Geology Flashcards
Mohorovicic Discontinuity
boundary between crust and mantle
Where does Earth’s heat come from?
Collisions from early Earth days, radioactive decay and rocks are just poor conductors of heat
How do we know Earth has a large collision in it’s past?
Increased spin
Tilted axis
Moon rocks have similar composition to Earth rocks
What are the chemical layers of the Earth?
Crust
Mantle
Core
What are the 3 most common elements in the Earth?
Iron, oxygen, and silicon
What are the 3 most common elements in the CRUST?
Oxygen, silicon, and aluminum
What is the core mainly made of?
Iron
T or F: The mantle is liquid
false
what type of crust is thicker?
continental crust
what type of crust is denser?
oceanic
how do plate tectonics move?
convection in the mantle
how does convection work?
as material heats up, it sinks while the material that’s cooler will rise
what is uniformitarianism
the idea that the processes we see occuring today, most likely occurred in Earth’s ancient past
What was the theory of continental drift missing that plate tectonic theory is not?
a way to explain the plates moving
what do we find at the top of Mt. Everest
seashells
What fossils were found on the east coast of South America and the west coast of Africa that support the theory of Plate Tectonics?
mesosaurus
what’s the difference between a rock and a mineral
a mineral makes up rocks
3 different rock types
igneous, sedimentary, metamorphic
what makes a mineral a mineral?
Naturally occurring
Specific chemical composition
Relatively inorganic
Natural, crystalline substances
what are the mineral properties we test
hardness, luster/color, streak, cleavage, magnetic, reacts to acid
is synthetic diamond a mineral?
no, it is not naturally occuring
is ice a mineral
yes
is coal a mineral
no, it comes from organic material
is quartz a mineral
yes
what is the atomic number
the number of protons
what is the atomic mass
proton and neutrons
what are isotopes of
atoms of the same element with differing numbers of neutrons
is a cation positively or negatively charged
positive
is an anion positive or negative
negative
which chemical bond is stronger
covalent bonding
what are the two main types of bonding
ionic and covalent
how does covalent bonding work
electrons are shared
which are larger - cations or anions
anions
an atom that has gained electrons is called..
anion
Large, well defined crystals suggest what about it’s growth and space?
steady growth and lots of space
Small, poorly formed crystals suggest what about it’s growth and space?
smaller space and rapid cooling
The process of turning a liquid into a solid with crystals in it is called…
crystallization
What happens when we apply pressure to a mineral?
becomes denser, melting temp. increases, changes crystal structure
What do we call minerals made of the same thing but produced under different conditions? (Ex. Graphite and diamond)
polymorphs
what is the most common of the mineral groups?
silicates
what mineral class would calcite be (CaCO3)
carbonate
What mineral class would pyrite be (FeS2)
sulfides
what mineral class would hematite be (Fe2O3)
oxide
what mineral class would gypsum be (CaSO4)
sulfates
why do we use gypsum for drywall
it contains water, a natural flame retardant
what mineral class does gold fall into? (Au)
native element
what is the name of the scale we use to measure hardness
mohs scale
what is the softest mineral on the mohls scale
talc
what is the hardest mineral on the mohs scale
diamond
what is it called when a mineral breaks irregularly
fracture
what is luster
how a mineral reflects light
how do igneous rocks form
it forms from cooling and crystallizing of magma or lava
slow cooling means what for igneous rocks?
smaller crystals
which suggests faster cooling? extrusive or intrusive?
extrusive
what is weathering
breakdown of rock
what is erosion
process of sediments being carried away from their original location
what are the two types of sediments
clastic and (bio)chemical
what is lithification
process of making rock
what are the two processes of lithification
compaction and cementation
what is compaction
the process that presses sediments together
what is cementation
the process in which dissolved mineral crystallize and glue particles of sediments together
how do metamorphic rocks form
alteration of preexisting rock due to high T and P
what are the 2 types of metamorphism
contact and regional
how do the two types of metamorphism differ
contact - smaller areas, mainly high temperature
regional - large areas, mainly high pressure
with what type of metamorphism do we get foliation
regional
what rock types can be igneous?
sedimentary, metamorphic, and igneous rocks
what type of rocks can become metamorphic
sedimentary, metamorphic, igneous
which of these are extrusive? gabbro, basalt, granite, rhyolite
basalt and rhyolite
which of these are intrusive? gabbro, basalt, granite, rhyolite
gabbro and granite
which of these are felsic? gabbro, basalt, granite, rhyolite
granite and rhyolite
which of these are mafic? gabbro, basalt, granite, rhyolite
gabbro and basalt
how do we melt the mantle
add water
increase temperature
decrease pressure
what causes the mantle to melt at the ocean-continent subduction zones
adding water
what causes the mantle to melt at divergent boundaries
decrease pressure
How do we know there are magma chambers beneath the surface? Or how big they are?
seismic waves, s-waves cannot travel through liquid
how much of the mantle do we need to melt to form magma?
a little bit, <5%
Magma/lava coming from the mantle tends to be mafic, felsic, or intermediate?
