Geology Exam 2

Since felsic igneous rocks have the lowest percentage of ferromagnesian minerals, they are typically dark in color.

False

Soil is considered a renewable resource. True or False

False

In what type of climate is chemical weathering most severe?

Hot and Wet

What type of environment would typically produce a caliche hardpan?

Hot and dry

Explain the principle of superposition

It states that younger sedimentary rock layers are typically found on top of older rock layers.

Why is soil so important to man?

It supports plant growth, and plants are the base of the food chain on land

Cenozoic Era

Recent life

Rock and mineral fragments produced by weathering:

Regolith

This type of soil develops on bedrock:

Residual

What is the difference between a transported and residual soil?

Residual soils form in place, while transported soils form from sediment brought into the area.

What law states younger rocks are found atop older rocks?

Superpostion

Mechanical weathering results in an increase in this

Surface area

Sills are

Tabular and concordant

_______ along boundary lines may serve as a windbreak.

Tall, dense vegetation

The sloping pile of broken up rock in the lower portion of this photo is referred to as: (Look at question 11 quiz 5 for picture)

Talus

What do you call weathered rock that piles up at the base of a cliff?

Talus

Magma Mixing is

The process whereby magmas of different composition mix together to yield a modified version of the parent magmas

Oxidation:

The reaction of oxygen with other atoms to form oxides or, if water is present, hydroxides. Rust is formed (iron oxides)

What is columnar jointing, and how does it form?

The shrinkage of a lava flows as it cools from a hot solid to a cool solid may produce columnar jointing.

Correlation is the matching up of rock layers in different regions. True or False

True

Electron capture is essentially the opposite of Beta decay. True or False

True

Fossils are often used to help interpret the environment at the time the organism was living. True or False

True

A neutron is actually a proton and an electron combined. True or False

True

According to the principle of cross-cutting relationships, faults and dikes are always younger than the rocks they cut through. True or False

True

Most composite volcanoes are located:

along the Ring of Fire

Laterite soils are often mined for what metal?

aluminum

Why are cinder cones generally hills rather than mountains?

because they typically go extinct after one eruptive cycle

The volcanoes of the Cascada Range are largely all:

composite volcanoes

Where would you most likely find a transported soil?

floodplain

As soils develop, distinct layers are created. These layers are called:

horizons

Name a classic cinder cone

Capulin

Which radioactive isotope is continually being created in the atmosphere?

Carbon 14

Natural water combines with carbon dioxide to form

Carbonic Acid

Composite volcanic range in western U.S.

Cascade

What is a composite cone built up from?

Both pyroclastic material and lava flows

What is a crater? How do craters generally form?

A result of cinders piling up around the vent, but not being able to fall straight back into the vent during eruption.

Biologic activity plays no role in the weathering of rocks. True or False

False

Leaving stubble in a field may help prevent_____erosion

Both wind and water

Shows the sequence in which minerals crystallize from a magma

Bowens Reactions Series

What is the approximate Farenheight range of magma?

1,260 to 2,160`

0 Half-life

1.) 100% Parent 2.) 0% Daughter 3.) Ratio 100:0

3 half-lives

1.) 13% Parent 2.) 87% Daughter 3.) Ratio 1:7

4 half-lives

1.) 6% Parent 2.) 94% Daughter 3.) 1:15

Which two soil horizons below are the richest in organic matter and collectively called "topsoil"?

1.) A-horizon 2.) O-horizon

Soil type: Pedocal (aridisols)

1.) Climate: Are in climates with low rain 2.)Characteristics: Young soils in which the parent material is volcanic ash and cinders, deposited by recent volcanic activity

Soil type: Laterite (ultisols or oxisols

1.) Climate: very warm, humid climates, such as a tropical rain forest 2.) Characteristics: poor soil quality, with high concentrations of iron and aluminum oxides

Composition: Intermediate

1.) Common minerals found are: Diorite and Andesite 2.) Type of plate boundary where it tends to form: Convergent

Composition: Mafic

1.) Common minerals found are: Gabbro and Basalt 2.) Type of plate boundary where it tends to form: Divergent

Composition: Felsic

1.) Common minerals found are: Granite and Rhyolite 2.) Type of plate boundary where it tends to form: Convergent

Which three types of weathering processes listed below are physical (mechanical)?

