Geology 101 - Exam 2
Clemson Geology 101 Exam 2 Coulson
Terms in this set (233)
____ rocks are the most common rock type at earth's surface; used for building, fossil fuels, soils, landslides, and fossils
Sedimentary rocks start with some pre-existing rock called a ___.
breakdown of rock into sediment
causes of __ __: natural zones of weakness, biological activity, frost wedging, exfoliation, isotonic rebound
when roots and things break up rocks
when water fills cracks and freezes, breaking the rocks
process where the rock is peeled off in thin layers or sheets
material rises when press is removed
type of weathering that is more common in many environments, dissolves or changes rock into different minerals, different minerals react at different rates, and minerals react with air & water.
list the two types of weathering
Rain is/isn't pure water.
Rain is a type of ____ weathering.
Air is a type of ___ weathering.
parent rock type, climate, soil presence
Speed and type of weathering depends on three factors... list.
A wet environment gives rise to more ___ weathering.
A dry environment gives rise to more ___ weathering.
combination of rock fragments, weathered minerals, and organic matter; formed by weathering and promotes chemical weathering (water retention acidity) and physical weathering (roots)
covering that forms on the outside of the rock that protects the rock from water / gases
movement of sediment via water, wind, gravity, ice; requires energy
as energy level drops, sediment can't be carried any farther
depression location where sediment is deposited
the lowering of the ground level of the bottom of the basin due to heavy contents in the basin compressing the bottom
the amount of space available to accommodate sediment in a basin
Sediment is deposited into layers, aka ___or ___
the process of becoming solid rock
due to the weight of all the layers on top of it, the bottom layer is now a lot more compact
The process during compaction in which minerals precipitate into pore spaces between sediment grains and bind sediments together to form rock.
type of sediments produced by physical weathering processes; classified by grain size (gravel, sand, silt, clay)
gravel sand silt clay
list in order from large to small the grain size classifications of clastic sediments.
trait of clastic sedimentary rocks; used to classify grain size (all grains similar in size, more variation, all different, eroded farther)
poorly, moderately, well, better
list the order from all grains similar in size to eroded farther for "sorting" of clastic sediments
trait of clastic sedimentary rock; a measure of how smooth the surface of the grains are
poorly, moderately, well, longer
list the order from not smooth to smooth for "roundness" of clastic sedimentary rocks
trait of clastic sedimentary rock; the combination of roundness and sorting
very mature, moderately mature, immature
list the order from very rounded and sorted to very poorly rounded and sorted for "maturity" of clastic sedimentary rocks
Conglomerate is ___ rounded than breccia.
Chemical sediments form via ___ ___ such as dissolution & re-precipitation and salt water evaporation.
___ factors don't apply to chemical sediments b/c the sediments were transported as dissolved ions, so they don't really go for the physical transport distance.
process where water accepts electrons from other elements (chemical weathering with air)
type of sediment produced by plants & animals (chalk, limestone, coal)
transport of sediment & associated materials downhill via gravity
type of mass wasting (the general term); transport of sediment & associated materials downhill via gravity
4th highest peak in South America (Peru); 1970 earthquake dislodged an ice block 1 mile long x .5 mile wide x .5 mile deep; traveled 11 miles in 5 minutes killing 20,000 in the town of Yungay
cohesive forces bind the material together; becomes unstable if binding agents are removed (clear-cutting)
angle of repose
the maximum angle of stability; can vary a lot, depending on moisture, grain shape, etc.
if too dry, it will crumble; if too much water, sediment will flow; so you have to get it just right
___ usually helps stabilize, but can destabilize
includes landslides, rockslides, avalanches, mudslides, mudflows, creep, solifluction..
type of mass wasting; when the sediments on a slope "__" they move down a hill at a very slow rate.
type of mass wasting; slow like creep, but caused by repeated freeze/thaw actions
Unstable slopes do/don't automatically have a landslide occur.
