rock on 9, 10, 11
In Pennsylvania today (or at most other places on the world's land surface):
The land surface is accumulating sediment in a few small places, building up records of geologic history, but most places are eroding. Today in Pennsylvania (and across most of the land surface of the planet), sediments are accumulating in a few human-made lakes, a few natural wetlands or natural lakes, along some streams and in some caves, but almost everywhere else is eroding. This is the typical state of affairs, so you need to correlate events across large regions to get a good geologic record.
Dr. Randall Irmis is a famous paleontologist, who has gone on to make important discoveries since he showed the Penn State CAUSE class this fossil plate from the armored vertebrate Buettneria. Based on the discussions in the class materials on the topic of evolution, it is likely that:
The most similar species alive today are related to but recognizably different from Buettneria. Evolutionary theory indicates that living things change from generation to generation, but that all living things are related. Consistent with this, Buettneria is recognizably similar to, yet different from, amphibians still alive today.
The picture above shows an outcrop along Interstate 70 in Utah. The green arrow points to a person, for scale. The pink arrows pointto the ends of an interesting surface. Some rocks are below this surface, and other rocks above it. What happened to make this outcrop?
The rocks below were deposited, hardened, turned on end, eroded to make an unconformity with a soil developing on top, and then other rocks were deposited on top of the soil. A is a pretty good description. The rocks below are ocean sediments, and the rocks above the soil are from a lake.
Considering long-term averages, and assuming that we don't deploy space-based defenses against incoming meteorites, a reasonable estimate of the chance of an average U.S. citizen being killed by the effects of a meteorite or comet impact is that this risk is about the same as the chance of being killed by:
Crash of a commercial airplane. Nobody that we know eats Pepsi cans, and while there are still meteorites in the solar system that can hit and kill, there are no dinosaurs left except on "The Flintstones". A reputable study found that a meteorite impact might not occur for millions of years (or might occur next year...) but then might kill billions of people; plane crashes usually kill a few to a few hundred each year. Add up the deaths over a sufficiently long time, and plane crashes and meteorite impacts likely are similarly dangerous. But car crashes, smoking, and being fat and lazy are way more dangerous to us.
To get gas from the Marcellus shale, drillers:
Drill into and then along the shale, and then pump in high-pressure fluids to fracture the rock and release the gas. Fracking involves raising the pressure in holes drilled into and along the shale layer, by pumping in water with special chemicals, and this breaks the rock to release the gas. It is still possible that some water wells have been contaminated by leaking gas, but this is not part of the gas-recovery plan.
The consensus of the world's climate scientists, as generated by the UN-sponsored Intergovernmental Panel on Climate Change (IPCC), is that:
Human activities have raised CO2 levels in the atmosphere, warming the planet, and the changes so far have been small compared to the changes that are likely over the next centuries unless we humans alter our behavior.
The picture above shows the stem of devil's club, a plant of the northwestern coast of North America. The native people use devil's club for medicinal purposes. We now know that:
Plants protect themselves in many ways, including thorns but also through chemicals that are poisonous to many things that would eat the plants; those chemicals are sometimes harmful to humans (poison ivy, for example) but sometimes beneficial to humans, and have given us many of our medicines. Most plants have physical protections of some sort (hairs, thorns, hardened parts, bark, etc.), but almost all plants have chemical defenses. Those chemical defenses may kill us if we eat too much, but they also may kill microbes that would kill us before the chemicals kill us. A whole lot of our medicines have come from plants, and there undoubtedly are more to be discovered. There is a race on to find those new medicines before we exterminate the plants containing the medicines. Devil's club has been around longer than Pepsi has.
Geologic history involves learning the order of events in the past (which came first?), and, what happened. Part of "what happened" is reconstructing what the environment was like in the past. What is accurate about the human effort to learn about past environments?
Sediments and sedimentary rocks provide much information about whether they were deposited in the ocean or on land, whether the climate was hot or cold and wet or dry, and more. Lake or ocean or sand dune or glacier, warm enough for crocodiles, wet enough for trees, and so much more—sediments and sedimentary rocks are books in which the details of the past are written.