1.) Frost Wedging 2.) Thermal Expansion 3.) Sheeting and exfoliation

Volatiles are material dissolved in magma that will vaporize (form gas) when the magma reaches a low pressure condition at or near Earth's surface. The three most common volatiles in magma are:

1.) H20 2.) C02 3.) SO2

This rock wall: (Look at question 15 quiz 4 for picture)

1.) It is a dike 2.) Formed from magma squeezing into a fracture 3.) Has been exposed by weathering and erosion 4.) Is composed of igneous rock

Time of Formation: Last three minerals formed (at lowest temperature)

1.) Minerals: Quartz, muscovite mica, potassium feldspar 2.) Composition of rock: Felsic

Which three statements below are correct? (Look at question 11 on quiz 4)

1.) The dark of the this rock suggests that it is mafic. 2.)The "holes" in this rock are gas bubbles and the rock has a vesicular texture. 3.) This rock is a vesicular basalt.

Which three statements below are true regarding types of unconformities?

1.) The rocks below an angular unconformity have been deformed 2.) Disconformities can be difficult to identify because the rocks layers on either side are parallel 3.) For a nonconformity to form there must be a perion of uplift and erosion

Which three statements below are true regarding this image? (Look at question 6 quiz 5 for picture)

1.) These are sedimentary rocks 2.) These rocks have been deformed 3.) These rocks were originally horizontal

Which four statements are correct regarding the image below. (question 30 quiz 4)

1.) This is pahoehoe lava 2.) This may turn into aa lava if it developes a large amount of gas bubbles and continues to flow as it cools 3.) This is mafic lava 4.) This is basaltic lava

Which three statements below are correct regarding this image? (Look at question 23 quiz 6 for picture)

1.) This is showing Alpha emission 2.) The atomic number will be reduced by two because there will be two less protons in the nucleus. 3.) The atomic mass number will be reduced by four because two protons and two neutrons escape, and each has a mass of 1 amu.

Which three statements are correct regarding this image? (Look at question 24 quiz 6 for image)

1.) This is showing Beta emission 2.) A neutron in the nucleus becomes a proton 3.) There atomic number will increase by one because there will be one more proton, but the mass number will not change because the Beta particle is so small

This rock is most likely rounded because it has been rolled around in a river or on the beach. Which three statements below are true regarding this rock? (Look at quiz 4 question 8 for picture)

1.) This rock has a porphyritic texture. 2.) The white minerals in this rock are phenocrysts. 3.) This rock went through two stages of cooling, slow cooling followed by more rapid cooling.

Which three statements are correct regarding this rock? (Look at quiz 4 question 9 for picture)

1.) This rock is coarse-grained. 2.) This rock formed from the slow cooling of magma below Earth's surface. 3.) This rock is granite.

Which three statements about this rock are correct? (Look at question 10 in quiz 4)

1.) This rock is fine-grained 2.) This rock is rhyolite 3.) This rock cooled fast and is probably from a lava flow.

Which three answers below are correct regarding the pumice rock? (Look at quiz 4 question 7 for picture)

1.) This rock is highly vesicular. 2.) This rock is volcanic 3.) This rock is pumice

Which five statements below are true regarding this picture? (Look at question 2 quiz 5 for the picture)

1.) This rock is weathering by sheeting and exfoliation 2.) This rock cooled from magma deep in the crust 3.) The fracturing of this rock is due to expansion from unloading 4.) This type of weathering often results in the formation of an exfoliation dome. 5.) This rock is exposed on Earth's surface due to uplift in the region and erosion of the overlying rock

Which three statements below are correct regarding this image? (Look at question 27 quiz 4 for picture)

1.) This type of volcano is generally composed of mafic material 2.)This type of volcano is comprised almost entirely of pyroclatstic material. 3.) This is a cinder cone

Which three statements are true regarding unconformities?

