Lawler Test 4

Match the following stage in the life of a star with the size of star. A planetary nebula is

small (about the size of our sun)

The lower mantle of the earth (the mesosphere) is thought to be mostly

solid

How far away is a distant galaxy in the observable universe?

10 billion light years

Apprioximately how far apart are interglacial periods on average?

100000 yrs

What type of galaxy is the Milky Way?

A spiral galaxy

Information from fossils would most likely be useful to do which of the following?

Determining relative ages of sedimentary layers.

what is one piece of the evidence for an iron-nickel core in the center of the earth?

Earth has a magnetic field.

What happens to the sediment in the stream as the speed of the water increases?

More sediment is carried by the stream

The most important erosional agent of the hydrological system is which of the following?

Running water

What hydrologic feature causes Deltas?

Running water

The Big Bang

The discovery that the galaxies were not only moving away from each other, but they were moving away with a linear relationship between their speed and the distance they had traveled implied one thing. Everything started out at the same place. All of the matter and energy in the universe originated from one single point in space and time, known as a singularity. This implication was first realized by a graduate student by the name of Georges Lemaitre (shown below) in the late 1920s. He published the connection between the Hubble law and a starting point for the universe in 1931. Initially, his work was not well received. Lemaitre was an ordained Catholic priest who taught at a Catholic university, and many of his contemporaries viewed his theory as a blatant attempt to impose a moment of creation on science. They began referring to his theory derisively as "The Big Bang," and the name stuck Religious scholars of the time, on the other hand, embraced his theory. In 1951, Pope Pius XII declared that it was scientific validation of creationism. Lemaitre was reportedly very upset by this mixing of science and religion. He is reported to have said, "As far as I can see, such a theory remains entirely outside any metaphysical or religious question." His theory was based on observation, could be tested, and he resented the implication that he was biased in his efforts to figure out how the universe worked. Science makes progress by collecting data that can confirm or refute ideas. If the Big Bang theory were true, then the conditions in the very early universe would have been so extreme that there would still be evidence today. Leftover radiation from the initial "Bang" should fill space. The elements found in the universe should match those that would be formed during a short burst of fusion before the universe expanded and cooled. By the mid-1960's both the existence of a cosmic microwave background radiation and the expected hydrogen to helium ratio from fusion had been confirmed. At that point, the Big Bang moved from a controversial idea to the only theory that was consistent with all of the observations. None of the other models could explain how space came to be filled with microwave photons that are nearly perfectly uniform in all directions. None could explain why the gases in interstellar space are a perfect match for the gases that would form from hydrogen fusion taking place for a short time and then stopping. The Big Bang model was also the only model that could account for the observed relationship between speed and distance seen in cosmologic red-shifts. So, all of the other models were abandoned in favor of the Big Bang theory. Small details of the Big Bang theory continue to be tweaked every time new information is discovered, but at this point there is a huge body of evidence that the core idea is correct. All of the matter and energy found in the universe came into existence at the same point and time. Strangely enough, as scientists became more and more accepting of the theory, the religious community became less enthusiastic. Some religious scholars began to regard the Big Bang theory as an attempt by scientists to explain away the existence of God. Today, when the term "Big Bang" is used derisively, it is almost always by a religious non-scientist. This leaves those of us who are both religious and scientists shaking our heads in confusion.

Match the following stage in the life of a star with the size of star. A Black hole is

Your answer: "large (more than 10 times the size of our sun)

Moon Craters

check out questions 28-12 through 28-19 about the moon craters

What two things are plotted on an H-R diagram?

color true brightness

The big bang theory unanswered questions: missing energy

Because of gravity, cosmologists used to think that the rate of expansion would continue to slow with time, but it appears now that the expansion of the universe is actually speeding up. Besides looking for dark matter, astronomers are looking for dark energy—the energy which drives the extra repulsion and increasing rate of expansion of the universe.

What two things are plotted on an H-R diagram?

Color True brightness

death of a star

How a star dies depends upon its mass. The smallest stars end up as white dwarfs and eventually black dwarfs. The more massive stars end up going supernova and a neutron star remains. The most massive stars of all experience a supernova and then turn into a black hole. Because all stars lose mass during the red giant stage, the bounds of "small," "medium," and "large" are approximate.

Interstellar distances

In order to determine the distance to a star based on how bright the star looks, we have to be able to figure out how bright that star really is. Depending on where a star is in its life cycle, there are three different techniques: 1) H-R diagrams and main sequence stars ---Most stars fall on a central band known as the main sequence which is when the star is in its longest stage of life - the main sequence stage we discussed earlier in the lesson. A star forms and takes its place in the main sequence with its position on the main sequence based on its temperature and brightness. It stays there until it leaves the main sequence as the star becomes a red giant. The Hertzprung-Russell (H-R) diagram provides a way to determine the intrinsic brightness or absolute luminosity (absolute brightness) of a star if one observes its color, which is easy to do if it is not too far away. The absolute brightness is compared with the apparent brightness to determine the distance. Astronomers have calibrated the H-R diagram using stars whose parallaxes have been measured, and then extended the distance ladder to about 300,000 light years. 2) Variable red-giant stars ---Red-Giants are larger in size and brighter than main-sequence stars. So, they can be seen over larger distances. Some red-giants, called Cepheid variable stars, vary in brightness as the star expands and contracts. The star's oscillation time is related to the star's size and true luminosity. In the 1890s and early 1900s, an astronomer named Henrietta Leavitt discovered the brightness-period relationship for these Cepheid variable stars. So if you can measure the oscillation time which is generally over a period of a few days to a hundred days, you can determine the star's absolute brightness and compare it to the apparent brightness of the star from Earth to determine the distance of the star. In the 1920s, Edwin Hubble (for whom the Hubble Space Telescope is named) used Cepheid variable stars to gauge the distances to several nearby galaxies. He showed without doubt that they are very far away from our own galaxy. These variable red-giant stars extend the distance ladder out to about 20,000,000 light years. 3) type IA supernovas ---The brightest stars ever become is when they blow up in a supernova explosion. These explosions are bright enough to be detected billions of light years away. However, for most supernovae there is no way of knowing how bright the explosion actually is. Different stars have different masses and so will blow up differently. If we can't figure out the true luminosity, we can't determine distance regardless of whether or not we can see the exploding star. There are, however, a few supernova explosions that are so well behaved that we know exactly how bright they really are. It takes a very specific set of circumstances, so these supernovae are rare. These start with two stars that formed together and orbit each other closely. Both must be small stars destined to become white dwarfs, but one of them is only a little too small to blow up in a supernova. The larger star has a shorter life and turns into a white dwarf first. When the smaller star becomes a red-giant and expands, the white dwarf steals some material. If the white dwarf steals enough mass, it will blow up in a supernova. Because the white dwarf had already lost its hydrogen atmosphere, the light from these supernova explosions doesn't contain hydrogen's characteristic emission lines, and it is easy to distinguish from other supernovae. All of these supernova explosions start with a star that has the exact minimum mass needed to explode. So, they all have exactly the same brightness. This takes us nearly to the edge of the universe with our distance ladder.

Arrange the stages in the life of a certain star in order. Which of the following appears third?

Red Giant

Which of the following factors that impacts climate is wholly a natural factor rather one that is influenced by human activity?

The amount of energy the sun outputs

Where does the water in the stream bend travel the fastest?

The outside of the bend

The above picture shows the plates in the northern hemisphere. The Mid-Atlantic ridge runs down the middle of the Atlantic Ocean. What direction is the North American plate moving relative to the Eurasian plate?

West

which are compression waves?

just P waves

The distance to galaxies very far from our own can best be estimated using

the cosmological redshift

The sun will eventually become a

white dwarf

The three configurations that help the Earth heat up the most are as follows:

1) Having a rounder orbit (as compared to more elliptical) 2) Having less tilt so that the sunlight is more evenly distributed 3) Having a northern winter when the Earth is closest to the Sun

evidence that nebular hypothesis process of solar system formation is happening elsewhere:

1) In recent years, evidence that some nearby stars are accompanied by planets has been accumulating quite rapidly. The sensitivity of the techniques available to astronomers means that larger and very massive planets can be detected more easily, but planets about the size of Earth have also been detected. 2) The Hubble Space Telescope has revealed the presence of flattened disks of gas and dust around several stars. These disks are particularly prevalent around young, newly formed stars. This is consistent with the idea that the matter has not yet had time to condense into planetary systems.

The big bang theory unanswered questions: missing mass

1) The Big Bang theory explains the present state of the universe as arising from an initial catastrophic explosion. Understanding the future of the universe depends upon knowing some things that have not yet been determined with certainty. If there were sufficient mass in the universe, then the total gravitational attraction would be sufficient to eventually stop the expansion and begin a contraction. This type of universe is called a closed universe. If the universe were closed, then it would eventually collapse to the volume it occupied at the time of the Big Bang. This has been called a "Big Crunch," and assuming that it resulted in another Big Bang, we would then be living in an oscillating universe—one that cycled between big bangs and big crunches. -----This model appealed to scientists because it provides a nice self-contained package. But all of the current experimental evidence points to the second option. 2) If there is less than the amount of mass required to close the universe, we then live in an open universe that will expand forever. There isn't anywhere near enough matter that we can see, because it emits light, to close the universe. There is good evidence to indicate that a mysterious form of dark matter we have not yet identified exists, but that still isn't enough matter to close the universe. Current evidence is that the universe is precariously balanced just short of closed. That is, it will expand forever and will not collapse.

The speed of plate motion in the tectonic system is approximately

1-10 centimeters per year.