In childhood stories (such as Little Red Riding Hood), we humans worry about predatory mammals such as wolves or tigers rather than worrying about predatory dinosaurs such as allosaurs or tyrannosaurs. This is because:
Small mammals coexisting with the dinosaurs were not able to outcompete the dinosaurs for big-animal jobs, but after the dinosaurs were killed, some large mammals evolved from small mammals to fill the large-animal jobs, including the big-predator job.
The yellow line lies along the contact between sandstone (on the left) and reddish mudstone (on the right). The red arrows point along a place where the sandstone continues into the mudstone. The four sides of the picture are labeled A, B, C and D. What is most likely correct about these rocks?
When the rocks were deposited, side B was the highest (it was on top). This is a cliff in the Grand Canyon. The picture was taken and then turned on its side. Originally, the muds of side D were deposited on a floodplain, a mud crack formed and sand fell into it (the red arrows) as the sand-dune rocks of side B were deposited on top.
You start with 400 parent atoms of a particular radioactive type, which decays to give stable offspring. You wait just long enough for three half lives to pass. You should expect to have how many parent atoms remaining (on average):
50 After one half-life, you've gone from 400 parents to 200; after a second half-life you go from 200 parents to 100, and after a third half-life you go from 100 parents to 50. (Typical studies of radioactive decay use many more atoms, to avoid statistical fluctuations, but the question says "on average", so we asked you about 400 rather than 400,000,000,000,000 to make the math easier.)
The extinction of many types of dinosaurs occurred about:
65,000,000 years ago. Humans were trotting around 65,000 years ago, and met dinosaurs only in The Flintstones. 650,000 years is barely enough time for evolution to have changed large animals a bit, and although 6,500,000 years is enough time for noticeable change of large animals—increase in maximum size of members of the horse family, for example—the huge changes since the dinosaurs needed 65,000,000 years. 650,000,000 years goes back before any land creatures, and before all but the simplest of multi-celled organisms.
The picture above shows:
A right-side-up dinosaur track This is a dinosaur track, from dinosaur ridge, and the dinosaur stomped down into the mud, so the track is right-side-up.
An unconformity is:
A time gap in a sequence of sedimentary rocks caused by a period of erosion or nondeposition. Most of the land is eroding most of the time. Streams carry rocks and mud away from the mountains, lowering the mountains. Eventually, if mountains are lowered enough, by erosion or by Death-Valley-type faulting or some other process, new sediments may be deposited on top, but there will be a surface separating older rocks from younger rocks, and no rocks from the in-between time. This surface is called an unconformity. One can see older clasts in younger rocks, but these are usually called "older clasts in younger rocks", not unconformities. Whatever events made the old rocks, broke them up, and transported them to the site where the new rock formed must have happened before the new rock formed. A rock must exist before it can be cut, so an igneous rock cutting a sedimentary rock is younger than the sedimentary rock, and geologists do study such cross-cutting relationships, but they aren't unconformities. Younger sedimentary rocks do occur on top of older rocks unless turned upside-down by mountain building, but this goes by the fancy name of the "principle of superposition", not "unconformity". And younger fossils looking more like living things than do older fossils is William Smith's "law" of faunal succession, not an unconformity.
Look at the picture above which shows a region just less than a foot across, of a stream deposit from the base of the same pile of rocks that show up in Bryce Canyon. This picture was taken in the face of a cliff in Red Canyon, just west of Bryce Canyon National Park. A indicates a piece of limestone that has been rounded off in a stream; B indicates a mass of sand glued together by hard-water deposits, and C indicates another such mass of sand glued together by hard-water deposits. In order of time of formation, they are:
A was formed first, then B was glued together by hard-water deposits, then C was glued together by hard-water deposits. The clast A existed before it was included in a conglomerate glued together by the sand and hard-water deposits of B, so A is older than B; the whole reddish clast containing A and B is glued into another conglomerate by the sand and hard-water deposits of C, so C is youngest of these three.
