressures. Encompass different regions or temperature and pressure. Zeolite: Low temp, low pressure. Greenschist: 400*C and 2-9 kilobars pressure. Amphiboles: 600*C and 2-9 kilobars pressure. Granulite: 800*C and 2-12 kilobars pressure.

What metamorphic rock is thought to form by partial melting and in situ crystallization of the melted portion?

Migmatite

The subdivision of years in dating is subdivided into:

Millions of years.

Describe the global distribution of earthquakes. Where do most earthquakes occur? Intermediate and deep earthquakes primarily occur along which of the three types of plate boundaries?

Normal faulting (divergent plate boundary) • Reverse and thrust faulting (convergent plate boundary) • Strike-slip motion (transform plate boundary)

Waves arrival: three groups

P-waves S-waves Surface waves all travel at different velocities

Foliation Textures

Parallel Alignment of platy minerals like chlorite and micas. Parallel Alignment of flattened minerals grains and pebbles. Compositional Banding Slaty Cleavage where rocks can be easily split into thin, tabular sheets.

Which of the following refers to the idea or concept that ancient life forms succeed one another in a definite, evolutionary pattern and that the contained assemblage of fossils can determine geologic ages of strata?

Principle of faunal succession

In a ___________ fault, the hanging wall block moves up with respect to the footwall block.

Reversal

How does foliation form?

Rotation of platy of elongated minerals. Recrystallization of minerals in direction of preferred orientation. Changing the shape of equidimentional grains into elongated shapes that are aligned. Example: unmetamorphased rock --> high grade metamorphism ---> gneissic texture

Jointing in rocks is characterized by...

Roughly parallel fractures separating blocks that show no displacement

Can earthquakes be predicted?

Short range quakes- no Long range quakes- given the probability of a certain magnitude earthquake occurring on a time scale of 30-100 years or more

Why is the Mercalli Scale subject to uncertainty in determining the size of an earthquake?

The Mercalli Scale is based on the amount of damage from an earthquake, which depends on many factors such as the strength of buildings, type of foundation, distance from the epicenter, and duration of shaking.

Which of the following describes radioactive decay by beta particle emission?

The atomic number of the daughter isotope is one more than the parent; the mass numbers are the same.

Hing line diagram would be

oldest youngest oldest

Identify the parent rock for each of the following metamorphic rocks: slate, quartzite, marble, greenstone, and anthracite.

slate-shale quartize-sandstone marble-limestone greenstone-basalt anthracite-bituminous coal

Subduction zones

typically low temp. high pressure

Describe the principles behind carbon-14 dating. What types of materials can be dated using carbon-14? Is carbon-14 useful for dating most geological samples? Why or why not?

- Carbon 14 dating is a method for determining the age of an object containing organic material by using the properties of radiocarbon (14. C), a radioactive isotope of carbon. - Good for dating materials younger than 80,000 years old.

Know how the Geologic Time Scale is subdivided in terms of eons, eras, periods, and epochs. Know the names of the eons and eras as listed in the table of terms above. Given an outline of the time scale, be able to place the names of eons and eras in the appropriate spaces. Know in general what divisions represent periods and epochs, but do not memorize the names.

- Geologic time scale: A "calendar" of Earth history - Subdivided into various units of time: (Eons, eras, periods, epochs-- in that order) Eons: Phanny pros and had-beens. - Phanerozoic (542 million years ago to today) Include Cenozoic (recent), Mesozoic (middle) and Paleozoic (ancient) - Proterozoic (2500 M to 542M ago) - Archean (4000M to 2500M ago) - Hadeon (4600M to 4000M ago)

What types of rocks can be effectively dated using isotopic dating techniques? Why is isotopic dating not useful for most sedimentary rocks? How can the approximate ages of these sedimentary rocks be determined?

- Igneous rocks - Clastic sedimentary rocks do not give meaningful ages b/c minerals were derived from other sources. - Sedimentary rocks can be bracketed by dating underlying/overlying igneous and metamorphic rocks, interlaced volcanic ash deposits and cross-cutting igneous dikes.