1.) Unconformities are generally buried erosional surfaces 2.) A large span of time is missing between the rocks above and below the unconformity 3.) No place on Earth has a complete set of conformable strata

Beta Decay

1.) What happens? A neutron is converted into a proton by beta decay. No change in mass, however the nucleus gains one proton in the process 2.) Atomic number change: 1 more 3.) Atomic mass change: no change

Alpha Decay

1.) What happens? The nucleus loses, 2 protons and 2 neutrons (called an alpha particle) 2.) Atomic number change: 2 fewer 3.) Atomic Mass change: 4 fewer

Electron capture

1.) What happens? The opposite of beta decay. A proton is converted into a neutron reducing the atomic number by one 2.) Atomic number change: 1 fewer 3.) Atomic mass change: No change

Composite volcanoes are typically built up from:

1.) pyroclastic material 2.) viscous lavas

2 half-lives

1.)25% Parent 2.) 75% 3.) Ratio 1:3

1 half-lives

1.)50% Parent 2.)50% Daughter 3.) Ratio 1:1

This image is showing the batholiths in the western U.S. Which three statements below are correct regarding batholiths.

1.)Batholiths are plutons 2.) Batholiths are exposed by millions of years of uplift and erosion of overlying rock. 3.)Batholiths are similar to stock, only larger.

Soil type: Pedalfer (alfisols)

1.)Climate: Are in climates with high rain. 2.) Characteristics: Rich in iron and aluminum fertile, productive soils because they are neither wet nor dry.

Which three statements below are true regarding this image? (Look at question 4 quiz 6 for picture)

1.)Dike A is younger than the conglomerate 2.) The sill is older than dike A 3.) Fault B is older than the batholith

When were the two largest mass extinctions on Earth?

1.)End of the Permian period 2.)End of the Cretaceous period

Which two minerals listed below are commonly created by oxidation?

1.)Hematite 2.) Limonite

According to Bowen's Reaction Series: (Look at question 12 quiz 4 for picture)

1.)Mafic minerals tend to form at a lower temperature than ultramafic. 2.)Intermediate minerals tend to form at a lower temperature than mafic. 3.)Felsic minerals tend to form at a lower temperature than intermediate. 4.) Quartz would typically be the last mineral to crystallize out of a melt. 5.) Olivine would typically be the first minerals to crystallize out of a melt.

Time of Formation: First three minerals formed (at highest temperatures)

1.)Minerals: Olivine, Pyroxene (augite), and Amphibole (hornblende) 2.) Composition of rock: Mafic

What is humus?

Carbon that forms by bacterial decay of organic matter, and is very resistant to further decay.

This image is of Mt. St. Helens before it erupted in 1980. Which three statements below are correct? (Look at question 28 quiz 4 for picture)

1.)Mt. St. Helens is a composite volcano 2.)Mt. St. Helens is composed of both lava flows and pyroclastic material 3.)Mt. St. Helens is probably composed primarily of material intermediate in compostition.

Which two conditions below favor preservation?

1.)Rapid burial 2.) Hard parts

Which volcanoes below are cinder cones?

1.)Sunset Crater 2.)Capulin 3.)Paricutin

This photo is of a volcanic neck or plug. Which three statements below are true? (Look at question 23 quiz 4 for picture)

1.)The name of this structure is Shiprock 2.) This structure has been exposed by erosion 3.)This is the remains of an eroded extinct volcano

Which three statements below are true? (Look at question 13 on quiz 4 for picture)

1.)This photo shows columnar jointing 2.) This rock is igneous. 3.) The fractures formed from shrinkage as the rock cooled.

Which three statement are correct regarding obsidian rocks? (Look at quiz 4 question 6 for picture)

1.)This rock formed from a very high viscosity (thick and sticky) lava flow. 2.)This rock is obsidian 3.) This rock was used by Native Americans for arrowheads, knives, and spear points.

Which three statements about this rock are correct? (Look at question 35 quiz 4 for picture)

1.)This rock is a pegmatite. 2.)This rock cooled slowly below Earth's surface. 3.) This rock has exceptionally large minerals because the magma was very fluid (low viscosity) which allowed the atoms to migrate easier and build onto the first-formed crystals.