Mafic
Which magma/lava type has the highest silica content?
Felsic
which magma/lava type has the lowest silica content?
mafic
what is fractional crystallization
crystallization of part of a magma, leaving behind melted rock with a different composition from the original magma
highest to lowest silica content. andesite, basalt, granite
granite, andesite, basalt
if we melt the mantle, what type of magma do we get
mafic
what are the large intrusive magmatic bodies called
batholiths
do sills cut across rocks or travel along the rock layers
along
What are the two requirements to create foliation?
directed pressure and platy minerals
what is the term used for a not-foliated metamorphic rock
granoblastic
geothermal gradient
increasing in temperature with depth
do we get a higher or lower geothermal gradient with a thinner plate
higher
what is a geothermometer
mineral that tells you the temperature at which the rock was formed
what is geobarometer
mineral that tells you the pressure at which the rock was formed
metasomatism
hydrothermal fluid metamorphism that can alter minerology
what are the two types of metamorphism
regional and contact
what is regional metamorphism and where does it occur
metamorphism altering rocks due to temperature and pressure. Happens at convergent boundaries, forming large-scale linear belt regions.
what is contact metamorphism and where does it occur
Metamorphism due to high temperature. Happens when magma or lava comes into direct contact with surrounding country rock. This can occur around magma chambers and lava flows.
what type of metamorphism do we get at subduction zones (ocean-continent)
regional metamorphism with high pressure and low temperature
example of platy minerals
mica, chlorite, biotite
burial metamorphism
progressive burial of sediments (low-grade metamorphism). Example: Shale to Slate
shock metamorphism
metamorphism due to ultra-high pressure (meteorite)
foliation
rock that is sheeted. due to directed pressure. must have platy mineral
directed pressure
pressure coming from one direction. example: convergent boundary
confining pressure
pressure coming from all directions equally
banding gneiss
present in high-grade metamorphic rocks. Minerals have separated into alternating layers. because of very high temperatures and pressures. Example: Gneiss
what is the parent rock (protolith) to slate
shale
what is the parent rock (protolith) to marble
limestone
why do we get granoblastic (non-foliated) rocks
from a lack of deformation and lack of platy minerals
example of a granoblastic rock
quartzite and marble
what is the parent rock of quartzite
quartz sandstone
slate
low grade metamorphic rock, minerals not visible
phyllite
low grade metamorphic. glossy. mica and chlorite crystals are larger
schist
mid-grade metamorphic. platy minerals large enough to see (mica and chlorite). Bands start separating. Wavy foliation
gneiss
high-grade metamorphic rock. coarse. banding present. poor foliation
migmatite
high grade metamorphic rock. almost igneous again
sedimentary cycle
1) Weathering
2) Erosion
3) Transportation
4) Deposition
5) Burial
6) Diagenesis
two categories of sedimentary rocks
clastic and biochemical
clastic sedimentary rock
forms from physical weathering. mineralogy varies according to parent rock
two categories of sedimentary rocks
clastic and biochemical
clastic sedimentary rock
forms from physical weathering. mineralogy varies according to parent rock
biochemical sedimentary rock
precipitation of dissolved products of weathering. Made up of remains of organisms as well as precipitation via biological processes
continental environments
alluvial (rivers), desert, lake, glacial
shoreline environments
deltas, tidal flats, beach
marine environments
continental-shelf, organic reef, continental margin, deep sea
lithification
making sediments into rock
diagnesis
physical and chemical changes due to mild temp and pressure
cementation
chemical diagnosis, minerals, precipitate in pore spaces, minerals bind clastic sediments together.
compaction
physical trait. compression due to pressure
coarse-grained sedimentary rocks
gravel, conglomerate
medium grained sedimentary rocks
sandstone
fine-grained sedimentary rock
siltstone, mudstone, shale, clay
carbonates (sedimentary rocks)
derived from shells and organic structure
low to high grade metamorphism
slate, phyllite, schist, gneiss, migmatite
