Geology Test 2

how did crater lake oregon form

About 1500 meters of summit of a composite volcano collapsed after an explosive eruption of about 50 cubic kilometers of pyroclastic material. Later the caldera was eventually filled with water.

spheroidal weathering

Any weathering process that tends to produce a spherical shape from an initially blocky shape

Why is soil considered an interface within the Earth system?

Changes in the climate in the atmosphere create changes in soil texture and composition. Water from the hydrosphere that is added to soil from various sources allows the soil to be able to sustain plant life, which returns to the geosphere once it expires.

How do the eruptions that created the Columbia Plateau differ from the eruptions that create large composite volcanoes?

Eruptions that created the Columbia Plateau ejected basaltic magma from fissures; eruptions that create large composite volcanoes eject silica-rich magma from vents.

sheeting

Large masses of igneous rock are exposed by erosion and concentric slabs break loose due to release of confining pressure, exfoliation dome formed after continued weathering causes slabs to seperate

Which statement describes the composition and viscosity of the lava associated with shield volcanoes?

Lava from shield volcanoes is mafic and has a low viscosity.

differential weathering

Variations in local climate and the composition of the rock formation will produce uneven weathering of the rock

B horizon (subsoil)

Zone of accumulation of metals and nutrients material washed down from e horizon accumulates here accumulation of clay particles from upper layers.

Where does the clay that accumulates in the B horizon come from?

a and e horizons

fumaroles

a flank vent that emits gases

scoria

a glassy, mafic, igneous rock containing abundant air-filled holes

delta

a triangular landform created where a stream enters a body of water and deposits sediment.

pumice

a very light and porous volcanic rock formed when a gas-rich froth of glassy lava solidifies rapidly.

Which of the following defines depositional environment?

an area where sediment was deposited under certain conditions in Earth's past

intermediate igneous rocks

an igneous rock midway in composition between mafic and felsic, neither as rich in silica as felsic rock nor as poor in it as mafic rock

Type of lava at divergent boundary

basalt

Which three minerals are especially susceptible to oxidation?

biotite, olivine, and pyrite

shield volcanoes

broad, lots of basaltic (mauna loa), lava comes out of fissures

coal

buried quick for low grade metamorphism

calcite dissolution

caco3 + h2co3 ----> ca^2+ +h^+ +Hco3^-

environments that support shale

calm lake deep ocean basin low energy environments

volcanic cone

cone-shaped structure created by successive eruptionsof lava and pyroclastic materials

Where are composite volcanoes found?

convergent plate boundaries

fissure

crack develops in crust as magma moves to the surface

three types of calderas

crater lake type: filled with rainwater hawaiian type : collapse yellowstone type: grander scale, 47 mi across, domes form, cracks form, more viscous

mafic

describes magma or igneous rock that is rich in magnesium and iron and that is generally dark in color

types of chemical weathering

dissolution, oxidation, hydrolysis, spheroidal weathering

formation

distinct maleable unit

lava dome

dome-shaped landform of igneous rock that forms when thick lava cools near the vent of a volcano, filled with rhyolitic lava

Outcrop

exposed bedrock

A ________ describes the observation of successive changes in a laterally continuous sedimentary layer that are visible and are interpreted as a result of many depositional processes taking place over a large area.

facies

During hydrolysis, ________ commonly decompose into clay minerals, silica, and soluble constituents.

feldspars

parasitc cones

flank vet that emits lava and pyroclastic material form on the flanks of a larger volcano in the case of

Detrital Sedimentary Rocks

form from sediments that have been weathered and transported, classified by grain size, most sediment is detrital

cascade range

from convergent plate boundary (cascade subduction) then intermediate or mafic partial melting because felsic and intermediate materials melt first

Types of mechanical weathering

frost wedging, salt crystal growth, sheeting/unloading, biological activity

crater

funnel-shaped depression at summit, <1 km diameter is formed on the volcano summit by explosive eruptions and is composed of accumulated volcanic debris.

volatiles

gaseous components of magma dissolved in the melt. They will readily vaporize at surface pressures

how does the carbon cycle relate to rocks

moves from fossils to coal to sedimentary rocks and limestone

lahar

mud flows, triggered when snowfields or water satured cause landslides, often caused by eruptions

Which soil horizon will contain the greatest amount of organic material?

o

what makes top soil

o and a horizons

interplate volcansim

occur far from plate boundaries, when mantle plume ascends to surface, superplume responsible for flood basalts (ex: hawaii)

controls of soil texture

parent material climate plants and animals time topography (soil orientation) soil profiles/horizons

c horizon

partially altered parent material that is easily identifiable.

