GOL 105 CH4-8

dissolution

certain minerals dissolve into water.

fissure

crack that develops as magma moves towards the earths crust.

Recrystallization

creation of new mineral grains from preexisting ones.

crystalline texture (non-clastic)

- minerals form a pattern of interlocking crystals - common examples: rocks deposited when saline water evaporates - consist of inter-grown crystals (may resemble igneous rocks)

3 factors that volcanologists monitor in order to determine weather magma is migrating toward earths surface?

1. Changes in the pattern of earthquakes produced by the movement of magma 2. Magma entering a near-surface magma chamber, which leads to inflation of the volcano 3. Changes in the amount or composition of gases released from a volcano

What is the process thought to generate most basaltic magmas? Most granitic magmas?

A basaltic pond of magma becomes trapped below continental crust and partially melts this silica-rich crust into a granitic magma.

crater

A bowl-shaped area that forms around a volcano's central opening

regional metamorphism

A change in the texture, structure, or chemical composition of a rock due to changes in temperature and pressure over a large area, generally as a result of tectonic forces.

Oxidation

A chemical change in which a substance combines with oxygen, as when iron oxidizes, forming rust. Electrons are lost.

intermediate (andesitic) composition

A compositional group of igneous rocks that contains at least 25 percent dark silicate minerals. The other dominant mineral is plagioclase feldspar.

Magma can be generated in three ways:

A decrease in pressure, introduction of water, heating of crustal rocks above their melting temperature.

Viscosity

A liquid's resistance to flowing

shield volcano

A low, flat, gently sloping volcano built from many flows of fluid, low-viscosity basaltic lava. They generally begin as seamounts.

Laccolith

A massive igneous body intruded between preexisting strata

lava tubes

A natural conduit where lava travels under the surface of a lava flow.

cinder cone volcano

A small, steeply sloped volcano that forms from moderately explosive eruptions of pyroclastic material.

aphanitic texture

A texture of igneous rocks in which the crystals are too small for individual minerals to be distinguished without the aid of a microscope.

gneissic texture

A texture of metamorphic rocks in which dark and light silicate minerals are separated, giving the rock a banded appearance.

columnar jointing

A type of fracturing that yields roughly hexagonal columns of basalt; columnar joints form when a dike, sill, or lava flow cools.

pumice

A type of igneous rock that contains air bubbles

composite volcano (stratovolcano)

A volcano constructed of alternating layers of pyroclastics and rock solidified from lava flows.

effusive eruption

An eruption that yields mostly lava, not ash.

pyroclastic (fragmental) texture

An igneous rock texture results from the consolidation of individual rock fragments that are ejected during a violent volcanic eruption. Welded tuff

What is the geothermal gradient? Describe how the geothermal gradient compares with the melting temperatures of the mantle rock peridotite at various depths.

An increase in temperature with depth. 20-30 degrees Celsius per kilometer. The temperature at which peridotite melts is higher than the geothermal gradient.

How is carbonic acid formed in nature?

Atmospheric carbon dioxide dissolves in raindrops.

Briefly describe why patrial melting results in a magma having a composition different from the rock from which it was derived.

Because different minerals melt at different temperatures, minerals that melt at lower temperatures will melt from the rock first, creating a magma formed from the minerals that melted first.

Loam

Best suited to support plant life. A mixture of gravel, sand, silt, clay, and organic matter

3 most noticeable changes in a volcano caused by the migration of magma are:

Changes in earthquake patterns, inflation or deflation of a volcanic cone, changes in the amount and/or composition of gases released from a volcano.

How do cinder cone volcanoes compare to shield volcanoes?

Cinder cones are steep whereas shield cones are not.

List and describe the differences among the three basic sedimentary rock categories.

Clastic: are transport4ed accumulations of rocks weathered by both physical and chemical processes. Chemical: soluble material produced largely by chemical weathering. Organic sedimentary: carbon-rich

5 types of controls of soil formation. Which factor is most influential in soil formation?

Climate is most influential. Others include parent material, plants animals and microbes, time, and topography within a climate zone.