Nebular Hypothesis

A good model for the formation of the solar system will account for all of the features we observe. It has to explain why the planets orbit in a flat plane, why there are two groups of planets with different densities, and finally, why the Moon, Mercury, etc are covered with craters. Our current model, which is still a work in progress, is called the nebular hypothesis. According to the nebular hypothesis, the solar system is thought to have formed from a condensing cloud of gas and dust. Most of the mass formed the sun. As gravity pulls the cloud together, it flattens out into a disk The planets were formed when regions of higher density in the flattening outer disk drew in material by the force of gravity. Comets and asteroids are also remnants of the solar nebula. Eventually the cloud of gas and dust became a central star (or stars in the case of various other solar systems) orbited by planets and smaller bodies. According to this hypothesis, as the cloud collapsed gravitational potential energy was converted into kinetic energy. Eventually the center became very hot and dense. This temperature difference is responsible for the differences in the terrestrial and Jovian planets that you see in our solar system today. Due to the increased temperature near the center of the cloud, only material with high melting temperature could condense to form planets. metals and metal compounds have higher melting temperatures so the terrestrial planets could have rocky and more metal-rich compositions. Covalently bonded molecules have lower melting temperature so the Jovian planets which formed farther from the center where it was cooler were able to form with hydrogen, helium, methane, ammonia, etc The nebular hypothesis is also able to explain why the ages of the planets and the sun seem to be the same. They formed from the same cloud of dust and gas. Also, all of the planets orbit the Sun in the same plane because they formed from the same cloud of gas and dust that was spinning in one direction.

white dwarf star

A star 8 times the mass of our sun, more or less, will end its life as a white dwarf, producing a spectacular planetary nebula along the way. As the star's nuclear furnaces shut down, gravitational collapse begins. Layers outside the core, which consist of helium and hydrogen, reach temperatures at which they undergo explosive fusion. When helium fusion occurs in small stars, there isn't enough gravitational force to hold on to the outer layers of the star. This time, it is not a red giant that is formed. These outer layers expand away from the star and a planetary nebula is formed. Planetary nebulas take shapes that range from spherical and expected to very strange, apparently governed by magnetic fields in the star and whether or not there are other stars in the system. When the planetary nebula forms, the star blows off enough mass so that its size is significantly reduced to be about the size of Earth. It is a core of carbon, a shell of helium outside that, and an outer shell of hydrogen. These small stars do not have sufficient mass for the carbon core to collapse and heat up enough for carbon fusion to occur. Eventually the white dwarf cools to a temperature too low for it to glow from thermal emission. It is then called a black dwarf - a carbon cinder, the size of Earth with the mass of a small star. We detect them only by their gravitational effect on other objects.

an expanding universe

An important part in understanding our galaxy and universe is measuring the distances to other objects in our universe Brightness-distance using type IA supernovae can get us out to the edges of the universe. However, those supernovae are rare. We often want to know the distance to objects that haven't experienced a recent supernovae. Brightness-distance methods using main sequence stars only reach tens of thousands of light years. We are able to reliably measure the distance to Cepheid variable stars tens of millions of light years away. But, that is no where near the ten billion light years we want to measure. So, that leads us to our last distance measuring method: cosmological redshift

Spiral and barred spiral galaxies

Around seventy-five percent of the known galaxies are spiral galaxies - either spiral galaxies or barred spiral galaxies. Spiral galaxies have a central bulge with a spiral arm structure where the majority of the star formation occurs. Barred spiral galaxies are very similar - they just have a bar of material running through the center as the following picture shows. Our own Milky Way galaxy is thought to be a barred spiral galaxy. It has four arms and a small bar.

Which mechanical layer of the Earth is mostly plastic solid with a small percent molten material?

Asthenosphere

Which of the following best describes the relative age of A and B (oldest to youngest)

B is oldest

Why is helium harder to fuse than hydrogen?

Because Helium contains 2 protons.

What would be the best method to determine the distance to Mars?

Bounce a radio wave off of it and time how long it takes to make the round trip

If you wanted to measure the distance to a distant galaxy, which of the following distance measurement techniques could you use?

Brightness-distance relationships using type IA supernova

There are four major types of studies used to determine the structure and composition of the earth's interior.

Comparing the density of the surface rocks to the density of the earth determined from calculations (Cavendish Experiment). The study of S and P wave behavior as they travel through the Earth The nature of the earth's magnetic field The composition of meteorites

right before star death

Eventually the helium core is compressed enough that it reaches around 200 million degrees. Helium fuses to carbon explosively, dispersing the nuclei so that fusion again shuts down. Gravity once again begins to collapse the star, and within a few thousand years, this red giant phase has ended. It may not be the last one, though. If the mass of the star is large enough, the helium in the shell around the core will begin to fuse helium into carbon, and the same sequence of events will be repeated, leading to another expansion in a second red giant stage. Our sun will have a second expansion and this time it will be large enough to swallow the Earth. However, it will go faster, and if it is followed by a carbon-to-oxygen-and-neon-fusion stage, that will be faster yet. Even faster episodes of collapse, expansion, and renewed fusion, leading to the production of heavier nuclei in the interiors of the stars can follow. The largest stars can produce elements as heavy as iron in their cores. During the final stages of a star's life, the hot gases that make up the outer layers of the star are pushed into space. These form glowing clouds surrounding the dying star like the planetary nebula

What is a feature most commonly associated with converging plate boundaries between two continental plates?

Fold mountain belts

Which of the following mechanisms is occurring at the sun's core?

Fusion

The energy source driving plate tectonics is

Gravitational potential energy

What do we call a gas which transmits higher energy visible photons but absorbs a large fraction of infrared photons?

Greenhouse gas

Black Holes

Happens to much more massive stars (greater than 25 times the mass of our sun). For these stars, there is no known force that can stop the collapse of the star after the supernova occurs. The gravitational force for something this massive turns out to exceed the strength of the electromagnetic force and the star collapses until it is arbitrarily small. The gravitational force of such an object is so large that even photons cannot escape it—hence the name, black hole. How we can detect it because it doesn't shine---Many stars are members of gravitationally bound pairs that revolve around a common center of mass. If one of the stars of a binary pair becomes a black hole, it begins to pull gas from the other. As gas falls toward the black hole, it forms an orbiting disk around it and gradually spirals in. The charged particles spiraling into the black hole should, theoretically, emit enormous amounts of X-rays. Such emissions have been observed, and there appears to be no other explanation for them. Thus, we have "seen" black holes. Supermassive black holes are thought to be at the center of most galaxies

Why are higher temperatures necessary to cause helium to fuse into carbon?

Helium nuclei have a higher charge than hydrogen nuclei do so more kinetic energy is necessary to overcome the electromagnetic repulsion and allow the nuclei to get close enough for the strong force to take over

Arrange the stages in the life of a certain star in order. Which of the following lasts the longest?

Hydrogen Burning Star

Global temperatures have increased over the last 100 years. What evidence is there that human activities are at least partially responsible for this increase?

Ice cores show a correlation between global temperature and CO2, and humans have released a lot of CO2 in the last 100 years

Match the following rocks with a rock classification. Basalt is

Igneous

Measurement by brightness-distance

Imagine someone walking towards you holding a flashlight at night. The farther away they are, the dimmer the flashlight looks. As they get closer, the amount of light that hits you increases. There is a mathematical relationship between the distance and brightness As long as you know how bright a light source is, you can calculate how far away it is. Understanding the process of how stars produce light allows us to determine how bright a star actually is based on the colors of light it produces. And from there astronomers are able to calculate how far away stars are.

Where is a proto-planetary disk (the cloud of gas that is turning into a solar system) the hotest?

In the middle

When water chemically combines with surrounding rock in subduction zones, what happens to the melting temperature of that rock?

It gets lower

How can you determine the mass of a planet you haven't been to?

Measure the motion of something that orbits the planet

How can you determine the chemical composition of the atomsphere of a planet you haven't been to?

Measure the spectra of light it emits

Neutron Star to supernova

More massive stars (usually more than 8 times the mass of the sun but less than 25 times the mass of the sun) end in a much more spectacular way than do smaller stars. We pick up where the red giant left off, but in this case, we are looking at a much more massive star. Now there is sufficient mass that collapse of the carbon core yields fusion to oxygen and neon. Subsequent collapse of that oxygen and neon yields fusion to silicon and sulfur, then followed by iron. Each time there is a shell outside the core that does not experience renewed fusion so the star finally resembles an onion with an outer layer of hydrogen and layers below that of successively heavier elements, up to iron from inside to outside---Fe, Si, O, Ne, C, He, H ---iron is the heaviest element that can be produced in this manner---all the heavier ones require a very large input of energy to be created by fusion of less massive elements When fusion to iron in the core shuts down (this happens within a day of when it started, things are happening so rapidly at this stage), gravity again takes over, and the core collapses in seconds. The outer layers collapse so violently that the whole core is heated to enormous temperatures and rebounds in an explosion that releases as much energy as all of the normal stars in a galaxy combined. One of the most recent nearby supernova was detected in 1987. The energy of a supernova is great enough to fuse lighter elements into all of the heavy elements (even those beyond iron in the Periodic Table). Our current best theory about the origin of all of the chemical elements heavier than atomic number 8 involves supernova explosions that have scattered the elements into interstellar space to become the raw materials for later generations of stars and planets. Supernova explosions also create supernova nebulae called supernova remnants. The Crab Nebula is an example of a supernova remnant from a supernova which was observed in 1054 A.D. After the supernova explosion occurs, a substantial amount of matter is still left after the outer layers have been ejected. This matter rapidly collapses gravitationally to the size of a small city. The resulting pressure is so large that the electrons and protons in the plasma are squeezed together to form neutrons. We call this a neutron star. This neutron star may have a strong magnetic field that accelerates charged particles, causing them to emit X-rays, radio waves, or visible light in searchlight-like beams. If those beams sweep past Earth's location as the neutron star rotates, we detect them as rapid pulses, and call them pulsars. The Crab Nebula contains a pulsar.

Consequences of global warming

Negative consequences: if humans keep doing what we have been, the temperature appears likely to keep going up several degrees, no matter what natural climate drivers do. ---In the past, sustained temperature changes of several degrees have been associated with things like mass extinctions, when most of the world's species quickly disappeared from the fossil record. ---This kind of massive upheaval would certainly affect the human population, as well, so even if large climate changes have happened naturally in the past, it is certainly something most people would want to avoid, if possible. Computer models of the Earth's climate system indicate that the temperature will continue to increase somewhat even if the amount of greenhouse gas concentrations in our atmosphere remain the same. ---With greater increases in greenhouse gases, we can expect even more warming. ---More frequent and more severe storms are predicted. ---Extinction of certain types of plants and animals are also predicted. ---Additionally, this increase in temperature will surely cause the sea level to rise. ------An increase of 3 meters would have a significant effect on our shorelines as the figure showing the southeast portion of the United States illustrates. ----------Such a large increase is not out of the question over the next century, and smaller changes (which are all but certain to occur) will have large impacts in low-lying coastal areas like Bangladesh and parts of Europe Postive consequences: ---Some areas will experience an increase in agricultural productivity with a small temperature increase ---But, scientists and economists who study such issues have generally concluded that the negative consequences will soon far outweigh the positive, if humans continue business as usual

The picture above shows the western part of North America. Some geologists believe that a continental rift zone is forming between Baja California and the rest of North America. If this rift zone were to continue, what would be the eventual result in this region and the Gulf of California?

New ocean

The Himalayan Mountains are found at the northern edge of the Indian plate. What direction is the plate moving?

North

Which of the following is a correct statement regarding the major source of energy for our sun?

