Geology Midterm 2

False

The texture of a rock refers to just it's feel. True or False

felsic

The walls of Yellowstone Canyon are_____ash (felsic, mafic)

quartzite and marble

Two common metamorphic rocks that typically lack foliation are : . a..slate and phyllite b..gneiss and migmatite c..quartzite and marble d..schist and metaconglomerate

T

Very early in Earth's history, it was so hot that the surface was likely entirely molten. (T or F)

ash

Volcanic ash is mostly what?

Mt. Pelee

Volcanic eruption where 2 people survived. Little girl and prisoner.

Lake Nyos

Volcanically derived carbon dioxide gas bubbled from the lake and suffocated people and animals nearby.

tephra

What is a cinder cone made of?

silicon and oxygen

What is magma made of (2 biggest).

Drowning

When Krakatoa blew, most deaths were caused by (a) drowning (b) burning (c) burial (d) explosion

F

When rock is melted within Earth, typically the entire volume of rock is transformed from a solid state to a liquid. (T or F)

pressure, volatiles, heat

Why magma forms. Decrease in______, adding______, _____transfer from rising magma.

B

Would it be reasonable to say that (a) granite comes mainly as the liquid phase from fractional crystallization of mafic magmas or (b) granite is mainly a product of partial melting of metamorphic rocks (A or B)

dynamic

____ metamorphism: shear taking place along a fault. rock deforms plastically so the minerals in the rock recrystalize

burial

______ metamorphism: due only to the consequences of very deep burial

mafic, felsic

_____magma less viscous than ____ magma. (type of magma)

hot, cold

___magma is less viscous than ___magma. (temperature)

block

a chunk of prexisting rock as a pyroclastic deposit

graded bed

a layer of sediment in which grain size varies from coarse at the bottom to fine at the top

metaconglometate

a protolith of conglomerate becomes this under metamorphic conditions. pebbles and cobbles flatten into a pancake shape without cracking

metamorphic rock

a rock that forms when a preexisting, or protolith, undergoes a solid-state change in response to the modification of its environment

dormant

haven't erupted for hundreds of years

conduit

how magma travels from magma chamber to the surface

texture

how the crystals fit together in an igneous rock

felsic

if magma cools slowly allowing fractional crystalization (mafic or felsic)

mafic

if magma solidifies quickly before fractional crystallization (mafic or felsic)

fragmented texture

igneous chunks or shards packed together

oceanic, continental

igneous rocks make up all _____ crust, and most_______crust.

assimilation

incorporating chemicals or blocks from the surrounding rock (contamination)

stoping

assimilation of rock wall, not all rocks melt completely, become xenoliths

delta

topset beds of gravel, foreset beds of gravel and sand silty bottomset beds

oxidation

transfer iron-bearing minerals into a rusty brown mixture

lithification

transformation of loose sediment into rock

landslides

tsunamis generated from hawaii come from (a) underwater eruptions (b) underwater caldera collapse (c) landslides (d) earthquakes

True

"All lava is magma" is truer than "All magma is lava" True or False

hydrothermal

-____metamorphism: fluid rises through the crust near the mid ocean ridge causing this

Mt. Vesuvius

. In 79 C.E., the citizens of Pompeii in the Roman Empire were buried by pyroclastic debris derived from an eruption of

at places in continental interiors termed shields

. Precambrian metamorphic rocks are exposed at the surface : . a..on Mars and Venus, but nowhere on Earth b..at places in continental interiors termed platforms c..at places in continental interiors termed shields d..at the bottom of the deep sea

False

A Strobolian eruption is more dangerous than a Plinian eruption (true or false)

felsic

A lava dome is (mafic, felsic, intermediate)

Tuff

A volcano emits ash, which falls from the sky, settles in layers, and is eventually cemented. The resultant rock is termed ___

F

All crystaline rocks are igneous (T or F)

F

All of the Earth's internal heat was acquired very early in its history through meteoric impact and differentiation of the core. The Earth's interior loses heat to space but does not currently receive heat through any known process. (T or F)

Porphyritic

An igneous rock with a mixed texture of coarse grains (phenocrysts) surrounded by fine crystals (groundmass) is termed

Flood basalts

At continental rifts, vast bodies of basaltic lava flow forth from fissures, forming

columnar jointing

Basalt lava flows contract and may fracture in roughly hexagonal columns.

