Geology Final Exam

HW1: Sketch a cross-section and label the key features of a convergent boundary

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HW1: Sketch a cross-section and label the key features of a divergent boundary

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hw10: Describe several factors that contribute to the stability of slopes

water content: loosens land grain size of the material: can cary smaller grain sizes with it discontinuities: fractures, cleavage and bedding gravity: leads to angle of repose for material

hw2:Describe at least two lines of evidence we have about the bulk composition of the Earth.

(1)samples of rock and meteorites:Look at the rocks found in the mantle and the crust. We can also use meteorites since it is believed that they have a similar composition to the core because it is very difficult to access samples from the core(2)Seismic observations:There are seismic waves that propagate through the earth and by measuring the velocity of these waves one will find variations in the velocity dependent upon density and therefore the composition of the rock through which the waves are traveling. Therefore we can use seismic observations to get constraints about what the possible chemical composition of the earth may be(3)Astronomical measurements:Universal law of gravitation- force of gravity is related to the masses - we can observe how the earth interacts with the sun, the moon, and with other bodies in the solar system to get an overall bulk mass and density of the earth might be

hw9:Explain how each Milankovitch cycle impact Earth's climate.

- They don't change the magnitude the sun is still producing the same amount to energy but tis changing how the earth is receiving hat energy over the course of time in respect to its two hemispheres and one the course of a year Eccentricity - Low eccentric orbit we tend to receive a more constant level of energy from the sun over the course of a year - When things are highly eccentric the earth will be closer to the sun during part of its journey and will recover more energy during those times and will receive less energy when its father away Tilt - the greater the tilt the more that one hemisphere will get a greater proportion of that energy - increasing the tilt tends to magnify the significance of the seasons Precession - Change when in a given year you're going to have summer versus winter can interact with the other cycles

quiz9: Earth's climate is a complex system with many interrelated components. The climate system is affected by many feedbacks, in which a change in one component is enhanced or reduced by the changes it induces in other components. Identify and explain three separate feedbacks that affect the Earth's climate system, specify whether each feedback is positive or negative.

1. Radiative Dampening: Negative Feedback: As energy from the sun heats up and increases the temperature of the earth, the earth radiates more energy back into space. Then the radiation decreases the temperature of the earth and when the radiation goes down, the earth begins to warm back up again. 2. Albedo Effect: Positive Feedback: Ice is better at bouncing energy back into space in comparison to darker land or water. As the world gets hotter, ice melts, as ice melts, the darker land or water underneath is revealed which attracts the sun more which leads to more warming, which leads to more ice melting. 3. Greenhouse gases: Positive Feedback: As the temperatures drops, there is an increase in wind, which effectively scatters nutrients into the ocean where organisms can absorb CO2, which decreases the CO2 concentration, which lowers the greenhouse effect, which then lowers temperatures again

HW1:Describe three different ways we can measure the velocity of a tectonic plate

1. analyzing the relationship between the age of rocks and the distance from a specific location. For example, this was applied to the chain of islands near Hawaii. Hawaii was used as the focal point to measure the distance and then the age of the rocks were used to find that the pacific plate was moving 10cm/yr. 2. through modern GPS. A modern GPS can measure horizontal distances and can pick up changes in latitude over a certain amount of years. 3. by using the data that people have found by mapping out the polarity of the magnetic field across oceans and relating the times of reversals to particular ages.

HW1:Describe two different ideas that have been proposed to explain why particular animals/plants are seen on the margins of continents adjacent to opposite sides of oceans.

1. at some point in time there was a land bridge connecting the continents by which the animals/plants could transport across to get to one continent from the other 2. at some point in time all of the continents were connected into one giant continent, known as Pangea, and since then have broken apart and drifted into separate continents

hw11: Identify four ways that sediment is transported within a stream

1st - we can dissolve material - limestones are really obvious examples - silicate rocks as well - soluble ions are dissolved in and carried by moving water 2nd - really fine particles can be suspended - continuously floating in water - doesn't have great density - silt and clay 3rd - sand can be carried so sometimes it rolls and bounces along the bottom - transported by saltation 4th - bed load - cobbles boulder mostly roll and slide during high flows

hw11:Calculate the discharge in a stream with an average height of 2m, an average width of 20m, and a water velocity of 0.8m per second

2m x 20m = 40m^2 x 0.8m/s = 32 m^3/s = discharge

HW1: If the temperature of the mantle asthenosphere were increased, what would happen to the thickness of the lithosphere?

???If the temperature of the mantle asthenosphere were increased, the thickness of the lithosphere would decrease. This is because as the temperature of the mantle asthenosphere increased, the warm and softer it would become, flowing in a gooey fashion. Therefore the thickness of the mantle lithosphere would decrease because it would be heated by the mantle asthenosphere making it softer and not as thick and rigid.

quiz5: What is a chemical sedimentary rock? Identify at least two examples of sedimentary rocks. Further, describe a scenario in which a chemical sedimentary rock may form.

A chemical sedimentary rock is a rock in which a material such as calcium's, for example, ions are dissolved and then they become very saturated in an environment where they can then precipitate out. Two examples of chemical sedimentary rocks would be limestone and gypsum. Chemical sedimentary rocks are formed in very hot, low latitude, evaporative environments. A scenario in which a chemical sedimentary rock may form is when ocean water that contains materials like sodium and calcium which then evaporate.

quiz3:The image above shows common igneous rock types and how they vary in terms of their silica and mineralogic content. Note that for each composition, there are two rock types listed - one intrusive (cooled within the Earth) and one extrusive (cooled at or near Earth's surface). Notice that there is no extrusive rock type listed for an ultramafic composition. However, it turns out that, while they are uncommon and do not occur in the modern Earth, geologists have indeed found examples of ultramafic volcanic rocks. However, these are always very old (from the Archean Eon, greater than 4.0 billion years old). Consider what a komatiitic melt should be like, in terms of: a) melting temperature b) magnesium and iron content c) sodium content and d) mineralogy

A komatiitic melt should have a very high melting temperature. B) A komatiitic melt should have very high magnesium and iron content. C) A komatiitic melt should have low sodium content. D) A komatiitic melt would include pyroxene and olivine.

hw5:What is a "sedimentary structure"? Describe two sedimentary structures and indicate what can be learned from them.

A sedimentary structure is a feature within a sedimentary rock that developed at the time of the rocks being deposited. One sedimentary structure is graded bedding. This bedding shows coarser material in the bottom of a the bed and then a continuous change in grain, but it is still one bed. It doesn't have a sharp boundary and is very gradational. Cross bedding is another sedimentary structure in which sand from dunes are driven by wind or water to form laters that are at an age to the initial horizontal bed. Individual depositional events can be learned from the different sedimentary structures.

hw10:The three phase diagrams below schematically illustrate situations in which rocks may melt. For each of the three panels, identify a tectonic setting or geologic scenario in which melting may form by the illustrated process.