This snow-capped mountain in the background is of Mauna Loa, one of the five volcanoes making up the Big Island of Hawaii. Which three statements below are correct regarding this volcano? (Look at question 29 quiz 4 for picture)

1.)This volcano is most likely composed of mafic material. 2.)This volcano is composed of multiple low-viscosity lava flows 3.)This snow-capped mountain is a shield volcano

Mafic magma:

1.)Typically has a low viscosity 2.)Often produces both shield volcanoes and cinder cones. 3.)Is rich in ferromagnesian minerals.

If a rock was found to contain 25% Uranium-235 and 75% lead-207, approximately how old would the rock be?

1.4 billion years

After two half lives, what is the ration between parent and daughter material?

1:3

What is the ratio of parent isotope to daughter isotope after two half-lives? (Look at question 18 quiz 6 for picture)

1:3

What is the name of the composite volcanic mountain range in the northwest U.S.?

Cascades

This soil develops on unconsolidated deposits such as floodplain deposits

Transported

How old is a rock that has a 1:7 parent/daughter ratio if the half life is 200 million years?

600my

Discounting the O-horizon, what major soil horizon is the "top soil"?

A

Which horizon is a mixture of mineral matter and humus?

A

What is a volcano?

A cone-shaped hill or mountain built up from lava flows, pyroclastics, or a combination of the two.

Define viscosity

A fluids resistance to flow.

Explain the principle of cross-cutting relationships

A principal holding that an igneous intrusion or fault must be younger than the rocks intrudes or cuts across

Assimilation is

A process whereby magma changes compositions as it reacts with country rock

Dike are

A tabular and discordant pluton

Thermal expansion and contraction

A type of mechanical weathering in which the volume of rocks changes in response to heating and cooling.

What are nuee ardentes (pyroclastic flows)?

A very hot, dense, turbulent ash cloud that surges down the flanks of a composite cone.

What is the optimum climate for chemical attack?

A warm, moist climate results in the most rapid chemical weathering and therefore soil formation

The law of original horizontallity state that deformation must happen_____ depostion

After

What do you call two protons and two neutrons emitted from the nucleus of an atom?

Alpha particle

What are index (guide) fossils?

An easily identified fossil with an extensive geographic distribution and shot geologic range useful for determining the relative ages of rocks in different areas.

What is a volcanic neck (plug)?

An erosional remnant of the material that solidified in a volcanic pipe.

The processes involved in this image are showing the formation of what type of unconformity? (Look at question 9 quiz 6 for picture)

Angular unconformity

Whether from an accumulation of clay in a humid climate, or from the accumulation of calcite in an arid climate, where in the soil horizon is a hardpan most likely to develop?

B-horizon

What is the characteristic rock type associated with lava flows that "flood" the surrounding terrain?

Basalt

A very large exposure of a massive pluton generally grantitic in compostion

Batholith

What do you call an ourtcrop of a pluton over 40 sq.mi. or more?

Batholith

Why is rain water naturally acidic?

Because H2O combines with CO2 to form carbonic acid.

A neutron turns into a proton during:

Beta decay

What radioactive isotope is continually being created in Earth's atmosphere?

C-14

This 6-mile diameter basin is Crater Lake in Oregon. This large basin formed from collapse of the top of the volcano after the emptying of the magma chamber below. This basin below is called: (Look at question 17 quiz 4 for picture)

Caldera

This large circular depression is usaully the result of collapse

Caldera

What is a large collapse structure over a volcanic vent called?

Caldera

Commonly found in the B horizon of pedocals

Caliche

This process alters the rock's composition:

Chemical weathering

Small, steep volcanic cone produced by a gas-rich basaltic magma

Cinder

What type of volcano cone is build up almost exclusively of pyroclastic material?

Cinder

What type of volcano is typically the smallest due to its short eruptive history?

Cinder

Which volcanic cone is typically the smallest?

Cinder

These small ejectiles are also called "lapilli"

Cinders

What do you call pea to walnut-sized pyroclasts?

Cinders

Feldspars alter into ______ minerals by a process called hydrolysis.

Clay

What mineral group do feldspars typically alter into via hydrolysis?

Clay

Of the 5 factors affecting soil formation, which typically plays the biggest role?

Climate

The most influential control of soil formation

Climate

Plateau in northwestern U.S. formed from huge outpourings of basaltic lavas

Columbia

Give an example of fissure eruptions and flood basalts in the U.S.

