Study guide EXAM #3

Which of the following events happened most recently ?

Deposition of unit A which is the oldest unit

What COMPONENT of MAGMA is required to cause violent volcanic eruptions?

Dissolved gases

The process that breaks rocks into smaller pieces that are not changed in composition:

Physical Weathering

The weathering process is subdivided into :

Physical and chemical

The THREE major rock products of erupted lavas are ?

Rhyolite, andesite, basalt

Pillow basalts

Round rocks (basalts)

As sediment is transported down stream, the particles tend to become :

Rounded and smaller

What is the proper term for the huge Volcanoes with very gentle slopes?

SHIELD Volcanoes

Kileauea

SHIELD volcano

Volcanic domes are associated with __________ MAGMA.

SIALIC

Andesite is an example of a (n) _________ igneous rock.

intermediate

A nonconformity is :

A gap in geologic record bounded below by metamorphic or igneous rocks and bounded above by sedimentary rocks.

What do MAGMA and LAVA contain?

Abundant gases WATER VAPOR and CARBON DIOXIDE • biggest thing that comes out of Volcanoes

Archean is an eon that comes :

After Hadean and before Proterozoic

When did the faulting occur ?

After deposition of unit C and before deposition of unit B.

The study of sedimentary rocks helps geoscientists determine ____________.

All of the above (Ancient ocean environment, former plate tectonic events, history of climate change. )

Sedimentary rocks are primary source of information about :

All of the above (Past climates, evolution of the life on earth, energy resource)

Which of the following is NOT involved in classifying igneous rocks?

All of the above are INVOLVED Group of minerals making up rock, chemical composition of the rock, and texture.

Which of the following gases is NOT an important constituent of volcanic gas?

All of these are abundant in volcanic gases. Carbon dioxide, sulfur dioxide, water vapor, hydrogen sulfide.

Sedimentary Rocks

Are important because they record the entire history of the earth surface. -ANCIENT CLIMATE -ANCIENT LIFE(fossils) *also they contain all of our fossil fuels - oil - gas - coal - and majority of FRESH WATER on PLANET. Gravel(conglomerate) Sand(sandstone) Silt & Clay (SHALE) Dissolved irons( limestones)

Aa

Blocky, jagged, flows with some difficulty. Because it's lost a lot of its gases.

Aa

Blocky, jagged, flows with some difficulty. Because it's lost a lot of its gases. (MAFIC) (SHIELD volcanic)

Which type of unconformity has sedimentary rocks both above and below the unconformity surface ?

Both angular and disconformity

What is the term for a large, steep walled, basin-shaped depression that forms by the collapse of a MAGMA chamber roof after a violent eruption?

Caldera

Home Sapiens first appear during which geologic era?

Cenozoic

The type of Weathering whereby rocks may be dissolved is called ____________.

Chemical weathering

Which of the following statements about the viscosity of lavas is true?

Lava VISCOSITY increases as the lava increases as it becomes more SIALIC.

Flood Basalt Eruptions

Mass Extinction

Physical weathering involves the breakdown of rocks at the Earth's surface through __________.

Mechanical processes

Dinosaurs lived during which ERA of geologic time ?

Mesozoic

What is the name of the scientist whose work laid the foundation for the modern science of stratigraphy ?

Nicolaus Steno

If dinosaurs became extinct at the end of the Mesozoic, could they ever have coexisted with humans?

No; humans first evolved in the Cenozoic, long after the extinction (disappearance) of dinosaurs.

The dominant rock of Earth's MANTLE is?

Peridotite

The JURASSIC is a geologic:

Period

Chemical Weathering

RAINFALL H2O (water) plus CO2 turns into H2CO3 then carbonic acid (weak acid) RAINFALL (breaks bonds in rocks)

What scientific avenue of investigation gave scientists the best estimate of the absolute age of the earth ?

Radiometric or isotope dating

Which of the following igneous rocks is the most MAFIC?

Gabbro

During which eon did multicellular algae and animals first appear in the fossil record ?

Phanerozoic

Ultra Plinian Eruptions

"Super Volcanoes" LARGEST and MOST VIOLENT Eruptions. Highly explosive Eruptions produce a precipitate PUMICE more common and widespread of the plinian. -associated with "RESURGENT CALDERAS" -calderas that are Actively refilling with MAGMA. PLANET KILLING EX: long Valley CALDERA, CA -YELLOWSTONE CALDERA

Igneous rocks with crystals TOO SMALL to be seen WITHOUT a MICROSCOPE are?

APHANITIC

Deposition

As the water VELOCITY drops, competence and capacity also drops.

