question

Shield Volcanoes are composed primarily of __________ lava flow

answer

Basalt

question

Hazard

answer

The existence of a potentially dangerous situation or event (ex. potential landslide of a steep slope or lava flow erupting from a volcano)

question

Risk

answer

An assessment of whether the hazard might have some social impact (ex. loss of life, damage to property, etc.)

question

What is erupted by volcanoes?

answer

Ash, Pumice, Lava

question

A composite cone would be expected to have a _________ slope than a shield volcano

answer

steeper

question

Eruption Styles

answer

1. Lava flow- least explosive, magma erupts onto surface and flows away from a vent. 2. Lava fountains- medium explosive, caused from high initial gas content and less vicious lava-> the gas propels the lava and separates it into discrete pieces 3. Eruption Column- most explosive, Tephra (magma that is blown apart by volcanic gases), erupts high into the atmosphere then falls back to Earth as solidified and cooled pieces of rock 4. Pyroclastic flow- most explosive, some ash does not jet straight up but collapses down the side of the volcano as a dense, hot cloud of ash particles and gas (ash flow) - devastating because of high speed and high temp.

question

Characteristics of actively erupting volcanoes:

answer

billowing clouds of ash rising into the air, fragments of molten rock blasting into the air, glowing orange lava flowing down hill

question

Scoria Cone

answer

Steep-sided cone shaped hill hundreds of meters high, with a small crater at the summit; composed of cinders (scoria) and volcanic bombs - basaltic or andesitic composition

question

Shield Volcano

answer

Broad, gently sloping conical hill or mountain with fissures along its summit; composed mainly of basaltic flow

question

Composite Volcano

answer

Moderately steep, cone-shaped mountains thousands of meters high with a crater at the top; composed of interlayered lava flows, pyroclastics, and volcanic mudflow- mostly composed of intermediate rocks (ex. andesite) but can have felsic or mafic rocks

question

Volcanic Dome

answer

Steep-sided dome-shaped hill hundreds of meters high; composed of felsic lava- consist solidified lava

question

What kind of volcanoes produced pyroclastic flows that killed tens of thousands of people at Pompeii & St. Pierre?

answer

Composite

question

Most composite volcanoes are found along ___________ plate boundaries

answer

convergent --> subduction zones (ex. Ring of Fire)

question

Rocks found typically in calderas

answer

Top: volcanic tuff Middle: Hard, welded volcanic rock Bottom: finely crystalline granite

question

Typical shape of most volcanoes is

answer

conical

question

Hazards of Scoria Cones

answer

falling volcanic cinders and bombs, volcanic ash and gases

question

Hazards of lava flow

answer

burial of roads, bulldozing and crushing of houses and other structures

question

Felsic Magma

answer

-high gas pressure commonly lead to highly explosive eruptions - high viscosities - do not allow gas bubbles to escape --> hence build up of gas & explosions

question

Formation of Crater Lake:

answer

1. Massive ash column eruption of a composite volcano empties the magma chamber 2. Overlying volcano collapses into the resulting void 3. Scoria cone forms in the caldera 4. Rain & snowmelt fill the caldera, producing a large and deep lake

question

Characteristics of volcanic domes:

answer

-viscous silicic magma -often occur in clusters -rubble covered surface -steep-sided

question

Basaltic Magmas

answer

fluid lava, flows from shield volcanoes; low viscosity

question

Felsic Magmas

answer

explosive eruptions from composite volcanoes; high viscosity

question

Rock Type associated with Volcanic Domes

answer

rhyolite & andesite

question

Events of 1980 Mount St. Helens eruption

answer

order from 1st event to last: 1. Earthquake 2. Landslide 3. Lateral blast & eruption column

question

Flood basalts

answer

represent the largest igneous eruption on Earth, with some covering tens of thousands of square kilometers

question

How do we assess the danger posed by a volcano?