Nuclear potential energy is converted into kinetic energy

3 types of seismic waves

P, S, and surface waves. They are generated whenever an earthquake occurs because the earth, on a large scale, is an elastic body. P waves are compression waves. S waves are shear waves. An easy way for me to remember this is compression has a "P" in it. Shear doesn't - it only has an "S". P and S waves travel through the deep interior of Earth and can be used to tell us something of Earth's nature. Because P and S waves travel with different speeds, the differences in their arrival times at different seismometers can be used to pinpoint the location of the earthquake that caused them. shear waves cannot travel through liquids but compression waves can travel through any medium. Also, both types of waves slow down in less rigid rock. Seismic waves are detected by a seismometer.

The outer planets are much more massive and much lower density than the inner planets. Why did they form that way?

Planets form from solids. Near the sun, only rock and metal were solid. Further away, low density material solidified

The outer planets are much more massive and much lower density than the inner planets. Why did they form that way?

Planets form from solids. Near the sun, only rock and metal were solid. Further away, low density material solidified. NOT: There was more gravitational force on denser material, so it ended up closer to the sun. The less dense material stayed further away.".

Measurement by Radar/laser ranging

Radar ranging and laser ranging are the methods of choice for smaller distances. With radar ranging, a radar beam is pointed at the object of interest (usually a space probe orbiting a planet or moon). The radar bounces off the object and the travel time is measured. Because the radar beam is electromagnetic radiation, we know the speed is the speed of light. With the time of flight and speed of light known, we are able to determine the distance to the object ---It takes 2.6 seconds for the light to get there and back. distance = time * velocity, put 1.3 s in for the time (1/2 of the round trip), 300,000 km/s as the speed and the resulting distance is 384,000 km. Radar ranging is a variation on the same technique when a radio waves are used instead of a laser beam

Measurement by Triangulation

Radar ranging is used for "small" distances, but the distance to even the closest of all other stars is amazing. If you made a model of part of the universe, with the earth one meter from the sun, the nearest star to the sun in your model would be 271,000 km away (roughly 70% of the way to the moon from Earth). By the way, in a model built to that scale, the sun would be only nine millimeters across, and the earth would be a speck about nine hundredth of a millimeter in diameter. Soon expressing distances to stars in kilometers becomes unwieldy and we use light years instead. (A light year is the distance light travels in one year—about 9.4 x 1012 km - just less than 6 trillion miles.) The distance to Proxima Centauri, the nearest star to our sun, is 4.3 light years. This distance can be determined by geometrical triangulation The distance which can be determined by triangulation depends only on accurate measurements, but not on any astronomical theory, so the more accurately the very small angle can be measured, the more accurately distances can be determined. The Hipparcos satellite, which completed its mission in 1996, increased the number of stars whose distance can be determined by triangulation to 120,000 and pushed the distance out to 3000 light years.

Which of the following is a method to find the absolute age of geologic events:

Radiometric dating

Which of the following is a method to find the absolute age of geologic events?

Radiometric dating

There are four major types of studies used to determine the structure and composition of the earth's interior. Which of the following is NOT one of these?

Relative dating based on erosion and deposition patterns

What happens to the sediment in the stream as the speed of the water decreases?

Sediment is dropped from the stream

distance ladder

Series of measurement techniques from shortest to furthest radar ranging--solar system geometrical triangulation using stellar parallax--1st rung on the ladder used by astronomers brightness-distance methods then doppler shift takes us the furthest distances

What provides evidence for a liquid core in the earth?

Shadow zone for S waves

What best describes, from surface to center, the chemically distinct layers of the earth

Silicates, dense oxides, iron

red giant

Sooner or later, the balance between gravitational collapse and internal pressure is disturbed when the supply of hydrogen in the core of the star diminishes and nuclear fusion in the core decreases and even subsides. As the internal pressure drops and gravitational collapse begins, a region outside the core becomes hot enough to support H-He fusion. This creates large internal pressures that overcome gravity and push the outer layers of the star away from the core. The star becomes very large and its surface cools until it is only red hot. The bright yellow sphere in the center is the core, and it consists mostly of helium. It is hot enough for hydrogen fusion, but the core is out of hydrogen, and it is not hot enough to support the fusion of helium to carbon. Because fusion is not occurring in the core of the star, gravity is able to overcome the internal pressure and the star begins to collapse. This heats up the volume just outside the core to temperatures at which hydrogen previously unable to undergo fusion now can fuse. In the image, hydrogen fusion is taking place in the orange-yellow ring around the center. This new fusion in this shell creates so much internal pressure that the outer layers of the star expand to dozens of times their original diameter.

Spiral galaxies typically contain large numbers of blue stars and bright nebulae, while elliptical galaxies typically contain mostly yellow and red stars. What can you conclude based on this information?

Spiral galaxies are actively forming new stars, while elliptical galaxies have little or no star formation going on

Which of the following statements is true concerning streams?

Streams carry more sediment when moving quickly since the stream has more kinetic energy which is used to carry more sediment

Which of the following statements is true concerning streams?

Streams carry more sediment when moving quickly since the stream has more kinetic energy which is used to carry more sediment.

What would be the best method to determine the distance to Proxima Centauri, the star nearest to our sun, at a distance of 4.3 light years away?

Take pictures of Proxima Centauri 6 months apart and measure how far it has traveled though the sky in that time relative to the background stars

What would be the best method to determine the distance to Proxima Centauri, the star nearest to our sun, at a distance of 4.3 light years away?

Take pictures of Proxima Centauri 6 months apart and measure how far it has traveled though the sky in that time relative to the background stars.

Continental Rifts

The East African Rift zone is an example of a continental rift zone. In this type of plate boundary, earthquakes are common. They are shallow but fairly severe. Volcanism also occurs. Mt. Kilimanjaro is an example of this. If the rifting continues, a sea will form between the two fragments. The Red Sea is an example of this stage. Eventually, a widening ocean in between the two continental fragments forms, such as the Atlantic Ocean.

Which of the following are true of the Jovian planets?

The Jovian planets are larger (both in volume and mass) than the terrestrial planets

Jovian planets

The Jovian planets consist of the four outer planets: Jupiter, Saturn, Neptune, and Uranus. They are characterized by large, low density, gaseous planets. They have large masses to go with their large sizes and very large atmospheres which appear to surround a rocky core. They all have ring systems, although Saturn's is most well known.

greenhouse gases and temp

The amount of the greenhouse gases changes with time. The amount of greenhouse gases in the atmosphere, as measured by ice cores, also correlates well with the temperature when the greenhouse gas concentrations are higher, the temperature is higher. However, while it is clear that the greenhouse gases fit the temperature patterns well and we know from the basic physics of radiation and greenhouse gases that more greenhouse gas in the atmosphere produces a higher temperature --- it happens that, during the glacial-interglacial cycles, the greenhouse gases were not the ultimate cause of warming and cooling. Instead, the greenhouse gases were operating as a positive feedback in the system ----some other factor (e.g., changes in the amount and distribution of incoming solar radiation) would start the ball rolling toward warmer or cooler temperatures, which would then cause more or less greenhouse gases to come out into the atmosphere, respectively, rather than being stored in the ocean or biosphere. ---This would enhance or suppress the greenhouse effect, and therefore cause even stronger warming and cooling trends.

Two main sequence stars, one red and one blue, are located the same distance from the Earth. If these stars are observed, what will you see?

The blue star is brighter.

Based on the natural cycles found in the graph, what would you predict the climate will be like in 50,000 years?

The climate will be cooler than it is now

moon

The closest non-manmade object to Earth in the solar system is our moon. If you look at the moon even without a telescope or binoculars, two distinct types of terrain can be seen: One is the bright, heavily cratered lunar highland. ---The lunar highland continues on behind on the "dark" side of the moon which never faces Earth. ---The second type of terrain is the darker, smoother terrain known as the maria. ---Using the principle of superposition we determine that the lunar highlands caused by intense meteor bombardment formed first across the entire moon's surface. ---The maria, which are chemically different than the highland, formed afterward by large asteroids crashing into the moon's surface and melting the surface. ---Lava flows filled in the large impact basins. Periodic impacts occurred later as indicated by the bright craters seen on top of the maria

How does the plate tectonic model account for the movement of continents?

The continents rest on rigid plates. The plates sit on a "mushy" layer which allows them to slide and move.

In the cross section below, A is an igneous rock formation radiometrically dated at 37 million years, and C is an igneous rock formation radiometrically dated at 24 million years. E is a fault. In the following questions you are asked to use the principles of relative dating to come to conclusions about the rock layers. The rock layers labeled B are tilted and folded. Which of the following is a possible explanation as to why? If you put the items depicted in the cross-section above in order from oldest to youngest, which of the following gives the correct order? Which principle of relative dating allows you to determine the relative age of formations C and D in the cross-section above? Rock C is dated at 25 million years old? How could that date have been determined? (the fissure--or number 4 in the picture)

The crust moved after they were deposited, tilting and folding them You can't tell what's youngest; more than one of the above could be correct." cross cutting By counting the number of microscopic cracks formed by fission products.

Which of the Milankovitch cycles has the biggest impact on climate?

The cycle that last 100,000 years (changes in the shape of the orbit

planets

The eight major planets, as well as their moons, are remarkably diverse in terms of their sizes, chemical makeup, and visible surface and geologic features. These eight planets are broken into two separate categories: the terrestrial planets (the planets similar to Earth) and the Jovian planets (the planets similar to Jupiter).

Which of the following correctly describes how energy from the sun drives the hydrologic cycle on Earth?

The energy from the sun is transferred by radiation through the atmosphere to the oceans. This radiation is strongest near the equator, and most evaporation occurs there

Which of the following statements best explains how a double moraine could form?

The glacier initially advanced to the position of the leftmost moraine, then receded (melted) back to the right. This was followed by a second episode of advance to the left, but it halted before reaching the moraine that had already been deposited

Main Sequence star

The hydrogen burning, carbon fusion stage--where our sun is at now Most of interstellar space is a better vacuum than we can produce in laboratories on earth. The few atoms in a cubic meter of it are heated to very high temperatures by ultraviolet radiation from surrounding stars. Here and there, however, are fairly dense clouds left over from galaxy formation. These clouds are dense enough to shield their interiors from this radiation. Therefore, they are fairly cool, and molecules can form. Like terrestrial clouds, they are clumpy and irregular, and they tend to collapse in places because of local concentrations of gas. Assuming the protostar has enough mass and fusion begins and continues, the outward pressure generated inside the star matches the force of gravity pulling inward. A balance is struck and the star stops collapsing. This marks the beginning of its mature life. Most of the life of a star—about 90% of it—is spent in this stage called the main sequence phase. Deep in the star, hydrogen is fused to form helium. Astronomers often call this the hydrogen "burning" phase of a star's life. Hydrogen is not really being burned like we know it, but fusing the hydrogen together produces a lot more energy! The heat produced radiates from the core outward, eventually reaching a zone of convection, which transfers the heat to the surface of the star. This is what we see—not the nuclear fusion, but the light that results from transmitting that energy to the surface. The temperature at the surface is far below the temperature required for fusion. How long the star remains in this main sequence stage depends upon its mass. If it is a very massive star, then it will fuse its supply of fuel very rapidly and last a relatively short time. The smallest stars last the longest. A star like our sun is pretty average. It will last for about 10 billion years before it leaves maturity for the next stage of its existence. This means according to our best estimates, we have 5 billion years left.

irregular galaxies

The least common type of galaxy (about five percent) is known as the irregular galaxy. These galaxies are just the oddballs. Their shapes can vary and are often the result of a collision with another galaxy. Often active star-forming regions are found in irregular galaxies.