There are many greenhouse gases, including carbon dioxide (CO2), methane (CH4). and vaporized water (H2O). These and other greenhouse gases warm the Earth primarily by:
Absorbing some of the infrared radiation emitted from the Earth Although it is true that squeezing air warms it, the pressure does not set the temperature (change in pressure brings change in temperature), and, the greenhouse gases are really very rare and don't affect pressure much. Clouds are not caused by greenhouse gases, and while clouds warm nights, clouds cool days, and the net effect of clouds is probably slight cooling of the planet. Convection currents are blocked by the glass of greenhouses, but not by greenhouse gases. But CO2does absorb some of the infrared radiation emitted from the planet. Absorbing an infrared photon puts a CO2molecule into an excited state, and fairly quickly the molecule returns to its unexcited state by emitting a photon of the same energy. Some of those photons emitted by excited CO2 molecules head back toward Earth (the emission direction is random). So, the CO2serves to trap energy in the Earth system, warming the planet so that it glows more brightly to shove infrared radiation past the CO2, achieving a new balance.
A widely accepted scientific idea usually is based on
An interlocking web of important experimental results or observations that support the correctness of the idea. At last observation, Pepsi commercials were not highly scientific, even if science is involved in figuring out what sells. It is a romantic notion that you could overturn great knowledge with a single observation; however, observing nature is not easy, and nature occasionally fools us (you can, rarely, flip an honest coin twenty times and get twenty heads), so if a single observation disagrees with a lot of other information, that single observation will be checked in various ways to see if the new result "stands up" before the older body of knowledge is discarded. Before an idea gains wide currency, that idea is tried in various ways, in many labs, in many places in nature, while models are run and theory is developed. The interlocking of all of these provides the confidence that scientists can use in doing things successfully. Although received wisdom from sacred books can be used for inspiration, scientific ideas must be tested against nature. Social scientists have quite rightly learned that scientists are affected by their prejudices, their funding sources, their mating habits, and other things, and that the path of science is not nearly the straight-ahead road to understanding presented in some textbooks. Unfortunately, some of those social scientists have then gone off the deep end and claimed that science is no more useful than any other human story—claiming that astrology and astronomy are equally valid, for example, or palm-reading and modern medicine. These same social scientists seem to know where to find a real doctor when they get in trouble, however. Science is appealed to nature, and builds on the learning of people from around the world. Airplanes that fly, computers that calculate, small devices that make big explosions, etc. are not socially conditioned ideas but instead are demonstrations of the success of science coupled to engineering.
When geologists consider sedimentary rocks, those rocks:
Are classified first based on origin (clastic or chemical precipitate). We do divide the rocks based on origin first. We saw with weathering that physical weathering makes chunks or clasts, and then chemical weathering also makes chunks (clay, rust, sand grains) and dissolved things. The clasts give clastic rocks, and when the dissolved things come out of solution, chemical precipitates are formed. Color is not often a useful indicator—rock colors change a lot during weathering, and colors also may change when oil or water move through. Grain size matters to clastics, but not much to precipitates.
Transitional forms between distinct types (species) of different ages in the fossil record:
Are common for commonly fossilized types, but rare for rarely fossilized types. Most living things are recycled, not fossilized. Most of the world is eroding, so no fossils are made in most places. Where fossils are being made, only a few percent of living types typically end up producing fossils. And in those few types, new species often appear in small, isolated populations. But careful search has shown many, many transitions in commonly fossilized types. In rarely fossilized types, transitions are much rarer. Lots of people refer to transitional forms in debating evolution. Anti-evolutionists often claim that transitional forms are unknown. When transitional forms are demonstrated, the anti-evolutionists usually argue that all known transitions are "micro-evolution" which somehow is not "real" or "macro-evolution". Because some transitions will always be missing, there is no way to show every possible transition in the fossil record, so this anti-evolutionist argument can't be totally disproven. But that does not make this argument a good one.
Look at the picture above, which shows a small section of a "fossil" sand dune (a sand dune in which the grains have been "glued" together by hard-water deposits). When the dune was first deposited, which was up (which letter is closest to the arrow that is pointing in the direction you would have looked to see the sky when the dune was deposited)?
B Just to the left of the letter B there is a small unconformity. The layers farther to the left are cut along that surface. Layers must exist to be cut, so the left-hand layers are older, the right-hand layers are younger, and up was to the right.
Look at the picture above, which shows a small section of a "fossil" sand dune (a sand dune in which the grains have been "glued" together by hard-water deposits). When the dune was first deposited, which was up (which letter is closest to the arrow that is pointing in the direction you would have looked to see the sky when the dune was deposited)?
