Earth Science Unit #2

a type of land formation created when lava solidifies into rock

volcano

the scientists that study volcanoes

volcanolists

about how many volcanoes around the world are active?

1500

How long can eruptions last?

hours to decades

On average, about how many eruptions per month causes significant damage in the world?

1

About how many eruptions each decade may be considered major disasters?

2-3

What program was established to assist damage caused by volcanic disasters and when?

Volcano Disaster Assistance Program (VDAP) in 1985

About how many active volcanoes worldwide have a complete network of monitoring instruments?

20

Fewer than how many volcanoes have any instrumentation at all?

200

What does interplate mean?

between plate boundaries

most volcanic activities occur where?

interplate (between plate boundaries)

What type of boundaries are most active volcanoes located at?

convergent boundaries

What type of boundaries are the most common for volcanoes?

divergent boundaries

What is the main source for intraplate volcanism?

hotspot

How did a volcano form if it is formed in the middle of a plate?

hotspots

What is viscosity?

the thickness of the magma (resistance of flow)

Doing what to the fluid makes it less viscous (more fluid)?

warming

What are the 3 different types of magma?

basaltic, andesitic, rhyolitic/granitic

Where type of boundary is basaltic magma found and what is the silica content?

divergent boundaries, low silica

Where type of boundary is andesitic magma found and what is the silica content?

convergent boundaries, intermediate silicia

Where is rhyolitic/granitic magma found and what is the silica content?

partial melting of the continental crust, high silica

For Basaltic magma what is the silica content, gas content, eruptive temperature, viscosity, tendency to form pyroclastic, and volcanic landform.

least (50%), least (0.5-2%), highest 1000-1250ºC, least (most fluid), least, shield volcanoes, basalt plateaus, cinder cones

For Andesitic magma what is the silica content, gas content, eruptive temperature, viscosity, tendency to form pyroclastic, and volcanic landform.

intermediate (60%), intermediate (3-4%), intermediate (800-1050ºC), intermediate, intermediate, composite cones

For rhyolitic/granite magma what is the silica content, gas content, eruptive temperature, viscosity, tendency to form pyroclastic, and volcanic landform.

Most (70%), Most (5-8%), lowest (650-900ºC), greatest (thick), greatest, pyroclastic flow deposits, lava domes

what two things affect the viscosity?

silica content and temperature

Decreased viscosity is caused by what?

decreased silica and increased temperature

Increased viscosity is caused by what?

increased silica and decreased temperature

increased viscosity leads to what resulting in what?

increased pressure resulting in more violent eruptions

most of the world’s active volcanoes about sea level are located along what type of plate boundary?

convergent

What is the area where most volcanoes located called?

ring of fire

What are the 3 common indicators that are typically observed before an eruption?

1. increased frequency of earthquakes

2. rapid changes in the shape of the volcano (changes in land surface orientation and elevation)

3. large scale emissions of common volcanic gases

What are cinders?

small rocks “raining” down on the earth during an eruption

During an eruption, what are lateral blast effects?

blasts directed horizontally

During an eruption, what is tephra? What is the most common?

particles that are blasted into the air by eruption, volcanic ash

During an eruption, what is volcanic gases?

water vapor, carbon dioxide, and sulfur dioxide

What is magma that exits onto the Earth’s surface?

lava

What is a movement of a portion of the earth down a slope called?

landslide

During an eruption, what is pyroclastic flow?

mixture of hot gases and ash, cinder, and other debris that forms a dense, hot cloud that races down the volcano’s slope (“movie scene”)

During an eruption, what are lahars?

mudflows formed when fine-grained tephra mixes with water from snowmelt or stream

How can tsunamis form?

collapse of volcanic landforms in the ocean

What are the following characteristics of shield volcanoes? (shape, viscosity, size, silica content)

broad, gently sloping sides built up from thousands of fluids, dome shaped, low viscosity, largest volcanoes, low silica, (Hawaii volcano)

What are the following characteristics of Stratovolcano volcanoes? (shape, type of boundary, silica content) What is another name for this volcano?

composite, steep sides and are cone shaped, majority of the world’s active volcanoes, convergent boundaries, typically have violent eruptions

What are the following characteristics of Cinder Cone volcanoes? (shape, size, how do they typically form)

composed of coarse tephra that is produced when gas escapes rapidly from molten lava, some of the smallest volcanoes, frequently occur in groups

What are the following characteristics of Plug Dome volcanoes?