Seismic Vibrations: Seiches

-Shaking causes rhythmic sloshing of water in lakes reservoirs and encloses basins -waves an weaken and destroy reservoir walls

Seismic Vibrations: liquefaction

-ground shaking draws groundwater up to the surface -unconsolidated soils become saturated with water and turn into a mobile slurry no longer capable of supporting structures

The proportion of parent to daughter isotopes in a radioactive decay process is 40% parent and 60% daughter. How many half-lives have elapsed since the material was 100% parent atoms?

1 and 2

San Andreas Fault displacment

100 to 200 kilometers long. Most likely source of the next major earthquake

Using the time-travel graph below, how far away is the epicenter from a seismic station that records a time interval of 3 minutes between the first arrival of P waves and first arrival of S waves?

2000 km

Describe how foliation is produced in a metamorphic rock (3 mechanisms). Name two common platy minerals that produce foliation in metamorphic rocks. Can non-platy minerals exhibit foliation (think metaconglomerate)?

3 mechanisms of foliation: Rotation of platy and/or elongated minerals Recrystallization of minerals in the direction of preferred orientation Changing the shape of equidimensional grains into elongated shapes that are aligned Two common platy minerals: Mica and chlorite

Approximately how much more energy is released in a 6.5 Richter magnitude earthquake than in one with magnitude 5.5?

30 times

What is the age of the Earth accepted by most scientists today?

4.5 Billions Years

A syncline is.

A fold in which the strata dip towards the hinge line (fold axis)

Metamorphic Facies

A grouping of rocks formed under different temperatures and pressures.

A thrust fault is best described as...

A low-angle reverse fault

How does metamorphism affect the isotopic date of a mineral? If the whole-rock age of a metamorphic rock is older than its mineral age as determined by radiometric dating, then what might each of these ages represent (see my power point slides)?

A metamorphic rock can provide an age for the last metamorphic event. If the rock experienced more than one episode of metamorphism, then usually only the most recent event can be dated.

Which of the following statements is true for anticlines but not for synclines?

After erosion, strata become older towards the fold axis (hinge line) of an anticline, but not a syncline

During metamorphism, what is the major effect of chemically active fluids?

Aid in the movement of dissolved silicate constituents and facilitate growth of the mineral grains

The ________ is directly related to the Richter earthquake-magnitude rating.

Amplitude of the seismic waves

What goes up the chimney down but not down the chimney up?

An umbrella

Short range quake predictions

Animal behaving strangely before an earthquake Tilting and other types of ground deformation in the area of eminent fault slippage prior to main shock Increase in frequency of small earthquakes (foreshocks) prior to the main shock Opening of micro-fractures in bedrock Wells exhibit changes in the water level and increase random concentration

What are the characteristics of an anticline versus a syncline in terms of the relative ages of strata, directions that strata dip relative to the fold axis, and outcrop patterns where strata are repeated on opposite sides of the fold axis?

Anticlines are folds with two, well-defined limbs dipping in opposite directions away from a long, linear, fold axis. Strata are raised or buckled upward along the axial part of the fold relative to their elevations farther out on the limbs; thus after erosion, older strata are exposed along the axial part of the fold. Synclines are folds with two, well-defined limbs that dip inward toward a long, linear, fold axis. Strata are lowered or buckled down in the axial region; thus after erosion, younger strata are exposed in the axial portions of synclines.

Know the stages of the Elastic Rebound Theory in explaining earthquakes.

As rock is deformed, it bends and stores elastic energy. Once strained beyond it's breaking point, the rock ruptures and releases energy in the form of seismic waves. OR Original position, buildup of strain, slippage and strain released

In which setting would regional metamorphism be most likely?

At great depths in the crust where two continents are colliding

What term describes the zone of contact metamorphism surrounding an intrusive magma body?

Aureole

Given a diagram showing sedimentary strata, faults, igneous intrusions, inclusions, and unconformities, rank each of these rock units and geologic events (e.g. faulting, erosion, etc.) in order of oldest to youngest.

Basically go identify the oldest to the youngest.

Which of the following foundation materials is most stable during earthquake shaking?