B Just to the left of the letter �B� there is a small unconformity. The layers farther to the left are cut along that surface. Layers must exist to be cut, so the left-hand layers are older, the right-hand layers are younger, and �up� was to the right.
What do we know about the effects of humans on extinction of plant and animal species on Earth?
Both prehistoric and modern humans have been responsible for extinctions. Extinction has happened naturally, but humans have greatly accelerated the rate. Early humans caused extinctions, and so have modern humans, with real worries that the rate of extinction will accelerate a lot more in the near future.
You are the chief biodiversity officer for the National Park Service in the eastern US, responsible for maintaining as much diversity as possible, and your boss has told you to focus on maintaining biodiversity of things big enough to see with the naked eye (so you don't need to worry about microorganisms). You have two parks, and enough money to buy 10,000 acres of land. You may add the 10,000 acres to one of the parks, add 5,000 acres to each park while leaving them as isolated parks, or buy a 10,000-acre corridor connecting the two parks. All of the land for sale is now wilderness, but the land you do not buy is going to be paved for a super-mega-mall. You would be wise to:
Buy the corridor connecting the two parks; this keeps one big "island" rather than two smaller ones, and so keeps more species. Remember the terrarium—you will have more diversity in an undivided terrarium than in a divided one. Your park area is your terrarium; keep it undivided. Malls have low biodiversity.
The diagram above shows a geologic cross-section of some rocks, such as you might see in a cliff. The tree is growing on top of the modern surface. Rock layers A, B, C, D, E, and F are sedimentary; E contains mud cracks and fossil footprints as shown. G is igneous rock that hardened from hot, melted rock. H, I and J are faults, and K and L are unconformities. Sedimentary rocks are right-side-up unless there is some indication given to show something else. Referring to the rocks you see here ......Which is the oldest sedimentary rock layer?
C The package of sediments C, D, E, and F is upside-down, as shown by the footprints and mud cracks, so C is the oldest one.
Which formula describes the chemical changes that occur and release energy when you start with plant material and then burn it in a fire or "burn" it in a stomach?
CH2O + O2 → CO2 + H2O CaCO3 is shell or cave-rock; the equation with CaCO3on the left is dissolution of rock to make caves, and the equation with CaCO3 on the right is formation of shells. CH2O is a pretty good estimate of average plant composition; the equation with CH2O on the left is burning of plant material for energy, and with CH2O on the right is how plant material is made. Diet Coke plus Mentos does produce an interesting effect, but this is not the way plants grow.
Sediment is changed to sedimentary rock by:
Cementation by hard-water deposits, intergrowth of new minerals, and squeezing under the weight of additional sediment. Hard-water deposits are especially important in hardening coarse clastic deposits, especially sandstone and coarser. The finer-grained deposits are more controlled by compaction under additional weight, and intergrowth of new minerals. But all of these processes can contribute.
Regarding global warming, most scientists (including those who have advised the United Nations through the Intergovernmental Panel on Climate Change) agree that if we continue to burn fossil fuels at an accelerating rate:
Climate changes will primarily hurt poor people in warm places, but the climate changes are primarily being caused by wealthier people in colder places Blizzards play havoc with airline travel, which hurts the economy in the mid- and high-latitude wealthier countries. If you have winter (so that warming reduces blizzards), air conditioners (so you can keep the economy humming when the weather is otherwise too hot for office work), and bulldozers (so you can build sea walls or haul things out of the way as the ocean rises), a little warming might even help your economy, although too much warming will be bad. If you are missing any of winter, air conditioning, or bulldozers, all warming is likely to be bad. Most of the world's people are missing all three, and will be hurt by warming, but the warming is being caused primarily by people who have all three.
Among fossil fuels:
Coal is made by heating of woody plant material, and oil is made by heating of algae. Slimy algae gives slimy oil; chunky wood gives chunky coal. Works great. Duct tape and WD-40 are the quick-fix tool kit; if something moves but it shouldn't, apply duct tape, and if something doesn't move but it should, apply WD-40. None of you would be so bad as to merit coal in your stocking, but we presume Santa gets it from a mine somewhere.
What cause probably was not important in contributing to extinction of most species on Earth, including the dinosaurs, in a very short interval of time at the end of the Mesozoic Era?