The __________ is the main source of MAGMA for the production of igneous rocks.

Asthenosphere

Sedimentary processes take place ___________.

At or near the Earth's surface

Almost the entire ocean floor is comprised of which igneous rocks?

Basalt

MANTLE PLUMES are thought to originate at the _________ boundary.

Core-MANTLE

Sediment is deposited as :

Current slows down

Hadean is a geologic :

EON

Which of the following are the largest divisions of geologic time ?

Eon

The process that mobilizes (transport) the particles produced by weathering:

Erosion

Which is the oldest unit?

F

Mechanical Weathering types

Frost Wedging -water in the rock freezes, expands and cracks rock. Repeated Heating - (expansion) and cooling of the rock (contraction of rock) Faulting Exfoliation - expansion rock due to decompression. *weight pressure of everything above it. * if material above the rock is removed, pressure is released. - rock expands and cracks. EX: half dome -formed at miles and miles below the surface and because of plate tectonics.

HAWAIIAN STYLE ERUPTIONS

Generally the quietest type of volcanic eruption (MAFIC, high temp, low VISCOSITY) glowing red rivers.

Hawaiian style Eruption

Generally the quietest type of volcanic eruption. ( MAFIC, high in temperature, low VISCOSITY) -glowing red rivers Lava as it is erupted may take on 2 forms. PAHOEHOE and Aa PAHOEHOE- very smooth, ropes looking lava, flows easily still retains a lot of DISSOLVED GASES. Aa- blocky, jagged, flows with some difficulty. Because it's lost a lot of its gases. (SHIELD Volcanoes/MAFIC lava) Huge structures completely built from highly fluid flows of MAFIC lava. EX: MAUNA LOA highest mountain

Hawaiian Style Eruptions

Generally the quietest type of volcanic eruption. (MAFIC, high in temp, low VISCOSITY) glowing red rivers.

Viscous

Having a thick, sticky consistency between solid and liquid; having a high VISCOSITY.

Who first discovered radioactivity ?

Henri Becquerel

Vesicles

I popped bubbles of gas in lava

Weathering

Is the breakdown of rocks at the Earth's Surface, by the action of RAINWATER, extremes of temperatures, and biological activity. It does not involve the removal of rock material. There are 2 basic types of Weathering. 1. MECHANICAL WEATHERING - physical fragmentation of rock into smaller and smaller pieces. 2. CHEMICAL WEATHERING- allow chemicals to break chemical bonds and allow the rock to DISSOLVE.

Volcanism

Is the phenomenon of eruption of molten rock (MAGMA) onto the surface of the Earth or a solid-surface planet or moon, where lava, pryroclastics and volcanic gases erupt through a break in the surface called a vent.

The liquid MAGMA that reaches Earth's surface is called?

Lava

Vulcanian Type Eruption

Moderate sized Explosive Eruptions - INTERMEDIATE in composition. (Andesites) INTERMEDIATE in temp and VISCOSITY. Dissolved gases have lots of difficulty escaping. Build a volcano out of alternating layers of ASH and lava. Stratovolcano or Composite Volcano. Ex: Mt St. Helens

Which of the following volcanic eruptions resulted in the deaths of over 20,000 people ?

Nevado del Ruiz, Colombia, 1985

The most likely explanation for varying thickness of unit C on either side of the fault is that :

Sediment was eroded from the right side of the fault.

In which type of rocks are fossils most commonly found?

Sedimentary

Which of the following is the best statement of the principle of original horizontality?

Sediments are deposited as horizontal layers.

Sorting

Separate particles according to size. -once particles have been deposited they may be "lithified" (turned into a rock)

Which of the following rocks is composed of clay-sized clastic sediment?

Shale

Carbon-14 is not useful for dating most rocks primarily because :

The effective dating range is much too short to be useful for most rocks.

Why are lava domes associated with felsic lavas ?

The highly SIALIC lavas bulge upward but wing flow.

Which of the following statements about rubidium - 87 radiometric dating is true?

The rate at which rubidium -87 decays to strontium -87 is constant.

The concept of half -life with respect to geologic time refers to:

The time it takes for half of a parent isotope to change to the daughter isotope.

Erosion

Transportation of WEATHERED MATERIAL.

Which of the following volcanic features is NOT generally associated with basalt?

Volcanic domes

What is the most abundant gases emitted during basaltic volcanism ?

Water vapor and carbon dioxide

What two factors does water VELOCITY control?

