GSCI 1052 Lab Practical

ultramafic (igneous composition)

rich in mafic material and poor in silica (peritodite)

mineralogical changing conditions (metamorphic)

some minerals recrystallize to larger grains; some convert to more stable minerals.

why might the timescale be much sparser before 550 Ma

something about how most of the evolution of life (and correspondingly, the fossil record) occurring in the past ~550 Ma and that the geologic timescale was based off of differences observed in the fossil record.

what determines how much slip will occur on a fault and how big the earthquake will be

the build up of stress on a fault overtime; -Stresses build up in rocks where plates interact. Friction along the fault surface is enough to cause most faults to "stick". -All rocks are slightly elastic. The buildup of stress causes the rock to deform (change shape) prior to fault movement. -After decades or centuries, stress builds up to sufficient levels to overcome friction and cause an existing fault to break (again). -Earthquake activity is cyclical; after the break, there will be a period of relative quiet along the fault while plate tectonic forces slowly build up to a level sufficient to break the fault again. The length of time necessary to build up enough stress to cause a fault to break again is known as the recurrence interval. The recurrence intervals for the largest earthquakes are measured in centuries but more moderate sized earthquakes may reoccur on intervals measured in decades.

periodotite

the minerals composition of this rock is mostly pyroxenes and olivines. That is why this rock is dark green in color. The composition of this rock can be described as ultramafic. Its grains are large and visible and therefore meet the criterion for being considered phaneritic, indicating that this is an intrusive rock.

oceanic crust

the portion of Earth's crust that is usually below the oceans and not associated with continental areas, thinner and higher in density that continental crust and basaltic rather than granitic in composition; the denser oceanic crust is less thick but denser and therefore, shows less above the mantle; state of matter is solid

mesozoic era

time of dinosaurs triassic: follows permian extinction, earliest dinosaurs, true mammals, pterosaurs jurassic period: first birds sauropods ceratopsians stegosaurus cretaceous large dinosaurs pangea breaks up earliest flowering plants (angiosperms)

calculating density in a physical environment

to find the mass of the object, put it on a scale. To find the volume of an irregular object, place it in a cylinder of water, the amount of water displaced is the volume of the object (displaced water is final volume minus initial volume of water). To find the volume of a regular object such as a block of wood, find its length, width, and height and multiply them all together.

relationship between foliation and regional metamorphism

when rocks undergo metamorphism usually associated with mountain building. In these areas rocks may be buried to great depths. Added pressure causes sheet-like minerals (mica) in the rock to rotate or grow in a preferred alignment. Those minerals are layered parallel to each other (like a stack of papers on a table) and perpendicular to the direction of pressure (pressing down on the stack of papers). This alignment of minerals into sheets is termed a foliation.

when did the first multicellular animals appear in the fossil record

~500 Ma

phanerozoic era

-Paleozoic -Mesozoic -Cenozoic

gypsum

-hardness: can be easily scratched with a fingernail, Moh's scale is 1.5-2 -breakage/crystals: 1 is "good" cleavage, plane tabular crystal habit -color/luster/streak: aka selenite or moonstone

height of mt everest on a globe

.21 mm

calculating the density example

Density = mass / volume Pine = 73.50 / 175 = .42 Mahogany = 113.75 / 175 = .65 Balsa = 28 / 175 = .16 - add units g/cm^3

hydrograph

a graph which shows the the discharge of a river, related to rainfall, over a period of time

conglomerate

the rock has many rounded grains with the size larger than 2 mm. All of the grains are harder than glass. You can see that the grains do not fit readily together and that they are held together with natural cement.

archean era

(4.6 to 2.5 billion years ago) oxygen producing cell appear; oldest oceans and earliest evidence of life at 3.6 Ga

hypothesis: earthquakes are 'time-predictable'

(i.e., earthquakes associated with more slip are associated with longer waits and those with less are linked to shorter waits). This idea was formulated in the 1980's by Shimazaki and Nakata in Japan, and has been widely used.

transform plate boundaries (conservative)

-C-C: Two plates slide along each other - lots of earthquake activity and faulting, but no volcanic activity. -O-O Transform: Two plates slide along each other - lots of tectonic activity, but no volcanic activity.

different components of the earthquake model represent in the real world and how we used the model to test for earthquake recurrence (patterns in time).

