Kratzmann GEO Test 2 SRJC

Pyroclastic density currents are formed from

convecting eruption plumes

Explosive volcanism is most likely to be associated with

convergent plate boundaries

Intrusive rocks are more coarser-grained, than extrusive rocks because they have different __________

cooling histories

Very poorly sorted

indicates that the sediment sizes are mixed (large variance)

well sorted

indicates that the sediment sizes are similar (low variance)

Clastic Sediment

Composed of solid fragments of pre-existing rock

Difference of igneous: intrusive v.s. extrusive rocks

Crystal size intrusive: large crystals extrusive: small cystals

rift basins

Deep, narrow and long, with thick successions of sedimentary rocks and extrusive and intrusive igneous rocks.

shoreline sedimentary environments

Delta, tidal flat, beach (environment)

Which of the following explosive eruptions was enhanced by seawater flooding the magma chamber

Krakatau, Indonesia, 1883

_________ are mixtures of water (maybe ice), volcanic ash, and rock fragments that flow down-slope, driven by gravity.

Lahars

continental sedimentary environments

Lake, river, desert, glacier (environment)

sedimentary basins

Regions of variable size where the combination of sedimentation and subsidence has formed thick accumulations of sediments and sedimentary rocks.

volcanic eruptions

Strombolian, Vulcanian, Plinian

Magma is formed at ________ zones through flux melting.

Subduction

chemical weathering

The process that breaks down rock through chemical changes.

What is viscosity?

The resistance of a liquid to flow. If the honey is too thick it will resist flowing. If the honey is less thick it will not resist flowing as much as the thick honey will.

What are the two types of magma?

Mafic and Felsic

Granite is a good example of an igneous rock that is

felsic and coarse-grained

Several surface processes of the rock cycle contribute to the formation of sedimentary rocks

1.) Weathering 2.) Erosion 3.) Transportation 4.) Deposition (sedimentation) 5.) Burial 6.) Diagenesis

volcanic plug

A ______________, is created when magma hardens within a vent. A plug can cause an extreme build-up of pressure if rising volatile-charged magma is trapped beneath it, and this can sometimes lead to an explosive eruption

Mineral Wedging

A form of chemical weathering resulting in the formation of new minerals that have greater aggregate volumes than the old ones. These expanding minerals then act as wedges to split adjacent minerals and rocks apart.

Stratovolcano

Also known as a composite volcano

roundness

Angular to rounded

physical weathering

Any process that breaks rock down into smaller pieces without changing the chemistry of the rock; typically wind and water.

Biochemical Sediment

Biochemical Composed of shells from animals (metabolic chemical reactions)

The breakdown of rocks by near-surface processes involves mechanical and ___________ weathering

Chemical

Biological Sediment

Composed of remains of plants.

Types of Sediment

Clastic Chemical Biological Biochemical

lithification

Compaction and cementation of soft sediments lead to

bioclastic sediments

Composed of broken fragments of biologically precipitated particles.

marine sedimentary environments

Continental shelf, organic reef, continental slope, deep sea (environment)

Phaneritic

Course grain. Intrusive

How an igneous rock melts

Decompression and Flux

cross-bedding

Depositional feature of sedimentary rock that forms as inclined layers of sediment are carried forward across a horizontal surface.

current strength

Determines the size of the particles deposited in a particular place -Strong currents (50+ cm/s) carry gravel & smaller particles -Moderately strong currents (20-50 cm/s) lay down sand beds -Weak currents (<20 cm/s) carry muds

High Viscosity

Ex. This is thick, high viscosity honey.

Low Viscosity

Ex. This is thin, low viscosity liquid such as water.

There are two types of igneous rocks.

Extrusive & Intrusive

What is Felsic magma?

Felsic magma is magma that is rich in feldspars and silica (light minerals) and that is generally light in color.

biological sediments

Form from the remains of animals and plants -Coal, Amber

Scoria cones

Formed by the accumulation of scoria, pumice, and spatter around the volcano. Scoria cone built by explosive lava-water interaction at the wakupanaha ocean entry.

siliciclastic sediments

Formed by weathering processes which break down rocks into particles -Gravel (2+ mm), Sand (2-0.06 mm), Mud (<0.06 mm)

chemical sediments

From minerals that precipitate in water -Halite, Limestone, Salt

______ is a form of mechanical weathering.

Frost wedging

Porphyritic

Has a distinct difference in the size of the crystals, with at least one group of crystals obviously larger than another group. 2 different sizes

Processes that form igneous rocks

Igneous rock is formed through the cooling and solidification of magma or lava. Extrusive & Intrusive.

When magma rises through the surface and flows out of a volcano as a viscous fluid we call it _______ .

Lava

What is Mafic magma?

Mafic magma is magma that is rich in magnesium and iron (dark metals) and that is generally dark in color.

Chemical Sediment

Materials precipitated directly from water. *chemical reaction

deposition (sedimentation)

Process in which sediment settles in new locations or dissolved minerals precipitate.

erosion

Processes by which weathered rock, sand, and soil are carried away.