1. Competence- largest particle size running water can carry 2. Capacity- total amount of Material running water can carry. Where water VELOCITY is HIGH competence and capacity are ALSO HIGH! ! ! -largest particles drop out first, followed by progressively smaller and smaller particles (Gravel, sand, silt, clay, dissolved irons)

An igneous rock was formed with 8000 radioactive (parent) atoms but contains only 1,000 radioactive (parent) atoms today. If the HALF LIFE for the radioactive element is 10 million years, the rock is _______ million years old.

30

In Western Europe, when the study of Earth's age began, most people believed Earth was about __________ years old.

6,000

What is the eruption temperatures of rhyolitic lava?

600-800 C

Where do rivers start?

All rivers start in the mountains. Where the water VELOCITY is the highest. As the rivers flow downward the VELOCITY SLOWS DOWN.

Which of the following mountain chains is made up primarily of Volcanoes formed at an OCEAN-CONTINENT subduction zone?

Andes

INTERMEDIATE igneous volcanic rock is?

Andesite

What do composite Volcanoes produce ?

Andesite and rhyolite

Subduction zone Volcanoes produce rock of dominantly ______ COMPOSITION.

Andesitic

The unconformity along which TILTED older sedimentary beds have been eroded off before deposition of horizontal sedimentary beds is called:

Angular unconformity

Which of the following lava types erupts in SHEETS from Fissures to build a lava plateau ?

Basalt

Which of the following type(s) of rock(s) crystallize at the highest temperature?

Basalt

Which of the following pairs of intrusive and extrusive igneous rocks do NOT both have the SAME CHEMICAL COMPOSITION?

Basalt and peridotite

Which of the following sequences of volcanic rocks are in the correct order of increasing SIALIC content?

Basalt, andesite, Rhyolite

Cinder cone Volcanoes

Cinder cones are the simpest type of volcano. They are built from particles and blobs of congealed lava ejected from a single vent. As the gas charged lava is blown violently into the air, it breaks into small fragments that solidfy and fall as cinders around the vent to form a circular or oval cone. Most cinder cones have a bowl shaped CRATER at the summit and RARELY RISE more than 1,000 feet or so above their surroundings. Cinder cones are numerous in western NORTH AMERICA as well as throughout other volcanic terrains of the world

Most violent volcanic activity is ?

Composite

Which of the following sedimentary rocks has the largest particle sizes?

Conglomerate

Which of the following lists is written in order of DECREASING particle size?

Conglomerate, sandstone,siltstone

Volcanic Gases

EX: Lake Nyos problem - is a crater lake in the northwest region of Cameroon(area in Africa). -Lake sits in a CALDERA. -Gases(carbon dioxide) release into the lake. A pocket of MAGMA lies beneath the lake and leaks CARBON DIOXIDE(CO 2) into the water, changing it into carbonic acid. Boys is one of only three known exploding lakes to be saturated with carbon dioxide in this way, the others being Lake Monoun, also in Cameroon, and lake Kivu in democratic republic of Congo.

Large igneous provinces like the COLUMBIAN RIVER PLATEAU are formed from the successive eruption of ?

Flood basalts

Magmas un subduction zones are produced primarily by ?

Fluid-induced melting.

Plinian Style Eruptions

Highly Viscus Magmas (Rhyolites) characterized by the EJECTION of large VOLUMES of ASH, followed "CALDERA" Collapse(Cauldron Kettle) - Top of volcano collapses down into the empty MAGMA chamber. -is a very explosion eruption of MAGMA of high VISCOSITY or acid MAGMA, magma composition is Andesitic to riolitik. PUMICE Eruption material in BULK FORM. EX: Mount Mazama Oregon Crater Lake is the remains of a LARGE VOLCANO. (Composite or Stratovolcano)

Deccan Traps, India

Huge volumes of gases expelled into the atmosphere with these eruptions. -caused climate change

Convergent Plate Boundary

INTERMEDIATE (andesite) and SIALIC (Rhyolite) volcanism.

Yellowstone national park

Intraplate, hotspot volcanism

Caldera

Is a volcanic feature formed by the collapse of a volcano into itself, making it a large, special form of VOLCANIC CRATER. A caldera collapse is usually triggered by the emptying of the MAGMA chamber beneath the volcano, as the result of a large volcanic eruption. If enough MAGMA is erupted, the emptied chamber will not be able to support the weight of the volcanic edifice(the mountain) above. Fractures will form around the edge of the chamber, usually in a roughly circular shape. These ring fractures may in fact serve as volcanic vents. As the MAGMA chamber emptied, the center of the volcano within the ring fractures begins to collapse. The collapse may occur as the result of a single massive eruption, or it may occur in stages -/ the result of a series of eruptions.