Columbia Plateau

Jointing of lava flow or sills due to shrinkage from cooling

Columnar

Composition: Ultramafic

Common minerals found are: Peridolite and Komatilite

These picturesque volcanic cones are generally the result of gas-rich andestic magma

Composite

Pressure release (unloading), sheeting and exfoliation

Confining pressure is reduced on deep seated plutons (generally granite) through the weathering and erosion of the overlying rock , the expansion will cause the rock, naturally fracture into sheets. The removal of the sheets by erosion often results in the formation of an exfoliation dome.

How might soil be protected in very gently sloping farmland?

Contour plowing

How might soil be protected in steeper terrain?

Contour terracing

This depression at the top of many volcanic cones is may be the result of ejecta building up around the vent:

Crater

This photo shows a: (Look at question 19 quiz 4 for picture)

Crater

Which geologic period ended around 65 million years ago with the extinction of the dinosaurs?

Cretaceous

What law states that dikes, fractures, or faults are younger than the rocks they cut across?

Cross-cutting

Are Mafic rocks dark or light colored?

Dark color

What is correlation?

Demonstration of the physical continuity of rock units or biostratigraphic units, or demonstration of time equivalence as in time-stratigraphic correlation.

What do you call a discordant, tabular pluton?

Dike

What do you call a pluton that form from magma filling in a fracture?

Dike

What type of pluton often forms a rock wall from differential weathering?

Dike

These tabular, discordant plutons form when magma squeezes into a fracture:

Dikes

Batholith or stocks are

Disconcordant pluton with at least 100km of surface area.

Chemical weathering that dissolves away rock such as rock salt or limestone:

Dissolution

The tombstone on the left is made of granite (silicate minerals), while the tombstone on the right is made of marble (metamorphosed limestone made of the mineral calcite). It appears the tombstone on the right side of this image has been weathering by: (Look at question 10 quiz 5 for picture)

Dissolution

What type of landform often form from exfoliation?

Dome

Paleozoic Era

Early life

Weathering that breaks rock into smaller pieces without chemical alterations is called?

Either mechanic or physical

What does a beta particle turn into once it escapes the nucleus?

Electron

A famous exfoliation dome in Texas is:

Enchanted Rock

Which category of geologic time incorporates the most amount of time?

Eon

The peeling away of rock layers due to unloading and sheeting

Exfoliation

What do you call the removal of sheets of rock?

Exfoliation

Large, rounded outcrop of granite

Exfoliation dome

What does the removal of overlying rock cause a pluton to do?

Expand

Unloading results in ________, which results in sheeting and exfoliation

Expansion

What is the typical magma compostion of a lava dome?

Felsic

What type of magma would tend to cool to stone at the lowest temperatures?

Felsic

What type of magma would tend to produce a lava dome?

Felsic

Which type of magma typically has the highest viscosity?

Felsic

What composition of magma of magma typically has the highest silica content and therefore produces the most explosive eruptions?

Felsic Magma

What are fissure eruptions and flood basalts?

Fissure eruptions occur when lava erupts from open fractures (fissures) in the ground. Low viscosity basaltic lavas erupting from fissure are called flood basalts

Most volcanic material is extruded from these fractures in the crust

Fissures

What do you call fractures that lava may flow out from?

Fissures

Describe the principle of fossil succession

Fossil succession is a principle holding that fossils, and especially groups or assembleges of fossils, succeed one another through time in a regular and predictable order. It as well states that the evolutionary changes of life are documented in the fossil record.

What are fossils?

Fossils are the remains or traces of once living organisms.

Phanerozoic means "visible life". What is this referring to?

Fossils in rock

What does expansion cause a pluton to do?

Fracture into sheets

What is pyroclastic material?

Fragmental substances, such as ash, that are exposively ejected from a volcano.

Water breaking down rock by freezing in fractures is called

Frost action or Frost wedging

This physical process breaks rocks down when water freezes

Frost wedging

The chemical weathering of most silicate minerals produces three main solids, clay minerals, iron oxides, and:

Grains of quartz

What two gases combine in the atmosphere to form carbonic acid?

