Geo 3

What are the steps in the formation of sedimentary rocks?

weathering, erosion, deposition, lithification

major types of siliciclastic sedimentary rocks

conglomerate, sandstone, siltstone, shale

major types of biochemical sedimentary rocks

limestone, coal, rock salt

What are the main minerals that make up sedimentary rocks?

sandstones, mudrocks, carbonate rocks

How is sediment transported

erosion

what is considered fluid transport?

water, wind, waves

what is considered nonfluid transport?

ice, mass wasting

What is the difference between a High Energy and a Low Energy depositional environment?

A high-energy environment might consist of a rapidly flowing stream that is capable of carrying coarse-grained sediments, such as gravel and sand. Sedimentation in a low-energy environment, such as an abyssal plain, usually involves very fine-grained clay or mud.

What are examples of high Energy depositional environment

river channels, beach and shallow offshore environments with high wave action, and wave-battered coral reefs

What are examples of low Energy depositional environment

lakes and swamps

What is lithification?

change from sediment to rock

How does lithification occur?

compaction and cementation

Graded Bend

sudden decrease in energy, large grains settle first

Well sorted sediment

A sediment in which particles are of uniform size.

Poorly sorted sediment

A sediment in which particles of many sizes are found.

cross beds

layers inclined to main layering, form by migrating ripples or dunes

mudcracks

Polygonal cracks on rock surface caused by drying of mud

What does relative age dating determine?

put in correct sequence

what does absolute age dating determine?

determine how old rocks are

What is Original Horizontality?

Layers of sediment are originally deposited horizontally. If the layer is not horizontal than something else happened

What is Stratigraphic Superposition?

oldest on bottom, youngest on top

What is Cross Cutting Relations?

if one geological feature cuts across another, the feature that has been cut is older. the feature cutting it is younger.

What is Faunal Succession?

fossils succeed one another in a definite recognizable order. result of evolution. determine older rock by older fossils

What is absolute age dating

the numerical age, in years, of a rock or object

How is absolute age dating different from relative age dating?

harder then relative age dating

what is an isotope

Atoms of the same element that have different numbers of neutrons

What is radioactive decay?

The process in which unstable isotopes decay into other elements and emit radiation as they attempt to become more stable

How is radioactive decay used in absolute age dating?

scientists can measure the amount of decayed material in the sample, determine the ratio between original and decayed material, and then calculate the sample's age

What is half life?

It is the time for 1/2 a substance to decay by radioactive processes.

What is the significance of the ratio of daughter isotope to parent isotope in age dating?

daughter isotope increases as parent decrease

What is the blocking temperature?

the temperature of a system, such as a mineral, at the time given by its radiometric date

What are the limitations on using radiometric age dating?

The material being dated must have measurable amounts of the parent and/or the daughter isotopes

What is the geologic time scale

a record of the geologic events and the evolution of life forms as shown in the fossil record

How has life on Earth changed over geologic time?

organisms change over time (evolution)

What is progradation?

growth of a river delta farther out into the sea over time

What are transgressions?

sea level rises

What are regressions?

type of saccades, have to go back to reread a word because you didn't get full meaning

What are unconformities?

gaps in the geologic record signals erosion

What is deformation?

change of shape, size, location of rock

What is stress?

measure of force intensity causes deformation

What is strain?

effect of stress, measure of change in size and shape

how do stress and strain relate?

Strain is the change in shape that happens when rocks are deformed by stress

What are the characteristics of elastic behavior?

linear relation, reversible, rupture, brittle deformation,

What are the characteristics of plastic behavior?

nonlinear relation, permanent, rupture, ductile deformation

What happens when rocks undergo brittle deformation?

fracture into joints and faults

What happens when rocks undergo ductile deformation?

rock will contort and change shape without fracturing

What conditions favor brittle and what conditions favor ductile deformation?

low Pressure, temperature and rate of deformation determines brittle versus ductile deformation

What is strike

horizontal line in plane

what is dip

The angle at which rock strata lie

Tilted layers

most sedimentary rocks form as horizontal layers

Anticlines

concave down, A shaped

Synclines

concave up

Normal faults

A type of fault where the hanging wall slides downward; caused by tension in the crust

Thrust faults

hanging wall moves up

Strike slip faults

rocks move horizontally

How are left lateral and right lateral strike slip faults recognized?

opposite block move left/right

What is the difference between the hanging-wall and footwall of a fault?