Light (Nonferromagnesian) Silicates

Contain greater amounts of potassium, sodium, and calcium. Rich in silica. Quartz, muscovite mica, feldspars.

Describe dikes and sills using the appropriate terms from the following list: massive, discordant, tabular, concordant.

Dikes are discordant bodies that cut across bedding surfaces or other structures in host rock. A sill is a massive nearly horizontal, concordant body that forms when magma exploits weaknesses between sedimentary beds or other structures, tabular

Describe each of the following in terms of composition and texture: diorite, rhyolite, and basalt porphyry.

Diorite has an Intermediate composition and phaneritic texture. Rhyolite has a Felsic composition and an aphanitic texture. Basalt Porphyry has a Mafic composition and a porphyritic texture.

Name two plate tectonic settings in which you would expect magma to be generated.

Divergent Boundary plates and subduction zones.

List two primary factors that determine the manner in which magma erupts.

Effusive, explosive.

Describe the following features or processes: evuluvation, leaching, zone of accumulation, and hardpan.

Eluviation - elimination of components of soil due to flow of water down through the E horizon. Leaching - removal of soil components from the upper layer of the soil to the deeper layers due to the downward flow of water is called leaching. Zone of accumulation - horizon B, soil from E horizon get accumulated into horizon B due to flow of water. Hardpan - strong and compact layer which is formed due to accumulation of clay.

List these magmas in order, from the most silica-rich to the least silica-rich composition: mafic magma, felsic magma, intermediate magma.

Felsic, intermediate, mafic

List the four basic compositional groups of igneous rocks, in order from highest silica content to lowest silica content.

Felsic, intermediate, mafic, ultramafic.

how is magma generated along convergent plate boundaries

Friction from the subducting plate raises the temperature of the rock under which it subducts, melting this rock into magma.

Classify each of the following as felsic, intermediate, or mafic: gabbro, obsidian, granite, and andesite.

Gabbro is Mafic. Obsidian is Felsic. Granite is Felsic. Andesite is Intermediate.

Volitiles

Gases in magma (mostly water & Carbon dioxide)

List the 6 igneous rock textures.

Glassy, porphyritic, Phaneritic, Vesicular, pyroclastic, aphanitic.

4 agents that drive metamorphism

Heat, Pressure, Stress, Chemicals

how coal is formed

Heat, pressure, and time turned the plant material into carbon-rich rock. Turns peat into anthracite coal.

Are volcanoes fed by highly viscous magma more likely or less likely to be a greater threat to life and property than volcanoes supplied with very fluid magma?

Highly viscus magmas are greater threat to life and property.

Mafic

Igneous Rock contains large amounts of Iron and Magnesium, dark in color. Basalt.

weathering

Involves the physical breakdown and chemical alteration of a rock at or near the earths surface

Explain how water can cause mechanical weathering

It can freeze and break apart rocks as well as erode rocks.

What does a porphyritic texture indicate about the cooling history of an igneous rock?

It indicates that crystals were formed at depth (slow cooling) and then the magma moved to a shallow depth or erupted (fast cooling).

Explain why soil is considered an interface in the earth system.

It is a common area where geosphere, atmosphere, hydrosphere, and biosphere interface. loam

Explain the process of decompression melting.

It occurs where hot solid mantle rock ascends in zones of convective upwelling, thereby moving into regions of lower pressure.

Hawaii's most active volcano

Kilauea

aa flow

Lava flow with jagged, blocky surface

How do light-colored igneous rocks differ from dark-colored rocks?

Light colored rocks are mostly silicate and darker rocks are mostly iron and more dense.

What is magma? How does magma differ from lava?

Magma is molten rock generated by partial melting of rocks in Earth's mantle and in the lower crust in smaller amounts. When molten rock reaches the surface, it is called lava.

Explain why headstones weather so differently.

Marble dissolves even in slightly acidic conditions whereas granite is more resistant to chemical weathering.

The largest shield volcano

Mauna Loa

When a rock is mechanically weathered, how does its surface area change? How does this influence chemical weathering?