Why is temperature important?

Is incredibly important because it controls VISCOSITY. ( inability of a fluid to flow) High VISCOSITY - does NOT flow easily (SIALIC ) Low VISCOSITY - flows easily (MAFIC )

Flood Basalt Eruptions

Large igneous provinces, RARE, occasional, Voluminous, widespread, highly fluid flows of basalt. EXAMPLE: COLUMBIAN River Basalts ( Washington, Oregon, California, Idaho, Montana, Wyoming)

Basaltic lavas form SHIELD Volcanoes and Flood basalt rather than STEEP STRATOVOLCANOES because?

Low silica results in low-VISCOSITY, fluid lava.

Consider three undeformed horizontal beds of sedimentary rocks. Which layer is the oldest ?

Lower

Temperatures of these different lavas

MAFIC -1200 C (2500 F) INTERMEDIATE- SIALIC -800 C ( 1500 F)

Hot Spots

MAFIC volcanism (basalt) -lower MANTLE

Divergent Plate Boundary

MAFIC volcanism (basalt) generates new ocean floor. Hot Asthenosphere partially melts.

What is the largest volcano on Earth?

MAUNA Loa, Hawaii

Which of the following Volcanoes is NOT a COMPOSITE volcano (STRATOVOLCANO)

MAUNA Loa, Hawaii

Are igneous rocks STABLE at the earth's surface?

NO -igneous rocks form at extremely high temperatures (800-1200 C) (1500-2500 F) These are the temperatures that they are stable at. - once exposed at the surface they tend to break down or they (weather)

An undefined sedimentary layer is _____________ than the layer above and _____________ than the layer below.

Older, younger

What is the name for a basaltic lava flow that has a ROPY, folded surface?

PAHOEHOE

What is the era of geologic time that refers to "Ancient Life" ?

Paleozoic Era

Which of the following sequences is written correctly from oldest to youngest?

Paleozoic, Mesozoic, Cenozoic

Pillow Lava

Pillow lavas are volumetrically the most abundant type because they are erupted at mid-ocean ridges and because they make up the submarine portion of seamounts and large intraplate Volcanoes, like the Hawaii-Emperor seamount chains. Round rocks (Basaltic Composition) are lavas that contain characteristic pillow-shaped structures that are attributed to the extrusion of the lava under water, or subaqueous extrusion.

The concept that sediments are deposited under the influence of gravity as approximately horizontal layers of particles is the :

Principle of Original Horizontality

The Mount Pelée eruption of 1902, mixture of hot air and ash, was a ?

Pyroclastic flow

Vulcanian Eruption 2 special types -Pelean type Eruption -Vesuvian Eruption

Relatively small. Its violent explosions of viscous lava create columns of ash and gas and occasional pyroclastic flows. (Nuee Ardente ) Pelean eruptions are named for the destructive eruption of Mount Peleé on the Caribbean island of Martinique in 1902. -Saint Pierre was the largest city in Martinique and one of the largest in the Caribbean. Population of 26,000 only 2 survived. The fluidized slurries produced by these eruptions are heavier than air but are of low VISCOSITY and pour down valleys and slopes at great velocities. As a result, they are extremely destructive. ( an island and French overseas department in the LESSER ANTILLES Island ARC of the Caribbean- curved chain of Volcanoes) -subduction zone Vesuvian type Eruption -characterized by the ERUPTION of MOUNT VESUVIUS, Italy A.D 79' that led to the burying and destruction of the Roman Cities of POMPEII and HERCULANEUM. (Composite Volcanoes or Stratovolcano)

What type of volcano has the LARGEST and most VIOLENT Eruptions ?

Resurgent calderas

Felsic, intermediate, and mafic igneous rock all are dominantly made up of _________ minerals.

SILICATE

What type of volcano consists of both lava flows and pyroclastic deposits ?

STRATOVOLCANO EX: Pompeii and Herculaneum

Strombolian Eruption

Short bursts of glowing lava, created from the bursting of large gas bubbles at the summit vent if a volcano typify. Strombolian eruptions are distinct bursts of fluid lava. (Usually basalt or basaltic andesite ) -Cinder cones

Lava VISCOSITY increases as?