Lapilli

pebble like bits of magma that cool in the air

Which of the following would decrease the viscosity of magma?

increase in temp

andesitic lava

intermediate (medium silica content and viscosity, more gas rich) composition and flows intermediate, constructs stratovolcanoes

soil

plants supporting system of disintegrated rock, organic matter, air, gas, nutrients, texture refers to proportion of different particle sizes (influence ability to transmit water and air)

clearing tropical rain forest case study

poor soil no time to get good top soil all nutrients held in vegetation, so when clearing vegetation in rain forest, only bad soil left

What kind of volcanic hazard can be triggered by the collapse of a lava dome?

pyroclastic flow

pipe

rare type of conduit originated in mantle

Hydrolysis

reaction of any substance with water, h ion attacks and replaces other ion, silicates primarily decomp by hydrolysis (clay minerals most abundant and stable) acid greatly accelerates it

joints

regular systematic breaks

volcanic neck

remains of magma solidified in volcanic conduit

magma chamber

results when magma collects or ponds due to its density being higher than that of overlaying materials.

aa lava

rough and jagged, further from vent, more viscous has a rough, broken surface. It is caused by rapidly moving basalt that cools quickly.

Which materials in Hawaii's lava help to keep it fluid for longer at the surface (as opposed to cooling and solidifying quickly), thus allowing extensive lava flows to develop?

iron and magnesium

Mudcracks represent

it was once wet environment that is now drying up

Which of Hawaii's five volcanoes are still considered to be active?

kilauea, mouna loa

volcanic dangers

lahar pyroclastic flows ash tsunamis volcanic ash (hazards to planes) poisonous volcanic ash

pyroclatic materials

large amount, bigger eruption, more sio2, (examples: pumice and scoria)

composite/strato volcanoes

large, classic triangle shape, steep, violent, lots of material (mt. st. helens), lava out of vents

pillow lavas

lava and water, cooled very quickly is composed of solid, bubble-like masses. It is caused by extremely quick lava quenching.

zoic means

life

E horizon

little organic matter, zone of eluviation and leaching light-colored, depleted of soluble materials, little organic material.

What is thought to be the source of magma for most intraplate volcanism?

mantle plumes

What are the three broad categories of sedimentary environments with an example of each?

marine environments, such as deep ocean floors; continental environments, such as deserts; transitional environments, such as tidal flats

Viscousity

measure of lavas resitance to flow

magma

molten rock

is syrup more or less viscous then water

more

Oxidization

rusting of iron rich minerals, o2 and fe make feoxide, slow process in dry environments, water increases speed, important in decomposition ferromags, acid mine drainage: sulfuric acid

Which type of sedimentary structure is characteristic of sand dunes?

sand dunes

What is the sequence of sediments you would pass over if you were to walk from the shoreline and then swim in the offshore direction?

sand, clay, carbonate

in what rocks do you mostly find fossils

sedimentary rocks

Which of the following has the single most immediate effect on lava's ability to solidify?

temp

magma behavior is dependent on

temp composition dissolved gases these all determine viscosity

how is viscosity affecte by temp

the hotter the lava the less viscous

Regolith

the layer of unconsolidated rocky material covering bedrock

weathering

the physical or chemical breakdown of rocks and minerals into smaller pieces or aqueous solutions on Earth's surface

vent

the surface opening of a conduit or pipe is an opening where volcanic materials erupt at the Earth's surface

environment for massive limestone

warm, shallow seas

most important agent for chem weathering

water, it is responsible for transport of ions and molecules in chemical process

what does a good job sorting particles

wind

Does livelihood sometimes depend on fertile soils from volcanoes

yes

does ash cool the planet

yes because it blocks sunlight

O soil horizon

—organic matter -The lower portion is composed of humus -This horizon includes bacteria, fungi, algae, and insects consists largely of organic material, still identifiable in uppermost layer.

flood basalts

(ex: columbia river basalts) form when lava flows out of long cracks in Earth's crust

Transitional Environments

- Beaches - Barrier Islands - Tidal Flats - Lagoons and Bays - Estuaries - River Deltas

Rock characteristics

- Dependent of mineralogy - Silicate minerals weather in the same order as crystallization (Bowen's reaction series), more stable as you go down the graph, more of whats on surface of earth - Carbonates and halides weather more quickly than silicates (more readily attacked by h2o)

sedimentary facies

- Different sediments often accumulate in adjacent environments - changes can be traced laterally -sand will drop first, then shale, then limestone

Types of sedimentary structures

- layers of sedimentary rocks are strata or beds (most common) -bedding planes: seperate strata -graded bedding: unique situation where sediment in strata gradually change from coarse grained to fine grained, fine grains settle at top, chunks -cross bedding: when layers in sedimentary rocks are inclined -ripple marks: form at low velocity, small waves lithified in rock -mud craxxks: indicates sediments form in alternating wet and dry environments

why is sediment important

-contains evidence of past environment -fossil fuels -groundwater -source of uranium, fe, a, mahganese, ph

climate

-temp and percip are crucial (freq of freeze-thaw, moisture for dissolution, conditioned favoring very growth)

volcanism at divergent boundaries

60% of earthly yearly output is at spreading centers, intense volcanism, basaltic

sediment covers ___ of land, only ____ of volume on earth

75% 5%

percent of common lava flows

90% basaltic <10% andesitic about 1% rhyolytic

basaltic lava

A lava type of mafic composition that has a low silica content, erupts at high temperatures, and flows readily collonade: more insulated flow, cools slowly scoria: vesicular portions of flow, gas escapes through it entablature: zones or tiers of irregular jointing in basaltic lava flows fast lava flow flows in sheets 90% of lava on earth

shale

A sedimentary rock formed by the deposition of successive layers of clay.