Cold from the change in Earth's orbit caused when the meteorite shoved the planet farther from the sun. Robert Frost once wrote "Some say the world will end in fire, some say in ice". For the dinosaurs, both were probably true, with acid thrown in. But the meteorite was not nearly big enough to change the planet's orbit noticeably. Frost went on "From what I've tasted of desire, I hold with those who favor fire, But if it had to perish twice, I think that for destruction ice, Is also great, and would suffice."
What is accurate about the history of extinction of species:
Extinction happens at a slow, "background" rate, punctuated by rare "mass extinctions" during which many types are eliminated rapidly. Numerous extinctions have occurred over the history of the planet, but extinctions have been especially rapid during the short "mass extinctions" including the one that killed the dinosaurs. Humans have accelerated extinction, but we didn't invent it. And if every type has become extinct, what are you doing reading this???
Religion and science always disagree.
False Pope John Paul II said that the Catholic Church has no problem with evolution, and Baptist Jimmy Carter also supported evolution, so it is clear that religion and science can agree.
If humans change the composition of the atmosphere in a way that would warm the world by one degree if everything else in the Earth system remained unchanged, most studies indicate that over the next years to decades:
Feedback processes will enhance this warming a little, causing the total warming to be a few degrees. Negative feedbacks stabilize the climate over long times of hundreds of thousands or millions of years or more, but feedbacks over years to millennia are mostly positive, amplifying changes. If there is a change in the sun, or CO2, or something else sufficient by itself to raise the temperature by one degree, this will be amplified to a few degrees by feedbacks.
The Paleozoic:
Is "old life", the age of shellfish. Paleo goes with Past, and is old life. The Paleozoic started with the "fast" (over a few million years) emergence of many creatures with shells, which greatly increased the richness of the fossil record because shells are preserved so well.
Which of the following is not part of the evidence that the odd layer marking the extinction of the dinosaurs was caused by a large meteorite impact?
High concentrations of silica found in the layer. We have seen several times that silica is very common, so its presence in a layer would not indicate much of anything. Features really observed in the layer that are associated with meteorites but not common elsewhere in rocks include shocked quartz from the impact, soot from wildfires, iridium from the meteorite, and a giant-wave deposit because the meteorite hit water as well as land at the edge of the Yucatan Peninsula.
The consensus of the world's climate scientists, as generated by the UN-sponsored Intergovernmental Panel on Climate Change (IPCC), is that:
Human activities have raised CO2 levels in the atmosphere, warming the planet, and the changes so far have been small compared to the changes that are likely over the next centuries unless we humans alter our behavior. Human activities have raised CO2 in the atmosphere, but if we continue with business as usual, we haven't seen anything yet—we haven't even doubled CO2, but a quadrupling or even octupling seems possible. Chlorofluorocarbons used as refrigerants are responsible for the ozone hole, and cow flatulence is not greatly affected by external methane levels, which are rising in any case. Besides, bovine belching is a larger methane source than is outlet through the other orifice.
Examine the two pictures above, labeled I and II. They are from the same sediment core collected in sea-floor muds from beneath the Atlantic Ocean off the coast of South Carolina. (The pictures are scanning electron micrographs by Brian Huber of the Smithsonian Institution, and the scale is the same on both, as shown at the bottom of each.) One picture shows a sample from just below the unique layer marking the extinction that killed the dinosaurs, and the other picture shows a sample from just above that unique layer. Which is which?
I is from below the unique layer, and II is from above the unique layer Before the impact, biodiversity was high, as shown in I, which includes fossils from below the unique layer and thus deposited before the meteorite hit. After the impact, most of the living types were killed, giving rise to the limited diversity seen in II from above the unique layer after the impact.
Which of the following is not a part of the modern theory of evolution?
If the body of an adult living thing is changed by its environment, those changes usually are passed on biologically to children. You can get a tattoo without worry that your children will be born with that same tattoo, but all the rest of these contribute to evolution.
What is one of the main, common-sense ideas that geologists use to learn what happened first and what happened later in geologic history?
If you see a push-together fault cutting a clastic sedimentary rock, you know that the sediment was deposited, and then broken by squeezing, because something must exist before you can break it. Something must exist before you can break it, so a rock is older than a fault that cuts it, and thus the fault is younger than the rock.