T

Bedrock covered in soil is not an outcrop of rock (T or F)

Plagioclase

Bowen's continuous reaction series describes the crystallization behavior of a single mineral (with variable chemical composition) a. olivine b. plagioclase c. pyroxene d. quartz

Granite

Coarse grained Silicic rock

Gabbro

Coarse grained mafic rock

T

Compaction and cementation is a sedimentary process (T or F)

Dry magma

Contains no volatiles

Basalt

Fine grained Mafic rock

Rhyolite

Fine grained Silicic rock

Hot spot island chain

Hawaiian Island chain is an example of what?

A

Humis had decayed further and mixed with minerals. Water percolates causing chemical weathering. (zone of leaching)

increase

If a body of magma becomes more felsic its viscosity will (increase or decrease)

H2O and CO2

Important volatiles in magma

Martinique

In 1902, a famous, deadly volcaniclastic flow killed thousands of people on the Caribbean island of (Puerto Rico/ Martinique/ Aruba/ Jamaica)

Olivine

In Bowen's discontinuous reaction series, the first mineral to crystallize from a mafic melt is

F

In metamorphic rocks some melting is always required (T or F)

discordant

Is a dike a concordant or discordant intrusion?

concordant

Is a laccolith a concordant or discordant intrusion?

True

Is it true that urban areas of Tacoma lie above lahar deposits from Mt. Rainier (true or false)

Mars

Larges volcano in the solar system is on which planet?

shield volcanoes

Largest of the volcanoes in Area

Igneous

Lava cools to form this type of rock

False

Lithification is a metamorphic process. True or False

Io

Most volcanic place in the solar system

stratovolcanoe

Mt. Fuji is an example of this type of volcano

False

One of the reasons volcanic eruptions are so deadly is that there is no way to predict where an eruption will occur in the near future. true or false

Hotter

Radioactive isotopes, differentiation of Earth's iron core, gravity-driven compression, and meteoric bombardment all caused early Earth to be much_____ than at present. (Hotter or Colder)

Intrusive igneous rock

Rock formed from the cooling and solidification of magma beneath Earth's surface. In magma chambers, cracks, or columns.

extrusive igneous rock

Rock that forms from the cooling and solidification of lava at Earth's surface. Lava flows, pyroclastic debris

intermediate magma

Rock with a chemical content between felsic and mafic compositions.52-66% silica

Igneous Rock

Rocks formed through the freezing of a melt. They can be produced above or below ground and are the most common type of rock within Earth.

T

Sand is not a rock (T or F)

low, basaltic

Shield volcanoes have (high/low) viscosity (basaltic/mafic) flows

continental hot spots

Simultaneous eruptions of basalt and rhyolite can occur where?

foliation

Slaty cleavage, schistosity, and compositional banding are all examples of : . a..mineral cleavage b..foliation c..recrystallization d..sedimentary structures

source rock

Solid from which magma is derived

Io

Surface resembles a pizza because of the sulfur gasses.

Exodus

The Biblical chapter that possibly describes a volcanic eruption is (a) Genesis (b) Psalms (c) Exodus (d) Corinthians 2

felsic

The Morro such as Bishop Peak are compositionally...(mafic, felsic, intermediate)

younger

The black parts of the moon's surface are ____ than the lighter parts

High pressure but relatively low temperature

The blueschist facies is a metamorphic realm of : . a..high temperature and pressure b..low temperature and pressure c..high temperature but relatively low pressure d..high pressure but relatively low temperature

F

The colored strata layers of the Grand Canyon are said to be a form of foliation (T or F)

F

The composition of a rock can be described as either being equant or inequant

schistosity

The development of a preferred orientation of large, flaky mica crystals within metamorphic rock is termed ...

