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