Which is accurate about the history of the Grand Canyon:
In the deepest part of the canyon, the river cuts through rocks formed by metamorphism of older sedimentary rocks in the heart of a mountain range. The Colorado River is cutting through the metamorphic rocks from the heart of an old mountain range. The sedimentary rocks above are right-side up, and the Kaibab Limestone slants down to the north beneath the rocks of Zion, which are older than the rocks of Bryce, among others. Many unconformities exist in the walls of the Canyon, including the one below the Precambrian sediments and the one above those sediments. The idea of the river narrowing over time was the hypothesis that an interested tourist presented to one of the professors and a ranger at the Canyon a few years ago. When the professor asked whether the tourist would want to go out on a narrow point with a jackhammer, the tourist said no, because the rocks might fall off and slide down into the Canyon. When the professor pointed out the many places that rocks had fallen off and slid down, the quick-witted tourist figured out that the Canyon has been widened by such rockfalls as the river has cut downward.
The Mesozoic:
Is "middle life", the age of dinosaurs. Meso goes with Middle, and is middle life. The Mesozoic time of dinosaurs started and ended with mass extinctions.
Using only uniformitarian calculations from the thickness of known sedimentary rocks, likely rates at which those rocks accumulated, and features in and under those sedimentary rocks, geologists working two to three hundred years ago estimated that the Earth:
Is more than about one-hundred-million years old Radiometric techniques reveal the Earth to be about 4.6 billion years old, but early geologists did not have the sophisticated instruments to measure the trace radioactive elements and their offspring. Working from the rocks, the geologists knew that the age must be in the neighborhood of 100 million years, plus extra time in unconformities and additional extra time in the oldest, metamorphic rocks.
What is accurate about the scientific theory of evolution today?
It is being applied successfully in the real world in many ways, including helping fight new disease organisms, and even guiding the thinking of computer scientists. As antibiotic resistance appears in disease organisms, evolutionary biologists are helping doctors find better strategies to keep us healthy. The processes behind evolution—try new things, keep the ones that work, repeat—has been used intentionally for guidance in many human endeavors, including "evolutionary computing" in computer science. Ecologists trying to rescue ecosystems are informed by understanding of the evolutionary processes that made, and are changing, those ecosystems. Even regulations for sport fishing are guided by our understanding of evolution. In the same way as other successful ideas in science, evolution is useful in many practical ways in the real world.
The above picture is from the Escalante-Grand Staircase National Monument. The pink arrows point along some interesting features. What are they?
Joints, formed when the sedimentary rocks were broken by physical-weathering or other processes. This is the Navajo Sandstone, and it is a sand-dune deposit, but you can't really see that in this picture. Almost all rocks have joints. Joints channel water, and make space for roots, so plants often grow along joints, as you see here. The change from red to white along the upper-left arrow is probably a record of places in the past where fluids carrying oil met fluids carrying water—the water rusted the iron and made red; the oil left the iron reduced and carried it away.
The above picture is from the Escalante-Grand Staircase National Monument. The pink arrows point along some interesting features. What are they?
Joints, formed when the sedimentary rocks were broken by physical-weathering or other processes. This is the Navajo Sandstone, and it is a sand-dune deposit, but you can't really see that in this picture. Almost all rocks have joints. Joints channel water, and make space for roots, so plants often grow along joints, as you see here. The change from red to white along the upper-left arrow is probably a record of places in the past where fluids carrying oil met fluids carrying water—the water rusted the iron and made red; the oil left the iron reduced and carried it away.
You wander around the world for a while and take pictures of many typical living things. If you then were to follow those living things to see what would happen to them after they die, and they behaved naturally, it is likely that:
Most of the living things would be "burned", combining with oxygen to fuel some other living thing, or would be burned in a real fire. Nature is a very efficient recycler, so almost everything that lives is recycled. The recycling is usually achieved through slow "fires" in other living things (including you!), using oxygen. However, sometimes a "real" fire such as a forest fire will do the job.