commonly occur within a crater or along the flank of a larger composite volcano

steeped walled depression at the summit (general <1km in diameter)

crater

crater that forms when a stratovolcano or shield volcano collapses in to a shallow, empty magma chamber below the volcano. (usually >1km in diameter)

calderas

low viscosity lavas that reach the surface through fissures

lava plateaus

resistant vents left standing after erosion has removed the cone

volcanic necks

groundwater circulating near hot magma

geysers

where heated waters rise to the surface

hot springs

when chemical reactions with heated, acidic waters convert rocks into a soupy clay

mud volcanoes

when volcanic gases escape in the absence of water

fumaroles

a natural opening in the ground extending beyond the zone of light and large enough to permit the entry of a person

cave

the scientific study of caves

speleology

landscapes and hydrologic features created by dissolving limestone

karst

describe the process of the formation of caves

water sit on the limestone, water infiltrates into the ground and mixes with carbon dioxide to creating carbonic acid that eats away at the bedrock

Where does the formation of caves occur? (below what and in what zone)

below the water table and in the zone of saturation

What are speleothems?

dripstone features (curtains, flowstone, stalactites)

Deposition of speleothems is not possible until caves are ______ the water table in the Zone of ________.

above, aeration

What are solution (dissolved) caves, examples?

caused by dissolving bedrock, most common types of caves, wind caves, (Cumberland Gap NHP, KY)

What are lava tubes/caves, examples?

open conduits in cooled field of lava, Lava Beds, NM, CA

What are Sea (Littoral) Caves?

caused by wave actions along sea or lake coasts, Channel Islands NP, CA, (longest in North America), Apostle Island NP, WI

What are Talus caves, examples?

formed between boulders that have naturally fallen, Pinnacles NP, CA

What glacier/ices caves, examples?

caves formed by ice, Craters of the Moon NM, ID, Sunset Crater NM, AZ, El Maloats NM, NM, Wrangell - St. Elias NP, AK

what are speleothems that hang downward from the ceiling? (being as soda straws →icicles or carrots)

stalactites

what are speleothems that grow upward from the floor?

stalagmites

what are speleothems that when stalagmites and stalactites grow together they form this?

columns

what are speleothems that are described as “melted cake icing” or “frozen waterfall”

curtain/drapery

what are speleothems that water builds up (calcifies) on a sloped ceiling (cave bacon)?

flowstone

How many known caves are in the US?

17,000

Every state except with two have caves?

Rhode Island and Louisiana

What houses the largest cave system in the world?

mammoth cave NP, KY

What houses the 3rd longest cave system in the world?

Jewel Cave NM, SD

What houses the 7th longest cave system in the world?

Wind Cave NP, SD

What contains the largest cave room (“big room”) and 2nd deepest cave in the world?

Carlsbad Caverns NP, NM

A mineral is defined by what 5 properties?

naturally occurring (must be found in nature), inorganic (must be from non-living things, solid (minerals cannot be liquids or gasses), must have a definite chemical composition, regular crystal structure (possess an orderly internal structure of atoms)

What is any naturally occurring solid mass of mineral or mineral-like matter?

rock

What are are 10 optical properties?

luster, color, streak, ability to transmit light, crystal shape, strength, hardness, cleavage, fracture, tenacity

appearance in reflected light

luster

can vary and not as diagnostic

colors

color of mineral in powder form

streak

light can travel through a mineral

ability to transmit light

hardness

strength

ability to resist scratching or abrasion

hardness

tendency to break along planes of weak bonding

cleavage

random pattern of breakage

fracture

resistance to cutting, breaking, bending, and deformation

tenacity

What are the 3 classification of rocks?

Igneous, Metamorphic, sedimentary

How are igneous rocks formed?

minerals formed and fused after being melted

How are metamorphic rocks formed?

minerals formed and fused together by heat, pressure, and time

How are Sedimentary rocks formed?

minerals cemented together with pressure and time

What is the crystallization above or below ground to form igneous rock?

magma

What is the breaking down material at the earth’s surface?

weathering

what are solid particles?

sediment

What is the study of layered sedimentary rock and involves placing events in the order in which they occurred?

stratigraphy

who hypothesized that objects were preserved when they sank to the bottom of a body of water and were covered up by sediment?

nicholas steno

Who hypothesized it must take a very long time for processes (weathering and erosion) to produce any significant change in the shape of the earth’s surface? What model was this?

James Hutton, uniformitarian model

What principle is when rocks get deposited on top of each other (horizontally)?

Principle of Original Horizontality

What principle is when rocks at the bottom of the stack are the oldest and the rocks at the top are the youngest?

Principle of Superposition

What principle is when the older rocks may be cut by younger rocks or other geologic features (ex. lava). What principle is that there can be older pieces of rock surrounded by younger igneous rock?

principle of cross-cutting relationships, principle of inclusion