A tectonic or geologic scenario in which melting may form by the illustrated process in Panel #1 is if there is a melt which is able to increase the temperature of the rock without increasing the pressure on the rock. A tectonic or geologic scenario in which melting may form by the illustrated process in Panel #2 would be a divergent plate boundary. As the plates move away from each other there is a decrease in pressure which results in a lower melting point for the mantle. A tectonic or geologic scenario in which melting may form by the illustrated process in Panel #3 would be a convergent plate boundary where the dense cold oceanic crust sinks beneath the continental crust. As it does so it brings water with it which lowers the melting point for the mantle.

quiz 1: What comprises a tectonic plate? Describe how oceanic plates vary spatially (for example, with proximity to a mid-ocean ridge) with respect to their thickness, age, and elevation. Explain the cause of these variations

A tectonic plate is comprised of layers of continental and oceanic crust on top, followed by two parts of the mantle. Closer to the continental and ocean crust is the lithosphere, and beneath that layer is the asthenosphere. With reference to a mid ocean ridge, oceanic plates are older the further they spread from the ridge. This is because new crust is formed from the asthenosphere cooling and therefore the youngest crust is right at the sight of the mid-ocean ridge. Ocean plates are also thicker the further they are from the ridge because as they spread apart there is more time for particles in the ocean to settle on the oceanic plate and to build up over time. In terms of elevation, oceanic plates rise in elevation the further they move from the ridge because as they spread apart from the ridge they move closer to sea level and further from the deepest elevation in the middle of the ocean.

4. Consider the image below, which presents a cross-section of a hypothetical block of crust. Reconstruct the geologic history of this area, based upon the relationships between the units. (For example, G corresponds to an igneous dike this cuts through several units, and therefore must be younger than them.). The letter D marks the time of a fault (be sure to note what type of fault it appears to be!). Your answer should include: deposition of layers timing of igneous intrusions (G, I) deformation events (rotating layers, faulting) and erosion.

A: most recent deposition no noticeable drastic erosion B: deformed by normal faulting and by igneous intrusions fourth most recent deposition layer C: second most recent deposition accumulation of deposits from igneous intrusion D: a normal fault through layers E and B and igneous instruction of I E: deformed by normal faulting and by igneous intrusions third most recent deposition layer F: angular deposition influenced by erosion deformed by ingenious intrusion third oldest deposition layer G: cuts through J, K, F, H, and B and is therefore younger than J, K, F, H, and B H: angular deposition influenced by erosion deformed by ingenious intrusion fourth oldest deposition layer I: cuts through J, K, F, B, E and C and is therefore younger than J, K, F, B, E and C J: angular deposition influenced by erosion deformed by ingenious intrusion oldest deposition layer K: angular deposition influenced by erosion deformed by ingenious intrusion second oldest deposition layer

hw7:Describe how stresses around along a fault change after an earthquake, both along the areas that experienced a slip and adjacent areas that did not.

After an earthquake, the stresses along the areas that experienced a slip decreases and then eventually builds stress back up. However, the areas that did to experience a slip increase in stress.

hw7: What is the difference between a "epicenter" and a "hypocenter"?

An "epicenter" is the position at the surface of the Earth above where that rupture occurred deep in the earth whereas a "hypocenter" is the certain point in the earth where an earthquake rupture begins.

quiz6: In the geologic record, what is an unconformity? Identify three types of unconformities, and include a simple sketch for each to supplement your answer.

An unconformity is a period of time within the geologic record that passed in which there are no rocks of that age. This can be due to either erosion or a lack of deposition. Three types of unconformities include: Disconformity Nonconformity Angular conformity

hw8: Consider the diagram below, which shows the distribution of elevations at the surface of the Earth. Explain why an understanding of isostasy is essential to explain this diagram.

An understanding of isostasy is essential to explain this diagram because the essential idea is that any column of earth has the same total mass. Something of higher density is going to push down to make the surface of the earth to go lower. If there is an area of relatively low density, a thicker column is going to be needed in order to create the overall same distribution of mass. hw8: Describe the structure within the earths mantle. What is responsible for changes in density? The mantle which is made of ultramafic rock. The mantle is by volume the biggest layer within our earth 29km thick - divided into upper mantle and lower mantle(most of the mantle - more viscous and thick than upper mantle). Changes in density is due to either composition or temperature

quiz2: The above images show the atomic structure for the mineral apatite, which has the formula Ca5(PO4)3(OH). This is a relatively uncommon but important mineral - it is the main constituent of your teeth (really!), and because of its tendency to accommodate trace amounts of uranium, it is an important tool for radiometric dating (as we will learn later in the semester).In the image above, Ca is colored light blue, O is red, P is black, and OH groups are a pale yellow. If you look closely, you should see that each P is connected to four O atoms. What kind of mineral is apatite (i.e., what is its chemical classification)? What is the charge on the P ion? (You may remember from chemistry that H typically forms a H+1 cation)What is the strength of the P-O bonds?If you look carefully (I understand that the images are small and it is difficult), you should see that each oxygen is connected to 1 P and 3 Ca. What is the charge on the Ca-O bonds?

Apatite is a silicate. The charge on the P ion is +5 The P gives 5/4 and then the O gives 3/4 The O gives 3/4 and the Ca gives 1/4

HW1:Describe and explain ways that the oceanic plates evolve as they move away from a mid-ocean ridge

As ocean plates move away from a mid-ocean ridge, there is a divergent margin where the rising melt at the ocean ridge cools, forming new rock. As the crust breaks apart and is pulled into opposite directions, new material rises and repeats the process again. This creates a characteristic and symmetric pattern. As oceanic plates move away from a mid ocean-ridge, the elevation drops off. Although the oceanic crust maintains its thickness, the plate itself increases in thickness as it cools. Also, as the plates move away from a mid-ocean ridge, it smooths out because there is more time for sediment to settle as the crust gets older.

quiz3: Sketch Bowen's reaction series, and use it as a basis to describe the processes of fractional crystallization and partial melting. How can these processes explain the differentiation of the Earth into distinct compositional layers (e.g., the continental crust versus oceanic crust)?

By looking at Bowen's reaction series, it maps out the processes of fractional crystallization as well as partial melting. Fractional crystallization happens as the magma cools and different materials crystallize. Partial melting occurs when a temperature is only high enough for certain materials to melt, but not all. Bowen's reaction series shows how different materials combine through fractional crystallization and partial melting, starting with olivine which is ultramafic, and going to quartz which is felsic. These processes explain the differentiation of the the Earth into distinct compositional layers as the oceanic crust is mafic whereas the continental crust is felsic. Partial melting occurs in the tectonic settings of both divergent and convergent plate boundaries. The partial melting of the mantle at a convergent plate boundary produces the continental crust through fractional crystallization. The partial melting of the mantle at a divergent plate boundary produces the oceanic crust through fractional crystallization.

hw10: What are the two major types of weathering, and how do they differ?

Chemical: some sort of chemical change Physical: break down of rocks

hw5: What are the two major groupings of sedimentary rocks? Describe how each forms, and provide an example.