-Elements of the earthquake machine and what they represent: the sandpaper surface- the fault surface the movement of the brick- slip along the fault (earthquake) the turning of the crank handle- stress from plate movement the stretching of the spring- elastic deformation of rocks -We can utilize the model to simulate an earthquake and compare it to that of one in real life and therefore model different earthquakes and estimate with the recurrence interval equation what it will be

convergent plate boundaries (destructive)

-O-C: Denser mafic plate subducts beneath the felsic continental crust. At the contact there is a trench formed. On land the compressional forces will drive mountain building. Earthquakes will occur at the contact between the plates, getting deeper farther inland. The subducted oceanic plate will begin to partially melt at depth and can cause landward volcanic activity. -O-O: Older, denser oceanic crust will subduct beneath younger oceanic crust. Where they meet you will find a trench. Earthquakes will occur along the subducted plate boundary. Stresses will cause shallow mountain and volcano formation on the younger overriding crust. You may see the formation of island arcs due to the volcanic activity. -C-C: Two low density continental crusts collide, and neither will subduct. You will get lots of shallow earthquakes and the formation of tall mountains.

divergent plate boundaries (constructive)

-O-O: Mid-ocean ridge. The formation of a lot of faults and thinning of the mantle. We get partial melting forming mafic magmas. Basalt flows create a new crust at the mid ocean ridge. Lots of earthquakes along the rift. Volcanoes directly above divergent boundaries. Crust age will increase the farther you get from the spreading center. -C-C: Shallow earthquakes, formation of new crust, big rift valleys

difference between contact and regional metamorphism

-contact: when a rock undergoes metamorphism because they came in contact with a heat source. The composition does not change but the texture does -regional: when rocks undergo metamorphism usually associated with mountain building. In these areas rocks may be buried to great depths.

types of metamorphism

-contact: when a rock undergoes metamorphism because they came in contact with a heat source. The composition does not change but the texture does -regional: when rocks undergo metamorphism usually associated with mountain building. In these areas rocks may be buried to great depths.

how sediment changes as it is transported farther away from its source

-grains are more poorly sorted closer to the source and become more well rounded further from the source -grains are larger closer to the source and become smaller further from the source

galena

-hardness: can be scratched with a copper penny, Moh's Scale: 2.5-3 -breakage/crystals: cleavage in 3 directions at 90 degrees -color/luster/streak: lead ore, metallic luster

calcite

-hardness: can be scratched with a copper penny, Moh's scale is 3 -breakage/crystals: cleavage in 3 directions at 60/120 degrees; rhombohe dral crystals -color/luster/streak: reacts with HCI

muscovite (mica)

-hardness: can be scratched with copper penny, Moh's Scale 2.5 -breakage/crystals: cleavage in 1 direction, -color/luster/streak: forms "books" - stacks of flat sheets

biotite (mica)

-hardness: can be scratched with copper penny, Moh's Scale 2.5-3 -breakage/crystals: 1 cleavage plane -color/luster/streak: dark in color

graphite

-hardness: can be scratched with fingernail, Moh's Scale: 1 -breakage/crystals: fracture -color/luster/streak: pencil "lead", dull metallic luster

halite

-hardness: fingernail can scratch it, Moh's scale is 2-2.5 -breakage/crystals: cleavage in 3 directions at 90 degrees; cubic crystals -color/luster/streak: NaCI, is table salt and tastes like salt

pyrite

-hardness: scratches glass, Moh's Scale 6-6.5 -breakage/cleavage: fracture, cubic crystal habit -color/luster/streak: "fool's gold"

