GEO 100 - Exam 2

Describe the relative movement along a strike slip fault.

A fault in which the dominant displacement is horizontal and parallel to the trend of the fault surface. produced a large earthquakes

Contrast the movements that occur along normal and reverse faults. What type of stress is responsible for each kind of fault?

A normal wall block moves down relative to the footwall block. They are associated with tensional stresses the pull rocks apart. A reverse faults is when the hanging wall block moves up relative to the footwall block. Normal fault is uses a tensional stress. Reverse fault uses a compressional stress.

Principle of Original Horizontality

A principle by which layers of sediment are generally deposited in a horizontal or nearly horizontal position

Principle of Cross-cutting Relationships

A principle of relative dating which states that a rock or fault is younger than any rock or fault through which it cuts

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 inclusions

An inclusion is a piece of rock that is enclosed within another rock. Inclusion is fragment of other rocks included into younger ones.

· What is the significance of an unconformity? Describe and identify the different unconformities (gaps in the rock record): Angular Unconformity, Nonconformity and Disconformity.

An unconformity is a break in the rock records produces by erosion and or non deposition of rock units Angular unconformity - tilted rocks are overlain by flat lying rocks Disconformity - strata on either side of the unconformity are parallel Nonconformity - metamorphic or igneous rock in contact with sedimentary strata

Describe the types of waves emitted during an earthquake. Which are typically most damaging?

Body waves travel through earth's interior. Primary waves and secondary waves. P waves can travel through all materials. S waves can not travel through liquids and gases. Also surface waves travel in the rock layers just below the earths surface. S waves are typically the most damaging

How is brittle deformation different from ductile deformation?

Brittle deformation is when rocks break into smaller pieces where as ductile deformation is when the object changes shape without breaking

List the several factors that can cause deformation in rocks.

Compression - Differential stress that squeezes a rock mass as if it is in a vise. Tension - Differential stress that pulls apart rock bodies Shear - Differential stress can cause rocks to shear which involves the movement of one part of a rock body past another.

What type of plate boundary is most commonly associated with compressional stress?

Convergent Plate Boundaries

Distinguish between between domes and basins

Domes are broad upwarping of basement rock deforms that produce a circular or slightly elongated bulge where as Basin is the inverse of a dome is a downward structure

Describe the textural differences exhibited by metamorphic rocks (foliated, non-foliated).

Foliation refers to any planar arrangement of mineral grains or crystals within a rock. Metamorphic rocks that do not develop a layered or banded appearance as a result of metamorphism

What information does a travel-time graph provide?

It will tell you how far away (distance to) the epicenter of an earthquake was.

What is Metamorphism? Describe the main changes that occur during metamorphism (mineral and texture changes)

Means to "change form". It is a process that transforms the mineralogy, texture, and sometimes chemical composition of the parent rock

Discuss the relationship between metamorphism and plate tectonics

Metamorphic rocks result from the forces active during plate tectonic processes. The collision of plates, subduction, and the sliding of plates along transform faults create differential stress, friction, shearing, compressive stress, folding, faulting, and increased heat flow.

Describe absolute and relative age of a geologic event: distinguish between numerical ages and relative ages

Numerical dates specify an absolute age in number of years, whereas relative dates determine the order of events in relation to one another.

Explain how the absolute age of a rock is determined: What are isotopes?

Radiometric dating determining the age of rocks using unstable isotope. atoms of an element that have the same number of protons and different number of neutron (and different atomic masses)

Explain the differences among Richter magnitude, Moment magnitude and Mercally intensity.

Richter magnitude is a scale of earthquake magnitude based on the amplitude of the largest seismic wave Moment magnitude is more precise measure than the Richter scale that is derived from the amount of displacement that occurs along a fault zone Mercalli intensity is based on observable earthquake damage.

What are seismographs?

Seismographs has a weight freely suspended from a support that is securely attached to bedrock hal

What is deformation

The action or process of changing in shape or distorting, especially through the application of pressure.

What are the focus

The focus is the place inside Earth's crust where an earthquake originates

What factors determine whether a rock deforms in a brittle or ductile manner?

The rock deformation tends to be brittle at shallow depths and ductile at greater depths. Four factors influence how a rock deforms are temperature, confining pressure, the type of rock, and time.

Identify Hanging wall and Foot wall.

The rock surface immediately above the fault where as the rock surface below

What are the agents of metamorphism?

The three agents of metamorphism are heat, pressure, and chemically active fluids

What is liquefaction?

The transformation of a stable soil into fluid that is often unable to support building or other structures

What are metamorphic rocks, and how do they form

They are formed by intense heat, intense pressure, or by the action of watery hot fluids.

Define earthquake.

a sudden and violent shaking of the ground, sometimes causing great destruction, as a result of movements within the earth's crust or volcanic action.

Distinguish between between anticlines and domes

anticlines is folding or arching where as domes are a circular bulge

Distinguish between anticline and synclines

anticlines usually form by the upfolding, or arching of sedimentary layers where as synclines are downfolds or troughs.

What are the two textural divisions of metamorphic rocks and the conditions associated with each occurrence?

metamorphic rocks with foliated textures contain platy and or elongated minerals and they display some kind of preferred orientation in which the mineral grains exhibits a parallel to subparallel alignment. Non foliated metamorphic rocks typically develop in environments where deformation is minimal and the parent rocks are composed of minerals that exhibit equidimensional crystals, such as quartz or calcite.

What are the names, textures, and compositions of the common metamorphic rocks?

phyllite, schist, gneiss, quartzite and marble.

What are the different types of metamorphism?

shale, phyllite, Schist, Gneiss, Marble, and quartz

Earthquakes hazards: List and explain the main hazards related to earthquakes.

surface faulting, ground shaking, landslide, liquefaction, tectonic deformation, tsunamis, and seiches.

epicenter of an earthquake?

the point on the earth's surface vertically above the hypocenter (or focus), point in the crust where a seismic rupture begins.

What is a half-life?

the time required for one half of the radioactive nuclei in a sample to decay Is the time it takes for half of population of parent corn kernel to pop (irreversible decay) into an equal number of popcorns (daughter isotopes)