Clastic Sedimentary Rocks: rocks that are composed of pieces of pre-existing rock that were broken down by physical processes and then transported eg: conglomerate, shale—————————Chemical Sedimentary Rocks: dissolve material such as calcium, carbonate, sodium- we dissolve various ions- they become super saturated in an environment where they can then precipitate out- they directly precipitate rocks such as limestone and gypsum

hw3: What commonly elements are commonly enriched in felsic rocks?

Common elements which are commonly enriched in felsic rocks include silica, sodium and potassium. *The more felsic something is, the lower the temperature it will melt at*

HW1: Which types of plate boundaries are associated with volcanic activity, and which are not? What is responsible for melting in each case?

Convergent plate boundaries are associated with volcanic activity whereas divergent plate boundaries are not associated with volcanic activity. In the case of convergent plate boundaries, the old, cold, oceanic lithosphere sinks deep into the mantle. This brings water which lowers the melting point and then the melted material rises up.

hw2:Describe the difference between covalent and ionic bonds. Which kind of bond tends to produce harder minerals?

Covalent bonds occur when atoms are sharing electrons. However ionic bonds occur when one atom donates and electron to another atom. Basically covalent bonds just share electrons between atoms whereas ionic bonds require one atom to give away an electron to another atom. Ionic bonds tend to be highly soluble meanwhile covalent bonds tend to be insoluble. Ionic bonds tend to make materials that are very weak however, covalent bonds make minerals with very strong bonds and produce harder minerals.

hw2: Describe the difference between a crystalline and clastic rock?

Crystalline -composed of visible or microscopic crystals -rocks in which the minerals within the rock grew in place adjacent to each other interlocking network Clastic - rocks which are generally sedimentary rocks - where taken minerals and rocks that were formed and break them down in the physical pieces and put those pieces adjacent to each other and then get this to lock together by increasing temperature and pressure - taking loose sediment and turning it into rock

quiz7:Explain how geologists determine the position of an earthquake.

Geologists determine the position of an earthquake by taking advantage of the fact that P-waves and S-waves travel at different velocities. Geologists measure the time between the P-wave and S-wave arrivals to determine the distance between the seismograph and the earthquake event.

hw9:What are the three main Milankovitch cycles?

Eccentricity (100,000 years) low eccentricity - high eccentricity Tilt (41,000 years) - axis of rotation Precession (23,000 years) - wobble of axis - axis or rotation

hw11:Describe and explain several problems that can arise from over pumping groundwater

Effects of over pumping groundwater - before overpumping, after pumping=cone of depression - along coast: freshwater floats on saltwater, so draw in saltwater - dropping of water table can remove pores which can lead to a compaction of the land surface

quiz10: Describe the factors that are used to classify slope failures (i.e., various types of landslides).

Factors that are used to classify slope failures include: The mechanism of movement - the mechanism of movement can be classified as either a fall or a flow The rate of movement - the rate of movement can be classified as either fast or slow The type of material - the type of material can be classified as either solid rock or unconsolidated materials/debris

hw3:Describe what is meant by the compositional terms felsic and mafic. Using these terms to describe the typical composition of a) the continental crust, b) the oceanic crust, and c) the mantle

Felsic - rocks that have a lot of feldspar and a lot of silicon - example is granite Mafic - rocks that have a lot of iron and magnesium the continental crust: Felsic composition the oceanic crust: mafic composition the mantle: ultramafic composition: very high content of magnesium and a lot of iron with very little silicon

quiz3: The three phase diagrams below schematically illustrate situations in which rocks may melt. For each of the three panels, identify a tectonic setting or geologic scenario in which melting may form by the illustrated process.

For the first panel, a geological scenario in which melting may form by the illustrated process would be a rising melt. This is because if the rock cannot be pushed any further down because the increase in pressure would increase its melting temperature. Therefore it needs to keep the same pressure and just increase the temperature. For the second panel, a tectonic setting in which melting may form by the illustrated process would be a divergent plate boundary. This is because the plates moving apart would decrease the pressure and therefore decrease the melting point. For the third panel, a tectonic setting in which melting may form by the illustrated process would be an oceanic convergent plate boundary. This is because the old, dense oceanic crust would bring water down with it. This water would decrease the melting point and therefore move the line on the diagram to the left and would melt the rock.

quiz8: Sketch out a column (or wedge if you prefer) of the Earth, from its surface to the center (at 6371 km). On one side, indicate and describe the chemical layering of the Earth (i.e., what are the main layers, and what is their approximate composition). What are some ways that geologists have been able to create this understanding?

Geologists are able to create this understanding due to tracking the velocities of s-waves. Liquids do not have shear strength and therefore s-waves cannot pass through liquids. By identifying that the velocity of s-waves is zero at the same depth of the outer core, yet pick up velocity at depths of the inner core, geologists have been able to create the understanding that the inner core is a solid whereas the outer core is a liquid. Although the outer and inner cores are both at extremely high temperatures, the pressure of the inner core overrides the temperature, allowing it to be solid.

quiz4:What style of deformation (elastic, plastic, or brittle) do you expect will dominant in each of the four layers? Explain the reasons for the predicted changes in strength in the diagram (i.e., what is responsible for the drop in strength at the boundary between layer A and B, between B and C, and between C and D).

I expect Layer A to have a brittle style of deformation. This is because the strong upper crust is made of cold, felsic material and the temperature is not as cooler than the other layers and it is more rigid than the other layers. I expect Layer B to have a plastic style of deformation. This is because the weak lower crust is made of warm, felsic material and the change from brittle to plastic is dependent upon temperature. The deeper into the earth, the more plastic deformation will be found because of the higher temperatures. I expect Layer C to have a brittle style of deformation. This is because the strong upper mantle is made of warmer, ultramafic material. I expect Layer D to have a plastic style of deformation. This is because it is made of hot, ultramafic material.The changes in strength have to do with the differing compositions as well as the changes in pressure and temperature. The crust is made of felsic material which melts at lower temperatures. However the upper crust becomes stronger the deeper it goes because the increase in pressure holds the rocks together. Layer A is strong because it is made of felsic material and is cooler and more rigid. However, Layer B is also made of felsic material, but is deeper in the earth which has a higher temperature which makes it more susceptible to the heat. The mantle is made of more mafic material which melts at higher temperatures. Layer C is stronger than Layer D because it is made of mafic material, yet is not as hot as Layer D because it is not as deep into the earth. Layer D however is made of mafic material at hot temperatures and is therefore not as strong as Layer C. The rocks in the mantle become weaker as the temperature increases.

hw6:Imagine an outcrop of rock composed of sedimentary rocks. The rocks near the base of the outcrop are mostly conglomerates. Above these are a series of sandstones, with coarse sandstones covered by finer sandstones. At the top of the outcrop are fine mudstones. Provide a brief geologic interpretation of the depositional history of this area. What may have happened over time to produce this sequence?

I think that an unconformity, specifically a disconformity, occurred at this area to produce this sequence. I think that this was created due to either erosion or a lack of deposition in this area over a certain period of time.

