Exam #3 (11/5) Flashcards
Where do we find volcanoes?
- convergent boundaries
- divergent boundaries
- hot spots
What comes out of volcanoes?
- dust
- ash
- cinders
- block and bombs
volcanic bomb:
- elongated shape
- tear drop
- bigger than cinder
- > 64mm
volcanic blocks:
- mostly rounded
- 65 mm
What is a fumarole?
small vents that emit only gases and smoke
What is lava?
molten materials present at Earth’s surface
What are the 2 types of lava?
- Aa
2. Pahoehoe
dissolved gases:
As pressure is reduced, the gases escape
Aa lava flow:
Rough texture, due to gases still being present when solidifying
Pahoehoe:
smoother, “ropey” texture
Lava viscosity
- aka thickness of lava
- higher viscosity= greater resistance to flow
- silica content can change viscosity
- (increase silica, increase viscosity)
Lava viscosity will effect what?
- the explosiveness of a volcano
- gas content
Mafic explosion:
- low explosion
- low viscosity
Felsic explosion:
- extremely explosive
- high viscosity
Crater:
summit depression < 1km diameter
Caldera:
- summit depression > 1km diameter
- produced by collapse following massive explosion
vent:
opening to the magma chamber
Shield Volcano:
- largest
- made of basalt
- low gas content
- low explosiveness/ viscosity
- ex. Mauna Loa
Cinder Cone Volcano:
- Around 500m high and 500m in diameter
- very short life spans (weeks to months)
- only one eruption cycle
- high gas pressure
- basalt, pumice
- moderately explosive
- ex. South of Young Valley, AZ
Conical Composite Volcano (Strato)
- layered from multiple eruptions
- long lived
- continental subduction zones
- felsic lava with a lot of gas
- high viscosity/gas pressure
- highly explosive
- ex. Mt Saint Helens, Mt vesuvius
- found around pacific plate
lava domes
- occur inside of existing volcanoes (mostly strato)
- hot and unstable
- ex. inside Mt. Saint Helens
Caldera
- large magma body supports large region
- sudden deflation from rapid expulsion
- usually ends up as a significant depression
- ex. Crater Lake & Long Valley caldera
Fissure eruption
“fountain but does not pile up enough to make a volcano
pyroclastic flows:
- massive, hot as and dust cloud racing at speeds over 100 mph.
- biggest killers from eruptions
pluton
cooled magma at depth
stock
pluton exposed over a small area
sill
horizontal, emplaced magma body
dike
cuts layers of rock at an angle
volcanic neck
exterior of volcano removed while internal pipe remains
xenoliths
pieces of “country rock” which fall into the magma body
Weathering
the breakdown of tock and minerals into smaller and smaller pieces
Erosion
the group of natural processes by which weathered materials are transported
What are the 3 main processes?
- erosion
- transport
- deposition
siWhat is the major key to weathering and erosion?
Water
Susceptibility to weathering is dependent on what?
the strength of molecular bonds
rocks former at _____ temps are more likely to weather.
lower
the _____ covalent bond tetrahedra, the ____ susceptible to weathering
less; more
Parent material:
starting off, before weathering
Daughter material:
comes from weathering of parent
What do quartz break down to?
Quarts can only breakdown to quartz
How are igneous rocks formed?
when molten materials solidify
Felsic rocks are not typically dark in content due to high iron content
False
Karst topography
the dissolution of limestone by groundwater which produces cavernous areas below ground
Which will weather at a faster rate, olivine or quarts?
Quartz: lower temperature,
Detrital sedimentary rocks are classified based on their _____ composition
chemical
bioturbation
life digging into sediments and rocks (animals, humans)
List grades of coal in proper order (lowest to highest)
- peat
- lignite
- bituminous
- Anthracite
What can feldspars and amphiboles be broken down into?
clay minerals
Agents of transportation
- water
- wind
- ice
- anything that can move materials
rounding:
corners of transported materials are knocked off as grains slam into each other
sorting:
as things travel they come more well sorted based on grain size and density
deposition
where transported materials end up
base level: lakes, ponds, local basins
ultimate base levels: ocean
lithification
after deposition, rocks can be made through compaction and cementation
pedogenesis
soil formation
5 factors of pedogenesis:
parent material, time, climate, plants and animals, topography
sedimentary rock:
rock made out of bits and pieces of other rocks
diagnesis
chemical, physical, and biological changes that take place after sediments are deposited
detrital sedimentary rocks, coarsest grain size
- conglomerate (well-rounded)
- breccia (poorly rounded)
detrital sedimentary rocks, moderate grain size
-sandstone
detrital sedimentary rocks, fine grain size
- siltstone
- shale
2 common cements
- calcium carbonate
- silica
Chemical sedimentary rocks, silica
chert, flint, jasper, diatomite
Chemical sedimentary rocks, evaporites
halite, gypsum
stages of coal formation
- burial (peat)
- Greater burial (lignite)
- Metamorphism (bituminous)
- Stress (anthracite)
depositional environment
The are characterized by similar physical processes that result in similar types of sediments being deposited; where sediments are deposited and make sedimentary rocks
What are the two types of depositional environments?
- continental (non-marine)
- oceans (marine)
- nearshore (waves)
- offshore (currents)
examples of continental depositional environments
- deserts
- alluvial fans
- glacial deposits
- rivers
Where do we find reefs?
continental shelf in a continental margin
bedding
when sediments of different grain sizes or compositions are deposited on top of one another
connetic living:
larger grains are at the top
laminated bedding
quiet, low-energy environment, usually no animals
mixed bedding
mixed usually by animals
what defines a sedimentary facies
- the nature of the sediment
- the sedimentary structure
- what fossils used to liver there
outcrops
exposed bed rock on earth’s surface
The units sharing similarities in their heterogeneity:
-formations, members, beds, laminations
Steno’s laws
rules for determining the order in which rocks were deposited in:
- superposition (stuff on top is newer than stuff on bottom)
- original horizontally
- lateral continuity
- principle of cross-cutting relationships
What do fossils tell us?
age of rock, community dynamics, types of environment
half-life
tome needed for 1/2 pf parent to decay
Basalt
magic, extrusive, igneous rock formed from the rapid cooling of magnesium-rich and iron-rich lava
Organic reefs
carbonate structures created by carbonate secreting organisms
Continental shelf
located in the shallow waters off continental shores, where sedimentation is controlled by relatively gentle currents
continental margin and slope
deeper waters at and off the edges of the continents where sediment is deposited by turbidity currents
deep sea
floors of the deep ocean not affected by wave activity