Silica content increases and lava temperatures decreases

Strombolian Type Eruptions

Slightly more explosive type of Eruption DUE to a slightly HIGHER VISCOSITY. Slightly more SIALIC Slightly more COOLER -gas cannot escape the lava quite as easily as they did with the Hawaiian Style Eruptions. CINDER CONE

Composite Volcanoes

Some of the Earth's grandest mountains are COMPOSITE VOLCANOES-sometimes called STRATOVOLCANOES They are typically STEEP-SIDED, symmetrical cones of large dimension built of alternating layers of lava flows, volcanic ash, cinders, blocks, and bombs and may rise as much as 8,000 feet above their basins. Some of the most conspicuous and beautiful mountains in the world are composite Volcanoes, including MOUNT FUJI in Japan, MOUNT St. HELENS AND MOUNT RAINIER in Washington.

The tendency for variations in current velocity to SEGREGATE sediments on the basis of particle size is called __________.

Sorting

In what tectonic setting would you expect to find INTERMEDIATE igneous rocks?

Subduction zones

In 1816, known as "the year without a summer," summer frosts and snowstorms occurred in the Northern Hemisphere as a result of?

Sunlight blocked by debris in atmosphere from eruption of tambora.

Lahars

Superheated mudflow generated by mixing volcanic ASH WITH WATER. The Colombian volcano NEVADA DEL RUIZ is an active STRATOVOLCANO with history of generating deadly volcanic MUDFLOWS (LAHARS) from relatively small-volume Eruptions. -the young village of ARMERO was built directly on top of the 1845 mudflow deposit. Over the ensuing years, ARMERO grew into a vibrant town with over 27,000 residents. On NOVEMBER 18, 1985, history repeated itself for the third time in 400 years, with another eruption and another DEADLY LAHAR racing down the River Lagunillas. This time, over 21,000 people were killed, including most of the resident of ARMERO. With proper planning, this tragedy could have been averted.

Shield Volcanoes

The third type of volcano, are built almost entirely of FLUID LAVA FLOWS. Flow after flow pours out in all directions from a central summit vent, or group of vents, building a broad, gently sloping cone of flat, domical shape, with a profile much like that of a warriors shield. They are built up slowly by the accretion of thousands of highly fluid lava flows called BASALT LAVA that spread widely over great distances, and then cool as THIN, gently DIPPING SHEETS. Some of the largest Volcanoes in the world are SHIELD VOLCANOES. The Hawaiian Islands are composed of linear chains of these Volcanoes including KILAUEA AND MAUNA LOA on the island of Hawaii -two of the world's most active volcanoes. -the floor of the ocean is more than 15,000 feet deep at the bases of the islands. As MAUNA LOA, the largest of the shield Volcanoes (and the world's largest active volcano), projects 13,677 feet above sea level, its top is over 28,000 feet above the deep ocean floor. In some eruptions, basaltic lava pours out quietly from long fissures instead of central vents and floods the surrounding countryside with lava flow upon lava flow, forming broad plateaus. Lava flows of this type can be seen in Iceland, southeastern Washington, eastern Oregon, and southern Idaho. Along the Snake River in Idaho, and the Columbia River in Washington and Oregon, these lava flows are beautifully exposed and measure more than a mile in total thickness.

Acid Rain is different

To generate electricity we BURN COAL. Contains IRON SUFIDE. H2O ( water vapor) + SO2(sulfur dioxide) + O (oxygen) = H2SO4 (sulfuric acid) All this Weathering creates SOIL(dirt) -once this soil is created, it may then be transported "EROSION" Major way this is transported is through RUNNING WATER-RIVERS

The principle of superposition states that _________.

Undistirbed sedimentary layers get progressively younger from bottom to top.

Pahoehoe

Very smooth, ROPEY looking lava, flows easily. Still retains a lot of dissolved gases. (SHIELD Volcano)

Pahoehoe

Very smooth, Ropey looking lava, flows easily. Still retains a lot of dissolved gases. (MAFIC) (SHIELD volcanic)

Lava Domes

Volcanic or Lava domes are formed by relatively small, bulbous masses of lava too viscous to flow any great distance; consequently, on extrusion, the lava piled over and around its vent. A dome grows LARGELY by expansion from within. As it grows it's outer surface cools and hardens, then shatters, spilling loose fragments down its sides. Some domes form craggy knobs or spines over the volcanic vent, whereas others form short, steep-sided lava flows known as "COULEES." VOLCANIC DOMES commonly occur within the craters or on the flanks of large COMPOSITE VOLCANOES. The nearly circular Novarupta Dome that formed during the 1912 eruption of Katmai Volcano, Alaska, measures 800 feet across and 200 feet high. - The INTERNAL STRUCTURE of this dome-defined by LAYERING of lava fanning UPWARD and OUTWARD from the center - indicates that it grew largely by expansion from within.

The probable source of Earth's oceans and atmosphere is?

Water and atmosphere escaped from Earths interior in volcanic eruptions.