Bedrock

Visualize five, horizontal, sedimentary strata exposed in a cliff or canyon wall identified by consecutive numbers, 1 being the lowest bed and 5 being the highest. Which of the following statements concerning the strata are true?

Beds l and 3 are older than bed 4

The half-life of carbon-14 is about 6000 years. Assume that a sample of charcoal is formed by burning of living wood 15,000 years ago. How much of the original carbon-14 would remain today?

Between one-fourth and one-eighth

In what tectonic environment do blueschists and eclogites form?

Blueschist Facies (very high pressures, relatively low temperatures) Occurs within subduction zones Metamorphosed basalt and shale contain blue amphiboles Eclogite facies (extremely high pressures,moderate-high temperatures)

Which one of the following is not likely to be genetically associated with impact of an asteroid or large meteorite?

Blueschists

Joints slide

Brittle deformation

Discuss the difference between ductile and brittle deformation.

Brittle materials have some a elastic behavior but only a small region of ductile behavior before they fracture. Here low temperature, low confining pressure and high strain rate are the factors of brittle materials. Ductile materials have a small region of elastic behavior and large region of ductile behavior before they fracture this represents the ductile nature of materials. Here high temperature, high confining pressure and low strain rate are the factors of ductile materials.

What are the differences between burial and regional metamorphism? Which is more extensive? Where does each type occur? Describe the stresses associated with burial versus regional metamorphism.

Burial Metamorphism: Mild type of metamorphism. Sedimentary rocks are buried to greater depths and results to partial changes to mineralogy and texture. Zeolite facies environment occurs here. Regional Metamorphism: temperatures and pressure increase beyond range of burial metamorphism. Takes place over large areas. Caused by major tectonic forces.

Amphibolite is a foliated metamorphic rock composed principally of hornblende and plagioclase. How does it form?

By regional metamorphism of volcanic rocks such as andesite and basalt

Cataclastic Metamorphism

Confined to mountain regions

What is the difference between differential stress and confining pressure? Which of these two stresses is most likely to produce foliation in a metamorphic rock?

Confining Pressure: Stress is applied equally in all directions. Like the stress you feel when you go deep under water. Differential Stress: Stress is applied unequally and predominates in one direction. Confining pressure is most likely to cause foliation in metamorphic rocks.

What are four factors that determine how a rock deforms?

Confining pressure, temperature, rock type, time

Which of the following refers to the investigative process by which geologists identify and match sedimentary strata and other rocks in one area with rocks of the same age at different locations?

Correlation

What is meant by the correlation of rock units? Identify different criteria (e.g. lithology, sedimentary structures, color, fossils, etc.) that can be used to correlate rocks from one exposure to another.

Correlation of rocks: matching a particular rock layer (formation) in one exposure with its counterpart at a different locality Strat or stratification are the layers that form on top of each other as time progresses.

What is the source of natural carbon-14?

Cosmic ray collisions and neutron-capture involving atmospheric nitrogen

What is cataclastic metamorphism? Where does it occur? What is the difference between a fault breccia and mylonite?

Crushing and shearing of rocks during tectonic movement. Generally localized along fault plains. Fault Breccia: Shallow depths Mylonite: Greater depths

How is the Richter magnitude determined?

Devised a procedure to measure the size on an earthquake on the basis of ground motion rather than the amount of destruction

What type of stress (pressure) is illustrated in the diagram below?

Differential Stress

Normal and reverse faults are characterized mainly by...

Dip Slip

Do folds reflect brittle or ductile deformation?

Ductile

Energy is stored in rocks adjacent to the site of a future earthquake as ___________.

Elastic Strain

Define an unconformity? What do unconformities represent in terms of rock units and geologic time? How do unconformities form? Be able to sketch and describe the following: Angular unconformity, disconformity and nonconformity.

Erosional surfaces or intervals of missing strata within a rock sequence. Types of Unconformities •Angular unconformity: An unconformity in which the older strata dip at a angle different from that of the younger beds. Lower rocks would be sedimentary. •Nonconformity: Old erosional surface separating younger sedimentary rocks above from older igneous or metamorphic rock below. Lower rocks are igneous. •Disconformity: Old erosional surface where layered sedimentary rocks occurring above and below the unconformity are parallel.