Consider a granite that contains crystals of zircon, a mineral that commonly contains uranium. Weathering breaks down the granite, and crystals of its zircon are transported and eventually deposited (along with lots of quartz) in a beach. With time, the sandstone is buried and transformed to a sedimentary rock. If a geologist were to date zircons from this sandstone, what would the age represent: the time the sandstone was deposited, or the time that the granite formed? Why?

If a geologist were to date zircons from this sandstone, the age would represent the time the sandstone was deposited. This is because in order to be accurately dated, the parents and daughter isotopes have to be kept wishing a rock or a mineral and not lost from the crystal.

quiz2: Most minerals in Earth's crust and mantle are silicates, meaning that they contain the silicate tetrahedron [(SiO4)4-] as an anionic complex. Because of the tendency for silica tetrahedra to link to other silica tetrahedra, there exists a great variety of silicate mineral structures. Name and describe the important silicate subclasses.

Important silicate mineral subclasses include, Isolated Tetrahedra, Single Chains, Double Chains, Sheets, and Framework. Isolated tetrahedra are singular tetrahedra alone not bonded to other tetrahedra. Single chains are tetrahedra that bond together to form a chain. Double chains are tetrahedra chains that bond together to form a double chain. Sheets are tetrahedra chains that continue to bond to each other so many times that they form a sheet. A framework tetrahedra is a three dimensional framework of tetrahedra silicates.

hw6: What is the principle of faunal succession? Describe how it can be used to relate the geologic history preserved in one location with that of another.

In distinctive sedimentary rocks going from oldest to youngest, there are consistent changes in the kind of fossils found. The fossils showed the relation between increasingly complex organisms as we move through time. This relates to the geological history preserved in one location with that of another because these fossils have been used to create a geologic time scale.

hw8: What is the principal of isostasy?

Isostasy is the greek word for "equal standing". The principal of isostasy is the idea that any column of earth has the same total mass

hw7:Explain how it is possible to identify the location of an earthquake?

It is possible to identify the location of an earthquake due to the fact that p waves and s waves travel at different velocities. Due to this difference, the process of triangulation, by measuring the time between the p and s wave arrivals, can be used to determine the distance between the seismograph and the earthquake event.

HW1:Explain how paleoclimate data from rocks suggest that continents have moved significant distances over Earth's surface.

It was not just shape of the coastlines of separate continents that matched, but it was the actual underlying rocks themselves which matched as well. The paleoclimate data from rocks suggest that continents have moved significant distances over Earth's surface due to an understanding of the distinct climate zones. Earth's climate varies on latitude and there are definite glacial deposits in equatorial areas. Therefore it only makes sense that all of the continents were once all put together in one supercontinent which moved significant distances over Earth's surface, allowing glacial deposits to be formed in equatorial areas such as Australia.

hw10:Describe some of the variation in slope failures that we can use to classify them (i.e., the type of movement, the kind of material, the rate of movement)

Mechanism of movement - fall or flow Type of material - solid rock or unconsolidated Rate of movement - fast or slow

quiz4: What is metamorphism? Describe some of the changes that commonly occur in rocks when they are metamorphosed.

Metamorphism is when a rock experiences a change in its texture, mineralogy, or composition without completely melting the rock. Change in temperature, change in pressure, and some sort of fluid coming through the rock can encourage metamorphism. Some changes that commonly occur in rocks when they are metamorphosed include a change in the texture of a rock from rough to smooth or smooth to rough. Another change could be the mineral content of a rock.

hw4: Explain the difference between metamorphism and metasomatism

Metamorphism is when a rock experiences some sort of transformation in its mineralogy, texture, or composition but it has to happen without completely melting the rock. Metasomatism is a special type of metamorphism which includes a change in the chemical composition of a rock. Faults or cracks can add materials into a rock or take other materials out.

hw9:Identify and explain one example each of a positive and negative feedback in the Earth's climate system.

Negative : radiative dampening - over time we are bringing energy from the sun that heats up the temperature of the earth and as the earth's temperature increases, it becomes hotter. Then the earth radiates more energy out into space and then the radiation decreases the temperature of the earth and then the rate of radiation goes down which allows the earth to warm back up again. Positive : Albedo effect - ice is more efficient at bouncing energy back into space compared to the ocean which is darker - as we increase temperature it triggers melting which decreases bouncing energy out into space which increases temperature and reduced ice cover further

hw2:List the major silicate mineral subclasses, and indicate the types of linkages between the silica tetrahedra.

Olivine ——> isolated tetrahedra: 1 plane Pyroxene ——> single chains: 2 planes at 90 degrees Amphibole ——> double chains: 2 planes at 80 degrees and 120 degrees Muscovite ——> sheets: 1 plane Feldspar ——> three-dimensional framework: 2 planes at 90 degrees

quiz9: Identify at least 3 geologic observations that led geologists in the late 19th century to recognize that Earth's climate was significantly colder than today in the recent geologic past (i.e., on 10 to 100 thousand year times scales

One geologic observation that led geologists in the late 19th century to recognize that Earth's climate was significantly colder than today in the recent geologic past include: glacial erratics - there are big rocks found in unlikely areas which led geologists to believe that the only way they could have gotten there is by being carried by a glacier glacial deposits - there are deposits with such a variance in grain size which led geologists to believe that the only thing that could have carried rocks with such large grain sizes in combination with small gain sizes would be a glacier Carved out grooves in the landscape - there are grooves left behind from a glacier's path which shows how it scoured out the land U shaped valleys - there are valleys that are V shaped due to water running through the area, however U shaped valleys led geologists to believe that a glacier went through the area Polished landscapes - the abrasion of the glacier traveling on the land leaves polished surfaces behind polished surfaces

hw2:What is one important and unusual property of the silica tetrahedra that enables the generation of a wide type of silicate minerals?

One important and unusual property of the silica tetrahedra that enables the generation of a wide type of silicate minerals would be that each since Si has a charge of +4 and is bonded to 4 Oxygens, the strength of each bond between Si and O is 1. Since Oxygen has a charge of -2, Oxygen only uses half of its charge to hold it to the Si. Therefore the oxygen uses its other charge to bond to other things, which includes another Si.

quiz1: Identify and briefly explain three methods that can be used to measure the velocity of tectonic plates

One method than can be used to measure the velocity of tectonic plates include measuring the distance from a specific location and then determining the age of the rocks. From this data one can create a velocity graph of the time versus the distance in order to find out how fast the tectonic plates are moving. Another method that can be used to measure the velocity of tectonic plates would be by relating the times of the magnetic field reversals of the ocean to particular time periods. The third method that can be used to measure the velocity of tectonic plates would be the use of modern GPS because the modern GPS can measure changes in latitude of certain plates within a certain amount of time.

hw3:Describe two processes that can change the chemical composition of a melt

One process that can change the chemical composition of a melt is partial melting. This process occurs because not all minerals will melt at the same temperature. Therefore some minerals melt at a certain temperature and others don't, which changes the chemical composition of a melt. Through the process of a partial melt, there will be different chemical compositions at different melting temperatures. Another process that can change the chemical composition of a melt is fractional crystallization. This process can be observed in Bowen's reaction series. Basically it follows a pattern starting with the first mineral to crystalize. Then the mineral above begins to react with the remaining melt of the first mineral to form another mineral. This process continues on amongst many different minerals and as different materials react with different melts, the chemical composition changes.

hw10:Two common processes that break down rocks are oxidation and hydrolysis. Describe these reactions.