olivine

-hardness: scratches glass, Moh's scale 6.5-7 -breakage/crystals: fracture -color/luster/streak: green in color but can also be yellow-green, greenish yellow, or brown; it is transparent to translucent with a glassy luster

pyroxene

-hardness: scratches glass, Moh's scale is 5-6 -breakage/crystals: cleavage in 2 directions at 87/93 -color/luster/streak: Usually dark green, dark brown or black, vitreous (glass-like)

amphibole

-hardness: scratches glass, Moh's scale is 5-6 -breakage/crystals: cleavage in 2 directions at 60/120 degrees -color/luster/streak: Dark green, dark brown, black, vitreous (glassy) to dull, opaque

hematite

-hardness: scratches glass, Moh's scale is 5-6.5 -breakage/crystals: fracture -color/luster/streak: rusty red streak

magnetite

-hardness: scratches glass, Moh's scale is 5.5-6.5 -breakage/crystals: fracture -color/luster/streak: magnetic, metallic luster, black streak

potassium

-hardness: scratches glass, Moh's scale is 6 -breakage/crystals: cleavage in 2 directions at 90 degrees -color/luster/streak: often, but not exclusively, salmon in color

plagioclase feldspar

-hardness: scratches glass, Moh's scale is 6-6.5 -breakage/crystals: cleavage in 2 directions 90 degrees -color/luster/streak: typically white to gray, may also range from colorless, through shades of off-white, to yellowish, pink, reddish brown or nearly black; common twinning in the crystal structure that creates fine parallel grooves or striations on some cleavage surfaces

quartz

-hardness: scratches glass, Moh's scale is 7 -breakage/crystals: fracture, hexagonal prism crystal habit -color/luster/streak: variable color,

fluorite

-hardness: scratches penny but not glass, Moh's scale is 4 -breakage/crystals: cleavage in 4 directions, can be octahedral -color/luster/streak: variable color but often teal or purple

finding recurrence interval for given magnitude of data

-recurrence interval is the length of time to build up enough stress to cause a fault to rupture again -to calculate the recurrence interval for a given magnitude earthquake, it is MRI = 1/average number of earthquakes. -If MRI is <1: probability of occurrence in a year is 1 -If MRI is >1: probability is 1/MRI

recurrence interval

-recurrence interval- the average amount of time between a flood event of a given magnitude and the next flood of that magnitude OR LARGER -calculating a recurrence interval: recurrence interval = (N + 1)/M, where N is the number of observations on record, and M is a ranking for each flood event such that the biggest flood is M=1 and the smallest flood is M=N

igneous rocks that are the characteristic of the oceanic vs continental crust

-rocks that form on the seafloor in oceanic crust are typically darker in color because they are composed of darker, denser minerals (mafic); basalt, gabbro, peridotite -rocks that form magma in/on the continents are lighter in color because they have a greater proportion of silica (felsic); andesite, rhyolite, granite, diorite

factors that control discharge

-weather conditions such as intense rainstorms that increase the amount of water in a river -changes to the environment such as vegetation that intercepts water flow -velocity of the water affects it; faster water means more passes per second so more discharge -width and depth of the river also affects it; a larger river at the same speed will have higher discharge.

depth of marianas trench on a globe

.26 mm

height of mt everest to earths diameter

0.0007 m

depth of mariana's trench to earth's diameter

0.00086 m

earth's diameter

12,747,175 m

proterozoic era

2.5 billion to 544 million years ago. Continents started forming, first multi-cellular life, and the atmosphere gains oxygen; oxygen builds up in atmosphere, earliest eukaryotes and multicellular organisms (~500 Ma)

inner core

A dense sphere of solid iron and nickel at the center of Earth; state of matter is solid

outer core

A layer of molten iron and nickel that surrounds the inner core of Earth; state of matter is liquid

nonconformity

A type of unconformity in which layered sedimentary rocks lie on an erosion surface cut into igneous or metamorphic rocks

boundary type associated with earthquakes

Convergent boundaries are the most associated with earthquakes, especially the oceanic to continental collisions. In that collision, the oceanic crust falls underneath the continental crust. This is where the subduction zone occurs, which heats up the plates from the mantle and in turn causes earthquakes to occur. I came to this conclusion by observing the subduction zone and realizing that is a main factor in earthquake formations.