Mechanical weathering breaks rocks down into smaller fragments, and increases the surface area of the over all material. By increasing the surface area, chemical processes may act more easily upon the rock surface.

Are pyroclastic materials a significant component of shield volcanoes?

No

Where do most shield volcanoes form? Ocean floor or continents?

Ocean floor

Igneous rocks are composed mainly of which group of materials?

Oxygen and silicon being the most abundant elements in Earth's crust, igneous rocks are composed mainly of silicate group minerals.

Compare and contrast marble and quartzite

Quartzite is made of primarily quartz whereas marble is composed of calcite.

How is regolith different from soil?

Regolith does not contain organic matter, water, and air.

How are Granite and Rhyolite...similar...or different?

Rhyolite is the intrusive equivalent of granite. Both are felsic in composition.

What name is given to the region having the greatest concentration of composite volcanoes?

Ring of fire

Vesicular texture (igneous)

Rock that has a spongy appearance due to trapped gas bubbles in the lava.

How does the volume of sedimentary rocks in earths crust compare to volume of igneous and metamorphic rocks.

Sedimentary rocks represent 5 to 10 percent of the crust, whereas igneous rocks and metamorphic rocks combined represent 90 to 95 percent of Earth's crust.

Why are soil in tropical rainforests not well suited for intensive farming?

Silica and calcium is leeched out and what is left is iron oxides.

____________ and ____________ are the most abundant elements in igneous rocks.

Silicon, Oxygen

How does the rate of cooling influence crystal size? What other factors influence the texture of igneous rocks?

Slow cooling promotes the growth of large crystals. Rapid cooling generates small crystals.

distinguish among batholiths stocks and laccoliths in terms of size and shape

Stocks are smaller plutonic structures similar in shape to batholiths. Laccoliths are the smallest of the three and tend to be mushroom shaped.

How does climate influence weathering?

Temperature and moisture are the main factors in weathering- warm temperatures with high moisture are best for weathering. Frigid areas are bad for weathering, as moisture is locked.

List the two criteria by which igneous rocks are classified.

Texture and composition.

slaty cleavage

The ability of a rock to break along closely spaced parallel planes.

Assimilation

The composition of magma changes when the molten mass incorporates pieces of surrounding host rock, in a process called assimilation.

pyroclastic flow

The expulsion of ash, cinders, bombs, and gases during an explosive volcanic eruption. They are driven by gravity.

What occurs when carbonic acid reacts with calcite-rich rocks such as limestone?

The limestone is dissolved and carried away by underground water.

frost wedging

The mechanical breakup of rock caused by the expansion of freezing water in cracks and crevices

Foliation

The metamorphic rock texture in which mineral grains are arranged in planes or bands.

vent

The opening through which molten rock and gas leave a volcano

Cementation

The process in which minerals precipitate into pore spaces between sediment grains and bind sediments together to form rock.

Lithification

The process that converts sediments into solid rock by compaction or cementation.

parasitic cone

The secondary cone forming on the side of the volcano.

Why is texture an important soil property?

The texture of soil strongly influences the soil's ability to transmit water and air.

List two ways in which sedimentary rocks are important

They contain evidence of past conditions, we can reconstruct the configuration of ancient landmasses.

How do joints promote weathering?

They're fractures that allow water to penetrate deeply and start the process of weathering long before the rock is exposed

How does biological activity contribute to weathering

Tree roots, burrowing animals, and humans can contribute.

How do tuff and volcanic breccia differ from igneous rocks such as granite and basalt?

Tuff and volcanic breccia are identified with a modifier; for example rhyolite tuff indicates a rock composed of ash-size particles having a felsic composition.

How can slate and phyllite, which resemble each other, be differentiated?

Unlike slate, which has a flat surface, phyllite has a glossy sheen and a wavy surface.

What role does water play in the formation of magma?