answer

Shape- steep slopes indicate high viscosity, explosive magma; gentle slopes indicate less explosive volcanoes Rock Type- chemical analysis determines magma composition and potential for explosiveness History- The sequence of layers and isotopic dating can indicate the timing and frequency of eruptions

question

Ways volcanic domes are destroyed

answer

1. collapse of steep flanks into block and ash flow 2. internally derived explosions from trapped gas pressure

question

Monitoring volcanoes/ preceeding eruptions

answer

- steam eruptions from the volcanic crater - increase in seismic activity - increased in gas flow from volcano - increased heat flow from the volcano

question

Formation of a Caldera

answer

1. Magma erupts as ash column, emptying a shallow magma chamber 2. Overlying material collapses into emptied chamber in a series of fault blocks 3. Ash and other pyroclastics fill the subsiding crater 4. Small rhyolite domes form form in caldera

question

Majority of transform boundaries are found ______________

answer

in conjunction with mid-ocean ridges

question

Characteristics of continental rifting:

answer

-stretching of the crust causes crustal blocks to drop down - if rifting continues the continent can be split in two pieces - rifting begins with a broad uplift as magma ascends

question

When divergent boundaries occur on continents the process is called:

answer

continental rifting

question

Seamount

answer

a mountain beneath the ocean that never reaches the surface

question

Mid-Ocean ridges

answer

broad symmetrical ridges that cross ocean basins

question

Tools used to measure to measure plate motion:

answer

GPS satellites, lasers

question

The Pacific Ring of Fire is formed by...

answer

a string of volcanos --> subduction on both sides

question

Oceanic fracture zones

answer

cracks and steps that cross the seafloor and run mostly at right angles to mid-ocean ridges

question

List the 5 oceans

answer

Arctic Ocean Pacific Ocean Atlantic Ocean Southern Ocean Indian Ocean

question

Island arcs

answer

curving island chains across the seafloor that are mainly volcanic in origin

question

Oceans cover ________% of Earth's surface

answer

71%

question

transform fault

answer

a fault that accommodate the horizontal movement of one tectonic plate past another

question

continental collision

answer

when two continental masses converge

question

Geological features of Earth include:

answer

dramatic mountains, intricate coastlines, beautiful valleys & undersea trenches

question

For a plate to move, the driving force must exceed the the ________

answer

resisting force

question

convergent boundary

answer

2 plates coming together

question

Volcano distribution on Earth:

answer

- there are many volcanoes along the edge of the Pacific Ocean are associated with earthquakes - there is a large volcanic belt along the west coasts of North & South America - Volcanism occurs along mid-ocean ridges

question

Along the boundary of oceanic-continental convergence...

answer

the oceanic plate subducts beneath the continental plate (because it's denser)

question

Continental shelves

answer

when continents continue outward from shoreline under the seawater (submerged benches)

question

Subduction

answer

the process of one plate sliding beneath another

question

What type of plate movement occurs at transform faults?

answer

horizontal

question

Tectonic plates are composed of the _______ and move around on the _________

answer

lithosphere; asthenosphere

question

Stages of continental rifting:

answer

1. Ascension of magma causes uplift of the crust 2. Stretching of the crust causes crustal blocks to drop into faults, forming rifts 3. Continuation of rifting splits the continent into two; a narrow ocean forms as seafloor spreading takes place 4. Continuation of seafloor spreading increases the ocean basin as it becomes wider

question

Oceanic crust forms from upwelling of magma that spreads outwards from mid-ocean ridges-

answer

- the oldest basalt should be farthest from the mid-ocean ridge - the thickest sediment cover should be the farthest from the mid-ocean ridge

question

Tectonics is the study of __________

answer

the origin and arrangement of the broad structural features of Earth's surface

question

Convergent boundaries

answer

when plates move towards eachother

question

Triple Junction

answer

a place where three boundaries meet

question

Outer Core

answer

The layer of Earth that behaves as a dynamo (electrical generator) --> producing the magnetic field (convection currents)

question

Abyssal Plains

answer

relatively smooth surfaces on the ocean floor

question

Plates move _______ per year

answer

1 to 15 cm

question

Geology

answer

the scientific study of the Earth

question

Isostasy

answer

the balance or equilibrium of adjacent blocks of brittle lithosphere floating on the ductile asthenosphere