Oxidation is a type of chemical weathering that happens when oxygen reacts with other substances to create compounds called oxides Hydrolysis is a type of chemical weathering that happens when a substance breaks down when combined with water

quiz8:Although there are over 100 known elements, just 8 comprise over 98% of the crust. What are they, and what is their common oxidation state? (E.g., chlorine, which is not one of the 8 most common elements, tends to make the ion Cl-1). These common elements combine to form minerals - what is a good definition of a mineral?

Oxygen (-2) Iron (+2,+3) Aluminum (+3) Magnesium (+2) Sodium (+1) Calcium (+2) Silicon (+4) Potassium (+1) A mineral is a naturally occurring substance with a definite chemical composition and is composed of a combination of elements.

quiz9:Explain how oxygen isotopes preserved in the shells of marine organisms can be used to reconstruct the record of Earth's climate

Oxygen isotopes preserved in the shells of marine organisms can be used to reconstruct the record of Earth's climate because it can be identified if there are oxygen 16 or oxygen 18 isotopes preserved. If there are oxygen 18 isotopes it indicates an ice age. This is because oxygen 16 is lighter than oxygen 18. Therefore oxygen 16 gets evaporated and normally precipitates down back into the ocean. However in the case of an ice age it gets precipitated down into an ice sheet and doesn't return into the ocean. This leads to a heavier oxygen isotopic composition in the ocean during glacial periods versus non glacial periods. Over the past million years, Earth's climate has been characterized by regular oscillations in temperature and greenhouse gas concentrations. Sketch and describe this pattern, and identify three processes that likely account for these regular variations.

hw9:Explain how oxygen isotopes preserved in the shells of marine organisms can be used to reconstruct the record of Earth's climate

Oxygen isotopes preserved in the shells of marine organisms can be used to reconstruct the record of Earth's climate depending upon if there is oxygen 18 or oxygen 16. When entering into glacial times, oxygen 16 is evaporated from oceans and then precipitated down. However, now it is stored in an ice sheet which grows and grows over time, instead of it going back into the ocean. So oxygen 16 is being preferentially taken out of the ocean and being put into ice sheets and it never makes it back into the ocean. Therefore the composition from the isotopic standpoint of the water in the ocean over time will get heavier. There is a greater abundance of oxygen 18 in glacial periods rather than non glacial periods.: hw9:Describe the correlation (or lack of correlation) between Earth's temperature and atmospheric abundances of methane and carbon dioxide over the past 400,000 years There is a very clear correlation between Earth's temperature and atmospheric abundances of methane and carbon dioxide over the past 400,000 years. There is a repeated trend of slow decline in temperature, as well as abundances of methane and carbon dioxide, followed by a rapid rise in temperature as well as abundances of methane and carbon dioxide.

quiz7: Geologists learn much about earthquakes from seismic waves. Three important types of waves are P-waves (primary waves), S-waves (secondary waves), and surface waves. Indicate how these waves are similar and different. What types of waves are responsible for most of the destruction associated with earthquakes?

P-waves are a type of body wave where material is compressed. The direction of the motion of the atoms is the same direction that the wave is moving. P-waves are the fastest waves. S-waves are also a type of body wave but these waves shear material. The direction of the motion of the atoms is perpendicular to the way that the energy in the wave is moving, therefore the wave migrates in an opposite direction fro the atom energy. Surface waves are waves that happen at the surface and involve significant shaking and motion which is why they are responsible for most of the destruction associated with earthquakes.

hw11:Describe how aspects of streams, such as discharge, sediment load, and sediment size evolve downstream

Particles are colliding with each other and becoming small - grain size drops off Water amount increases - discharge increases Amount of sediment increases as well

quiz5:Clastic sedimentary rocks are composed of pieces of pre-existing rock that are weathered, eroded, transported, deposited, and then lithified. Describe several physical attributes of clastic sedimentary rocks, and explain how these attributes may provide information about the physical processes and/or depositional environments that helped form the sedimentary rock. Provide examples.

Physical attributes of clastic sedimentary rocks include: Clast size: Based on size of particles: boulder, cobbles, pebbles Sand: course, medium, fine Indicative of how much the materials have travelledclast size gets smaller as the material is transported longer distances also indicative of the environment the material is in Example: course sand on a shore line will become more fine as waves repeatedly beat on the sand and break it down Clast shape: Roundness: angular, partially rounded, rounded Indicative of how much the materials have travelled, clast shape gets more rounded as the material is transported longer distances Example: a rock was once more angular but as it was carried down a stream for a very long time it became more rounded Range of sizes: Sorting: poorly sorted=big materials mixed with very fine materials, moderately sorted, well sorted=very narrow range of grain sizes Poorly sorted is a good indicator that the materials were transported by a glacier because it can carry all of the different sized materials with it Well sorted is a good indicator that the materials were transported by wind because the process was very selective and only chose the fine grained materials Example: well sorted would be fine grains of sand which were transported by wind because the wind could not carry any materials larger than the fine grains of sand, therefore decreasing the range of sizes

quiz2:Volcanoes are associated with some - but not all - types of plate boundaries. Identify the types of plate boundaries that commonly exhibit volcanism, and provide an example of such a boundary on Earth. Also, explain the cause of melting in each of these tectonic settings.

Plate boundaries that most commonly exhibit volcanism are convergent plate boundaries. An example of convergent plate boundaries would be the Andes. Convergent plate boundaries occur when the dense oceanic lithosphere sinks down to the mantle. The oceanic lithosphere drags down water with it which lowers the melting point of the mantle. This melted material then rises up and exhibits volcanism.Other plate boundaries that exhibit volcanism would be divergent plate boundaries. These plate boundaries are common along a mid ocean ridge. Divergent plate boundaries occur when the plates pull apart from each other. This creates a decrease in pressure which then lowers the melting point of the mantle. This melted material rises between the gap formed by the divergent plates to exhibit volcanism.

hw11: What are porosity and permeability, and how are they different? Provide an example of a material with a low porosity yet high permeability, and vice versa

Porosity: proportion of open space - how porous the rock is Permeability: pores connected so fluids flow - how readily fluids flow through a material Clay has high porosity yet low permeability

hw9:What is the difference between positive and negative feedbacks?

Positive - reinforce a change negative - counteract change

quiz4: What is the difference between prograde and retrograde metamorphism? Which process is responsible for creating most of the metamorphic rocks we find at the surface of the Earth? Why?

Prograde metamorphism occurs from increasing pressure and/or temperature conditions whereas retrograde metamorphism occurs from decreasing pressure and/or temperature conditions. Prograde metamorphism is responsible for creating most of the metamorphic rocks we find at the surface of the Earth. This is because retrograde metamorphism is not as common as prograde metamorphism. Some reasons for this is that chemical reactions occur at a slower rate as lower temperatures and also water is removed as prograde metamorphism occurs and therefore it is difficult to cool

quiz6: Explain the essence of the idea of radiometric dating of rocks. Briefly identify some reasons why not the origin of many rocks cannot be determined this way.