________ currents are formed from collapsing eruption plumes.

Pyroclastic density

_______ are far more dangerous than low-viscosity lava flows.

Pyroclastic density currents

What are igneous rocks?

Rocks that form from lava at the ground or above the ground. Igneous rock is formed through the cooling and solidification of magma or lava.

_____ is a fine grained (small particles) sediment than gravel

Sand

aphanitic

Small crystals. Extrusive.

weathering

The breaking down of rocks physically and chemically on the Earth's surface

Felsic =

The high viscosity lava produces sticky, thick lava that makes EXPLOSIVE eruptions.

Mafic =

The low viscosity magma produces runny lava that makes QUIET eruptions.

compaction

The process by which sediments are pressed together under their own weight.

Pegmatitic

Very course grain. Intrusive.

ripples

Very small ridges of sand or silt whose long dimension is at right angles to the current.

Exfoliation

When an intrusive rock begins to rise above surface and loses pressure, causing it to start to expand and as a result the rock cracks.

Which of the following best describes an explosive eruption with a very high degree of fragmentation, widespread dispersal of very fine ash, with hours to days of sustained activity?

a Plinian eruption

caldera

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

Aa

a slow-moving type of lava that hardens to form rough chunks; cooler that pahoehoe

composite volcano

a tall, cone-shaped mountain in which layers of lava alternate with layers of ash and other volcanic materials

A lahar is

a volcanic mud flow that resembles fluid concrete

The main rock of the oceanic crust is called

basalt

cementation

cementation The process in which minerals precipitate into pore spaces between sediment grains and bind sediments together to form rock. -Decreases porosity (% of rock's volume consisting of open pores between particles)

_________ are formed when the top of the volcano collapses down into the magma chamber (which is now empty).

calderas

In the 1980s, over 1700 people and thousands of heads of cattle from a village surrounding Lake Nyos, a volcanic lake in Cameroon, died unexpectedly after the lake overturned. They were not scalded, they were not poisoned, and the area did not smell bad. What volcanic gas killed the villagers and their cattle, and snuffed out their cooking fires?

carbon dioxide

Physical weathering speeds up ________ by increasing surface area

chemical weathering

Conglomerateis a relatively _________ clastic sedimentary rock composed of ______________.

coarse grained rounded clasts

Mount Vesuvius (Italy) is an example of a

composite volcano

The lithified equivalent of gravel is called

conglomerate

Extrusive

created above the ground. Cools rapidly

Intrusive

created in the ground. Cools slowly

When different rocks in an outcrop undergo weathering at different rates it is called

differential weathering

sorting

distribution of grain size of sediments, either in unconsolidated deposits or in sedimentary rocks

warning sign of imminent eruption

earthquake activity change in heat flow from the volcano's surface increase in gas emissions and hydrothermal activities

pahoehoe

freely flowing lava

Which of the following igneous rocks is the most mafic?

gabbro

The driving force for sediment transport is?

gravity

Rhyolite, andesite, and basalt

have the same cooling history but different chemistry.

Silica content

high content is more viscous (thick, explosive) low content is less (thin, quiet)

Which of the following chemical reactions breaks down feldspars into clay minerals

hydrolysis

The effects of mechanical weathering include

increased particle movement downhill. increase of particle surface area

Physical weathering speeds up chemical weathering by

increasing surface area

Decompression melting

involves the upward movement of the earth's mantle to an area of lower pressure. The reduction in overlying pressure enables the rock to melt, leading to magma formation. Magma is formed by the melting of the earth's mantle.

The formation of shield volcanoes is favored by

low SiO2 content and low viscosity.

Basalt is a good example of an igneous rock that is

mafic and fine-grained

Crystals of olivine are most commonly found in ______ and ______ igneous rocks.

mafic and ultramafic

silica

material found in magma that is formed from the elements oxygen and silicon; it is the primary substance of Earth's crust and mantle

maturity

mature and immature

Flux Melting

occurs when water and other volatile components are added to hot solid rock.

sediment

pebbles of basalt quartz crystals in granite

cinder cone

produced by ash falling around a vent

A glowing cloud of pyroclastic fragments and hot gas

pyroclastic flow

Granite and __________ are examples of igneous rocks that are related by similar chemical compositions but not textures.

rhyolite

Cross-bedding typically develops in ___________

sand dunes

The observation of asymmetric ripples in sandstone can be used to determine....

the direction of water flow.

diagenesis

the physical and chemical changes occurring during the conversion of sediment to sedimentary rock.

Weathering happens fastest on the corners, then edges, of broken blocks of rock because

the reactions can attack the corners from three sides and the edges from two sides

pyroclastic flow

very hot mixture of ash and lava that erupts with great force and speed

shield volcano

volcano that forms from lava that builds up slowly over time

During hydrolysis

water chemically reacts with minerals to break them down into different minerals. By this process, feldspars and other silicate minerals weather into clays.

Chemical weathering speeds up physical weathering by _____

weakening the rock.

What does the Bowen's Reaction Series explain?

why certain minerals found together, other combinations rare, certain minerals found in certain igneous rocks