question

2 main types of crust on Earth;

answer

continental, oceanic

question

Weathering

answer

Breaking down of rocks either mechanically or chemically

question

Shield Volcanoes

answer

mafic eruptions- (ex. Hawaii)

question

Transportation

answer

Moving pieces of rock by wind, ice or water

question

Deposition

answer

Occurs when the energy of transported material decreases

question

Uplift

answer

Upward movement of underground rocks to the surface

question

Lithification

answer

Process of sediments turning into rocks

question

Lithosphere

answer

the rigid portion of the Earth (crust and upper mantle)

question

Outer planets from the sun outward-

answer

Jupiter Saturn Uranus Neptune

question

Why is geology important to everyday life

answer

- we rely o it for energy resources - it helps us make decisions regarding the environment - we rely on it to locate raw materials for industry

question

Asthenosphere

answer

located beneath lithosphere

question

Earth's three major concentric zones:

answer

Crust Mantle Core

question

igneous rock

answer

rocks that have solidified from magma

question

what kind of crust is thicker?

answer

continental

question

Composite Volcanoes

answer

intermediate eruptions- anywhere where there are subduction zones - convergent boundary- most common volcano (ex. ring of fire)

question

3 factors that directly shape the surface of the Earth

answer

1. Atmosphere & it's movement 2. Water & it's movement (Hydrosphere) 3. Impact of diverse life forms (Biosphere)

question

Metamorphism involves:

answer

- heat - pressure - deformation

question

Magma

answer

molten rock underground usually rich in silica & containing dissolved gases

question

Composition of Layers of the Earth

answer

- continental crust: granite - oceanic crust: basalt - mantle: olivine - core: iron & nickle

question

Twenty-eight thousand years ago the Earth was __________

answer

colder than it is today - continental ice sheets covered large areas of the land

question

Rock Cycle

answer

the process in which a rock may move from one place to another or be converted into a new rock type

question

Flowing Water

answer

most important agent in sculpting the landscape

question

three terrestrial planets

answer

Venus, Mercury, Mars

question

Glaciers

answer

huge flowing fields of compressed ice & snow that carry large amounts of rocks and sediment

question

The decay of radioactive elements such as uranium creates ___________

answer

heat -in the Earth's crust

question

Qualitative Data includes:

answer

labels, images, sketches, descriptive words

question

Density Formula

answer

mass/volume

question

Cenozoic Era

answer

began 65 million years ago- most recent chapter in Earth history - continues to the present

question

Geologic map

answer

uses various colors to show the distribution of various rock types/ages, and features exposed on the land surface

question

Beds

answer

layers within sedimentary rock

question

Quantitative date may include:

answer

age of rock, specific temperature data, chemistry of water in stream, size measurements of sediments

question

Geological time scale

answer

the periods and subdivisions of Earth's history arranged in proper order

question

Topographic Map

answer

uses contour lines to indicate specific elevations and is useful for getting specific information about the shape of the land

question

Satellite image

answer

uses measurements of different wavelengths of light reflecting from a land surface to create a computer processed image to show the distribution of different types of plants, rocks & other features

question

Ga

answer

giga-annum billions of years before present

question

Ma

answer

mega-annum millions of years before present

question

Paleozic Era

answer

began with the appearance of many shelled creatures and ended with a widespread extinction event - began 542 million years ago - ended 251 million years ago

question

Relative Age

answer

the age of a fossil, organism, rock, geologic feature, or event as defined relative to other geologic features or events

question

Theory

answer

- a hypothesis that survives scientist scrutiny may become a theory - a theory is an explanation supported by experimental or factual evidence - theories encompass a larger body of knowledge than a hypothesis

question

Butte

answer

a smaller, steep sided mountain that has had its edges eroded away

question

Shaded Relief Map

answer

Simulates light and dark shading on hills and valleys

question

Rate

answer

how much something changed divided by the time required for the change to occur

question

Contour Lines

answer

indicate areas of equal elevation on a topographic map

question

When a fracture cuts across several layers of rocks we can determine that...