True

The devil's tower has its undisputed origin as a lava pipe in the center of an old volcano (True or False)

False

The eruption of Mt. St. Helens in 1980 was the greatest explosive eruption in the last two hundred years of world data. a. true b. false

ignimbrite

The lithification of material from a pyroclastic flow forms a rock called

False

The long valley caldera has shown no sign of activity in the last century (true or false)

hydration

absorption of water into the crystal structure of minerals, causing expansion and weakening

volcaniclastic deposits

accumulations of fragmental igneous rock

breccia

angular fragments with sharp edges

composite

another name for stratovolcano

bombs

apple to refrigerator sized lapilli

stratification

arrangement of sediment into beds

tuff

ash mixed with lapilli when burried and transformed into coherent rock

convergent boundaries

effusive or pyroclastic eruptions. yield composite volcanoes. (geological setting)

continental hot spot

basaltic and rhyolitic pyroclastic debris, partially melts the crust (geological setting)

oceanic hot spot

basaltic magma, broad dome shaped shield volcano (geological setting) [not sure about this one]

Olympus Mons

biggest shield volcano in the solar system. Located on Mars

pluton

blob shaped intrusion

bedding plane

boundary between two beds

shield

broad gentle dome with low viscosity basaltic flow (type of volcano)

conglomerate

burial and lithification of rounded and broken breccia. Final stage is a rounded rock

extinct

can no longer erupt

clastic sedimentary rocks

cemented together solid fragments and grains derived from preexisting rock

chemical weathering

chemical reactions that alter or destroy minerals in rock

crater

circular depression at top of volcanoe

gneiss

compositionally layered metamorphic rock, typically composed of alternating dark and light layers that range in thickness from milimeters tometers. stripped

chalk

consisting of plankton shells

soil

consists of rock or sediment that has been modified by physical and chemical reaction with organic material and rain water over time to produce a substrate that can support the growth of plants

Peleos hair

consists of thin strands of basaltic pyroclastic debris

Basaltic

contain more iron and magnesium than rhyolitic lavas

continental rifts

curtains of lava, basaltic fissure eruptions, array of different volcano types (geological setting)

metamorphic foliation

defined by the patallel alignment of platy minerals and the presence of alternating light and dark colored layers

sorting

degree to which clasts in a rock are the same size

magma mixing

different magmas from different sources can combine in one magma chamber

metamorphic aureole

distinct belt of metamorphic rock that forms around an igneous intrusion

cross beds

distinct internal laminations inclined at an angle to the boundary of main sedimentary layers

mid ocean ridge

erupts basalt which turns into pillow-lava mounds (geological setting)

pumice

felsic volcanic rock containing abundant vesicles (very light0

phyllite

fine grained metamorphic rock with a foliation caused by the prefered orientation of very fine grained white mica

tuff

fine grained pyroclastic composed of volcanic ash

James Hutton

first one to really study metamorphic rocks

platy

flat or broad

low viscosity

flows easily

mylonite

foliation that roughly parallels the fault. Made during dynamic metamorphism

thermal expansion

forest fire heats up outer rock but inner rock stays cool so the outer layer pops off

vesicles

form in high viscosity magma, bubbles

jointing

form of weathering, natural cracks that form in rocks dur to removal of pressure or cooling

slate

forms by metamorphism of shale or mudstone under relatively low pressures and temperatures. Finest grained foliated metamorphic rock

Quartzite

forms by the metamorphism of pure quartz sandstone.

sediment

forms by weathering of preexisting rock

pyroclastic rocks

fragmental rocks composed of debris that has been blasted out of volcanoes or vents. Already solid when stuck together

Pyroclastic debris

fragmented material that sprayed out of a volcano and landed on the ground or sea floor in solid form. Large fragments formed in the air. Includes volcanic ash.