H2O and CO2

The time requiered for 1/2 of any amount of a radioactive isotope to decay is termed the ______ of that isotope

Half life

Where would you most likely find a shield volcano?

Hawaii

What is the common mineral created by the oxidation of iron?

Hematite

Organic Matter:

Humus

This chemical process is how most silicate minerals decompose

Hydrolysis

What type of rocks form from the solidification of magma or lava?

Igneous

Where does spheroidal weathering generally occur?

In the shallow subsurface

Pieces of older rock entrapped in younger rock are referred to as:

Inclusions

What is the typical magma composition of a composite volcano?

Intermediate

Which two statements below are correct?

Intrusive igneous rock forms when magma crystallizes into rock below Earth's surface. Intrusive igneous rock is exposed at Earth's surface through a process of uplift in the region and erosion of all overlying rock.

What is a caldera? How do calderas generally form?

Is a large depression often found in the top of a shield or composite volcano. It usually the result of a collapse

Relative Dating definition:

Is placing events in a sequential order as determined from their position in the geologic record. It will not tell us how long ago

Why does mechanical weathering hasten chemical weathering?

It increase the surface area.

Define aa lava

It is a lava flow comprised of rough jagged blocks

Define pahoehoe lava

It is a lava flow that is smooth and ropy surface

How is Carbon-14 created?

It is continually being created in our atmosphere when a neutron slams into the nucleus of a nitrogen atom and a proton is then emitted.

How is Carbon-14 destroyed?

It is destroyed only when the organism dies.

What is chemical weathering?

It is the decomposition of rocks by chemical alteration of parent material.

Half Life

It is the time it takes for 1/2 of the radioactive atoms (parent isotope) to decay into a nonradioactive material (daughter isotopes.)

What type of material is C-14 used to date?

It is used to date formerly living material.

What causes spheroidal weathering to occur?

It occurs in the shallow subsurface from chemical attack along fractures. On a rectangular stone, the corners are attacked by weathering from three sides, and the edges are attacked from two sides, but the flat surfaces weather more or less uniformly.

How does mechanical weathering affect the rate of chemical weathering?

It speeds it up because it increases the surface area.

This is a common clay mineral formed from the hydrolysis of potassium feldspar

Kaolinite

What do you call a pluton that squeezes in between sedimentary rock layers and domes the overlying rocks up?

Laccolith

These non-tabular, concordant plutons form when magma squeezes between layers of sedimentary rocks doming up the overlying rock

Laccoliths

What is a volcanic mud flow called?

Lahar

What type of soil is often mined for its aluminum?

Laterite

This often forms as highly viscous lava is squeezed out of a vent

Lava Dome

Which statement below is correct?

Lava is magma that flows out onto the Earth's surface.

What do you call the openings left in a lava flow as the hotter interior flows out from within the solidified outer region?

Lava tubes

The principle of fossil succession states that the evolutionary changes of _____ are documented in the rock record.

Life

Are Felsic rocks dark or light colored?

Light color

What is the most common rock that dissolves in natural water?

Limestone

Which rock listed below is comprised of calcite and therefore commonly dissolved by natural water?

Limestone

What composition of magma is generated by partial melting of the mantle?

Mafic

What type of magma tend to produce a shield volcano?

Mafic

What type of magma typically contains the least amount of dissolved gas?

Mafic

What type of magma would tend to produce a cinder cone?

Mafic

You pick up a rock and see it has a small percentage of green phenocrysts in it. The mineral looks glassy is too hard to scratch with your pocketknife. You recognize the mineral as olivine. This leads you to conclude this rock is _______ in composition.

Mafic

What is the difference between magma and lava?

Magma is molten rock material generated within Earth. Lava is Magma that reaches Earth's surface.

What are plutons?

Magma that cools and solidifies with Earth forms Intrusive igneous rock bodies.

Describe the different types of pyroclastic material: Ash and Dust

Magma that has been blown into very small droplets of glass and minerals from a violent gas charged eruption. (Felsic to Intermediate)

Magma is generated at a subduction zone due to the introduction of _______ into the overriding plate.

Mantle plume

This process breaks rocks into smaller pieces without changing the chemical makeup:

Mechanical weathering

Which era is known as the "Age of Reptile" (including the dinosaurs?