T/F: Unstable slopes DO NOT automatically have a landslide occur. There must be a trigger such as an earthquake, over-saturation (snow melt / storm), grading slopes too steeply, removing vegetative cover).
can assess the risk along slopes, though factors may change over short timescales; these maps must continually be updated
Building codes, drainage control, retaining walls, rocks, bolts, & other stabilizing devices >>> these ___ mass wasting and are called for by a risk assessment
City, State of location of slide that caused $200 million in damage (was deemed preventable if $500,000 had been spent on drainage systems)
Estimated return for prevention building is ___ per $1.
rocks altered by heat, pressure, or fluid interaction; (mineralogy and/or texture has been changed) in a very slow process
Metamorphism is VERY ___.
changes in earth's crust
Metamorphism documents __... through time.
= temperature change over distance
the gradual increase in temperature with depth in the crust (avg is 30 degrees C per every km). dependent on crust's thickness.
A change in __ = a change in mineral stability for metamorphic rocks.
a change in the texture, structure, or chemical composition of a rock due to contact with magma (heat); local-scale events
Pressure is measured in ___.
1 bar = __ __ at surface
1,000 bars = 1 ___
the gradual increase in pressure with depth in the crust (avg is 300 bars / km)
The temperature increases __ degrees C for every km below the crust.
The pressure increases ___ bars for every km below the crust.
Most new rocks form at __-__ km depth (mid-lower crust).
Basically, if you want to cause metamorphism, you need both REALLY HIGH ___ AND ___ (in order to start the process).
During ___, sedimentary rocks erode away to gradually expose the underlying metamorphic rocks. << this is how metamorphic rocks get back to the surface.
type of pressure experienced by metamorphic rock: when the material is experiencing pressure from all around.
directed (differential) pressure
type of pressure experienced by metamorphic rock: cause the material to shape perpendicular to the pressure
a change in the texture, structure, or chemical composition of a rock due to changes in temerature and pressure over a large area, generally as a result of tectonic forces
type of metamorphism that is caused by an impact with the earth and results in metamorphic rocks being formed almost instantly.
little pieces of glass etc. that were created from the intense heat of an impact with earth (meteorite).
hydrothermal metamorphism; water squeezed out of rocks/minerals at depth; can add or remove minerals while migrating through the surrounding rocks/minerals; changes the chemistry of the rock; often forms ore deposits
basically a high concentration piece of rock/mineral; a localized concentration in the crust from which one or more minerals can be profitably extracted.
The parent's rock composition is key in determining the ___ of the metamorphic rock.
how much the rock was altered; used to identify metamorphic rocks.
group of minerals that form in a given Temp/Pressure range; provides more detail about temp/pressure conditions than grade does; helps ID tectonic setting/metamorphic environment in which the metamorphic rock formed; 7 major ones.
helps ID tectonic setting/metamorphic environment in which the metamorphic rock formed (7 major ones)
mineral changes that take place during burial and an increase in temperature
after prograde; decrease in pressure and temperature.
Changes within minerals can record ___ changes.
has layers/sheet-like structure; has undergone differential pressure; larger grain size with higher grade.
Metamorphic rock with a higher grade = small/large crystals
Metamorphic rock with a lower grade = small crystals
non-foliated rocks; confining pressure causes non-foliation;
granoblastic metamorphic rock that experienced high temp, low pressure and is low grade & non-foliated
granoblastic metamorphic rock that is non-foliated and contains quartz
granoblastic metamorphic rock that is non-foliated and has a lot of calcite (will efforesce)
studies deformation of rocks (results of forces acting upon rocks)
the cause of most deformations to occur; all types apply stress to rocks
type of tectonic force that pulls from opposite directions
type of tectonic force that pushes in from the sides
type of tectonic force that is basically ripping something in half; one half moving in one direction, the other half moving in the opposite direction.