block lava

Andesitic or rhyolitic lava with square surface faces, short flows has a rough surface composed of smooth-sided fragments. It is formed by viscous lava cooling quickly.

salt crystal growth

As water evaporates, crystals grow in cracks and expand the cracks, breaking the rock mechanically

what explains how dissolved gases drive volcanic eruptions

Confining pressure decreases on a rising magma, allowing gas bubbles to expand and fracture the magma. This process further decreases pressure on the magma and will result in an explosive event.

felsic

Describes magma or igneous rock that is rich in feldspars and silica and that is generally light in color.

3 types of sedimentary rock

Detrital (clastic), chemical, organic

deep marine

Fine clay and plankton are only source of sediment Finely laminated mudstone, chalk and chert.

how does gypsum form

Gypsum forms from evaporation of shallow seas by a chemical process

Which of these are true about intraplate volcanism?

Intraplate volcanism usually erupts basaltic lava. Intraplate volcanism occurs both on continental and oceanic landmasses.

shallow marine

Low energy so finer sands and silts are present. Siltstones and mudstones. Fossils common.

horizon order

O, A, E, B, C

what affects rate of weathering

Rock characteristics, climate, and differential weathering

Think about the soil horizons that make up the solum. Why isn't the C horizon part of the solum?

The C horizon contains mostly parent material.

Which of the processes listed below would transform an exposure of granite in the mountains into sedimentary rocks?

The granite would mechanically weather into small particles, which would travel down the slope of the mountain via mass wasting, be deposited, and undergo diagenesis when the sediments are buried under younger layers of rock.

a soil horizon

The layer of soil that differs in color and texture from the layers above or below it composed of a mixture of humus and mineral material.

What information can evaporites provide about the past environment of deposition?

The paleoenvironment was wet and in the process of drying up.

chemical weathering

The process that breaks down rock through chemical changes, decompositiion

Why is texture an important soil property for agriculture?

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

mechanical weathering

The type of weathering in which rock is physically broken into smaller pieces, increases surface area, disintegration

lava tubes

Tunnels and caves formed by lava movement in the moon's distant past. These tubes can serve as shelter from meteorites, radiation, and extreme temperatures, form in pahoehoe results from a relatively fluid lava cooling and forming an outer shell. The lava continues to flow inside the outer shell.

How does regolith differ from soil?

Unlike regolith, which consists only of weathered rock and mineral fragments, soil also contains organic matter, water, and air.

frost wedging

Water works its way into cracks in rocks and the freezing enlarges the cracks in the rocks, lenses of ice in soil grows, attracting water

dissolution

certain minerals dissolve in water, small amount of acid in water increases the corrosive force, causing dissolution, carbonic acid: calcite can be readily dissolved by water

Diagenesis

chemical, physical, and biological changes that take place after sediments are deposited, occurs within upper crust

conduit

circular pathway from fissure to surface 4. The pipelike feature through which magma travels upward from an underground magma chamber is called a conduit

mature sediment

has been weathered, sorted, transported, quartz, well rounded

rhyolitic lava

high silica content, rare, causes pyroclastic flow, very viscous and tend to form comparatively short, thick flows slow flows 1% of all earths lava

pyroclastic flows

hot gases, ash and lava flow down volcano, flows fast, felsic compositions, neu r dants, collapse of lava dome

biological activity

human mining, roots from plants

Ultramafic

igneous rock composed mainly of iron and magnesium-rich minerals

how is viscosity affected by composition

silica content more silica, more viscous

cinder cones

small, build up rather quickly

surge

smaller ash comes out of pyroclastic flow

pahoehoe

smooth, resembles twisted rope has a smooth, billowy surface. It is caused by slowly moving basalt that is still hot.

leaching

soluble in organic compounds washed to lower layers

eluviation

the washing out of fine soil components from the A horizon by downward-percolating water

how do volcanic necks and pipes form

through erosion

lithification

unconsolidated sediments compacted/cemented by pressure, sometimes iron oxide cements it otherwise fluid would pass through, where large pore spaces, holds aquifers

turbidites

underwater avalanches

volcanism at convergent

volcanic arcs: develop parallel to association subduction zone trench, most found in the ring of fire, explosive, volitile-richm andesetic magma

caldera

volcanic crater with diameter >1km, produced by collapse post massive eruption Depletion of the upper part of a magma chamber during a volcanic eruption can result in gravitational collapse of the volcanic summit to form a caldera