Mesozoic

Which era of geologic time below means "middle life" and is often referred to as the "age of the dinosaurs?"

Mesozoic

Mesozooic Era

Middle life

A-horizon

Mineral matter mixed with some hums Top Soil

What is the largest portion of soil?

Mineral matter weathered from rocks

A volcanic mud flow (called a "lahar") occurs when volcanic ash and water mix. While this may occur from rain falling on a volcanic ash deposit, it most often occurs when hot ash falls on the snow pack and/or glaciers located on the higher elevations of a volcano. Which volcano in the United States is considered to be the most dangerous for this very reason?

Mt. Rainer

Soil is considered a ______ resource

Nonrenewable

Laccolith are

Nontabular and concordant

Pyroclastic flows of hot gases, ash, and rocks

Nuee Ardentes

As a mafic magma begins to cool, what would typically be the first mineral to crystallize out of the melt?

Olivine

Where would you most likely see contour plowing?

On a very gently sloping hillside

Rust is the result of this chemical process

Oxidation

Known as the "Ring of Fire", most volcanic activity is located around this ocean basin. (Look at Question 33 quiz 4 for picture)

Pacific

Most composite volcanoes are located on the Ring of Fire encircling the_____ Ocean.

Pacific

This type of lava has a smooth surface "on which one can walk"

Pahoehoe

What do you call lava with a smooth, ropey surface?

Pahoehoe

Result is a more "felsic" melt than the compostition of the rock from which it came

Partial Melting

C-horizon

Partially altered parent material

These soils are common in Eastern U.S.

Pedalfers

These soils are common in the deserts of the southwest U.S.

Pedocals

Lava that cools underwater

Pillow

What do you call lava that erupts under water?

Pillow

How does pillow lava form?

Pillow lavas are bulbous lava flows that form as a result of very rapid cooling during underwater eruptions.

What do you call bodies of rock that cooled from magma below Earth's surface?

Plutons

The extensive leaching of laterite soils results in a very_____ soil quality?

Poor

Magma is generated at a spreading center (divergent plate boundary) by a reduction in

Pressure

Absolute dating definition:

Provides specific dates for rock unit or events expressed in years before the present. Radiometric dating is the most common method.

What is another name for a nuee ardente?

Pyroclastic flow

Matter ejected and solidified in the air during an eruption

Pyroclasts

What do you call material that (partially) solidifies in the air after being blown out of a volcano?

Pyroclasts

This silicate mineral is the most resistant to chemical attack

Quartz

What mineral would tend to be the last mineral to crystallize out of a felsic magma?

Quartz

Which silicate mineral is the most resistant to chemical attack?

Quartz

Explain the principle of original horizontality

Sediments are deposited in horizontal or nearly horizontal layer, and if they are deformed the deformation must have happened after they were deposited.

Gently sloping volcanic cone produced from multiple low viscosity basaltic lava flows:

Shield

What type of volcano is built up from multiple low viscosity mafic lava flows resulting in a very low slope angle?

Shield Cone

Famous volcanic neck in New Mexico

Shiprock

Name a famous volcanic plug in New Mexico.

Shiprock

Columnar jointing is the result of:

Shrinkage from cooling

Differentiation tends to make the resulting magma more:

Silica-rich and iron-poor

What do you call a concordant, tabular pluton?

Sill

What do you call a pluton that forms from magma flowing between layers of sedimentary rock?

Sill

These tabular, concordant plutons form when magma squeezes between layers of sedimentary rocks

Sills

Why do all major age dating isotopes (except carbon-14) have such long half-lives?

Since the Earth was created at the same time as the rest of the solar system, and the atoms forming the solar system were largely created in a nova eruption of an exploding star, only isotopes with very long half-lives still exist on Earth.

What is the most influential control of soil formation?

Slope of the land

A combination of mineral and organic matter, air and water that supports plant growth

Soil

Why is soil so important to man?

Soil is a nonrenewable which is why its important to man.

This type of weathering produces rounding of angular rocks in place

Spheroidal

The rounded corners and edges of the rocks in this image is showing: (Look at question 8 quiz 5 for picture)

Spheroidal weathering

Explain the principle of inclusions

States that a rock containing inclusions is younger than the age of the rock form which the inclusion came.