the ___ to stress can vary based on rock type, temperature, pressure, speed of deformation, etc.)
type of response to stress: basically snaps in half (really hot, if applied quickly, morel likely to get this response)
type of response to stress: will bend and twist (cooler, if applied slowly, more likely to get this response) (ex. century-old windows have lines in them due to this)
ductile response to compressional force
the flanks of the fold (and the hinge is where the ____s join together)
the point where the limbs of a fold have swung and moved around
shape of fold (in cross-section view) with shape ∩
shape of fold (in cross-section view) with shape U
shape of fold that is slanted over to one side (BUT if 90 degrees on its side, DON't classify it.
a type of fold that is convex up (∩) and has its oldest rocks at its core, innermost sections
a type of fold that is concave down (U) and has its oldest rocks on the outer edge surrounding the younger layers
fold geometry in which the two sides are compressing and the fold either folds up or down.
fold geometry in which the layers from the two sides are compressing AND also tilting up or down (into the ground)
brittle reaction to tectonic force; it's a break, but no movement of rocks along the break; occur in sets; found in almost every outcrop; one of the most common basic types of features in rocks
break in a body of rock along which rock layers are displaced (slip/offset); can vary in size from inches to 100s of miles; classified by shift direction (and relative motion)
A fault in which the movement is parallel to the dip of the fault; inclined fault plane with vertical movement; has a hanging wall and a foot wall
in a dip-slip fault; starts wide at the top and gets narrower toward the bottom
in a dip-slip fault; starts narrow at the top and gets bigger/wider as you go down.
normal dip-slip fault
type of dip-slip fault: the hanging wall moves down, foot wall moves up.
reverse dip-slip fault
type of dip-slip fault: the hanging wall moves up, foot wall moves down.
a very low angle of inclination reverse dip-slip fault (almost flat with the ground surface) common around subduction zones
a type of fault where rocks on either side move past each other sideways with little up or down motion; must have an aerial view; determined by putting oneself on one of side and looking across the fault line to see which way you moved relative to the other side
type of strike-slip fault; from standing on one side, the other side moved to the left.
type of strike-slip fault; from standing on one side, the other side moved to the right.
Haitian Earthquake of 2010
7.0 magnitude, 52 aftershocks; left lateral motion b/w Caribbean plate and North American plate; was predicted around 2007-08; 100,000 dead, 1 million homeless
a release of energy built up as rocks try to move past one another along a fault (or plate margin)
where the rocks have shifted when the earthquake happens; under the ground; basically the critical point; most are relativelyshallow
the point on the surface of the earth above the focus; an easy way to communicate where the earthquake happened
Deeper earthquakes are ___ because the plates under the earth are more ductile (they're brittle, so you can't really have an earthquake)
hit before the earthquake
hit after the earthquake; may occur on a slightly different area of the fault line (having to adjust to the movement that just happened)
P S L
list the three different types of seismic waves
P (primary) Waves
fastest seismic waves; are compressional waves; can move through any type of material (solids, liquids, fluid materials - speed may change, but nothing will block them)
S (secondary) Waves
half the speed of p-waves; not compressional (move up and down); can be more disruptive to the surface; can only move through solid materials; fluids will cancel them out
L (long or surface) Waves
slower than S-waves; restricted to near earth's surface
__ __ are used to study earth's interior; their speed is affected by materials encountered
In ___ material, the speed of seismic waves is constant; however, earth is NOT ___.
____ bounce of things and change course in the earth.
s wave shadow zone
outer core of the earth where s waves disappear (due to outer core being liquid)
Studying seismic wave patterns are very important to ___ companies to find out where to drill and not drill
The denser the material, the ___ seismic waves travel (will slow down if layer is ductile).
The denser the material, the faster seismic waves travel (will slow down if layer is ___).
the boundary where the P waves spedd up; contact b/w crust and mantle where the waves speed up; boundary between crust and mantle
Seismic waves move faster through the ____.