When the absorption spectrum of light from distant galaxies is measured, what is found?

The lines in the absorption spectrum are shifted towards the red end of the spectrum, with light from the most distant galaxies being shifted by the largest amount.

Which statement is evidence for the Big Bang model?

The microwave background radiation that fills the universe is left over from the early stages of the expansion process.

elliptical galaxies

The next most common type of galaxy (at about twenty percent) is the elliptical galaxy. Elliptical galaxies have a dense central core of yellow and red stars but lack the spiral arms of a spiral galaxy Elliptical galaxies vary greatly in size. Most elliptical galaxies have little gas and dust along with a general lack of active star-forming regions which are found in the spiral arms of spiral galaxies and are indicated by gas and dust and blue stars.

Suppose you have a rock sample containing uranium, some of which is 235235U, which decays to 207207Pb with a half life of 713 million years. You find that only 25% of the original 235235U is still present, the rest having decayed to 207207Pb.

The rock is 1.4 billion years old.

If you compare the gravitational force holding two stars with different masses together what is true?

The star with larger mass experiences a larger gravitational force.

If you compare the amount of fusion necessary to balance the inward gravitational force on two different stars with two different masses, what will you find?

The star with larger mass will require more fusion to balance gravity

terrestrial planets

The terrestrial planets consist of the four inner planets: Mercury, Venus, Earth, and Mars. They are characterized by small, dense, rocky planets. They have hard surfaces and the comparatively small atmospheres (at least compared to the Jovian planets).

Which of the following provides proxy data that can be used to estimate temperatures in ancient climates?

The thickness of tree rings in ancient wood

Hydrologic system

The water cycle system of fluids--liquids and gases=fluids --ice glaciers behave like fluids --affects deserts--groundwater, water that fills the pore spaces in the rocks or loose sediment beneath the earth's surface --streams/running water and reservoirs of standing water (lakes and oceans) The fluids in the hydrologic system are not static. --They move constantly, and there is a general systematic trend in their motions Fluids denser than their surroundings sink while those less dense rise. --This results in convection currents. --As water evaporates to water vapor, convection currents in the atmosphere move it, and as it cools, it condenses to liquid or solid water, which then falls to the surface as rain and snow.

The principle reason why the inner planets and outer have very different compositions is:

Their original positions in the young solar nebula.

Which of the following is true about our galaxy in relation to the rest of the universe?

There are a few dozen close galaxies that are moving towards the Milky Way or orbiting around it. But the rest of the galaxies are moving away

What is the defining feature of a greenhouse gas?

They absorb IR photons at frequences that are radiated by the Earth

alluvial fan

This looks like a delta but with one significant difference - instead of deposition occurring underwater as it does with a delta, the deposition occurs on the valley floor. To distinguish this from a delta, which by definition is a deposit in a body of water, we call this an alluvial fan Alluvium is a general word for material that is stream-deposited. You can see alluvial fans a lot in parts of the world that are both mountainous and arid, such as much of the American west

Solar System mass

We can determine the mass of any planet by measuring the gravitational acceleration Heavy objects and light objects dropped near the surface of the Earth all fall at the same rate. That gravitational acceleration is determined by the radius of the Earth and the mass of the Earth, and does not depend on the mass of the object being dropped. The same is true for any planet. If you measure the gravitational acceleration, you can calculate the mass of the planet. Gravity is what keeps things in orbit. An orbiting object is actually falling toward the thing it orbits. we know the masses of the planets and other objects in our solar system because: ---All we need to do in order to figure out the mass of a planet is to measure the planet's gravitational acceleration. ---An orbiting object is falling. So by measuring the orbit of any orbiting object, we know the gravitational acceleration.

cosmological redshift

When Edwin Hubble used Cepheid variable stars to gauge the distances to several galaxies, he was able to show conclusively for the first time that there were stars independent of our own galaxy and far from it. 1) He found that the spectra of distant galaxies were shifted toward the red end of the spectrum. The dark lines on these continuous spectra are absorption lines that are characteristic of the chemical elements that make up stars. The lower spectrum represents one from a typical nearby star. Hubble observed that, in the spectra of distant galaxies these lines are shifted toward the red end. ------Remember that a shift in the observed frequency indicates that the source and the observer are in motion relative to each other. If the shift is toward lower frequencies (red light, in this case), the source is moving away from the observer. If the shift is toward higher frequencies (blue light, in this case), the source is moving toward the observer. Also, the faster the source moves away from the observer, the greater the shift becomes ------Hubble discovered that the further away a galaxy is, as measured using Cepheid variables, the faster it is receding - that is, the greater its redshift. This cosmological redshift and its linear relationship between speed and distance adds another rung to our distance ladder. If we are able to measure the redshift of a galaxy, using the relationship between redshift and distance, the distance can be calculated. ------Cosmological redshift is a small change in the position of lines in the spectrum of the galaxy (or object, such as a quasar, for example). It is typically impossible to see any actual change in color. 2) The second implication of Hubble's distance measurements is that the redshift observed for all galaxies outside the Local Group is interpreted as evidence for an expanding universe. If galaxies were in random motion, one would expect random redshift and blueshift measurements to be made for the various galaxies. ------If all of the observed galaxies are moving away from us (except those 20 or so close enough to be gravitationally bound to our own galaxy in the Local Group), then one possible explanation is that we are in the center of the universe. This is not a very satisfying explanation for cosmologists, because it places us in an inexplicably special place, to the exclusion of everything else. ------Besides, there is a much more acceptable proposition: Imagine that you are about to blow up a balloon. However, before you blow up the balloon, you decide to draw little dots all over the balloon which are uniformly distributed on it. Now you blow it up.....Did you notice that the galaxies got further from one another as the sphere expanded? If you were a small inhabitant of one galaxy and could see all the other galaxies, you would conclude, correctly, that all the others are receding from yours. Yet, no galaxy would be in the center of anything. --------Hubble concluded from his observations that the universe, the entire fabric of spacetime, is expanding and taking the galaxies with it. So in a way, the cosmological redshift is not so much a Doppler effect as it is an expansion effect—the galaxies are not rushing away from each other, but are being carried apart as space expands. Running that concept backward implies that everything in the universe began in a very small volume and then "exploded." That explosion is termed the Big Bang, and it is the currently preferred model of cosmology because it explains what we observe very well. Not only are all of the galaxies moving away, but the farthest are moving the fastest.

Rock C is 24 million years old. What does this age represent?

When the rock solidified.

The Hawaiian islands are a linear island chain found in the middle of the pacific ocean. While all of the islands are volcanic in origin, the only active volcanos are found on the largest island. What is the most likely cause for this island chain?

a hot spot

protostar

a huge cloud of gas and dust—mostly hydrogen but with small amounts of other elements mixed in—that is loosely held together by its own gravitational attraction The few atoms in a cubic meter of space vacuum are heated to very high temperatures by ultraviolet radiation from surrounding stars. Here and there, however, are fairly dense clouds left over from galaxy formation. These clouds are dense enough to shield their interiors from this radiation. Therefore, they are fairly cool, and molecules can form. Like terrestrial clouds, they are clumpy and irregular, and they tend to collapse in places because of local concentrations of gas. globules isolated from the cloud, bound together by their own gravity, will continue to collapse to become stars. But in this early state they are huge, and called protostars (or early stars) as these protostars collapse, gravitational energy decreases and kinetic energy increases, temp rises, collisions between atoms increase, the cloud begins to glow from thermal emission. not powered by nuclear fusion yet so not technically a star yet

Which of the following is a description of the principle of Cross Cutting?

a younger layer slices through older surrounding layers

The shadow zone for P waves provides evidence for...

abrupt density changes at Earth's mantle-core boundary

Match the following stage in the life of a star with the size of star. A red giant is

all stars go through this stage

What feature is in the image below? Which of the following caused the feature above?

alluvial fan running water

The age of the Earth is approximately 4.6 billion years. This is an example of:

an absolute age

Which of the following forces apply to the movement of a magma body?

buoyant force gravity

What best describes the chemical composition of Earth's crust and core?

crust: granite and basalt core:iron and nickel

weather

describes the fluctuations in temperature, rainfall, etc. over short time scales but doesn't necessarily describe the climate

mass of planets

determine the mass of any planet by measuring the gravitational acceleration.

Match the astronomical distance measuring techniques with their approximate ranges. Triangulation:

distances up to about 1000 light years

Match the astronomical distance measuring techniques with their approximate ranges. Radar Ranging:

distances within solar system

The picture below shows the plates. The Cascade mountain range, famous for its volcanoes, is found on the west coast of North America. What direction is the Juan De Fuca plate moving assuming that the North American Plate is stationary?

east

When you compare the pictures of spiral, elliptical, and irregular galaxies, which have the largest percentage of red and yellow stars compared to blue stars?

elliptical

Which type of galaxy has the oldest average age of stars?

elliptical

P-waves cannot travel through the liquid outer core of the earth. true or false

false

Solar System composition

frequencies bounce off molecules of different gases in the atmosphere and tell us the composition of the pnkects

The light we see at the sun's surface is directly due to:

fusion

The force(s) causing a protostar to collapse is (are)

gravitational force

Protostars give off infra-red light. The ultimate source of light energy emitted by a protostar is:

gravitational potential energy

According to the big bang model, how do the temperature, density and structures found very early in the universe compare to those now? The earliest stages have

higher temperatures, higher densities, fundamental particles (quarks and electrons)

siccar point scotland

horizontal layers on top left (A) truncating or cutting off vertical layers on bottom right (B), with some inclusions of B in A. chronological order of events: 1) deposition of B 2) deformation (tilting) of B 3) erosion of B 4) deposition of A 5) deformation (tilting) of A 6) erosion of A

Which of the following is the fuel for the sun's energy?

hydrogen

Most stars spend the greater part of their active life as a

hydrogen burning star.