At current rates of use, and at prices not greatly higher than those of today:
Oil will run out in a century or so, and coal will run out in a few centuries. There is lots more coal than oil; oil has this habit of floating on water, thus rising through rocks and escaping to the sea floor where the oil is "burned" for energy by bacteria or other creatures. The size of the resource, in coal, oil, or anything else, depends on the price, and how long the resource lasts depends on rate of use, which is increasing rapidly for fossil fuels. The idea that immense pools of oil are out there, undiscovered but easy to get, is pretty silly—oil companies are really smart, drilled the easy stuff early on, and are now running out of oil that can be drilled and produced at prices close to modern.
Heating of some materials produces coal. With increasing temperature and time, one observes:
Peat, lignite, bituminous, anthracite This is mostly memorization. But the names hide a lot of history, the peat-bog cutters of Ireland, the brown lignites now being mined in Wyoming, the deep-mines and strip-mines of the bituminous coals of western Pennsylvania, West Virginia and elsewhere, and the hard-coal anthracite of the Scranton and Wilkes-Barre region. If you don't know any of this history, you might consider reading up on it a bit; it is fascinating.
The geologic time scale is, starting with the oldest and ending with the youngest:
Precambrian, Paleozoic, Mesozoic, Cenozoic. You could probably reason this out if you remember some Greek roots, or else just memorize it—Precambrian is oldest, then Paleozoic, Mesozoic and Cenozoic.
In age dating, geologists use:
Radiometric techniques and layer-counting for absolute dating of events that happened in the last 100,000 years, and other radiometric techniques for absolute dating of much older events. If you want an absolute date (number of years) rather than older/younger, you can count layers for young things, or use radiometric techniques for young things or for old ones.
Reasons why fossils of transitional forms are missing in some lineages that humans especially care about include:
Rapid evolution often occurred in small populations, and fossilization is less likely in smaller populations. Although more searching could be valuable, lots of scientists have looked for transitional forms, which are expected based on evolutionary theory. The common occurrence of transitional forms in commonly fossilized types shows that "Ford-Mustang-type" catastrophism did not occur, but the data also show that evolution often occurred rapidly in small, isolated populations that are hard to find, and that might not be fossilized in rarely-fossilized types.
There are many large mammals on Earth today. This is because:
Small mammals were not able to outcompete the dinosaurs for big-animal jobs, but after the dinosaurs were killed, some large mammals evolved from small mammals to fill the large-animal jobs. There are "big-animal" jobs—eating tall trees, eating smaller animals, etc. But the total number of big-animal jobs is limited. The dinosaurs filled the big-animal jobs before mammals really got going, and mammals were not able to displace the dinosaurs. Some small mammals survived the meteorite that killed the dinosaurs, and then evolved to give big mammals over millions of years and longer. There were almost no big mammals before the dinosaurs were killed off, volition has nothing to do with evolution, and running away doesn't avoid acid rain.
We humans are changing the composition of the atmosphere in many ways. Those changes will directly affect the planet's temperature, but the resulting change in temperature will affect other things on the planet that also affect the planet's temperature. Suppose that we could magically change the composition of the atmosphere enough to raise the temperature one degree if all other parts of the Earth system were held fixed, and after the warming, we allowed the other parts of the Earth system to react for a few years or decades. At the end of that time, what would be the total change in the Earth's temperature?
The Earth would end up a few degrees warmer than before the human influence, because positive feedbacks would amplify the original change. Negative feedbacks stabilize the climate over long times of hundreds of thousands or millions of years or more, but feedbacks over years to millennia are mostly positive, amplifying changes. If there is a change in the sun, or CO2, or something else sufficient by itself to raise the temperature by one degree, this will be amplified to a few degrees by feedbacks.
We humans are on track to increase the amount of CO2 in the atmosphere so that the concentration in the future more than double the atmospheric CO2 concentration that existed for the few millennia before the industrial revolution. If we could cause just a doubling and then hold the CO2 level constant at that doubled level for the next thousand years, we very likely would see:
The Earth would warm a few degrees, and then the temperature would stabilize at that new, warmer level. Doubling CO2 is estimated to warm the Earth by between 1.5 and 4.5oC, or 2.7 to 8.1oF, with some chance of slightly larger change and very little chance of smaller change. The physical basis of warming from CO2is quite well understood, and cooling or no response is very unlikely. You might compare the expected warming from CO2 to getting up to put another blanket on the bed in the night if you are cold. True, you might spill a glass of water into the bed, or your significant other might steal the other blankets while you're up, so getting the extra blanket might make you colder, but common sense says that getting the extra blanket warms you. Warming from CO2 is about as certain as warming from the extra blanket—maybe a huge number of volcanoes will explode in the near future and offset the effects of the CO2, but don't count on it.