Water causes rock to melt at lower temperatures.

compare and contrast extrusive igneous rocks and intrusive igneous rock

When magma crystallizes at the surface, extrusive. When magma crystallizes at depth, intrusive.

volcanic island arc

a chain of volcanic islands generally located a few hundred kilometers from a trench where there is active subduction of one oceanic plate beneath another

Caldera

a large crater caused by the violent explosion of a volcano that collapses into a depression

pahoehoe flow

a lava flow with a smooth-to-ropy surface

horizon

a layer of soil

List and describe the three components of magma

a liquid component, a solid component, and a gaseous component

Magma consists of

a liquid component, a solid component, and a gaseous component

mantle plume

a mass of hotter-than-normal mantle material that ascends toward the surface, where it may lead to igneous activity

nonfoliated metamorphic rock

a metamorphic rock that does not exhibit a banded or layered appearance

Lava Dome Volcano

a roughly circular mound-shaped protrusion resulting from the slow extrusion of viscous lava from a volcano

Fumaroles

a vent which fumes or gases escape

Process of formation of coal

accumulation of plant remains, formation of peat and lignite, bituminous coal, anthracite coal.

Volcanism at divergent plate boundaries is most often associated with which magma type?

basaltic magma

Explain how the formation of biochemical sediments differs from the formation of sediments by inorganic processes

biochemical (organic) sediments: processes of water-dwelling organisms also form chemical sediments (i.e. shells left behind & collected into a sediment, coral reefs: calcium carbonate)sediments by inorganic processes: processes such as evaporation & chemical activity that can produce chemical sediments (i.e. dripstone: limestone stalagmites & stalactites, salt left behind as a body of sweater evaporates)

Describe the materials that compose composite volcanoes

built from layers, or strata, of pyroclastic material, including lava, pumice, volcanic ash, and tephra.

Provide an example of carbon moving from the geosphere to the atmosphere

burning coal, burning oil

B horizon

clay transported from above

Phaneritic

coarse-grained, crystals are large enough to be seen w/out a microscope, formed by slow cooling (intrusive)

Ultramafic

composed of almost entirely ferromagnetic materials

porphyritic texture

composed of two distinctly different crystal sizes.

Describe the components of a cinder cone

cone-shaped hills mostly made of ash

Sedimentary Environments

continental, transitional, marine

Which type of plate boundary is associated with regional metamorphism?

convergent plate boundaries

Describe how sediments become sorted.

depends upon how much transport the sediment has undergone.

Clastic Texture (Sedimentary)

discrete fragments and particles

E horizon (zone of leaching)

dissolved and suspended materials move downward

The greatest amount of magma erupts along __________________ _______________ ____________.

divergent plate boundaries.

high grade metamorphic rocks

extreme temperatures and pressures. Folded gneiss.

When magma crystallizes at the surface, ____________ are formed.

extrusive igneous rocks (volcanic rocks)

List several minerals that are especially susceptible to oxidation and list two common products of oxidation.

ferromagnesian minerals: olivine, pyroxene, hornblende, biotite -> hematite & limonite sulfide minerals: pyrite -> sulfuric acid & iron oxide

Schistosity

foliation caused by the preferred orientation of large mica flakes

Are volcanoes in the Ring of Fire generally described as effusive or explosive? Name an example that supports your answer.

generally explosive

Most important agent in metamorphism

heat

subduction zone metamorphism

high pressure, low temperature metamorphism that occurs where sediments are carried to great depths by a subducting plate

What is the single most characteristic feature of sedimentary rocks

horizontal stratification, or horizontal beds

What is the agent of hydrothermal metamorphism?

hot, ion-rich water

interplate volcanism

igneous activity that occurs within a tectonic plate away from plate boundaries

Magma when cooled turns into ________

igneous rock

Glassy texture (igneous)

igneous rock that contains no crystals, such as obsidian.