Eclogite Facies

Extremely high pressure and moderate high temperatures. Occurs deep within subduction zones

Along oblique-slip faults, both blocks have horizontal but not vertical components of movement. (t/f)

False

Foliated metamorphic rocks are composed largely of equidimensional grains of minerals such as quartz and calcite.

False

For shallow-focus earthquakes, surface-wave amplitudes are usually smaller than P and S-wave amplitudes

False

Most sedimentary rocks are readily dated by radiometric methods.

False

P waves..

Faster than S waves and surface waves

Which of the following would exhibit sheared and mechanically fragmented rocks?

Fault movement at shallow depths.

Which of the following terms describes the strong, parallel alignment of coarse mica flakes and/or of different mineral bands in a metamorphic rock?

Foliation

12. Know the sense of relative motion of fault blocks for normal, reverse, and strike-slip faults in terms of hanging wall and footwall.

For a normal fault, the hanging wall moves down relative to the footwall. Normal faults develop in response to tensile stress. For a reverse fault, the hanging wall moves up relative to the footwall. Reverse faults develop in response to compressional stress. Strike-slip faults are also distinguished on the basis of the relative movement across the fault, except that the concept of headwall and footwall doesn't apply.

Figure with red domino looking pic. Metamorphism Resets Isotopic Ages: Metamorphism can reset the isotopic rock. -Whole rock age gives time of initial crystalization from magma. -Mineral age dates the time of the last metamorphic event

From review.

Which of the following metamorphic rocks is characterized by the segregation of light- and dark-colored minerals into thin layers or bands?

Gneiss

Which of the following metamorphic rocks forms at the highest grade of regional metamorphism?

Granulites

What are the agents of metamorphism?

Heat, Pressure (stress), Chemically Active Fluids

Bluechist Facies

High Pressure, low temp. Occurs within the shallower parts of subduction zones

Which of these two identical homes would suffer the most damage if an earthquake occurred along the active fault? Diagram and illustration

Home Y because it is built on loose sand and not hard bedrock

Which one of the following is consistent with deformation by folding?

Horizontal distance is shortened parallel to the direction of compressive stresses

What metamorphic rock forms by contact metamorphism of mudstones and shales?

Hornfels

Describe hydrothermal metamorphism. What types of reactions occur? Where does hydrothermal metamorphism occur? What metamorphic rock is a typical product of hydrothermal metamorphism?

Hydrothermal metamorphism: Chemical alternations that occur as hot. Ion-rich water circulates through fractures in rock. Regional sources: Geysers and hot springs, percolating sea water along mid ocean ridges Typical product: Mafic Rock

Plung diagram

In anticline: horseshoe pattern closes in direction of plunge In syncline: horseshoe pattern opens in direction of plunge

Brittle deformation would be favored over ductile deformation in which of the following conditions?

In cooler temperatures

What are inclusions? If a sedimentary rock layer contains inclusions of an adjacent igneous rock, what can we say about the relative ages of these rock units?

Inclusions are: A piece of one rock unit that is contained within another. Inclusions are used in relative dating.the rock mass adjacent to the one containing the inclusion must have been there first in order to provide the fragment. We can say that inclusion are always older than the rocks containing them

What are index minerals? How are index minerals used in mapping metamorphic terrain?

Index minerals are: mineral that is a good indicator of the metamorphic environment in which it formed; used to distinguish different zones of regional metamorphism They are a good indicators of the metamorphic conditions under which they were formed (only present for short amount of time)

What are some of the problems associated with using the Mercalli scale to measure the strength of earthquakes?

It measures intensity by the amount of destruction and not ground motion at all. The problem with the scale is that earthquake destruction depends on many factors. For example -the overall size of the quake -duration of the ground shaking -strength of the buildings -distance of the epicenter -nature of soil and bedrock

Distinguish the different types of stresses that produce normal, reverse and strike slip faults.

KNOW IT!