Where is wind erosion of cropland most severe in Texas?

The Panhandle

What is mechanical (physical) weathering?

The breaking of material down into smaller pieces without any chemical alterations.

Hydrolysis:

The chemical reaction between hydrogen (H+) ions and hydroxyl (OH-) ions of water and a minerals ions. Clay is formed.

Describe frost action (wedging)

The disaggregation of rocks by physical processes that yields smaller pieces that retain the composition of the parent material.

O-horizon

loose and partly decayed organic matter

Define weathering

The physical breakdown and chemical alteration of rocks and minerals at or near Earth's surface.

Magmatic differentiation or crystal settling is

The physical separation and concentration of minerals in the lower part of a magma chamber or pluton by crystallization and gravitational settling

What are unconformities

They are buried erosional surfaces where the rocks above the contact are much younger than the rocks below

What are lahars and how do they form?

They are mudflows of volcanic ash

Describe the different types of pyroclastic material: Cinders or Lapilli

They are pea to walnut sized particles produced from a somewhat explosive eruption (Mafic?)

Mafic Magmas are richer in

They are richer in iron and or magnesium. with less silica.

Felsic Magmas are richer in

They are richer in silica with less iron and magnesium.

A soil formed in a floodplain would be considered?

Transported

How does a lava tube form?

Thick pahoehoe flows may result in the formation of lavatubes if the surface hardens and the lava in the center flows out.

Inclusions are older than the rock they are found in. True or False

True

The law of superposition states younger rock layers are found on top of older rock layers. True or False

True

The principle of fossil succession states that the age of a rock unit can be recognized by its fossil content. True or False

True

The principle of original horizontality states that if sedimentary rock layers are folded or deformed from their original horizontal position, the deformation happened sometime after the deposition of the sediments. True or False

True

What has the lowest silica content resulting in the least explosive content?

Ultra mafic magma

What is the composition of the mantle?

Ultramafic

What is a buried, erosional surface called?

Unconformity

Dissolution:

Water is chemically attacking salt by plucking off sodium and chlorine atoms from the chrystalline framework

What soil type accounts for much of the foundation problems in the metroplex?

Vertisols

This italian composite volcano destroyed the town of Pompeii in 79 A.D.

Vesuvius

A measure of resistance to flow

Viscosity

Phanerozoic Eon

Visible life

What do you call the magma that cooled inside the conduit of an ancient volcano?

Volcanic neck or plug

What environment is chemical weathering most severe?

Warm and wet

What is soil?

Weathered materials containing water, air, and humus that can support vegetation.

Differential weathering:

Weathering that occurs at different rates on rocks, thereby yielding an uneven surface.

What portion of the U.S would you typically find a pedocal?

Western

What climatic conditions would make frost action most effective?

Where temperatures commonly fluctuate above and below freezing. Mountainous regions such as talus slopes.

What are the #1 and #2 erosional agents of soil?

Wind and water

What are some ways to minimize soil erosion and loss of productivity?

Wind breaks, contour plowing, plowing furrows, crop rotation, and leaving stubble

How was the geologic time scale first established?

World-wide correlation using fossil succession and superposition allowed geologists to build the geologic time scale.

Another name for the B horizon

Zone of Accumalation

This photo is showing: (Look at question 21 quiz 4 for picture)

a pyroclastic flow or nuee ardente

This basaltic lava has a surface of rough, jagged blocks

aa

What is the name for lava with a rough, jagged, blocky surface?

aa

B-horizon

accumulation of clay transported from above Hardpan developes here

What type of magma would tend to produce a composite volcano?

intermediate

A volcanic mud flow

lahar

These soils are heavily leached leaving behind iron and aluminum oxides

laterite

Cave-like tunnel formed in some lava flows:

lavatube

Carbon-14 is best used for dating rocks _________ 50,000 years old.

less than

Which two minerals would best define a rock as "felsic"?

potassium feldspar quartz

Igneous structures that formed from magma cooling within the crust

plutons

Predominantly

the A horizon

What do you call a piece of country rock that breaks off and becomes entrapped in a body of magma?

xenolith