migmatite

gneiss may begin to melt producing felsic magma, if it freezes again before flosing out of source area a mixture of igneous and metamorphic rock form called...

metamorphic texture

grains in a metamorphic rock have grown in place within the solid rock.

lava tube

insulated tunnel like conduit within a flow through which lava moves

explosive

intermediate and felsic magma is _______ (unexplosive or explosive)

andesitic lava

intermediate viscosity lava, higher silica content than some lava, solidifies into a jumble of rubble

laccolith

intrusions inject between layers and dome up

stratovolcano

large and cone shaped, steeper near the sumit. Alternating layers of lava, tephra, and debris

volcanic breccia

large fragments of volcanic debris that either fall through the air and accumulate or form when a lava flow breaks into pieces

dunes

large ripples

Melt

lava and magma (phase?)

fissure

lava erupts as a curtain from a long crack

pyroclastic debris

lava which cools in the air

C

layer of material derived from substrate that has been chemically weathered but hasn't undergone leaching or accumulation, grades down into bedrock

sedimentary structures

layering of sedimentary rocks, surface features on layers formed during deposition and arrangement of grains within layers

active

likely to erupt soon

geotherm

line of temperature as you go deeper into the earth

arkose

lithified mixture of quartz and feldspar

shale

lithified mud

siltstone

lithified salt

thermal metamorphism

local metamorphism caused by igneous intrusion (also known as contact metamorphism)

sediment

loose fragments of rocks or minerals broken off of bedrock, mineral crystals, and shells

Flood Basalt

low viscosity sheets of basaltic lava. Form when a mantle plume underneath a region undergoes rifting and erupts spectacularly

chert

made from tiny quartz crystals from shells of silica secreting plankton

scoria

mafic volcanic rock that contains abundant vesicles (darker and harder than pumice) the "scum" of lava

Felsic magma

magma with a high silica content and large volume of gas (explosive eruptions) 66-76% silica

mafic magma

magma with a low silica and gas content (non explosive eruptions) 45-52% silica

Ultramafic magma

magma with a very low silica and gas content. contains about 38 to 45% of silica

obsidian

mass of solid felsic glass

schist

medium to coarse grained metamorphic rock that posses a type of foliation defined by the prefered orientation of LARGE mica flakes

high

metamorphic rocks that form at a relatively high temperature (above 600C): ____ grade

low

metamorphic rocks that form at a relatively low temperature (250C-400C): ____ grade

regional metamorphism

metamorphism affecting a large area

dynamothermal metamorphism

metamorphism involving heat and shearing

marble

metamorphism of limestone. calcite composing the protolith recrystalize and distinction between grains and cement disappear

dissolution

minerals dissolve in water

volatiles

more _____ make lava less viscous

rhyolitic lava

most viscous type of lava, accumulates above the vent in a lava dome or in short bulbous flows. Broken and blocky surfaces when cooled.

Organic (O)

mostly organic matter, few minerals (layer of soil profile)

turbidity

muddiness created by stirring up sediment or having foreign particles suspended

metamorphic minerals

new minerals that grow only under metamorphic mineral assemblage

Hornfels

nonfoliated rock that contains a variety of metamorphic minerals.

inequant

not the same dimensions in all directions

batholith

numerous plutons in a region making up to 100km of igneous rock

partial melting

only part of an original rock melts. Tends to be more felsic than the original rock

magma chamber

open space that holds large quantities of magma

coal

organic chemicals in ____ come from plant remains

lapilli

pea to plum sized fragments of glassy lava and scoria, type of pyroclastic debris

diagenesis

physical, chemical, and biological processes that transform sediment into sedimentary rock and alter these characteristics

ptotolith

preexisting rock from which metamorphic rocks are formed

deposition

process by which sediment settles out of the transporting material

evaporites

products of saltwater evaporation

dolostone

replacing calcite with dolomite

tavertine

rock composed of crystalline calcium carbonate formed by chemical precipitation from groundwater that has seeped out at the found surface in springs or in the wall of caves