If you hike down into Bryce Canyon, and you look up the correct stream bed, you'll see this. The trees lying across the stream bed in the photo above (between the pink arrows) are a small dam. What has happened here?
The dam has trapped sediment upstream, and the clean water coming over the dam has picked up sediment downstream of the dam and lowered the stream bed there. Fast-flowing floods have lost their debris when slowed by the dam, filling the space above the dam with rocks. This basic pattern—dams collect debris and release clean(er) water that can erode more, is seen over and over in geology. And, marmots don't dig that much at Bryce!
Your friend wants to see some real Pennsylvania coals. Where should you send your friend to see coal in the rocks of Pennsylvania (if you honestly are being helpful), and what coals would your friend see?
To the sedimentary rocks of western Pennsylvania to see bituminous, and to the metamorphic rocks of eastern Pennsylvania to see anthracite. Bituminous is found with sedimentary rocks, but ones that have been squeezed and heated a bit so they are held together well and are not much like loose sediment; such rocks are common in western Pennsylvania. Anthracite is the most-cooked coal, and is found with metamorphic rocks in eastern Pennsylvania. Pennsylvania has lots of coal, but not much lignite, which would not be found in metamorphic rocks anyway.
The "Law" of Faunal Succession:
Was developed by an engineering geologist to aid in construction projects. In the late 1600s in England, William Smith discovered that putting the rocks in time order put the fossils in time order, allowing him to use the fossils as a shortcut in understanding the rocks. We will see soon that faunal succession is consistent with evolution but does not require it, does not require but might allow catastrophism, and informed but was not developed by theoretical biologists. Faunal succession was known before Congress was founded.
The "Law" of Faunal Succession:
Was developed by an engineering geologist to aid in construction projects. In the late 1600s in England, William Smith discovered that putting the rocks in time order put the fossils in time order, allowing him to use the fossils as a shortcut in understanding the rocks. We will see soon that faunal succession is consistent with evolution but does not require it, does not require but might allow catastrophism, and informed but was not developed by theoretical biologists. Faunal succession was known before Congress was founded.
Can a good geologist ever find a material that is somewhere between sedimentary rock and metamorphic rock?
Yes, because squeezing and heating sedimentary rock makes metamorphic rock, and intermediates exist. More heat and squeezing turn sedimentary rock to metamorphic rock. Where we change the name says a lot about us, and less about nature.
You develop a new idea, which is in conflict with a widely accepted scientific idea. For your new idea to gain widespread acceptance, you probably will need to show that:
Your new idea does a better job than the previously accepted idea in predicting the outcomes of an interlocking web of important experiments or observations. At last observation, Pepsi commercials were not highly scientific, even if science is involved in figuring out what sells. It is a romantic notion that you could overturn great knowledge with a single observation; however, observing nature is not easy, and nature occasionally fools us (you can, rarely, flip an honest coin twenty times and get twenty heads), so if a single observation disagrees with a lot of other information, that single observation will be checked in various ways to see if the new result "stands up" before the older body of knowledge is discarded. Before an idea gains wide currency, that idea is tried in various ways, in many labs, in many places in nature, while models are run and theory is developed. The interlocking of all of these provides the confidence that scientists can use in doing things successfully. Although received wisdom from sacred books can be used for inspiration, scientific ideas must be tested against nature. Social scientists have quite rightly learned that scientists are affected by their prejudices, their funding sources, their mating habits, and other things, and that the path of science is not nearly the straight-ahead road to understanding presented in some textbooks. Unfortunately, some of those social scientists have then gone off the deep end and claimed that science is no more useful than any other human story—claiming that astrology and astronomy are equally valid, for example, or palm-reading and modern medicine. These same social scientists seem to know where to find a real doctor when they get in trouble, however. Science is appealed to nature, and builds on the learning of people from around the world. Airplanes that fly, computers that calculate, small devices that make big explosions, etc. are not socially conditioned ideas but instead are demonstrations of the success of science coupled to engineering.