answer

the fracture is younger than the layers it crosscuts

question

Density

answer

the mass per unit volume of a substance

question

weight

answer

the amount of downward force exerted by an object under the pull of gravity

question

Properties of Water

answer

- water can dissolve materials by breaking apart ionic bonds as polar molecules attract individual ions away from each other - Hydrogen bonds form between water molecules and are responsible for the high surface tension of water - a water molecule is polar, and opposite ends of individual water molecules are attracted to anions and cations

question

There are more than 4,000 known minerals most of which are ...

answer

uncommon to rare

question

Ion

answer

an imbalance of protons and electrons within atoms or molecules

question

Cation

answer

a ion with a positive charge -> more protons than electrons

question

Anion

answer

an ion with a negative charge- more electrons than protons

question

silicon-oxygen tetrahedron

answer

- forms major building blocks for the vast majority of Earths minerals - has one silicon atom bonded with 4 oxygen atoms - may join with other tetrahedra or cations to form different types of silicates and a wide variety of minerals

question

Covalent Bonds

answer

When two atoms share an electron. Ex: water molecule strength: strongest mineral examples: diamond, bonds within sheets of graphite

question

Ionic Bond

answer

forms because of the attraction of two oppositely charge ions, such as when one atom loans one or more electrons to another atom strength: moderate mineral examples: halite, fluorite

question

Metallic Bond

answer

Electrons in a metallic bond are shared widely by many atoms; this holds the material together in a nonrigid way, which is why many metals are pliable strength: low Min. Examples: gold, copper

question

Intermolecular Force

answer

attraction due to polarity of molecules, which are bonded combinations of atoms strength: lowest (clay, mica) mineral examples: water ice and bonds between sheets of mica, clay or graphite

question

Internal Atomic Arrangement

answer

atoms in minerals are arranged in an ordered geometric pattern

question

Mineralogists

answer

geologist & other scientist who study minerals

question

Criterion required to be classified as mineral

answer

crystalline solid, naturally occurring, inorganic

question

Quartz uses

answer

may be used for chemical components; the element silicon is used to make computer chips & is mostly derived from this mineral

question

Hematite uses

answer

may be used for chemical components; iron is the main ingredient in steel & is mined from minerals like this

question

Clay uses

answer

may be used for its physical properties; used to produce bricks, cement and ceramics

question

Periodic Table

answer

- grouped elements tend to have similar chemical properties (like the two different types of metals, nonmetals, noble gases, etc.) - it begins with the lightest element and advances to higher atomic numbers and heavier elements from left to right and from top to bottom - it includes a elements atomic number and atomic symbol

question

Factors that contribute to a water molecule having polarity...

answer

- hydrogen atoms are grouped on one side of the oxygen atom - oxygen more strongly attracts electrons than hydrogen does - electrons spend more time around the oxygen atom and give the molecule a negative side and two positive ends on the other side

question

Silica

answer

A compound containing only silicon and oxygen in a ration of 1:2 (SiO2)

question

Silicon

answer

the 14th element of the Periodic Table; term may also be used to describe synthetic material used to make computer chip (or fake titties)

question

Silicone

answer

A synthetic material (often used for grease or caulk) in which carbon is bonded to silicon atoms to keep the material in long chains

question

Clastic

answer

forms in low-temperature environments; at or near Earth's surface

question

Crystalline

answer

Forms in high-temperature environments; minerals are interlocking

question

Igneous Rocks

answer

intrusive

question

Geothermal Gradient

answer

the temperature increase with depth

question

Pluton

answer

solidified magma chamber

question

Dike

answer

a sheetlike intrusion that cuts across layers in a hot rock

question

Sill

answer

an intrusion that is parallel to the layers in the host rock

question

Laccolith

answer

an intrusion that can eventually form a dome

question

Pegmatic texture

answer

forms deep within Earth in the presence of water

question

Vesicular texture

answer

near Earth's surface - as gas bubbles go through the lava

question

Porphyritic texture

answer

first deep within the earth then later near the surface

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