What fundamental concept states that in a horizontal sequence of conformable sedimentary strata, each higher bed is younger than the bed below it?

Law of superposition

Stratification

Layering of sedimentary rocks and individual layers are called strata

The radioactive isotopes uranium-238, uranium-235, and thorium-232 eventually decay to different, stable, daughter isotopes of

Lead

What platy, parallel, mineral grains are the most visual aspect of foliated metamorphic rocks?

Micas

What are migmatites? How do migmatites form? Do they represent low or high temperatures?

Migmatites are: a rock exhibiting both igneous and metamorphic rock characteristics; such rocks may form when light-colored silicate minerals melt and they crystallize, while the dark silicate minerals remain solid Migmatites form: at temperatures exceeding 700 degrees C where gneiss partially melts felsic minerals melt, mafic minerals remain solid silica-rich liquid invades partially melted rock softened rock contorts and deforms

____________ was struck by three, major earthquakes during the winter and spring months of the years 1811-1812.

New Madrid, Missouri

Describe contact metamorphism. Where does it occur? What type of geothermal gradient is associated with contact metamorphism? What is a contact metamorphic aureole?

Occurs at high temperatures Restricted to a small area around the margins of a magmatic intrusion Type of rock produced depends on parent rock. Geothermal gradients are high. Metamorphic Aureole: The area surrounding the intrusion where the contact metamorphism effects are present

Impact Metamorphism

Occurs when high speed projectiles called meteorites strike the earth. The impact shatters and melts rock, leaving behind and impact crater. Products called impactites

Approximately how often do locked segments of the San Andreas Fault (California) break, resulting in major earthquakes?

Once every hundred and fifty years

A deeply eroded, structural basin would exhibit...

Outcrops of the youngest strata in the center of the basin

Describe the particle motions for P-waves, S-waves and surface waves.

P waves move through solid rock, and move things in the direction of its path s-waves push things at a 90 degree angle surface waves clear everything in the path Surface waves: travel along the outer part of the Earth (have up and down and side to side motion) P waves: Push (compress) and Pull (expand) rocks in the direction the wave is traveling S waves: Shake the particles at right angles to their direction of travel

Which of the following is the best method for determining the probability of future earthquakes for a particular area?

Paleoseismology; history of past earthquake activity in the area

Which of the following refers to the process of fossilization where the pores of the original plant or bones of an animal are filled with precipitated mineral matter?

Petrification

Where are we on the Geologic Time Scale? Where on the time scale is the origin of earth represented and what is the age (in millions of years)? What is the age (in millions of years) assigned to the time line marking the boundary between the Precambrian and Phanerozoic Eons? What percentage of earth history falls into the Precambrian? Which Eon contains most of earth's fossils? Is more known about the Precambrian or Phanerozoic Eon?

Phanerozoic = us 4.6B years 542M years 88% Eon: Cenozoic More known about Phanerozoic.

Which of the following best describes the conditions of contact metamorphism?

Pressures are fairly low, the rock is in the upper part of the crust, and heat is supplied from a nearby magma body

Define each of the following: Principle of Superposition, Principle of Original Horizontality, and Principle of Cross-cutting Relationships. How are each of these principles applied to relative dating?

Principle of Superposition: A principle which states that in any undeformed sequence of sedimentary rocks, each bed is older than the one above and younger than the one below. Principle of Original Horizontality: Layers of sediment that are generally deposited in a horizontal position. Principle of Cross-Cutting Relationships: A principle of relative dating. A rock or fault is younger than any rock (or fault) through which it cuts.

Which of the following metamorphic rocks typically forms by metamorphism of a sandstone?

Quartzite

Explain how seismologists locate the epicenter of an earthquake?

Records the movement of the ground in relation to the stationary mass on a rotating drum or magnetic tape. A typical seismic observatory measures three components of ground motion. 1. vertical up-down motion. 2. Horizontal east-west motion. 3. Horizontal north-south motion.

Distinguish between relative and absolute (numerical) dating.

Relative: Determine sequence or order that geological events and processes occurred. No actual dates attached, just the order. Absolute: Determines actual datings of rocks and events. Uses isotopes and radiometric dating.