S waves have a speed of zero in the ~ due to the fact they cannot travel through the ~; P waves slow down here.
P waves slow down in the ~; S waves cannot travel in the ~.
pendulum with pen thing that DOES NOT move during an earthquake... the paper and instrument moves, but the pen does not.
Instrument used to measure horizontal or vertical motion during an earthquake.
The key to finding the focus is that the different waves travel at different speeds; use the difference in ~ to calculate the epicenter
How many scales are there that can be used to measure the magnitude/intensity of an earthquake?
scale to measure earthquake: measures how much property damage was done during the earthquake; reported as Roman Numerals; not good for scientists because it depends on where/what is hit... (if Manhattan hit, a lot of damage. If desert hit, not much damage).
scale to measure earthquake: measures the amount of ground shaking; logarithmic (mag. 3 = 10x the ground motion of a mag. 2); energy release increases by a factor of 33 (log base 33)
How many times more ground motion is there in a mag. 3 to a mag. 5 earthquake on the Richter scale?
Energy release increases by a factor of ___ on the Richter scale.
Moment Magnitude scale
rating system that estimates the total energy released by an earthquake by measuring the area of slippage on the actual fault line (replaced the Richter Scale)
Moment Magnitude Scale
replaced the Richter Scale
Moment Magnitude Scale
scale of measuring earthquakes with the following advantages: more accurate, easier to calculate from seismograph, can calculate field measurements, can be used to measure earthquakes that occurred before the Richter scale was invented.
Moment Magnitude Scale
This scale can be used to measure earthquakes from before the Richter scale was invented.
along plate boundaries
Where do most earthquakes occur?
South America, Eastern Asia, coast of Australia
Where do deep quakes seem to occur (actual names of places)?
Where do deep quakes seem to occur (technical term)?
T/F: Some quakes occur far from plate margins.
Earthquake that is in the middle of the plate; ex. New Madrid in Missouri and Charleston..
The earthquake that occurred in ~ was estimated to be 8.0 magnitude. There were reports of damage in Maine, and parts of the Mississippi River changed course (flowed backwards for a while).
Location of the largest earthquake on the East coast of the US
It was the Charleston, SC earthquake of 1886 that helped scientists learn how to calculate the __ of seismic waves.
the year California outlawed building on a fault
Buildings built on stop of saturated areas (a lot of water content) will ___.
The best thing to build a structure on in the case of an earthquake is ~.
You should/shouldn't build on loose, uncompacted sediments.
It's difficult to predict earthquakes because every fault is ___.
___ is exploring satellite systems to help predict earthquakes
In 2008, new instrumentation recording minute stress-related changes in rocks have predicted __ small earthquakes
In 1960, the most powerful earthquake ever recorded occurred in ___ with a 9.3 Moment Magnitude; The tsunami affected areas as far away as Alaska and New Zealand; FEW CASUALTIES (they knew they were prone to this, so they built away from the coast and on high ground.
Damage created in the 1960 most powerful earthquake recorded in Chile could have been worse if it had not been for ~ requiring stronger buildings built on higher ground.
How many methods of dating are there?
List the two dating methods
a technique used to determine the actual age of a fossil (ex. dinosaurs went extinct ~65 million years ago); only developed over the last century
method of determining the age of a fossil by comparing its placement with that of fossils in other layers of rock; (ex. dinosaurs lived before humans)
fossils are only found in ___ rocks.
If you want to understand fossils, you have to study the ___ (layers or beds of rock) they are found in.
the study of strata (layers of beds or rock) in an attempt to determine relative ages.
layers or beds of rock
T/F: No one place on earth has a continuous record of strata from all of earth's history, leading to gaps in the stratigraphic record.