describe the scientific method

Hypothesis: a testable prediction that can be verified or falsified Observation: facts, measurements, information, and data collected using the senses Prediction: a statement of what will happen in a given situation or set of circumstances.

how to measure the masses of rocks

I would go about measuring the volume by placing the rocks in a graduated cylinder with water. From there, I could measure the volume by seeing the amount of water displaced by the rock. In addition, to measure mass, I could measure the mass on a scale that is able to measure in units of mass

describe the concept of isostasy and apply it to the crust and mantle system

Isostasy is the state of equilibrium in which objects float at levels determined by their thickness and density. Process of lithosphere sinking into the asthenosphere. Objects adjust isostatically. Erosion, deposition, mountain building, volcanic eruptions and other processes can affect this adjustment when objects are added or removed. Because the continental and oceanic crust are floating on the mantle of the Earth, the way that they float is going to be determined by the thickness and density of the crust.

micritic limestone

It is a biochemical rock. It is white in color. The mineral grains are very small but you can see with a magnifying lens that they interlock. If you apply HCl acid to this rock, will it fizz? yes

slate

It is a foliated metamorphic rock since it notably has a series of flat planes running through it. The rock has a slight sheen to it as you turn it in the light. The mineral grains in this rock are far to small to see so you reason that the parent rock from which this rock had metamorphosed was probably also very fine-grained, which could be mudstone

thickness and density of earth's crust influences earth's topography

Less dense materials rise upwards which causes the lithosphere to be pushed upwards, influencing the topography of Earth and causing land formations like mountains. Denser materials sink which is how something like the Marianas Trench is formed.

the accuracy of textured globes

No, I don't think they are accurate because they are not measured to the same scale. Each part of the textured globe cannot possibly be accurate because there are so many small details that cannot be accounted for on a globe. In addition, the actual mountain ranges and parts of the Earth that are extremely textured have so many grooves and crevices that are not accurately portrayed on a globe, as well as their densities and volumes cannot be accurately portrayed either.

the amount of water flowing at a point in a stream

Q = V x A; Q is stream discharge, or the volume of water moving through a stream at a given point and time; V is velocity, typically determined with flow meters. Flow velocity can be estimated by timing how long it takes for a floating object to travel a set distance; A is cross sectional area, depth x width. If the stream channel was a simple rectangle, this would be an easy calculation. However, the channel is more likely to be irregular so you will have to measure depth at several locations across the stream to obtain an accurate area value.

what the texture and color can tell about an igneous rock

Texture: extrusive igneous rocks cool at the surface (aphanitic) intrusive igneous rocks cool underground (phaneritic) Color: the color of an igneous rock tells what kinds of minerals are in it. it is a measure of the ratio of dark colored mafic minerals to light colored felsic minerals

hadean era

The first 500 million years of Earth's history, when it was hot, bombarded by asteroids and the atmosphere was devoid of oxygen; formation of the moon; 4.54 billion years was formation of earth

mantle

The layer of hot, solid material between Earth's crust and core; state of matter is solid

gabbro

The minerals in this rock are almost exclusively dark in color. Most are black, some are a very dark greenish color. The composition of this rock can be described as mafic. The mineral grains are easily large enough to see and differentiate, indicating that this is an intrusive rock.

continental crust

The portion of the earth's crust that primarily contains granite, is less dense than oceanic crust, and is 20-50 km thick; the state of matter is solid; thicker and composed of less dense rocks, and at a higher level of the ocean floor because less dense than oceanic crust, shows more above the mantle

mudstone

The sedimentary grains that make up this rock are too small to see. You don't even feel much grit in the rock as you handle it. You apply HCl to the rock surface and nothing happened. You hit this rock with a hammer out of a sense of general frustration but find that when you do it breaks into a series of flat, sharp-edged chips. Since the grain size is so small, this rock should be formed far from the mountains.