When magma crystallizes at depth, ____________ are formed.

intrusive igneous rocks (plutonic rocks)

halite (common salt)

is the most water soluble mineral

Direction of the slope influences soil formation because _________

it may or may not get sunlight.

distinguish among limestone, dolostone, and chert.

limestone: most abundant, from mineral calcite - coral reefs: corals secrete calcium carbonate external skeleton - coquina: coarse rocks composed of poorly cemented shells - chalk: soft, porous rock made up of hard parts of microscopic marine organisms - travertine: stalacties & stalagmites, dripstone in caves (calcium carbonate precipitates) - oolithic limestone: grains rolled in warm calcium carbonate water & form layersdolostone: calcium -magnesium carbonate mineral dolomite, distinguished from limestone using hydrochloric acid (limestone fizzes)chert: compact & hard rocks made of microcrystalline quartz (SiO2) - flint, jasper, petrified wood, agate

low grade metamorphic rocks

low temp and pressure. Slate

Describe the composition and viscosity of the lava associated with shield volcanoes.

mafic and has a low viscosity

Three rocks produced by contact metamorphism

marble, quartzite, and hornfels

Liquid portion of magma

melt

briefly explain one way that basaltic magma can generate felsic magma

melting a mafic source thus yields a felsic or intermediate magma.

decompression melting

melting due to a drop in confining pressure that occurs as rock rises

A migmatite is a mixed ___ rock.

metamorphic and igneous

burial metamorphism

metamorphism due only to the consequences of very deep burial

impact metamorphism

metamorphism that occurs when meteorites strike Earth's surface

A horizon

mineral matter mixed with some humus

dark (ferromagnesian) silicates

minerals containing ions of iron and/or magnesium in their structure. Olivine, pyroxene, amphibole, biotite.

continental volcanic arc

mountains formed in part by volcanic activity caused by the subduction of oceanic lithosphere beneath a continent

If rock breaks into chunks its called ____ ______.

mud stone

3 ways to control soil erosion

no till farming, trees and shrubs used as windbreaks between fields, Flat surfaces slow runoff.

contact metamorphism

occurs on earths upper crust when rock immediately surrounding a molten indigenous body are baked by the high temperatures.

hydrothermal metamorphism

occurs when very hot water reacts with rock, altering its mineralogy and chemistry

O horizon

organic matter

What characteristic of a metamorphic rock is determined primarily by its parent rock.

overall chemical composition

Every metamorphic rock has a

parent rock

C horizon

partially altered parent material

Mechanical weathering (physical weathering)

physical forces that break rock into smaller and smaller pieces without changing the mineral composition.

What products result when carbonic acid reacts with potassium feldspar?

potassium carbonate (dissolved in water)

host rock (country rock)

preexisting crustal rocks

Place these phenomena related to soil erosion in the proper sequence: sheet erosion, gullies, raindrop impact, rills, stream.

raindrop, sheet erosion, rills, gullies, stream

Felsic

relating to or denoting a group of light-colored minerals including feldspar & quartz. Commonly solidify to form granite.

How have human activities affected the rate of soil erosion?

removing farming, logging, trees, shrubs, and grasses, has accelerated soil erosion

Tephra

rock fragments and particles ejected by a volcanic eruption.

Slate's parent rock

shale, mudstone, or siltstone

Pillow lavas are associated with ____________.

submarine basaltic eruptions

diagnesis

the chemical and physical changes that transform sediment into rock

Hydrolysis

the chemical breakdown of a compound due to reaction with water.

The metamorphic grade refers to ________.

the degree to which the parent rock changes during metamorphism

magmatic differentiation

the formation of one or more secondary magmas from a single parent magma

Compaction

the process by which sediments are pressed together under their own weight

magma mixing

the process of altering the composition of a magma through the mixing of material from another magma body

Erosion

the removal of weathered material from one location to another driven by gravity

Bowen's Reaction Series

the simplified pattern that illustrates the order in which minerals crystallize from cooling magma according to their chemical composition and melting point

scoria

vesicular ejecta that is the product of basaltic magma

Temperature affects ________ in magma.

viscosity

gaseous component of magma

volatiles

Describe the formation of crater lake

volcanic depression called a caldera that formed by the collapse of a volcano

How might mud cracks and ripple marks be useful clues about the geologic past?

when formed the sediment was wet and was dried out

How do evaporites form?

when water evaporates and leaves minerals behind