Radiometric dating of rocks is the process of calculating the age of a rock based off of radioactive substances within a rock. Some reasons why the origin of many rocks cannot be determined this way is because of: Influence of pressure, temperature, etc. Parent and daughter isotopes lost form crystal Not knowing or being able to measure the daughter isotope

hw3: Explain why the crystal size in minerals provides information about the cooling history of an igneous rock.

Rate at which minerals grow; process takes time to become larger; very slow cooling takes the time so that elements can organize to form very large crystals; if it cools extremely fast there is not time to organize the elements lots and lots of tiny crystals; freeze everything in place and not a lot of time to organize into larger groupings; Faster something cools the finer grained it's going to be

hw6:Identify and explain the requirements that must be met for a radiometers age determination to be accurate

Rate of decay is constant and know - we need to be able to accurately measure the rate of decay - we need to know how fast that breakdown process is occurring - we've got instruments that can measure radioactive decay Rate of decay is independent to pressure, temperature, etc. - we need to be certain the rate of decay is truly constant - it needs to be undefended of pressure and temperature - its gonna be a problem if we heat s rock up and it decays faster because then the amount of daughters going to reflex the age plus the temperature history - we believe because radioactivity has to do with these nuclear forces in the center of atoms it turns out to be insensitive to pressure and temperature at least over the kinds of conditions we see inside of the earth Parent and daughter isotopes can be accurately measured - if we can't measure the parent and the daughter we are out of luck - we need to be able to know how much parent and daughter there is qa Parents and daughter isotopes are not lost from crystal - we need to know that neither of these parent of daughter are being removed from the crystal - we need to have a situation where our isotopes are kept within a rock or a mineral Initial daughter isotope is known or measured - we need to be able to estimate or measure the amount of daughter product that was in the rock at the time that it formed

quiz5:Identify the sedimentary structures shown in each of the following images

Ripples Regular bedding Cross bedding Graded bedding

hw5:Roundness and sorting are two properties of clastic sedimentary rocks. Briefly describe each of these, and indicate what information they may tell us about the deposition of these rocks.

Roundness: angular, partially rounded, and rounded - how much have they been worn down, how much have they travelled - clasts get smaller as they're transported longer distances ————————Sorting is the range of sizes that we see in a sediment: poorly sorted(big things mixed with very fine things)good indicator that material was transported by ice(glacier), moderately sorted, well sorted(very narrow range of grain sizes)whatever process transported that was very selective-only chose the fine grain, indicates wind

hw8:Explain the key idea behind seismic tomography. Describe one type of tectonic feature geophysicists can map using this technique.

Seismic tomography involves seismic observations from different directions. Interpretation by comparing observed with what was expected if all same material Seismic wave velocity depends upon the density of the material that it is moving through and if we have an earthquake source at depth and come to different stations across the earth and the waves may have sped up or slowed down due to either composition or temperature - by looking at many seismic wave arrival times geophysicists can figure out the average density along the path and by looking at many earthquakes we can get a detailed scan of the interior of the earth.

hw7:Describe how seismologists estimate earthquake magnitude

Seismologists estimate earthquake energy by using seismographs. To calculate the magnitude on needs to know the size of the shaking as well as the distance to the earthquake. If one knows the distance and can measure the amplitude, they can measure the Richter magnitude.

quiz10:Identify and describe several processes that contribute to the physical weathering of rocks.

Several processes that contribute to the physical weathering of rocks include: Heating and cooling - the change in temperate can cause expansion and contraction of rocks which can lead to fractures which break down the rock Burrowing animals - animals can burrow into rock formations and break down the rock Frost wedging - fractures in rocks can be filled with frost which can pry open the rock even more and cause more fractures Mineral wedging - fractures in rocks can be filled by minerals that when wet will expand and pry open the rock even more Root wedging - fractures in rocks can be filled with roots of growing plants which can penetrate and build upon fractures

hw9:Sketch the trend in the CO2 concentration in Earth's atmosphere over the past 70 years. What is responsible for both the short-term (annual) and long-term variations?

Short term and long term variations are due to plant growth and seasonal changes.

hw3: What types of silicate minerals tend to be found in mafic rocks? What types are found in felsic rocks?

Silicate minerals that tend to be found in mafic rocks include, pyroxene, gabbro, and basalt. Silicate minerals that tend to be found in felsic rocks include, orthoclase feldspar, granite, and rhyolite.

hw11:What are some ways that groundwater can become contaminated? Explain how contaminated groundwater can be remediated.

Some ways that groundwater can become contaminated include: Mining and naturally mineralized rock factory wells, spills, emissions septic tanks, farms, landfills, truck fuel spills, leaking tank in gas stations, etc. Contaminated groundwater can be remediated be finding out which way the water is going to flow and then putting pumps downstream to suck up contaminated water and treat it. Dissolution is the solution to pollution.

hw7: Explain what is meant by the "earthquake cycle"

The "earthquake cycle" is the process in which stress is built up, stresses are suddenly released, there is a slip, there is an earthquake in which the stress drops, and then stress slowly builds up again to repeat the cycle.

quiz7:Describe the "earthquake cycle." Include a figure illustrating how stress develops over time on a fault.

The "earthquake cycle" is the process where stress is built up and rocks experience elastic strain, then the stress suddenly released and there is a fault slip. Then an earthquake occurs where the stress drops and then the stress slowly builds up again afterwards to repeat the cycle.

quiz2: Although there are over 100 known elements, just 8 comprise over 98% of the crust. What are they, and what is their common oxidation state? (E.g., chlorine, which is not one of the 8 most common elements, tends to make the ion Cl-1). These common elements combine to form minerals - what is a good definition of a mineral?

The 8 elements that comprise the earth's crust are Oxygen (O)(-2), Iron (Fe)(+2, +3), Magnesium (Mg)(+2), Potassium (K)(+1), Sodium(Na)(+1), Calcium (Ca)(+2), Aluminum (Al)(+3), and Silicon (Si)(+4). A good definition of a mineral would be a substance which is made of a combination of elements.

hw2: What are the 8 most common elements in the Earth's crust? What are the most common elements in the core?

The 8 most common elements in the Earth's crust are iron, oxygen, sodium, calcium, potassium, aluminum, magnesium, and silicon. The most common elements in the core are iron, nickel, sulfur, an oxygen

hw2:What is the basis for the chemical classification of minerals? Explain why mineralogists use this system, as opposed to group minerals based on color or other properties.