Most stars spend the greater part of their active life as a:

hydrogen/proton-fusing star

Match the following rocks with a rock classification. Granite is

igneous

Molecular clouds

in empty space between stars, there are small amounts of matter, mostly hydrogen with some helium and trace amounts of other atoms and molecules Random fluctuations in density allow gravity to pull this interstellar medium together into huge clouds of gas. Within these clouds, gravity can pull the material in the densest regions together to form the beginnings of a star.

Elements heavier than iron found on the Earth are produced

in supernova explosions

Can you explain why a river valley would be V-shaped? Where does a stream move the fastest?

in the middle

What happens when water subducted during plate tectonics chemically combines with the surrounding rock?

it makes it melt easier

Which mechanical layer of the Earth is rigid and completely solid?

lithosphere

Which of the following features would you expect to find at a converging plate boundary between two continental plates?

look this up

Which chemical layer has a composition of peridotite and dense oxides?

mantle

Match the following stage in the life of a star with the size of star. A supernova is

medium and large, but not small stars

Which mechanical layer of the Earth is plastic and completely solid?

mesosphere

In order to form a planet, individual atoms and molecules must first stick together. What types of materials will be solid in the inner parts of the disk?

metallic ionic

Match the following rocks with a rock classification. Marble is

metamorphic

The life cycle of stars

molecular cloud---condenses and collapses in on itself to form a protostar ---turns into a brown dwarf if small cloud ---if big cloud--releases energy in the form of light, heat, and radiation---nuclear fusion---hydrogen to helium ---Eventually runs out of hydrogen and condenses, getting hotter---carbon fusion (main sequence star) ---the star will get so hot that the outer layers expand, becoming a red giant ---runs out of helium so condenses again, but then expands once more suddenly--throwing off it's outer layers- --creating a nebula with a small, dense white dwarf in the center that releases stored up thermal energy ---eventually it will cool and become a black dwarf ---if the star is big enough it will keep contracting and expanding (heat and going from element to element) and eventually die---supernova creates heavier elements, and explodes them into space ---if small star, compacts into a sphere roughly 14 miles in diameter ---if big star, the star will become a black hole--packing the mass of 3 or 4 sounds into a tiny tiny point, sucking everything in

Part of the upper mantle, called the asthenosphere, is unique because

most of its material is near the melting point.

The cosmological red shift seems to indicate that other galaxies are...

moving away from the Milky Way galaxy with those farthest away moving the fastes

The cosmological red shift seems to indicate that other galaxies are

moving away from the Milky Way galaxy with those farthest away moving the fastest

The major source of all surface water on the continents is

precipitation

Which of the following methods are used to measure distances between objects in our own solar system?

radar ranging triangulation

Greenhouse gases change how the Earth transfers heat back out into space. Which of the following methods of heat transfer do they impact

radiation

The energy of the sun reaches Earth by:

radiation

Which of the following is a description of the principle of Original Horizontality?

rock layers become tilted or buckled and folded after the layers were originally formed

The most important erosional agent of the hydrologic system is

running water

Match the following rocks with a rock classification. Limestone is

sedimentary

What best describes, from surface to center, the mechanically distinct layers of the earth?

solid, mushy, plastic solid, liquid metal, solid metal

Galaxies

stars positively exist outside of our galaxy. It turns out that there are many, many galaxies. Galaxies are classified according to how they look. Types of galaxies: ---spiral galaxies--either spiral or barred spiral ---elliptical galaxies ---irregular galaxies Our galaxy is part of a group that includes about 60 galaxies, three large spiral galaxies, several irregular galaxies, and a lot of dwarf eliptical galaxies.

The primary source of evidence that the earth is a differentiated planet comes from the study of...

the behavior of seismic waves

The energy that powers the sun's glow originates in:

the core

The forces opposing the expansion of the universe are due to

the gravitational interaction

Below are pictures of several different igneous rocks. Which of the igneous rocks cooled quickly above Earth's surface?

the ones with no obvious minerals showing

When measuring the positions of the lines in the absorption spectrum of a certain star, the lines are all shifted toward the red end of the spectrum. This means:

the star is getting farther away from the earth

In the picture below, each of the mechanical layers of the earth is indicated with a letter and an arrow. The lithosphere is layer:

the very outermost layer

In the picture below, each of the mechanical layers of the earth is indicated with a letter and an arrow. The mesosphere is layer:

third to deepest, thickest layer

The distances to the nearest 100,000 or so stars can be measured by which of the following techniques?

triangulation

Fast moving water can carry more sediment than slow moving water. true or false

true

Measurement by Doppler shift

using spectral lines in the light emitted by stars to tell whether stars are moving toward or away from the earth

When you compare water vapor and carbon dioxide in the graph above, which is the stronger greenhouse gas?

water vapor---has more absorption lines on the graph

The picture above shows two different rock types. Select the sequence from youngest to oldest Which principle of relative dating was used to provide the correct relative dates of these rocks?

youngest is the one that did the cutting cross cutting

faunal succession What interval(s) of time, as indicated by the diagram, is represented by the simultaneous existence of these two animals (the clam shell and the t-rex head)?

the pink strip A and the middle tan strip

parts of the hydrologic system that have the greatest effect on earth's surface

streams, ice, and groundwater While wind and reservoirs such as oceans and lakes certainly affect the Earth, their consequences, as far as erosion and deposition is more limited to very arid areas (for wind) or near the shorelines (for oceans and lakes)

Where will the stream remove the most material?

in the middle

The picture above shows three different types of rocks A and B. Which principle of relative dating can be used to provide the relative dates of rocks A and B?

inclusions

Compare and contrast the following pairs of rocks (refer to images found in Textbook on pg 381). Explain what is the same and different, and why. (a) Granite and Rhyolite (b) Rhyolite and Basalt (c) Granite and granitic gneiss (d) Limestone and marble

A) granite vs rhyolite -granite--larger minerals--the rock cooled below the surface of the earth--the cooling time was much longer, allowing larger minerals to form. -granite--Igneous--crystallized from magma -granite--plutonic--the cooling took place below ground -rhyolite--small minerals--cooled quickly as it hit the air/water above ground -rhyolite--igneous--crystallized from magma -rhyolite--volcanic--the cooling took place above ground B) rhyolite vs basalt -rhyolite--small minerals--cooled quickly as it hit the air/water above ground -rhyolite--igneous--crystallized from magma -rhyolite--volcanic--cooling took place above ground -rhyolite--light color--contains lots of silica -basalt--small minerals--cooled quickly above the ground -basalt--igneous--crystallized from magma -basalt--volcanic--cooling took place above ground -basalt--dark color--contains iron C) Granite vs granitic gneiss -granite--igneous--crystallized from magma -granite--plutonic--the cooling took place below ground -granite--larger minerals--the rock cooled below the surface of the earth--the cooling time was much longer, allowing larger minerals to form. -granite--unfoliated--doesn't have stripes or layers -granitic gneiss--metamorphic--originally igneous rock subjected to heat and pressure -granitic gneiss--plutonic--cooling took place below ground -granitic gneiss--larger minerals--cooled below the surface of the earth--the cooling time was much longer, allowing larger minerals to form---similar mineral composition to original granite rock -granitic gneiss--foliated--gravity causes pressure from one direction on the rock, causing layers or stripes to form D) Limestone vs Marble -limestone--sedimentary rock--form in layers from sediment by chemical precipitation -limestone--unfoliated--doesn't have stripes or layers -marble--metamorphic rock--formed when limestone is heated and squeezed underground, lowering the energy of the minerals -marble--foliated--gravity causes pressure from one direction on the rock, causing layers or stripes

Continental Drift

Alfred Wegener put a large body of evidence together and formulated a theory called Continental Drift. Wegener gave the name Pangaea to the supercontinent that he envisioned—it is from two Greek words meaning "all earth". Because radiometric dating had not become a reliable part of the geological toolbox by 1915, Wegener would not have known how long ago Pangaea began to break up, but we now place it at about 200 million years ago. Evidences for Pangaea: 1. Jigsaw fit of the continents - While small amount of wear and tear has occurred along the edges as well as later deposition of sediment by major rivers such as the Amazon, if North America and Europe and South America and Africa are placed together by their continental shelves, the fit is remarkable. 2. Structural trends of the continents when the continents are put back together - The Brazilian shield matches up with the shield in northwestern Africa. Other trends exist, as well, e.g., the Appalachians continue into the Ural Mountains in Europe. Not only do the locations of the trends match but the ages match as well. 3. Paleontological (fossil) evidence - The Glossopteris flora are a group of plants fossil evidence of which may be found in South America, Africa, Australia, and India. These locations are too distant from one another for the seeds of these plants to have spread so far, and their climates are too different to be able to support such similar plants. Additionally, the same fresh water animals are found in both South Africa and South America, but they could not have crossed a large ocean. 4. Paleoclimatic evidence - Evidence of a large continental glacier can be found in South America, South Africa, India, and Australia. Perhaps you say, o.k., there are the Andes in South America and the Himalayas in India, that would explain the pattern in those continents. It might, except the ancient remains are flowing uphill relative to today's mountains as the figure shows. When the continents are placed in the positions suggested by Pangaea, the explanation of the flow of the continental glaciers makes more sense. 5. Paleomagnetic evidence - In basalt lava flows, there is a mineral called magnetite. This mineral acts as a tiny compass. While the lava is still molten, the magnetite is free to move about and line up with the strongest magnetic field around - in the case of lava flows, Earth's magnetic field. Once the temperature drops below a certain point, the magnetite is frozen in place and serves as a marker of Earth's magnetic field at the time of the eruption. Magnetite from ancient lava flows that occurred at the time of Pangaea all point in different directions now. Either the Earth had multiple magnetic poles at that time (not likely given what we know about the source of Earth's magnetic field) or the lava flows themselves were moved. The magnetic fields all line up in the Pangaea configuration.

rock cycle

An igneous rock can be weathered away and the clasts can form a sedimentary rock such as a sandstone An igneous rock can also be subjected to heat and pressure and metamorphism occurs to form a metamorphic rock Sedimentary rocks can also experience metamorphism or erosion to form metamorphic or sedimentary rocks as well. The same process can occur with metamorphic rocks.

water table

At some depth under virtually all land surfaces on earth, there is water in the pore spaces of the rocks. The depth at which this saturation occurs is called the water table. The water table is related to surface drainage If the stream dries up, it is because the water table is below the level of the stream channel. In that case, the stream bed would feed the water table, instead of the other way around.

