Geology Final

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What is an earthquake?

An episode of ground shaking.

Approximately how many earthquakes happen each year?

Billions

Most earthquakes are due to slip on faults. True or False?

True

3 main types of faults

Normal- (sides pull apart) Reverse- (sides push together) Strike-slip- (move sideways) Thrust Fault- shallow sloping

Other causes of earthquakes

-Movement of magma -Sudden change in arrangement of atoms in rock minerals, landslides, meteorite impacts & nuclear-bomb tests

Hanging Wall

Block positioned over the fault

Normal Fault

When hanging wall slips down the slope of the fault (tensional)

Reverse Fault

When hanging wall slips up and it is steep sloping (compressional)

Strike-slip Fault (lateral slip fault)

Near-vertical planes on which slip occurs parallel to the strike line on the fault plane (no up or down motion)

What is a fault scarp?

When a fault intersects the ground surface producing a step

Where is the epicenter of an earthquake located?

The point on the Earth's surface located directly above the focus of an earthquake.

Where is the focus of an earthquake located?

The location where the earthquake begins. The ground ruptures at this spot, then seismic waves radiate outward in all directions.

What type of fault is found at the foot of the Wasatch Range?

Normal fault

What is an aftershock?

They happen because of slip during the mainshock leaves the fault in an unstable configuration.

On the earthquake magnitude scale, how much more powerful is each whole number step? Ex: how much stronger is a 6 magnitude earthquake compa

10 times

Where on the earth do most earthquakes occur?

80% of earthquake energy released on earth comes from the plate-boundary belts surrounding the Pacific Ocean, also known as the Pacific Ring

P-waves

(compressional waves) (primary waves) waves that cause particles to move back and forth (parallel) to direction of wave

S-waves

(shear waves) (secondary waves) waves that cause particles to move perpendicular to the direction in which the wave itself moves.

What is liquefaction?

the process by which water-saturated, unconsolidated sediments are transformed into a substance that acts like a liquid, often in an earthqu

The amount of ground shaking and displacement depends on:

Magnitude Distance for epicenter Nature of substrate Frequency of waves Acceleration

What causes a tsunami? Why are they different than regular beach waves?

The wavelength can be miles wide, beach waves might only be a few feet. (know what is meant by wavelength)

Mountain occur in ranges formed when the crust of the earth is uplifted. Mountain formation causes deformation, a process in which rocks be

Joints Faults Folds Foliation

What is ductile deformation?

When rocks bend or flow, like clay

What factors affect whether rocks are ductile or brittle?

Temperature Extreme pressure Slow deformation rate composition

Brittle structures are:

Joints Mineral filled cracks Faults- a fracture where sliding occurs

What is isostasy?

the state of gravitational equilibrium between Earth's crust and mantle such that the crust "floats" at an elevation that depends on its th

What is isostatic equilibrium?

When a certain area of Earth's crust reaches the state of isostasy

What drives most of the erosion on Earth?

Gravity

What is a craton?

the stable interior portion of a continent characteristically composed of ancient crystalline basement rock.

What are fossils and how are they formed?

most are formed when a plant or animal dies in a watery environment and is buried in mud and silt. Soft tissues quickly decompose leaving th

What is an extinct species?

occurs when there are no more individuals of that species alive anywhere in the world

What is Paleontology?

the branch of science concerned with fossil animals and plants.

What type of rock contains fossils?

Sedimentary rocks

One or more of the following needs to happen to preserve a fossil:

Anoxic environment Rapid burial Presence of hard parts

What is evolution?

The change in a population over a succession of generations due to the transfer of inheritable characteristics.

What is natural selection?

When beneficial characteristics get passed onto the next generation.

Know the three eras during the Phanerozoic Eon

Cenozoic Mesozoic Paleozoic

The Paleozoic

-Epicontinental Seas -Amphibians -The Appalachian Mountains -Ended with -Cambrian Explosion the Perm

Archaea and Bacteria appear in rocks as old as...

3.7 billion years

The Mesozoic

-The climate continued to warm and sea levels were higher than any other time since the Cambrian 200 million years ago -small mammals -this

The K-T boundary event at the end of the Mesozoic

-The fossil record shows an abrupt sudden mass extinction took place -the dinos along w/90% of plankton species and 75% of plant species dis

The Cenozoic

65 million years ago to the present-- an era which included many documented ice ages including the last one which was 11,000 years ago when

Uniformitarianism

Physical processes that operate in the modern world also operated in the past at about the same rates. Why would this be important to geolo

Numerical Age

The age given in years determined by radiometric methods

Relative Age

The age of one feature with respect to another in a sequence

How we determine relative age in rock layer

Unconformities

Radioactivity

The result of spontaneous decay of an atom’s nucleus

Energy

The capacity to do work

Oil and gas

Fossil fuels

Unconformities

gaps in the record created by non-deposition or erosion, they represent period of erosion and/or non-deposition of sediment.

Oil and gas contain...

Hydrocarbons (which are chain-like or ring-like molecules of carbon and hydrogen)

What are hydrocarbon molecules derived from?

Fatty molecules called lipids that were once in plankton. (oil and gas are NOT created from plants or dinosaurs)

Oil and gas are found in a...

Hydrocarbon reserve

Above 90 degrees C (194 degrees F)...

Kerogen turns to oil or gas

Above 160 degrees C (320 degrees F)...

Oil and gas lose the H and is turned to pure graphite

There are NOT pools or lakes of oil underground… True or False?

True

To fill the pores in the reservoir rocks… (rocks like sandstone that are both porous and permeable)

The hydrocarbon must migrate upward from the oil shale

Describe Porosity

the percentage of void space in a rock.

Describe Permeability

a measure of the ability of a porous material to allow fluids to pass through it.

Oil and gas are ____ than water so they ___

Less dense, rise towards the surface

Geologic strata needed to form oil reserves:

Source rock- oil shale Reservoir rock- a rock with pores and permeability Trap or sea- usually shale or another impermeable rock

Source rocks are always ____ as are most reservoir rocks and seal rocks

Sedimentary

Coal

Black, brittle sedimentary rock consisting of carbon mixed with small amounts of organic chemicals, quartz and clay.

What does coal come from?

Plant material that once grew in swamps, wetlands and rainforests.

Where did most coal-forming swamps grow?

In the Carboniferous and Cretaceous periods due to the high sea levels, and lots of land near the equator.

Conditions needed for formation of coal:

-- vegetation & plants material in an ancient swamp -- quick burial in an oxygen-poor environment -- compaction and burial by at least 4-10k

Landslides

Mass movement or mass wasting The downslope transport of rock, regolith, snow or ice

Features useful to distinguish different types of landslides:

Type of rock Velocity of movement Character of the moving mass Environment where the slide takes place

Creep

Occurs when the soil or bedrock expands and contracts on a gentle slope

Solifluction

Occurs when the top 1-3 m of ground thaws in permafrost areas.

Slumping

Relatively slow-moving mass movement event Rock & earth stays coherent Slides on a failure surface

The upslope edge of a failure surface forms a

Head scarp

Toe

the bottom edge of a landslide

Mudflow

Moving slurry of mud

Debris flow

Mixture of mud and larger pebble to boulder size fragments

Lahars

Mudflows that travel down river valleys bordering volcanoes and consist of a mixture of volcanic ash and water from the snow and ice that me

Rock Slide

Sudden movement of rock and debris down a nonvertical slope

Debris Slide

If the slide is rock and earth both

Angle of Repose

the steepest angle of descent or dip relative to the horizontal plane to which a material can be piled without slumping.