The chemical classification of minerals is based upon their anions or anionic complexes. Mineralogists use this system, as opposed to group minerals based on color or other properties because there are a lot of advantages doing it this way. One advantage would be that we can easily figure out what kind of mineral is being dealt with just by looking at its chemical formula. A second advantage would be that minerals within each class have a very similar chemical structure so it is easier to classify them that way. There are also properties that vary between a certain type of rock, such as color, that isn't always reliable in terms of classifying minerals.

quiz10:During the Eocene Epoch (~ 55 Ma), global temperatures are believed to have been about 10°C greater than they are today. Since that time, the Earth has experienced a long-term cooling trend. One leading hypothesis to explain this change invokes the uplift of the Tibetan Plateau and the Himalayan Mountains, which began about 40 Ma. Describe how the collision between India and Asia might cause the observed long-term cooling - be certain to discuss any chemical weathering reactions that may play a role.

The collision between India and Asia might have caused the observed long-time cooling because the collision brought silicate rocks to the surface and exposed these rocks to the atmosphere. The process of chemical weathering of silicate rock consumes CO2. These silicate rocks reacted with the CO2 in the atmosphere by consuming the CO2 and thereby removing CO2 from the atmosphere. Therefore the removal of CO2 and greenhouse gases leads to a cooler earth.

hw4: Identify the common factors that lead to metamorphism

The common factors that lead to metamorphism include a change in temperature, a change in pressure, and a fluid coming through the rock.

hw7:At what type of plate boundary do the greatest magnitude earthquakes tend to occur?

The greatest magnitude earthquakes tend to occur at subduction zones. hw7: The deepest known earthquakes were associated with what type of tectonic setting? The deepest known earthquakes were associated with subduction tectonic settings.

hw2:What controls the macroscopic properties of minerals? Describe an example.

The internal atomic scale structure controls the macroscopic properties of minerals. An example of this would be a mineral named halite. Halite is comprised of sodium and chlorine. Those atoms are arranged in a perfect cubic grid and because of that grid, halite grows into rectangular prisms. Since the bonds are all equally strong, when halite is broken, it breaks into perfect cubes. This is because the mineral is reflecting its internal atomic structure.

HW1:What is the most important force driving plate tectonics? Describe evidence that supports this interpretation.

The most important force driving plate tectonics is slab pull. This interpretation is supported by two plots of tectonic plate velocity. One plot shows a poor correlation between ridge length and velocity. However, the other plot shows that where there is very little subduction occurring, there is very low velocity. Likewise, this plot also shows that where there is a lot of subduction occurring, there is high velocity. Therefore this supports that the most important force driving plate tectonics is slab pull, not ridge push.

quiz6: The Earth's surface is comprised of two types of continental crust: continental and oceanic. What is the range of ages of rocks found in each type of crust? Provide an explanation that accounts for the differences.

The range of ages of rocks found in the continental crust is a lot larger than the range of ages of rocks found in the oceanic crust because the continental crust is billions of years old meanwhile the oceanic crust is only millions of years old. Subduction is what accounts for the difference. The cold, heavy oceanic crust sinks into the mantle and is basically recycled. This is why the oceanic crust is not as old as the continental crust, which does not subduct like the oceanic crust.

quiz8:The adjacent image is a cross-section through a tomographic model of part of North America. The cross-section line is oriented approximately north-south and it cuts through the Yellowstone spot in Wyoming (which is indicated by the red triangle on the surface of the model, near 21°). The position labeled as 0° in the Pacific Ocean just off the coast of Mexico, and the position labeled 30° in Canada. The model shows variations in seismic wave velocity - red areas are places where seismic waves move more slowly than average, and blue areas are places where seismic waves move more quickly than average.Interpret this model. What do the red areas represent? What does the model suggest about the structure of the mantle and the origin of the volcanic activity in Yellowstone?

The red areas represent areas where seismic waves move more slowly than average. The velocity of seismic waves is dependent upon the density of the area through which they travel. For example, the less dense the material, the slower the seismic waves travel whereas if the area is more dense, the waves travel at greater velocities. The density of the material is dependent upon the temperature as well as the composition. The higher the temperature, the less dense the material and the lower the temperature, the more dense the material. Therefore the red areas most likely have higher temperatures. The model suggests that the structure of the mantle is not very dense due to the fact that there is a decent amount of red areas and barely any blue areas. The model suggests very hot temperatures at the origin of the volcanic activity in Yellowstone due to the red area which means less dense material which suggests higher temperatures.

hw7:What is the relationship between earthquake magnitude and earthquake frequency?

The relationship between earthquake magnitude and earthquake frequency is reverse in that as the magnitude increases, the frequency decreases.

hw7: Describe the tectonic settings where most earthquakes occur.

The tectonic setting where most earthquakes occurs are at divergent margins, where the plates diverge, convergent margins, where the plates converge and one subducts, as well as transforms margins, where plates slide past one another.

HW1:Describe the fundamental differences between the oceanic crust, continental crust, and mantle

The thin layer known as the crust has two different parts, one called continental crust and the other called oceanic crust. Beneath this crust is the mantle. The crust and the mantle have different chemical compositions, the mantle is denser and is more iron and magnesium rich. The typical thickness of the continental crust is 35-40km and the typical thickness of the oceanic crust 5-7km. The average density of the continental crust is 2.8g/cm^2, the average density of the oceanic crust is 2.9g/cm^2, and the average density of the mantle is 3.3g/cm^2.

quiz7:Volcanoes are associated with some - but not all - types of plate boundaries. Identify the types of plate boundaries that commonly exhibit volcanism, and provide an example of such a boundary on Earth. For each of these types of plate boundaries, discuss the earthquakes that may be present (likely depth, relative magnitude)

The types of plate boundaries that commonly exhibit volcanism are divergent and convergent plate boundaries. An example of a divergent plate boundary is at a mid ocean ridge. Divergent boundaries occur when the tectonic plates move away from each other. Convergent boundaries occur when two tectonic plates converge and the oceanic crust subducts. An example of a convergent plate boundary would be the Andes. The biggest earthquakes occur at subduction zones because the pressures involved are so huge because it is at such great depths and the pressure acting on the rocks is larger which results in more energy. Therefore earthquakes of greatest depth and magnitude occur at convergent plate boundaries.

hw7: What are the types of seismic waves produced by an earthquake? Which move with the greatest speed?

The types of seismic waves produced by an earthquake are surface waves and body waves. Body waves have two main types, primary waves and secondary waves. Primary body waves move with the greatest speed.

quiz8:The photograph below is of Nunavit Bay, in the northernmost part of mainland Canada. The "grooves" you see are a series of ancient shorelines. These shorelines all formed since the end of the last Glacial Maximum (say, 18,000 years ago). Describe how these shorelines formed, including an explanation for the physical mechanism responsible for uplifting the land.