In a cross-section view of a fault, the rock above the fault zone is called the hanging wall. The rock below the fault zone is called the foot wall.

What are earthquakes?

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.

How do earthquakes form?

As rocks move past each other along a fault, their rough surfaces catch temporarily, halting movement along the fault. However, forces keep driving the rocks to move, causing stress to build up. When the rocks are stressed beyond the elastic limit, they break and move along the fault causing earthquakes to occur.

Where do earthquakes occur?

along plate boundaries and faults

Why is elastic behavior of rocks important for earthquakes?

Earthquakes occur when energy stored in elastically strained rocks is suddenly released. This release of energy causes intense ground shaking in the area near the source of the earthquake and sends waves of elastic energy, called seismic waves, throughout the Earth.

What is the elastic rebound theory?

rocks away from fault move slowly, fault locked. elastic deformation stores energy, fault fails, rocks jump forward, energy released

What is the significance of seismic waves?

our ability to understand and predict earthquakes and tsunamis, it also reveals information on the Earth's composition and features

What are the prosperities of P waves?

vibrate in direction they travel

What are the prosperities of S waves?

vibrate perpendicular to direction of travel

What are the prosperities of surface waves?

rolling ground waves

How are seismic waves used to locate the epicenter of an earthquake?

When seismic data is collected from at least three different locations, it can be used to determine the epicenter by where it intersects

What is earthquake magnitude (how it measured and what does it tell you)?

measure the size of the earthquake at its source. based on amplitude of seismic waves

What is earthquake intensity (how it measured and what does it tell you)?

describe the severity of an earthquake's effects on the Earth's surface, humans, and buildings at different locations in the area of the epicenter

What is the difference between magnitude and intensity?

magnitude is based on amplitude of seismic waves. intensity is based on damage

What are the major causes of damage during an earthquake?

ground shaking, ground rupture, landslides, tsunamis, and liquefaction

What factors determine the severity of damage during an earthquake?

the intensity of earthquake shaking

What is metamorphism?

change in mineral assemblage and/or texture in solid state

What is contact metamorphism?

rapid heating by magma

What is regional metamorphism?

Regional Metamorphism is where the rock is subjected to extreme pressure and temperature. Results in major changes.

What changes occur in rocks during metamorphism?

grains grow, foliation develops

What is foliation and how does it form?

parallel alignment of minerals. forms when pressure squeezes the flat or elongate minerals within a rock so they become aligned

What can happen to a mineral assemblage during metamorphic rocks?

reflect the chemical composition of the original rock and the new pressure-temperature conditions to which the rock was subjected

What is the significant of the presence of a particular Al2SiO5 mineral in terms of the condition of metamorphism?

same composition, different structures.

What is a protolith?

pre metamorphic rock

What is an index mineral?

Minerals that form under a fairly narrow range of temp/pressure

What is an isograd?

line of equal metamorphic grade

How are isograds used to measure metamorphic intensity?

a rough measure of the degree of metamorphism a rock has undergone

What is a metamorphic zone?

A belt of rocks displaying the same general degree of metamorphism.

What is a metamorphic facies?

a group of metamorphic rocks that contain the same assemblage of minerals

Under what conditions are rocks of the hornfel facies metamorphosed?

when heat and fluids from the igneous intrusion alter the surrounding rock

Under what conditions are rocks of the blueschist facies metamorphosed?

very low temperature, medium to high pressure

Under what conditions are rocks of the greenschist facies metamorphosed?

lowest temperature and pressure

Under what conditions are rocks of the amphibolite facies metamorphosed?

moderate-high temperatures and pressures

What is the relationship between metamorphic facies and plate tectonics?

Metamorphic rocks result from the forces active during plate tectonic processes

What is a hypothesis?

an unproven exploration for the way things happen

What is a theory?

A hypothesis that has been tested with a significant amount of data

What is continental drift?

the gradual movement of the continents across the earth's surface through geological time.

What was the original evidence for continental drift?

- fit of continents

- matching geology in continents

- similar fossils found on different continents

What is sea floor spreading?

The process by which molten material adds new oceanic crust to the ocean floor

What is the evidence that seafloor spreading occurs?

- aseismic ridges

- paleomagnetism

- remanent magnetism