ESSC 101 Sherman Exam 21

felsic magma

magma, high silica, lots of gas (explosive eruptions)

Ocean continent Melting

island volcanic arc

most distinctive feature E horizon

lack of both organic matter and soluble minerals

Ophialite

ocean crust sequence

conduit

pipe carries gas-rich magma to surface

caldera

greater than 1 km

weathering processes

•Frost wedging •Unloading •Biological activity

Water function in chemical weathering

*participates in the reactions. *carries away products of the reactions. *carries ions to reaction sites

Weathering by thermal expansion and contraction involves:

*the addition of water to the surface of the rock influences the rate of mechanical weathering. *the outside of a large rock experiences more temperature fluctuations than the inside of the rock. * different kinds of minerals within a rock expand at different rates when heated.

What determines the violence of an eruption?

- sufficient gas dissolves under pressure within a viscous magma - expelled lava violently froths into volcanic ash when pressure is suddenly lowered at the vent

crystalline structure

Atoms must be arranged in an organised, repetitive manner.

rich soil accumulates in

A relatively flat topography in a moist, mid-latitude climate.

metamorphic rock

A type of rock that forms from an existing rock that is changed by heat, pressure, or chemical reactions. They are NOT melted all changes happen in solid state

sedimentary rock

A type of rock that forms when particles from other rocks or the remains of plants and animals are pressed and cemented together

explosive eruption

A violent and unpredictable eruption— the result of magma that is thicker, stickier (more viscous), and higher in gas content and silica than that of an effusive eruption; tends to form blockages within a volcano; produces composite volcanic landforms (see composite volcano; compare effusive eruption).

effusive eruption

An eruption that yields mostly lava, not ash.

spheroidal weathering.

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

B horizon

B is more fertile than E. Some B horizons contain a high concentration of humus In arid and semi-arid climates, calcium carbonate accumulates to form a caliche layer within or below the B horizon

differential weathering

Caused by variations in composition Creates unusual and spectacular rock formations and landforms (example the angel arch)

Cementation/ Compaction

Gluing together of sediment and rock

Feldspar Group

Group of most common minerals of Earth's crust. Si,fe,and ox (may contain K,C,Na).

Most abundant mineral in the Universe

Hydrogen, helium

As the rate of cooling decreases, particle size in an igneous rock:

Increases

Most abundant element in entire Earth

Iron, Oxygen, silicon, magnesium, nitrogen (FEOSMN)

What drives an eruption?

Magma rises through cracks or weaknesses in the Earth's crust. When this pressure is released, eg as a result of plate movement, magma explodes to the surface

Magma v. lava

Magma: Molten rock inside of the Earth. (contains dissolved gas vapor) Lava: Molten rock on the Earth's surface. (gas has already escaped)

igneous, sedimentary, metamorphic

Name the three types of rock.

(OAEBC) Horizons

O- Organic A- Topsoil E- Eluviated B- Subsoil C- Parent material

Most abundant element in Earth's crust

Oxygen, silicon, aluminum, iron and some metals O, S, Al, I (Na, Mg, K, Ca)

What is the last mineral to form according to Bowen's reaction series?

Quartz.

Continental crust is composed mostly of rocks formed by:

Regional Metamorphism

transported soil

Soil that has been moved away from its parent material by water, wind, or a glacier.

residual soil

Soil that remains above its parent rock

Cinder cones

Steep, conical hill formed over a vent from lava fragments accumulating over single vent. Generally form around composite and shield volcanoes.

Weathering

The breaking down of rocks and other materials on the Earth's surface.

C horizon

The least-weathered soil horizon, which always occurs beneath the B horizon and is similar to the parent material consists mostly of rock chunks that differ little from the underlying bedrock.

soil

The loose, weathered material on Earth's surface in which plants can grow.

In an igneous rock with two distinct classes of crystal size, which of the following is true?

The rock cooled slowly at first, but then the cooling process speeded up

Role of volatiles

Volatiles (primarily water) cause rocks to melt at lower temperatures Important factor where oceanic lithosphere descends into the mantle

weathering v. erosion

Weathering is the breaking down of rocks; erosion is the transporting of rock fragments

Viscosity of magma

a measure of a material's resistance to flow, depends on silica content

Loam

a mixture of all three sizes) is best suited for plant life (sand, silt and clay)

igneous rock

a type of rock that forms from the cooling of molten rock at or below the surface (If it melted, it's igneous) Ions slow down, attract and begin mineral formation.

shield volcano

a wide, gently sloping mountain made of layers of lava and formed by quiet eruptions(usually largest)

adding water moves the geothermal gradient boundary

adding water lowers the melting temp of the rock

what lowers melting temperature of rocks

adding water, and decompression

rock cycle

an idealized cycle of processes undergone by rocks in the earth's crust, Magma/lava forms igneous, oceans erode igneous rocks (physical and chemical) weathering and eroding creates sediments, transported, lithification, changing pressure or temp of rock creates metamorphic, eventually melting back to magma and recycled

ophiolite

an igneous rock consisting largely of serpentine, believed to have been formed from the submarine eruption of oceanic crustal and upper mantle material.