Foliation

Because gravity pulls down, not sideways, the pressure typically comes from one direction rather than being uniform in all directions. ---This often leads to stripes and layers, called foliation forming in the rock. -----stripes---foliated -----spots---non-foliated While foliation occurs in many metamorphic rocks, not all metamorphic rocks exhibit this layering or banding. ---Marble is an example of a metamorphic rock that often doesn't have foliation. It is called a non-foliated rock ---Other metamorphic rocks, such as gneiss, are foliated. Using foliation it is possible to determine the direction of the unbalanced force on the rock. ---An unbalanced force due to the pressure causing the metamorphism is placed upon the rock. ---The minerals are "squished" to the side due to this force. ---This squishing causes the foliation and it is perpendicular to the applied force. Examples: marble, gneiss, and schist

greenhouse gases

Besides the amount of solar radiation Earth receives, the other factor which affects the global climate is how much heat is radiated back to space. This heat radiated back is largely affected by greenhouse gases. Greenhouse gases are gases which allow the visible light (and higher energy light) in to the surface of the Earth but block the infrared light from escaping back to space. Carbon dioxide (CO22), water (H22O), methane (CH44), and nitrous oxide (N22O) are all important greenhouse gases on Earth. ---These gases are very important to life on Earth. ---Without them, the temperature on Earth would be much lower than it currently is.

Lithosphere and Asthenosphere

Discontinuity between the lithosphere and the asthenosphere. The lithosphere is the top area of Earth which is rigid and includes the crust and the uppermost mantle. The asthenosphere is below the lithosphere and is the region of the upper mantle where the temperature and pressure is just right to make the peridotite semi-molten. The asthenosphere is not completely solid nor is it completely liquid. --"mushy" or a toothpaste consistency.

streams

Erosion by streams is the most effective agent in lowering the elevations of the continents over long time periods and the effects of stream erosion can be seen almost everywhere geologists call any confined body of running water a stream, even if you might call a large one, a river, and a small one, a creek. streams that only carry water during flash floods are called "intermittent streams." egypt dam prevents nutrients from coming to Egypt, delta coastline receding-being swallowed up by the sea --mississippi delta and Egypt delta ex. fertile crescent--created by streams --floodplain--dropped nutrient rich soil right here ex. flood of 1927 floodplain alluvial plan--streams that slow down coming off a slope and fan out and drop their sediment

current climate measurements

First, the climate has been changing, lately. ---Sea level has increased ---arctic sea ice and alpine glaciers have been gradually melting (while some alpine glaciers are advancing, most are receding) ---thermometer measurements show a net increase in global temperature Second, human influences have been dominating natural causes of climate change for the past few decades. ---While natural climate drivers like solar radiation and volcanoes have been holding steady or even pushing the Earth toward cooler temperatures, humans have been pumping enormous amounts of extra greenhouse gases into the atmosphere. ---This increases the greenhouse effect and pushes the Earth toward warmer temperatures. ---The extra greenhouse gases have been winning, and the Earth has been steadily warming, despite nature pushing the other direction.

Sedimentary rocks

Form in layers. As sediment is deposited in the form of erosional debris of other rocks, chemical precipitates, or organic material, the layers on the bottom are compressed, and the particles are cemented together into rock by minerals precipitated from ground water. Two ways that sediment can form: physical weathering ---mostly due to water---flowing or freezing ---The elements and ions in the water can also precipitate to form the cement between the clasts formed by physical weathering. chemical weathering ---when acidic water dissolves the rock (dissolution) ---water now has dissolved elements in it derived from the rock---elements in the water can form new sedimentary rocks ---hydrolysis and oxidation---the formation of a new mineral occurs as well as the release of ions to the water---where clay minerals come from biological activity ---Organisms making CaCO33 are responsible for making most limestones. ---Limestone, rock salt, and gypsum (used in wallboard) are examples of sedimentary rocks formed by chemical precipitation. examples of sedimentary rocks---sandstone, conglomerate, and shale

ice/glaciers

Glaciers can be classified as either alpine glaciers or continental glaciers. Alpine glaciers occupy valleys initially carved by streams--they "scoop out" the valleys they occupy to make them U-shaped ---Because a glacier is made of ice, the ice can just pick up sediment of all sizes. This sediment scours the sides of the valleys to the U-shape. ---Alpine glaciers tend to produce very angular, sharp, and abrupt topography Continental glaciers are sheets of ice that cover very large areas. ---Just as an alpine glacier picks up sediment of all sizes, a continental glacier follows the same pattern. ---Large boulders can be carried along with the ice leaving characteristic erosion streaks behind when the glacier finally melts. ---It is these streaks that Wegener and others used as evidence to support the idea of continental drift and plate tectonics Both are very effective at shaping landscapes, but they are not as geographically widespread as streams. ex. alpine glaciers-- Ural mountains-- In heavily glaciated mountains, the adjacent U-shaped valleys meet in sharp, angular ridges. The clouds fill many of the U-shaped valleys, but the ridges between them are still visible. ex. continental glaciers--Canadian Shield--topography that has been "planed off" by the abrasion of a continental glacier.

metamorphic rocks

If rocks are buried deeply enough and subjected to high temperatures (without melting) and pressures, chemical reactions may take place that alter the rock into something recognizably different from what it was often formed along the contact between a body of magma and the surrounding rock and also at convergent plate boundaries ---At these locations, there is enough heat and pressure to cause the intense temperatures and/or pressures needed to cause the minerals in the rock to change to lower its energy and/or increase its entropy ---This metamorphism occurs deep within Earth's crust. ---Then, other tectonic forces cause the metamorphic rocks to be raised and subsequently exposed by erosion

stream erosion and stream deposition

If you look at a single stream tributary and its main stream, the tributary and the main stream almost always meet at the same elevation ---This is very strong evidence that the streams have carved their valleys -----the water does not just happen to occupy the topographically low places, but instead, the streams have eroded the land to create the low places This erosion occurs in two ways: downcutting and slope retreat Streams erode the land because they carry material such as sand and pebbles that wear away at the sides and bottom of stream channels during periods of rapid water flow

Igneous rocks

Igneous rocks crystallize from magma. If the rocks cool below the surface of Earth, the igneous rock is called a plutonic rock ---Because it is below ground, the cooling time is much longer. This additional time allows larger minerals to form. Granite, diorite, and gabbro shown in the pictures below, are examples of plutonic rocks When the cooling takes place above the ground, the igneous rock is termed a volcanic rock. ---Because the rock cools quickly as it hits the much cooler air or water, the minerals are much smaller - often microscopic. ---Basalt, pumice, and obsidian are examples of volcanic rocks. ---In fact, pumice and obsidian cool so quickly that they are called glassy volcanic rocks - minerals did not have time to form at all in pumice and obsidian Need to know granite and basalt---igneous rocks At places such as convergent plate boundaries where an oceanic plate is subducted, water can be added to overlying rock through the heating of water-bearing minerals. These water-bearing minerals were formed earlier at mid-oceanic ridges by hydrothermal circulation. The addition of water is significant. ---This water, released as the minerals melt and break down, changes the chemical makeup of the overlying rock. It allows the rock to melt at a lower temperature and become more buoyant. As this occurs, the resulting magma begins to rise. If the magma does not rise to the surface, plutonic rocks are formed. An ascent to the surface creates volcanic rocks

Hot Spots

In many places on earth, volcanic activity occurs that is apparently not linked to plate boundaries; or if it is, the activity greatly exceeds what is typical for the boundary. Examples are the Hawaiian Island chain (in the middle of an oceanic plate), Iceland (on an oceanic divergent boundary), and Yellowstone (in a continental plate). These are interpreted as being caused by heat from a source deep in the mantle (a mantle plume) over which the lithosphere moves. Over time, this creates a linear chain of volcanoes. We call these places "hot spots".

mid atlantic ridge magnetic

In the 1950s it became possible to map the ocean floor with greater precision. A large mountain range was discovered in the middle of the Atlantic Ocean. It was named the Mid-Atlantic Ridge. As part of the mapping, magnetic readings were also taken. When the rocks at the bottom of the ocean are examined with a remote magnetometer, this is what is found: The colored areas indicate rocks that show normal polarity, and the grey areas in between the colors represent rocks in which the magnetic field is reversed so the seafloor basalts exhibits "stripes" of normal and reverse polarity which are parallel to the oceanic ridge. This discovery, along with the observation of the similar phenomenon in layered basalt flows on the continents that we just discussed, led to the recognition that : (1) the earth's magnetic field has repeatedly reversed itself, and (2) the seafloor is spreading apart at the ridge. Each set of two matched stripes represented basalt lava that had been erupted during a single episode of magnetic orientation and then been split in two as the sea floor had spread away from the ridge. This solves the problem of how to get the continents to "drift" and opens up Wegener's theory to examination again.

Moraines

Just as a stream erodes and deposits sediment, a glacier will both erode and deposit sediment as well both types of glaciers deposit sediment in ridges called moraines. Moraines are characterized by angular and unsorted debris —angular because, unlike water, glaciers do not round pieces of rock —unsorted because ice carries sediment of all sizes and drops it wherever the ice melts. two ridges of sediment- a double moraine

ice cores

Much of our information about past temperatures and greenhouse gas concentrations over the last several hundred thousand years comes from ice cores taken from continental glaciers in Greenland and Antarctica. The ice has annual layers, so we know how old each layer is, and certain measurements can be made on these layers to infer past climate conditions. Ex. the Vostok Station in Antarctica, one of the sites where ice core drilling has taken place. The photo of the ice cores shows summer layers (bright white areas) and winter layers (darker ice.). figure 31.5 in ch 31 Besides studying ice cores, there are other ways that we know the climate has changed in the past. ---Studies of Arctic Ocean sediment tell us there have been periods of increased ice. -------During these periods coarse sediment is carried by the ice and dumped in the central Arctic Ocean. ---We also have geologic evidence that the sea level has risen and fallen in the past - sometimes with changes of hundreds of meters. -------This is due both climate change and plate tectonics.

Continental-continental plate boundary

None of the plates is either entirely continental or entirely oceanic, although the Pacific Plate comes close to being a solely oceanic plate. So eventually an oceanic-continental plate boundary can become a continental-continental plate boundary as the continent that was on the oceanic plate being subducted runs into the plate boundary. When this occurs, subduction stops - the continental material is too thick and not dense enough to be subducted. However, the plate movement doesn't have to stop. The two continents continue to press against each other making higher and higher folded mountain belts. The Appalachian Mountains and Sierra Nevada Mountains are examples where this occurred in the past. The Himalayas are an example of where this type of plate boundary is still active. Severe but fairly shallow earthquakes are also common. Volcanoes, however, do not generally form. This type of plate boundary is where continental accretion occurs: ---Continents are collections of smaller pieces that have been assembled through plate tectonic collisions over time. ---When continental collisions occur, the two slabs of continental lithosphere are "welded" or "sutured" together, resulting in a thickened section of lithosphere and a folded mountain belt. ---Eventually the mountains are worn away by erosion, but the continent is larger than it was before the collision. ---Continents grow by accretion as this process is repeated. The geologic ages of the rocks in any one block of accreted continental crust tend to be about the same, so we can recognize the boundaries of the accreted blocks by looking at the ages of the rocks.

kuril islands is an example of what kind of plate boundary? What type of earthquakes would you expect to find here? What type of landforms would you expect to find at this plate boundary? Based upon the geologic map, what plate is being subducted?