arkose

The sediments in this rock look like a bunch of fragments that have been cemented together. You can tell this because the grains do not fit neatly together and if you look with a magnifying lens you can see the cement material between them. Many of the grains are visible but all are smaller than 2 mm. This is a clastic sedimentary rock.

calcite (mineral that can be present in a rock)

There are clamshells in this rock, indicating that it is a biochemical rock. Because of the presence of these clamshells you know that this rock formed in marine environments. You feel a slight sense of accomplishment and satisfaction at having found these fossils (this has nothing to do with the rock, this is just what you feel in this scenario). The rock and the shells themselves both fizz vigorously when you apply HCl acid.

equation for crust thickness above

Thickness of crustabove = Total thickness - {Total Thickness x (Dcrust/Dmantle)}

hypothesis: earthquakes occur randomly in time and slip amount

This hypothesis is also widely used, particularly when little information about a fault and its past earthquakes is available.

marble

This rock exhibits no planes running through it. It is composed of a series of interlocking grains that fit neatly against each other. You apply HCl acid to this rock and find that it fizzes when the acid comes in contact with it

gneiss

This rock has a notable alternating pattern of light and dark coloration. While the planes are pretty wavy in this case, there are planes present running through this rock. The grains in the rock are fairly large and readily visible which leads you to think that the rock was produced by high-grade metamorphism (that is, the heat and pressure applied to form this rock was greater than that which formed other metamorphic rocks of lower grade)

quartzite

This rock has mineral grains of a size comparable to sandstone but as you look at the grains with a magnifying lens you see that their is no apparent cement and the grains are compressed together. There are no obvious planar features of this rock. This is called the non-foliated metamorphic rock. You apply HCl acid but the mineral in this rock does not react with the acid. You test the rock's hardness and find that the mineral it is made of is harder than glass and you cannot find any cleavage planes.`

andesite

This rock is gray in color. Most of the mineral grains are too small to be visible, but there are a few larger white mineral grains that are visible. This is a/an intermediate, with porphyritic.

rhyolite

This rock is light in color. There are not a lot of dark colored minerals that you can see. The composition of this rock is felsic. There are some visible flecks of mineral grains in the rock but the vast majority of grains in the rock are too small to see. This texture can be describe as phaneritic, which also tell us that this is an extrusive rock

schist

This rock is very shiny. It looks like it is mostly made of thin, platy minerals that you saw in the Minerals lab. The platy minerals are aligned such that there are clearly planes running through the rock. The fact that the mineral grains are quite large leads you to believe that this is a high-grade metamorphic rock. This particular sample also contains visible garnets (this won't necessarily affect the name that you will call the rock but it is pretty neat nonetheless).

how to measure the densities of wood blocks

To determine the density of wood blocks, I would measure the length, width and height of the block since it is bound to be more accurate than the rock samples, since it is in block form. From there, I would find the volume, and then I would be able to measure the mass on a scale.

where on earth to find a deep crustal root

a mountain range. Mountain ranges are formed by tectonic plate movements and overlapping, so therefore they have quite a deep crustal root. They extend down very deeply into the crust since they are connected to tectonic plate movements

disconformity

a type of unconformity in which the sedimentary layers above and below the unconformity are parallel

angular unconformity

an unconformity in which younger sediment or sedimentary rocks rest on the eroded surface of tilted or folded older rocks

which rock floats the highest in a fluid medium?

