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