Oceanic-oceanic convergent zone Frequent, severe, and varying in depth from shallow to deep The volcanoes can break above the surface of the water and form islands. Since the islands form in arcs that follow the trench, they are called island arcs, and linear island chains The southeast plate

Relative dating principles

Original Horizontality - Rocks are deposited in horizontal layers. Any tilting, folding, other deformations occurred after the initial deposition. Superposition - The rocks on the bottom are older than the rocks on the top (unless the rock units have been overturned completely). The bottom layers were deposited and then the next layers were deposited on top of it. Note that this doesn't mean the deposition of the sediment has been continuous. There might have been layers that have been eroded away. Cross-cutting - Rock that is cut is older than the other rock, fault, crack, etc. that did the cutting. The cut rock had to exist first in order to be cut. Inclusions - Rock that is included (surrounded by) other rock must be older than the surrounding rock. Faunal succession - Fossil assemblages (groups) found in sedimentary rocks are diagnostic of rock age. Extinct assemblages never appear in younger rock. Examples: Using these principles, it is possible to decipher the sequence of geologic events. None of the principles provide direct evidence for the age of anything but they allow the order of events to be worked out. Sometimes the sequence of events can be fairly straightforward and sometimes it can be pretty tricky - kind of like the range that exists with Sudoku or crossword puzzles. Let's look at some examples to learn how geologists use these principles. Those who study fossils for use in relative dating (or for a host of other reasons) are called paleontologists. Often times they must examine minute details of a fossil to determine its species and the time period during which it lived.

Mantle

Pieces of the upper mantle that have been carried up to the surface in volcanic eruptions have been found. These pieces are a relatively dense silicate called peridotite. Also, about 80% of the meteorites seen to fall on earth are stony meteorites that have an approximate peridotitic composition. It's believed that these meteorites represent remnants of planet-size parent bodies disrupted in the early history of the solar system and that are now orbiting the sun. Laboratory experiments indicate that peridotite is unstable at the conditions of the lower mantle called the mesosphere. At these conditions, peridotite undergoes chemical reactions that yield compounds called dense oxides that have denser packing of atoms. This accounts for the seismic discontinuities within the mesosphere.

Radiometric dating

Radiometric dating is based on the assumption that the half-lives of radioactive isotopes do not change with time. If the amount of un-decayed radioactive isotope of some element in a rock can be determined, along with the amount of its daughter product, then, in principle, the age of the rock can be calculated. The methods by which the amounts of parent and daughter isotopes in a rock are determined for radiometric dating involve meticulous and sometimes tedious laboratory procedures as well as some corrections for things such as the amount of daughter isotope that was originally in the rock, but they are done routinely. Once the amounts of remaining parent and daughter isotopes in the rock are known, a decay curve can be used to determine the age of the rock. So what does the "age" of a rock mean? Well, that depends. ---If the rock is igneous, then it is the time since the rock formed from molten material. At that point, there was either no daughter product present (as in the case of argon, because argon is a noble gas and would not be present in a rock unless from the decay of potassium), or we can correct for how much there was (as in the case of lead that did not come from the decay of uranium after the rock formed.) ---If the rock is metamorphic, then it has been significantly heated during its history, and, for many types of radiometric dating, that has reset the decay clocks. This means a radiometric date from a metamorphic rock usually gives us the time since its most recent heating. ---If the rock is sedimentary, the minerals of which it is made may have come from several different (and generally unknown) sources. This means the ages obtained from different grains pertain not to the formation of the sedimentary rock, but to the preexisting rocks from which the sediment was eroded. Radiometric dates are, therefore, generally not very useful for sedimentary rocks. Earth is obviously older than the oldest rocks found on it. These rocks are between 3.8 and 3.9 billion years old. There are minerals found in sedimentary rocks that are about 4.2 billion years old, but the sedimentary rocks themselves are, of course, younger. Earth must therefore be older than 4.2 billion years. How much older? According to the nebular hypothesis, the currently accepted model for solar system formation, meteorites and the moon should be of the same age as the earth. The oldest meteorites and the oldest moon rocks both date to around 4.6 billion years. So we take that as the age of the Earth.

delta

Streams eventually carry their sediment to wherever they end (i.e., base level) and deposit it. When the end of the stream is at a body of water like the ocean or a lake, the deposit of sediment is called a delta As the stream empties into the ocean or lake or larger stream, the speed of the water slows and much of the sediment the stream was carrying is dropped to form the delta the reason it is called a delta is that sometimes it resembles an uppercase Greek delta, Δ

Oceanic rifts

The Mid-Atlantic Ridge is the most famous oceanic rift. Oceanic rifts are characterized by a central rift valley. On either side of the valley, abyssal hills are formed by the volcanic eruptions. Eventually sediment covers the abyssal hills to form abyssal plains. ----heat rising in mantle causes: 1) hot mantle rock to rise 2) melt to form beneath the lithosphere 3) magma to rise and solidify forming the ocean crust 4) plates to move apart, cool, and thicken plates diverge at about 3-10 cm/yr At an oceanic rift, earthquakes also occur frequently. However, these earthquakes are shallow and relatively mild since the lithosphere isn't strong enough or hard enough yet to allow a lot of energy to be stored. ex. Iceland is a location where the rift comes to the surface.

The rock that makes up the ocean floor has alternating bands where the magnetic field points north, then south. What is the significance of these bands.

The bands occur symmetrically to each side of the ridge where new ocean crust is slowly being made. The Earth's magnetic field flips, and the field in the basalt points the same direction as the Earth's field when the rock formed.

Core

The core is too deep for any of it to be erupted on the surface of the earth. There are two reasons, however, to think that the core is made mostly of iron with some nickel. --The other 20% of meteorites seen to fall on earth are metallic meteorites consisting mostly of iron with some nickel. --The earth has a magnetic field. A piece of iron may be made into a permanent magnet. But if an iron magnet is heated about 760°C (its Curie temperature), it loses its magnetic properties. The core of the earth is definitely hotter than 760°C, so the core cannot be a permanent magnet. There is, however, another way to create a magnetic field-- by creating an electric current. Convection currents present in the outer liquid core form a moving conductor that can carry an electric current which could have been generated by a weak magnetic field in the early solar system (perhaps from the sun). That electric current in the liquid core would have, in turn, generated a magnetic field, which would reinforce the electric field, which would strengthen the magnetic field, and so forth. Based on this, we say that the core consists of iron with some nickel. (The outer core may also contain some lighter elements like minor oxygen and sulfur that lower its melting point.) These compositions provide an outer core with a density around 10 g/cm3 and an inner core with a density around 13 g/cm3—just what is needed to provide the correct density for Earth. goes from top to bottom-- crust, top layer of mantle (these two are the lithosphere), the middle layer of mantle (this is the asthenosphere), and the bottom layer of mantle

Earth's density in layers

The existence of the shadow zones is explained nicely if we assume that Earth's density changes in abrupt layers. Crust, mantle, core ---chemically or compositionally different. ---there are mechanically different layers where the composition is the same but the behavior of the layers changes due to temperature and pressure differences ---------ex. the liquid outer core and solid inner core The P wave shadow zone (from 103° - 143°, relative to the earthquake focus) is the result of the P waves being refracted as they enter an abrupt change in its medium. This change in medium represents the boundary between the mantle and the core. The S wave shadow zone (from 103° and beyond, relative to the earthquake focus) is caused by the S waves encountering a liquid layer - the liquid outer core. Since shear waves cannot travel through liquids, the S waves are stopped. Further studies of the P waves detected beyond the P wave shadow zone indicate there is another solid layer after the liquid layer. This corresponds to the solid inner core. Other studies of seismic data show that there is an abrupt transition closer to the surface of Earth which marks the end of the crust and the beginning of a new layer called the mantle. This abrupt change is affectionately known as the Moho.

At subduction zones, rocks are "hydrated" when the original minerals combine with the water present in the subducted ocean plate to form new minerals. What will happen to a solid rock that was near its melting point once it has been chemically combined with water (hydrated)?

The hydrated minerals will melt.

Where does the most deposition take place in a stream bend and why?

The most deposition takes place at the inside of the bend because water traveling on the inside of the bend must slow down due to the bend so it cannot carry as much sediment and therefore drops the sediment in the bend

Where does the most erosion take place in a stream bend and why?

The most erosion takes place at the outside of the bend because water traveling on outside of the bend must speed up due to the bend so it can carry more sediment and therefore picks up sediment from the side.

A divergent plate margin runs between Antartica and South America. What will happen as a result?

The ocean separating them will grow wider.

Oceanic-oceanic convergent plate boundary.

The oceanic plate is subducted and a trench forms. As before, water released from the subducted oceanic plate causes mantle rock to melt and rise to the surface. This time it interacts with the continental material to form a volcanic mountain chain with volcanoes that can be more explosive than those found with island arcs. Examples of these volcanic mountains include the Andes where the Nazca plate is being subducted under the South American plate and the Cascades where the small Juan de Fuca plate is being subducted under the North American plate. Matter from the oceanic plate that is not subducted is scraped up onto the continental side to form a thicker continental margin. Earthquakes are similar to the earthquakes found in the previous convergent boundary. --They are frequent and severe. --They vary in depth from shallow near the trench to deeper under the continent as the oceanic plate is subducted.

Shadow Zones

There are regions where no seismic waves are detected. These areas of no detected seismic activity are called shadow zones. To illustrate this idea, suppose that a large earthquake were to occur in Alaska, as a very major one did in 1964. Seismometers nearly all over the earth would record the event and they would produce seismograms, similar in their broad outlines, to the one you saw in the previous section. The furthest stations would receive the waves later than nearby stations. But there would be a ring-shaped zone around the earth, called the seismic shadow zone, in which no seismic waves from this quake would be recorded. Additionally, no S waves would be detected after the ring-shaped seismic shadow zone. Only P waves would be detected.