country rock

any preexisting rock that has been intruded by a pluton or altered by metamorphism

unloading joints (unroofing)

are often horizontal as well as vertical and form as a result of lower pressure near to the surface. like sheeting

pyroclastic sizes

ash dust pumice lapilli(walnut size) cinders (pea sized Blocks (hardened lava Bombs (ejected as hot lava, hard on outside, liquid interior)

Rhyolitic volcanoes usually form

calderas, while basaltic volcanoes form shield cones

Strato Volcano (composite cone)

cause the most problem, don't have to erupt to kill you. make lava flow, slide off mountain because of pyroclastics (mt. Ranier) (debris avalanches

partial melting

causes longer chains and higher silica

Mechanical weathering

changes the size and shape of rock structures.

carbon dioxide

comes from respiration, lava and volcanic eruption

factors of eruption violence

composition, temperature, gases

Volcano features

conduit Vent crater caldera

Strato Volcano (composite cone)

conical, steep-side, symmetrical volcano (ratio of height to breadth relatively large) composed of alternating layers of silicic lavas and pyroclastics. Typical of subduction zone volcanism.

Continent-Continent melting

continental volcanic arc

Violent volcanoes tend to occur at

convergent plate boundaries,

gentle volcanoes tend to occur at

divergent plate boundaries.

LAM scale

dynamic of eruption low is quiet, high is big eruption

What is a caldera? An example of one?

ex: Crater Lake, Oregon = a large cauldron-like depression that forms after magma exits a chamber/reservoir. - A lot of magma leaves, the structure for the crust above it is gone. The magma chamber is lost.

Pahoehoe

fast-moving, hot lava that has low viscosity

felsic

high silica, light-colored, lower density rock, slow and thick magma

glassy rocks

form when magma cools very quickly without growth of mineral grains, obsidian

double chain silicates

form when two single chains of tetrahedra link to each other by sharing oxygen atoms

Pressure

holds lattice of molecules together

fumaroles

holes or cracks serving as escape vents for underground gases

Gabro

igneous intrusive rock, mafic (texture: rough, grainy, sandy. Black with white flecks which are of feldspar not quartz) least silica, coarse grain

As pressure increases, the melting-point of a rock:

increases

crater

less than a kilometer

cooling

loss of thermal energy

mafic magma

magma that is silica poor, low viscosity, releases volatiles, high density, high temperature

partial melting

melting of subducting slabs, happens at convergent boundaries

decompression melting

melting that occurs as rock ascends due to a drop in confining pressure, occurs at ocean ridges (divergent boundaries)

Frost wedging would be most prominent in:

mid-latitude regions where temperatures hover around 0°C (32°F) during certain seasons.

Partial melting is an important process in the formation of

migmatites

Melting rock

molecules speed up and breaks down the lattice, eventually they turn to liquid.

activities that threaten soil

overgrazing, erosion, removing vegetation, soil contamination

melting at ocean-continent boundary

partial melting

Vegetation promotes chemical weathering by

producing organic acids upon decay

B horizon

receives the minerals and organic materials that are leached out of the A horizon. a zone of illuviation that contains soluble materials derived from overlying horizons.

Chemical weathering •Alters the internal structures of minerals by

removing or adding elements

Regolith

rock and mineral fragments produced by weathering that support plant life

intrusive igneous rock

rock formed from the cooling and solidification of magma beneath Earth's surface

extrusive igneous rock

rock that forms from the cooling and solidification of lava at Earth's surface

fragmental igneous rock

rocks consisting of igneous chunks and/or shards that are packed together, welded together, or cemented together after having solidified

weathering makes the oceans

salty

Example of metamorphic rock

sandstone to marble

oxidation

the chemical combination of a mineral's ions with oxygen.

C, O, U, Ar, K, and Pb

some of the most common isotopes used in geologic investigations.

Igneous rocks

structurally strong, but geologically not strong.

vent

surface opening connected to magma chamber by a pipe

Soil Taxonomy

system for classifying soils

The two properties used most to classify igneous rocks are:

texture and mineral composition

O horizon

the abundance of both organic and living organisms

an objects temperature

the average thermal energy in a system

Lithification

the cementation, compaction and hardening of sediments into rock

Hydrolysis refers to:

the displacement of a mineral's ions by the H+ or OH- ions from water.

geothermal gradient

the gradual increase in temperature with depth in the crust

eroding

the process of wearing or washing away slowly. Sediments transported to a basin and deposited

The primary cause of mechanical exfoliation is

the removal by erosion of overlying rock and soil

Chemical exfoliation

the weathering of rocks in concentric layers, occurs because chemical weathering attacks the outside of the rock before attacking the inside.

Rounding occurs on rock edges and corners bc

they offer more surface area than its planar faces

A horizon

topsoil

effusive and explosive

two types of eruptions

Aa lava flow

very rough, jagged surface; flows very slowly due to higher viscosity jagged blocks

In general, chemical weathering would occur most rapidly in

warm moist climate

The single most important factor controlling the rate of chemical weathering is

water