andesite

vesicular (igneous grain size)

bubble texture

classifying igneous rocks

by grain size, by composition and color, by place of formation (extrusive or intrusive)

thicknesses and density

can both affect how an object floats. Two objects with different thicknesses but the same density, one will float higher. If they have different densities but same thicknesses, one will float higher

particle size (sedimentary rock)

can range from clay (mudstone) to cobbles (conglomerate)

sorting

can range from very well sorted to very poorly sorted with moderately sorted in the middle

classifying metamorphic rocks

changing conditions in metamorphism can cause 3 possible changes that occur in rocks (mineralogical, physical, fluids), types of metamorphism, foliation

types of sedimentary rocks

clastic, chemical, biochemical

phaneritic (igneous grain size)

coarse grained (grains clearly visible)

porphyritic (igneous grain size)

coarse grains within fine grained matrix

mafic (igneous composition)

dark in color, silica poor (gabbro, basalt)

determining the cross sectional area of a stream

depth x width

longtitude

distance east or west of the prime meridian, measured in degrees

latitude

distance north or south of the Equator, measured in degrees

paleozoic era

earliest skeletal fossils modern animal body plans arise plants move to land invertebrates and vertebrates move onto land ends with permian extinction

aphanitic (igneous grain size)

fine-grained (grains not visible)

cenozoic era

follows K-Pg extinction birds and mammals survive rise of mammals and birds with larger body size and

classifying sedimentary rocks:

form at earth's surface and therefore record information about earth's environment at the time and place the rock formed, at its depositional environment. particle size, rounding, sorting, type of sedimentary rock

main events of history of the earth in order (oldest to youngest)

hadean, archean, proterozoic, phanerozoic (paleozoic, mesozoic, cenozoic)

physical changing conditions (metamorphic)

high pressures can result in bent or folded rocks and distorted mineral grains

diorite

his rock has phaneritic texture because the crystal grains are large and visibile. This indicates that this rock is an intrusive igneous rock. The coloration of the mineral grains has a salt-and-pepper character, and there's a lot of light-colored grains and a lot of dark-colored grains. The composition of this rock is intermediate

hypothesis: earthquakes are periodic

in other words, all are caused by the same slip, and all separated by the same amount of time. There is some evidence for this, particularly among very small earthquakes on creeping faults.

when did the earth form its first continents and oceans

late archean (~2.8 Ga)

felsic (igneous composition)

lighter uniform color, silica rich (granite, rhyolite)

biochemical (sedimentary)

made of accumulated biominerals (coquina). Formed by the actions or remains of living organisms.

clastic (sedimentary)

made of broken fragments but are one solid rock (breccia)

chemical (sedimentary)

made of chemical precipitates (salt flat: halite). crystallized from solution as a result of changing physical conditions such as evaporation.

density

mass/volume; determines how objects float in fluids

intermediate (igneous composition)

mix of different colors, contains approximately equal amounts of dark and light minerals and have a speckled appearance (diorite, andesite)

fluids changing conditions (metamorphic)

new minerals may precipitate from hot fluids to fill rock fractures and form veins.

foliation (metamorphic rocks)

non-foliated metamorphic rocks do not have aligned mineral crystals; foliation forms when pressure squeezes the flat or elongate minerals within a rock so they become aligned. These rocks develop a platy or sheet-like structure that reflects the direction that pressure was applied

calculating density

objects with a lower density than their medium tend to float in that medium (ex: wood floating in water). Mass is in grams, volume is in cm^3, therefore density is in g/cm^3. Lower density objects will float more than higher density objects and will also stick out of the water or fluid more.

half-life

of an isotope is the time taken for half of the parent isotopes to convert to daughter atoms

variety of factors that influence the degree of earthquake risk at a given location.

proximity to fault, tsunami threat, age of buildings, landslide risk, ground shaking, groundwater, saturation, liquefaction, population

process of radioactive decay used to date rocks

radioactive decay occurs when an unstable isotope changes to a new element during a change in the number of neutrons or protons. An isotope produced by the radioactive decay of the nuclei of another isotope is the daughter isotope. -Radioactive decay is used to date rocks by comparing the observed abundance of the naturally occurring radioactive isotope and its decay products, using known decay rates.

rounding (sedimentary rock)

range from unrounded to well-rounded with subangular in the middle