Convergent Plate Boundaries

There are three types of convergent plate boundaries: 1) a convergent boundary where oceanic lithosphere meets another slab of oceanic lithosphere 2) a convergent boundary where oceanic lithosphere meets continental lithosphere 3)a convergent boundary where continental lithosphere meets continental lithosphere.

milankovitch cycles

There are three ways that the sunlight can change due to the orbit of Earth around the sun. They are known as Milankovitch cycles, after the Serbian astrophysicist who discovered them. 1) change in how elliptical the orbit of Earth is around the sun ---Over a period of 100,000 years the orbit changes from quite circular to more elliptical ---changes the amount of sunlight received by Earth 2) Changes in tilt of the Earth vary over a time period of about 41,000 years ---Earth goes from a "larger" tilt of 24.5° to a smaller tilt of 21.5° ---While this change doesn't seem very large, it does seem to trigger advances of large continental glaciers ---changes the intensity of the sunlight over certain areas on Earth 3) the change in the direction the Earth's axis points (a.k.a. the precession of the Earth's axis) as it orbits the Sun ---This takes place over a period of 23,000 years. ---Over this time, the amount of direct sunlight received by the northern hemisphere versus the southern hemisphere changes. ---This affects the seasons as well and can help cause continental glaciers to form and advance or to melt and retreat ---changes the intensity of the sunlight over certain areas on Earth

Divergent Plate Boundaries

There are two types of divergent plate boundaries: Divergent boundaries occurring under oceanic lithosphere, known as oceanic rifts. Divergent boundaries occurring under continental lithosphere, known as continental rifts.

Which is a main function of a transform boundary?

To connect segments of a spreading center ridge

Transform Plate Boundaries

Transform boundaries can also occur in either oceanic lithosphere or continental lithosphere. They are boundaries that connect other types of boundaries: --ridge-to-ridge --trench-to-trench --ridge-to-trench. They are most commonly found connecting different pieces of divergent plate boundaries Some transform faults, such as the San Andreas Fault, occur in continental lithosphere. Severe earthquakes are common with this type of plate boundary.

groundwater

Water that seeps into the ground flows mostly through pore spaces in rocks below the water table is called groundwater It flows very slowly compared to surface water. Some types of rocks have more pore spaces than other types of rocks. --We say that the rocks with more pore spaces have greater porosity. The ability of the ground water to flow through the rock depends upon its permeability. Groundwater has the capacity to dissolve some types of rock, especially limestone, resulting in sinkholes and caverns.

Crust

We can see the crust, therefore, we know the continental crust is, on average, granitic in composition. The oceanic crust, however, is basalt. Both granite and basalt are types of silicates

wells

Wells are a major source of groundwater for human use. In order for a well to be useful and produce water, it must be drilled lower than the water table. As water is taken from the well, a cone of depression is produced if the water is taken from the well faster than the aquifer can deliver water to the well. The well can run dry if too much water is taken from the well. cones of depression in the high plains aquifer supplies much of the irrigation water for the "bread basket" of the United States. Another way a well can run dry is if the cone of depression from another well nearby causes the smaller well to become higher than the water table---look at figure 30.20 in chapter 30 Unlike mineral or ore deposits, groundwater isn't static and moves over large areas. Water right claims can therefore be quite complicated Another source of concern for groundwater is contamination. In costal areas, sea water entering the aquifer is a large problem. ---Manmade pollutants can also seep into ground water. ---Because the source of the ground water can be hundreds of miles away, contamination of water can affect the groundwater and, therefore, the drinking water of people, animals, and plants far from the source. ---While it is possible that passage through the rocks can filter pollutants out, this does not always occur. For example, recent studies indicate that the source of the ground water that feeds Ash Meadows, an oasis in the Death Valley area, is located near the Nevada Test Site, a site established for the testing of nuclear devices. It is not currently possible to say if, or how, this testing will affect the ground water at this oasis. The time it takes the groundwater to make its journey of 50-60 km (10-37 miles) is about 15,000 years

Streams cut deep valleys as they travel through mountains, but the same streams deposit large amounts of material to form deltas when they reach the ocean. Why?

When streams are traveling down steep slopes the water has more kinetic energy. When the water is near the ocean, it slows down and moves slower

A solid rock near the melting point that contains no water is located below a divergent plate boundary. As the lithosphere above it moves apart, the pressure on the rock is reduced. What will happen?

When the pressure drops, the rock will melt

Consider the features shown in the photograph above.The gray igneous rock is (younger, older) than the red sandstone. Which principle of relative dating did you use to obtain your answer? Where are the youngest visible beds of sandstone located in this photograph? Which principle of relative dating did you use to obtain your answer? Could the igneous rock be successfully dated by radiometric means? Could the sedimentary rock be successfully dated by radiometric means? Could either the sandstone or the igneous rock be candidates for the oldest rock on the earth? If the igneous rock is dated to be 34 million years old, what principle of relative dating was used to get this result? If the igneous rock is dated to be 34 million years old, what happened 34 million years ago?

Younger Cross-cutting At the top Superposition yes no No, the sandstone consists of fragments eroded from rocks that are older than it is, and the igneous rock is younger than the sandstone. None, that's an absolute date. The lava solidified.

Look at the map found here https://static1.squarespace.com/static/53109b11e4b05040160f0a8f/59086c6c197aea1972858b78/59086f97d482e9bebd1f36e3/1493727007731/volc.100percent.gif?format=1000w a) What tectonic activity is causing the volcano on Hawai'i? How do you know? b) What tectonic activity is causing the volcano in Guatemala? How do you know? c) What tectonic activity caused the Earthquakes in Japan? How do you know? d) What tectonic activity caused the Earthquakes in Nepal? How do you know?

a) Hawaii is in the middle of an oceanic plate, and apparently not linked to plate boundaries, so it must be a hot spot. We know the volcanic activity in Hawaii is caused by a heat source from deep in the mantle (a mantle plume) over which the lithosphere is moving. The mantle plume creates a linear chain of volcanoes over time called hot spots. b) Guatemala is an example of oceanic-continental plate boundary activity, where the oceanic plate is subjected and a trench forms, releasing water causing the mantle rock to melt and rise to the surface. Interaction with the continental material forms volcanic mountain chains that can be very explosive. c) Japan is an island arc created on an oceanic-oceanic convergent plate boundary where frequent, severe earthquakes occur. Island arcs form when a trench forms as an older, cooler, more dense oceanic slab is subducted, releases water as it heats, and part of the mantle above it melts and rises to form volcanoes which can form islands along the trench. d) the Himalayas in Nepal are an example of a continental-continental plate boundary where subduction has stopped because the continent that was on the oceanic plate being subducted ran into the plate boundary. But plate movement has continued there-- the two continents pressing against each other creating folded mountain belts, where severe but fairly shallow earthquakes are common.

floodplains

also an example of a situation where a stream deposits sediment. everything is generally low in elevation when tectonic plate activity happens and the land goes up or down, floods will happen in the floodplain As the stream spreads out due to overflowing its regular bed due to flooding, the water slows thus losing energy. There is still an active part of the river though Sediment is dropped from the stream

The picture above shows some layered sedimentary rocks. Which of the following best describes the age of the rock layers (oldest to youngest)? Which principle of relative dating was used to provide the correct relative dates of these sedimentary layers?

bottom layers are oldest and top are youngest Superposition

Seismic Discontinuities wave speed layers of the earth

boundaries between: Lithosphere and Asthenosphere (topmost sections) Asthenosphere and Mesosphere (mid-mantle) (bottom of top sections) Mesosphere and Outer Core (top of the bottommost sections) Outer Core and Inner Core (bottom most layer) S waves stop at the outer core. This is how we infer that the outer core is liquid. The increase in speed of P waves at the top of the inner core leads us to believe that it is solid.

Minerals

building blocks of rocks criteria: --Is naturally occurring --Is an inorganic solid --Has a fixed or narrowly limited chemical composition --Has a definite internal crystal structure --Has a unique set of physical properties --Has some stability in the face of varying pressure, temperature, or in the presence of water.

climate

describes the average rainfall, temperature, etc. over a long period of time - basically the weather averaged over many, many years it turns out to be a lot more predictable than the weather.

Most rocks found at the surface of the earth are ________ the entire planet.

less dense than The average density of Earth is about 5.5 g/cm3

factors that affect the climate of a particular location

mountains, ocean currents, and wind others in the textbook chapter 31

Plate Tectonics

plate tectonics is a useful tool for geologists as they seek to understand the large-scale geologic processes that shape the Earth. Alfred Wegener's theory led to the plate tectonics model: Plate tectonics says that the surface of the Earth is broken into lithospheric plates. These plates rest or float on the mushy, semi-liquid, weak asthenosphere. The boundaries of the plates are marked by the earthquakes around the globe The plates move anywhere from one centimeter/year (the African plate) to twelve centimeter/year (the Indian plate). The plates, or slabs of lithosphere, move due to the gravitational force and the electromagnetic force. The two major forces are called ridge push and slab pull ---Ridge push is a result of the oceanic ridges being topographically elevated. Gravity then causes them to slide "downhill". ---Slab pull is the tug of the slab that is going down under another slab and into the asthenosphere. Additional forces that take place include friction and a contact force. ---Friction between the plate and the asthenosphere works to slow the effect of ridge push and slab pull. ---Convection in the asthenosphere also takes place, and the resulting contact force may, to a small extent, help move the plates. These slabs of lithosphere moving upon the less solid asthenosphere beneath must inevitably bump and jostle against one another. When they do, the consequences can range from interesting to disastrous. ---Two plates may interact in only three ways: 1) they may pull away from each other, forming a divergent boundary; 2) they may push towards each other, forming a convergent boundary; 3) or they may slide past each other, forming a transform boundary

downcutting

type of erosion of the land to create the low places Downcutting is accelerated when the base level of the stream is dropped. --This causes the stream to no longer be at its equilibrium profile and erosion occurs to achieve a new equilibrium. ---While there are different ways to change a stream's base level, one is to raise the land the stream flows over. Ex. The Colorado River and the land in western US--The Grand Canyon was the result ---The region known as the Colorado Plateau experienced tectonic uplift and the Colorado River cut the Grand Canyon in a manner similar to the way one applies pressure on a slab of wood when using a table saw In any given stream channel, deposition and erosion may occur at different places at the same time. Deposition and erosion may occur in the same places at different times. ex. Grand Teton National Park flat terraces--evidence that the stream has eroded into material that it formerly deposited in the same place. At one point, the upper terrace was deposited then partially eroded away and then the second terrace was deposited and partially eroded as well Erosion through sediment can take place much more quickly than erosion through bedrock, but the peaks and valleys in the background are testimony that solid rock can be eroded over time.

Meanders

winding stream