Which one of the following statements regarding rock deformation and strength is correct?

Rupture and plastic deformation occur when stresses exceed the elastic limit of a material.

Which one of the following statements is correct?

S waves travel through solids while P waves travel through both solids and liquids.

The ____________ in California is the boundary between the North American and Pacific plates.

San Andreas Fault

Which of the following metamorphic rocks forms at very high pressures but moderately low temperatures associated with subduction of oceanic crust and sediments?

Schistosity

Long range quake predictions

Seismic gaps along faults

Which low-grade metamorphic rock, composed of extremely fine-sized mica and other mineral grains, typically exhibits well-developed rock cleavage?

Slate

An angular unconformity is a:

Surface of erosion separating younger strata above and older strata below

What are the characteristics of symmetrical, asymmetrical and overturned folds

Symmetrical is when limbs mirror each other Asymmetrical is when they do not mirrior each other Symmetrical fold: axial plane is vertical and limbs go down in opposite direction Overturned is when a asymmetrical fold limbs are tilted beyond the vertical (one or both) Both limbs are dipping in the same direction

In Thrust Faulting ...

The crust is shortened and the fault plane is inclined at an angle less than 45 degrees

What is the Principle of Fossil Succession? How is this principle useful for correlating rocks from one exposure to another? What are the criteria for a good index fossil?

The definite and determinable order in which fossil organisms occur. Fossil succession enables us to identify many time periods by their fossil content. Fossil organisms succeed one another in a definite and determinable order Geographically widespread fossil that is limited to a short span of geologic time.

Compressional Stress

The differential stress usually results from tectonic forces that produce compressional stresses in the rocks, such as when two continental masses collide. Thus, regionally metamorphosed rocks occur in the cores of fold/thrust mountain belts or in eroded mountain ranges. Compressive stresses result in folding of rock and thickening of the crust, which tends to push rocks to deeper levels where they are subjected to higher temperatures and pressures.

Which one of the following statements concerning foci and epicenters is correct?

The epicenter is at the surface directly above the focus where the earthquake initiates

Which of the following observations would not bear directly on working out the sequence of geologic events in an area?

The feldspar and quartz contents of a granite

Sandstone strata and a mass of granite are observed to be in contact. Which of the following statements is correct geologically?

The granite is older if the sandstone contains pebbles of the granite.

Rank the following metamorphic rocks in order of increasing grade of metamorphism: schist, granulite, phyllite, slate, gneiss.

The increasing rate grade of metamorphism is Slate , phyllite,schist , gneiss , granulite Reason : metamorphic grade is a scale of metamorphic intensity which uses indicator minerals as geothermometers and geobarometers to indicate the grade and the increasing grade is as above given

What is a formation? What are the different ways (criteria) by which rocks can be grouped into formations?

The most basic local unit of stratigraphy is the formation • A particular rock unit is grouped into a formation based on a distinctive appearance and/or other characteristics: - Lithology (rock type) - Color - Sedimentary structures - Certain depositional patterns

What is the minimum number of seismograph stations needed in order to determine the location of an earthquake epicenter?

Three

Describe a thrust fault. What type of stress is associated with thrust faulting?

Thrust faults: • Faults angles less than 45o • Can accommodate large displacements (tens to hundreds of kilometers) 1. reverse fault; shear stress 2. normal fault; compression 3. reverse fault; tension 4. thrust fault; compression

_____________ in layered sedimentary rocks are evidence for horizontal compression and shortening

Tight Folds

Which of the following is a direct measure of the distance from a seismic receiving station to the focus of a distant earthquake.

Time interval between the first P and first S-wave arrivals

What are fossils? Describe at least five different types of fossils.

Traces or remains of prehistoric life now preserved in rock The remains of relatively recent organisms - teeth, bones, etc. - Entire animals, flesh included - Given enough time, remains may be petrified (literally "turned into stone") - Molds and casts - Carbonization

Following a major earthquake, aftershocks diminish in magnitude but may still be powerful enough to destroy or further damage weakened buildings.