sedimentary rock

rock formed at or near the surface by cememting together loose grains that had been produced by weathering of preexisting rock, precipitation of minerals, cementing of shells, or by growth of masses of shell-producing organisms

xenolith

rocks which are broken off of country rock and fall into magma but do not melt completely

porphyritic rocks

rocks with large crystals surrounded by smaller crystals

Salt Wedging

salt water precipitates and grows crystals in open pore spaces breaking off particles(type of weathering)

equant

same dimensions in all directions

formation

sandstone, consists of solid grains stuck together to form a distinct solid mass of sedimentary rock

mafic

scoria would most likely be found with ___ lava. (felsic, intermediate, mafic)

sedimentary basin

sediment filled depression

stratigraphic formation

sequence of strata which can be traced across a large region

strata

several beds together

ash

shards of glass and pumice fragments

tabluar

sheet like intrusions (no particular direction)

ignimbrite

sheet of tuff

bed

single layer of sedimentary rock

subsidence

sinking of the lithosphere

ripple marks

small elongated ridges that form on a bed surface at right angles to the current flow

glassy

solid mass of tiny crystals, not crystaline structure

cinder cone

steep pile of tephra, type of volcano

sand dune

strong winds can more dust and sand to accumulate into sand dunes

B

sub-soil, ions and clay accumulate

a'a'

surface layer freezes and breaks forming sharp angular fragments, type of basaltic lava

dike

tabular intrusion that cuts across preexisting layers. Perpendicular to direction of stretching that occurs during rifting

sill

tabular, injects parallel to layering

sphericity

the degree to which a rock is equidimentional

quartz

the last mineral to survive in a river

rift basin

the name of the troughs which fill with sediment

magma chamber

the pocket beneath a volcano where magma collects

exhumation

the process by which deeply burried rocks come back up to the surface

erosion

the process by which rock fragments are separated from its substrate

metasomatism

the process of changin a rock's chemical composition by reactions with hydrothermal fluids

metamorphism

the process of changing from one rock into another

foliation

the repetition of planar surfaces or layers in a metamorphic rock

angularity

the roundness of a rock

scoria

the scum formed by oxidation at the surface of molten metals

volcanic ash

tiny particles of glass that form when a spray of lava erupts and freezes instantly

caldera

top of volcano collapses into emptied magma chamber

welded tuff

tuff formed when the ash particles remained hot enough to fuse; consists mainly tiny glass shards. tuff which contains flatened bits of obsidian

pyroclastic

type of eruption made by cinder cones

effusive

type of eruption made by shield volcanoes

effusive and pyroclastic

type of eruption made by stratovolcano

effusive

type of eruption. Produces lava flows with low viscosity, basaltic lava.

explosive

type of eruption. produce clouds and avalanches of debris

basaltic

type of lava flow with low viscosity, flows quickly on steep slopes

tephra

unconsolidated deposits of pyroclastic grains

E

undergone leaching but not yet mixed with organic material

Limestone

usually formed by accumulations of shells made from CaCO3 (biochemical)

soil profile

vertical sequence of soil layers

micrite

very fine mud

lahar

very wet mixture of ash that quickly flows downstream

pahoehoe

warm pasty surfaces of lava wrinkle into smooth glassy rope like ridges, a type of basaltic lava

hydrolysis

water chemically reacts with minerals and breaks them down to form other minerals

Frost wedging

water getting into pores of rock and freezing and pushing it apart

alluvial fan

wedge shaped apron of gravela nd sand deposited by the stream

weathering

what breaks up and corrodes solid rock turning it into sediment

fractional crystalization

when minerals in magma crystalize at different rates

regression

when sea level drops, the coast migrates seaward

transgression

when sea level rises, the coast migrates inland

zone of leaching

where rainwater carries dissolved ions and clay flakes downward

tephra

which is the most all encompassing term (tephra or tuff)

transportation

wind, water, or ice move sediment