You will often find random ___ in stratigraphic records (jump from 10 to 9 million years ago).
a gap in the stratigraphic record caused by the running out of sediment or accommodation space, or the erosion of sediment.
type of unconformity: sedimentary rocks above and below the unconformity; hardest to identify in the field.
type of unconformity: sediments overlie igneous/metamorphic rocks
type of unconformity: several steps involved; the orientation of the strata is angled; takes a long time to make.
The problem with unconformities is that you don't know how much ___ was lost.
Principle of Original Horizontality
Stratigraphic principle: sediments must have started out as flat, horizontal layers.
Principle of Superposition
Stratigraphic principle: layers from bottom to top: oldest to youngest...
Principle of Cross-Cutting
Stratigraphic principle: if you have two features intersect each other, whichever feature cuts through the other one is the youngest.
Principle of Faunal Succession
Stratigraphic principle: fossils in rock layers are found in a very predictable sequence; organisms that lived the longest ago will be found in the lower-most layer. Younger organisms will be higher up.
a very powerful tool in identifying important rock layers; allows strata in different places to be linked in time; links layers together to same time; not all fossils are good for this.
fossils of ___ are NOT good for correlation.
remains of species that existed on earth for a reletively short period of time,were abundant, and were widespread geographically
Types of ___: correlation with fossils (link same organisms together to a time period), correlation with rock type (link same rock types/layers to time period), and correlation with unconformities (link unconformities to time period).
Changes in ~ produces lots of unconformities.
the use of chemical analysis to identify time rock units; ex: things from outer space contain iridum... you can tell where things from space have hit the earth due to this.
The comparison of the pattern of magnetic reversals in a sequence of strata; useful for rocks that are very old when nothing else works.
earth's magnetic field periodically flip-flops... what is this called?
varves dendrochronology skeletochronology
List the three types of absolute dating methods
type of absolute dating: limited to the lake; layers must remain undisturbed; can be used for dating b/c each of the lineations represent a different layer of time (lighter layer = warmer months... darker layer (organic material) = winter months
The number of ___ in varves gives the age of the deposits; these ~ can indicate the conditions of the seasons.
The process of counting tree rings to determine the age of a tree; HOWEVER, some trees make non-annual rings.
using growth bands in bone, shell,etc to determine age of organism; count the number of rings to know age.
the process of measuring the absolute age of geologic material by measuring the concentrations of radioactive isotopes and their decay products
atoms of the same element may have different numbers of neutrons in their nuclei.
the process of atoms emitting radiation to become stable
energy in the form of high speed particles of electromagnetic waves
the original, unstable radioactive isotope that you start with
the parent isotope goes through some changes and gives rise to the ~; may also be radioactive
a lot of radioactive daughters... (basically start with a parent that decays to make the daughter which decays to make a daughter which decays....
the instrument that detects radiation
What is in the cylindrical part of a geiger counter that you wave around to detect radiation?
You cannot pick out an atom and determine when it will decay, BUT the ____ of radioactive decay is constant.
the amount of time needed for half of the parent material to decay
radioactive decay is ____.
half-life does/doesn't vary with any environmental factor
__ __ must be present for radiometric dating to work.
If no parent is present, the clock __ __.
If no daughters are present, the clock __ __.
A __ __ is required to do radiometric dating.
For most radioactive isotopes, you can measure back through ___ half-lives.
Half life of Carbon 14
C-14 is in a __ __ (the amount added to the system = the amount taken out)
C-14 is NOT good for dating most rocks / minerals
C-14 is good for dating plant / animal remains
When plants/animals ___, they stop getting C-14. No more parent is being added, so the clock starts keeping time.
ln(%C-14) / -0.693 x halflife
formula for halflife
A system must remain ___ after death for C-14 dating to work.
Even though there are known issues with C-14 dating, correction factors can be applied by dating things of ___ ages (mummies)
Scientists screwed up C-14 dating with __ saying that the ~ had died 30,000 years ago, but in actuality, that was the age of the local carbonate rocks.
What metamorphic facies would you most likely find in a subduction zone with volcano setting?