These shorelines originally had a big piece of ice on them which exerted a downward pressure, which then forced the mantle to flow out of the way. Therefore the weight of the ice sheet led to a depression in the crust and the lithosphere. Once the ice melted the weight was lifted and therefore the crust rebounded which led to a rise in the landscape. This process is known as isostatic rebound

quiz9:Briefly explain how they impact Earth's climate

This pattern can be described as a rapid spike in temperature and greenhouse gas concentration, followed by a slow gradual decline in temperature and greenhouse gas concentration, then followed by another rapid rise in temperature and greenhouse gas concentration. This pattern repeats itself. Three processes that likely account for these regular variations include: Eccentricity - the shape of the earth's orbit is not a perfect circle and is slightly elliptical which means that the earth will be closer to the sun during part of its journey and will be further away from the sun during another part of its journey. The earth will therefore receive more energy during the times that it is closer and will receive less energy when it is further from the sun Tilt - the earth's axis is on a tilt, which is why there are seasons because as one hemisphere is directed towards the sun and has summer, the other hemisphere is directed away from the sun and experiences winter. The greater the tilt, the more extreme the seasons are. Precession - the earth wobbles on its axis which can change when in a given year you are going to have different seasons, which can also interact with the other cycles and can contribute to making the seasons more extreme.

quiz5:Before you begin this question, I want to make sure you noticed something remarkable! In the first photograph on this exam, the highlighted sedimentary structure there appears in two generations! In the bottom half of the photograph, it is preserved in >300 Ma rocks in the top half, it is forming contemporaneously (i.e., the feature is probably less than 30 minutes old!). Go back and look at it! Right now!Amazing, eh? OK, now to question 4. There are three common mechanisms (or fluids) that transport sedimentary material. Identify each of these, and describe a depositional environment where we might find material transported by this mechanism. Describe what the result rock might look like.

Three common mechanisms that transport sedimentary material are wind, water, and glaciers. Wind example: Wind can pick up sand and stack it but if the pile gets too steep it will fail. As the wind keeps blowing the material slides down the back. This forms a bed that is inclined to the horizontal bed at the time. This is an example of cross bedding created by wind that is found in sand dunes. The resulting rock is fine grained sand because the wind cannot carry larger grained rocks. Water example: the ocean becomes increasingly salty because rainwater brings runoff into rivers that channel into the ocean. The river carries salt and minerals. The ocean collects deposited sediment from the rivers that flow into it. The sediment is then deposited into the ocean and onto the ocean floor. The resulting rock can be a greater range of sizes than wind can carry, but not as large as what glaciers can carry. Glacier example: A depositional environment where we might find material transported by glaciers would be an area with a boulder. Glaciers can transport the largest clast sizes and clast ranges. When the glacier melts it leaves behind these clasts. A glacier can melt and leave behind a boulder.

hw9: Identify and explain three different types of geologic observations that indicate Earth's climate has been substantially colder than now at times in the past

Three different types of geologic observations that indicate Earth's climate has been substantially colder than now at times in the past include: Glacial erratics-giant rocks left behind which had to have been carried by ice sheets Glacial deposits-huge range in grain sizes-glacier is large enough to transport large and small grain sizes Land carved out with grooves-shows the path of a glacier and how it scoured out the land leaving grooves U shaped valleys = glacier vs V shaped valleys = river polished surfaces

hw10:What are two typical end-products of chemical weather of silicate rocks?

Two typical end-products of chemical weathering of silicate rocks include clay minerals as well as quartz

quiz 1: Volcanoes are associated with some - but not all - types of plate boundaries. Identify the types of plate boundaries that commonly exhibit volcanism, and provide an example of such a boundary on Earth. Also, explain the cause of melting in each of these tectonic settings

Types of plate boundaries that most commonly exhibit volcanism are convergent plate boundaries. An example of such a boundary on earth would be the Pacific plate where volcanos are active near Hawaii. Convergent plate boundaries occur when the dense oceanic lithosphere sinks into the mantle. As the oceanic lithosphere sinks down it brings water down with it and this water lowers the melting point. Then this melted material in the mantle rises up to exhibit volcanism. Volcanoes are also common along a mid ocean ridge. Another type of plate boundary which volcanoes are associated with are divergent plate boundaries. Divergent plate boundaries occur when two tectonic plates pull away from each other. As the plates move away from each other, there is a decrease in pressure which lowers the melting temperature of the mantle. Then the melted asthenosphere rises up through the gap that was created by the plates moving apart.

quiz3:Consider the two images below. These rocks have very similar bulk compositions, yet appear quite different. A) Interpret what is different about the geologic history of each sample. B) What do you estimate to be the bulk composition of the rock (ultramafic, mafic, intermediate, or felsic) - briefly justify your answer

What is different about the geological history fo each sample is the time that was taken to crystallize. The sample on the left crystallized in a much shorter time span than the sample on the right. This is because the more time minerals have to chrystallize, the more time they can organize and create fine crystals. This is why the sample on the left has much larger, more visible crystals and the sample on the right is finely chrystalline. I estimate the belt composition of the rock to be felsic. This is because the sample on the left looks like granite, and the sample on the right looks like rhyolite. These two rocks are both felsic and contain feldspar and silicon. These rocks have pick, grey, white, and black color to them and have an abundance of quartz.

hw9:Describe the greenhouse effect and explain how it effects Earth's temperature. What are three examples of greenhouse gases?

When energy from the sun comes in it has some wave lengths and the carbon dioxide is transparent over most wavelengths of light - when that energy hits th surface of the earth some of it is converted into infrared rays which has a much longer wavelength and its because theyre slowed down and when they exit they now have this longer wave length and is it at these wavelengths which carbon dioxide can absorb that energy - helps warm the planet Three examples of greenhouse gases: carbon dioxide, nitrogen, and argon

HW1:Explain how the mantle lithosphere and mantle asthenosphere behave when stressed

When stressed, the mantle behaves by being predominantly brittle in the the mantle lithosphere and then will become more plastic in the mantle asthenosphere. Although the chemical composition throughout the mantle is the same, the mantle lithosphere is composed of a very strong, rigid material meanwhile the mantle asthenosphere is composed of a soft, weak material

hw10:Identify and describe several processes that contribute to the physical weathering of rocks.

heating and cooling(expansion and contraction can break rocks and cause fractures break them down) water can seep into these fractures and pry open rock and continue to break it more, frost wedging, burrowing animals, mineral wedging(cracks can be filled in by minerals that can expand when wet), root wedging(plants can grow into existing rock penetrating into existing fractures)

hw11:Describe how erosion and deposition typically occur in meandering streams

inner curve - as water is moving around the corner it has to have a greater velocity on the outer edge and a lower velocity on the inner edge - a lot more energy on outside of the curve that begins to erode which leads to cut banks - and on the inside with low velocity is a lot of deposition

hw4: Describe and explain some of the chemical and physical processes that occur during metamorphism chemical processes:

recrystallization = we can take minerals of certain composition and we can cause them to be broken down and then forming elsewhere growing in a different part of the rock and grow in a direction which allows the rock to be squeezed allowing the rock to change shape remobilization=where we can take some of the material and dissolve it or diffuse it into other areas and we tend to concentrate certain elements together - breaking down dark mineral and carrying that material and its aggregating together to form a banding - light colored and dark colored layers - breaking down preexisting and growing new ones physical processes: deformation of object=individual grains can be squeezes and change shape to become more elongated Rotation=can be rotated 3. shearing=also have shearing where one side is taken down and other side is taken up and grains can also be rotated this can help create foliation