True

Hydrothermal metamorphism involves chemical reactions between hot fluids and surrounding rocks such as occurs beneath mid-ocean ridges

True

Rapid burial and possession of hard parts are necessary conditions for the preservation of plant or animal remains as fossils

True

S-Waves do no travel through liquids

True

Some large earthquakes are preceded by smaller magnitude foreshocks.

True

The Richter earthquake magnitude scale is based on the total amount of energy released by the earthquake.

True

The oldest, sedimentary rock strata are exposed along the hinge line (fold axis) of deeply eroded Anticlines

True

The term Paleozoic describes the era of ancient life forms.

True

What causes tsunamis? Describe the changes to tsunami waves as they approach the shoreline in terms of wave velocity, wave height, the spacing between waves, and amount of destruction.

Tsunamis are also called seismic sea waves: - destructive waves that are often inappropriately called "tidal waves" - result from vertical displacement along a fault located on the ocean floor or a large undersea landslide trigger by an earthquake - in the open ocean height is usually <1 meter - in shallower coastal waters the water piles up to heights that occasionally exceed 30 meters - can be very destructive - waves are almost undetected in deep ocean and can become very destructive when hitting the coast

What are the various ways by which future earthquakes may be predicted?

Tsunamis are also called seismic sea waves: - destructive waves that are often inappropriately called "tidal waves" - result from vertical displacement along a fault located on the ocean floor or a large undersea landslide trigger by an earthquake - in the open ocean height is usually <1 meter - in shallower coastal waters the water piles up to heights that occasionally exceed 30 meters - can be very destructive - waves are almost undetected in deep ocean and can become very destructive when hitting the coast What are the various ways by which future earthquakes may be predicted? Short Range predictions: * currently no reliable method exists for making, short range earthquake prediction - animals behaving strangely just before an earthquake - tilting and other types of ground deformation in the area of eminent fault slippage prior to main shock - increase in frequency of small earthquakes (foreshocks) prior to the main shock - the opening of micro fractures in bedrock prior to the main earthquake changes physical properties of rock ; changes in conductivity of electric current ; changes in p wave velocities of foreshocks - in water wells; changes in water levels, increase in radon concentration Long Range Predictions: * give the probability of a certain magnitude earthquake on a time scale of 30-100 years or more - Paleoseismology: study the history of past seismic activity; used to predict probabilities of future earthquakes - seismis gaps along a fault: segments here fault is locked, strain not readily released along these segments and thus builds up; fault eventually slips within segment and enormous strain buildup is released as a major earthquake

Seismic gaps are...

Unusually quiet zones along known active faults

Which of the following best characterizes an angular unconformity?

a. tilted strata lie below the unconformity; bedding in younger strata above is parallel to the unconformity

The intensity scale is not a very good scale

as stated during the review

Dip is measured

at right angles so 90*

How does a building's structure, distance from epicenter and nature of the soil and bedrock affect the amount of damage caused by an earthquake?

buildings resting on unconsolidated soil experience more damage than buildings constructed on solid bedrock

Which of the following denotes the divisions of the geologic time scale in correct order of decreasing lengths of time beginning with the longest time interval and ending with the shortest?

eon, era, period, epoch

Red shale and lime stone

is geologic view

Cutaway view

is the cross section

_________ refers to the tendency for a foundation material to lose its internal cohesion and fail mechanically during earthquake shaking.

liquefaction

What are seismic gaps and what do they say about future major earthquakes

seismic gaps along a fault : - segments where fault is locked - strain not readily released along these segments and thus builds up - fault eventually slips within segment and enormous strain build-up is released as a major earthquake

What does the moment magnitude of an earthquake measure?

seismologists often prefer a scale that measures the actual energy released by an earthquake depends on: - amount of slip on the fault plane - area of the fault break - rigidity or strength of the rock the total energy of an earthquake can be related to its richter magnitude

Which of the following is an essential characteristic of an index fossil?

the organism lived only for a short period of geologic time

P waves can travel

they travel the fastest and can travel through solids, liquids, and gases. Push or pull particles of matter in the direction of their travel path.