Lab exercise objective: One important objective of most introductory science courses is to educate participants about the nature of the scientific enterprise. The reasoning is that since our society and culture are so heavily influenced and shaped by science an educated member of society should have some idea of how science works, what it can do, and what it can't do. Traditionally, this is introduced as lecture material. Arguably, it is better learned through experience. This lab is designed to give you some experience with the structure of scientific investigations. It should take anywhere from one to two hours, and is mentally challenging.
Questions are often the first step on the way to new understanding. Asking the right question is a very important scientific skill. It is one you may have little practice with. At the undergraduate level the focus is often on how to answer questions. In the space below write down three questions that are geoscience related and which you think may give you new understanding of the earth. These should be questions that you do not yet know the answer to. This may prove to be more difficult than you think. Yet asking questions is a very valuable skill for you to develop. Here are some suggestions that may help. Your question need not be complex nor sophisticated simple questions often provide crucial basic understanding, and at an introductory level it is best if your question is simple. For this exercise it is OK if you think it is likely that the question has already been answered. The question should be as specific as possible.
Very fruitful questions in geoscience: The idea here is to connect the question with the new understanding it provided. The first list is of questions that proved scientifically insightful and the second is of the associated insights. Match them.
In this exercise you are given two simple questions, some background information, and some options. From these you should assemble a way to answer the question.
Question 1: While panning for gold in a stream at location E (for Eureka), marked on the accompanying map, coarse gold nuggets were found (placer gold see below). Knowing that these were transported from some source (the hydrothermal gold mother lode), the question is where did the gold come from?
Background information: Gold occurs geologically as a native element, i.e. as pure gold, not bound to other elements in a more complex compound. This is partly because it is relatively inert, not reacting with other elements such as oxygen. Gold is also fairly rare, a very minor component of the earth's crust. When it occurs as an economically minable deposit (an ore) some geologic process has concentrated it. As a result there are two main types of gold deposits. The largest are formed by hydrothermal processes, involving the circulation of hot water through the crust. If the important parameters are just right gold is scavenged from the rocks by the circulating hot fluids in an area, and then concentrated by the growth/precipitation of gold in fractures. This hydrothermal gold often occurs in quartz veins. When these veins are exposed at the surface of the earth they are eroded and gold particles, from gold dust to gold nuggets get transported in streams and concentrated in select types of stream sediments. This type of deposit is known as placer gold. So placer gold comes from the erosion of some hydrothermal source rock. You can think of this background information as an exploration model. This should very much shape how you go about addressing this question.
There is a lot of information on the USGS topo map. What information is pertinent to the question you are trying to answer? Since the gold is transported by stream currents, the drainage pattern (shown with blue lines for rivers and streams) gives you crucial information. The brown lines are contour lines, which capture the topography.
- Sampling of surface sediments on a grid pattern throughout the map area.
- Sampling of stream sediments just upstream of every fork (two samples, one from each branch).
- Sampling of stream sediments every 500 m upstream of site E.
- Geologic mapping of bedrock exposures in a designated area (the larger the area the more time consuming).
- Field assessment of gold content of samples (less precise).
- Lab assessment of gold content (much more precise, but more expensive and time consuming).
- Creating map of measured gold values measured in the samples taken.
Instructions: Describe how you would solve this question in a step by step fashion (time-ordered sequence of steps). Mark on the map where you would take samples if any. 'Circle' (the area is unlikely to be actually circular, but to have a more irregular outline) on the map where you would map the bedrock, if you chose that option. For each step describe your reasoning for that step. Some steps are suggested in the list of options above. You should not use all of these, and you should also not limit yourself to these. Importantly, remember that resources and time are limited. Finally, discuss any possible problems with your approach (especially look for underlying assumptions that might not be met).
Question 2: How fast is the ice in the glacier depicted in the map and images below moving?
Background information: Glaciers are composed of ice, a substance normally thought of as a solid. Despite this they also 'flow', move, under the influence of gravity. They both can slide over the rock they sit on, and/or there can be internal movement within the ice.
Instructions: Describe how you would solve this question in a step by step fashion (time-ordered sequence of steps). Mark on the map where your measurement stations should be. For each step describe your reasoning for that step. Some steps are suggested in the list of options above. You should not use all of these, and you should also not limit yourself to these. Importantly, remember that resources and time are limited. Finally, discuss any possible problems with your approach (especially look for underlying assumptions that might not be met).
Read the account of Count Buffon's experiments provided you. This excerpt was taken from Claude Albritton's book The Abyss of Time (Freeman, Cooper & Company publishers), and is a summary of Buffon's 1778 book Epoques de la Nature. Then answer the questions below. For each question be as brief and to the point as possible. One or two sentences will suffice.
"Buffon set up an experiment in his iron foundry. He had his workmen fashion ten balls of iron graduated in diameter by half inches up to a maximum of five inches. These balls were heated to near the melting point. Then he measured the time required for each ball to cool, first to the point that it could be touched without burning the fingers, and then to the point that the temperature was the same as that of the air in a nearby cave. These experiments showed that with each increase of half-inch in diameter, the time required fro cooling to the first point increased by 12 minutes, and for cooling to cave temperature by 54 minutes. With a bold extrapolation he calculated that a globe of molten iron the size of the earth would require 49.964 years and 221 days to cool to the point it would not burn the hand when touched, and 96,670 years and 132 days for the temperature to fall to the present temperature of the earth. ...Buffon repeated the experiments in cooling, this time using mixtures of metallic and non-metallic substances more like the actual composition of the earth. He made corrections in his figures to allow for retardation in cooling due to the heat that earth would receive from the sun. ... the key figures he finally published are the following: 2,936 years for the earth to consolidate from a molten condition, 37,500 years for cooling before the earth could be safely touched, and 75,000 years for the earth to cool to its present temperature. "
What was the question being addressed?
What data was being collected?
How was the data collected?
How was the data treated or analyzed?
What was the basic conclusion?
Here is a link to a one description of the scientific process.
An obvious step to take when trying to answer
a question is to see whether someone else has already answered
that question, or a similar question, or if there is information
out there about how to answer this type of question. In other
words, you need to do some background research, a search for relevant
information in the scientific literature that can help you answer
your question. This is a crucial step!
A basic skill to have when evaluating information is that of critical analysis. This is especially true nowadays where the web is one often used source. Information is of variable quality. Conclusions can be poorly reasoned, data can be strongly biased. Discerning the quality of information can be especially challenging for the newcomer to the field. Here we are interested in giving you some experience with critical analysis and judging information quality.
Carl Sagan gave this some serious thought based on experience and offered a "baloney" detection kit to identify information of dubious scientific value (it can still have high persuasive value to the uninformed). Below is one of several versions of the kit that can be found on the web, that paraphrases and quotes from Sagan's book (p. 196-204).
Taken from: http://daphne.palomar.edu/jgilardi/carl_sagan.htm
CARL SAGAN'S BALONEY DETECTION KIT
Based on the book The Demon Haunted World by Carl Sagan
The following are suggested as tools for
testing arguments and detecting fallacious or fraudulent arguments:
o Wherever possible there must be independent confirmation of the facts.
o Encourage substantive debate on the evidence by knowledgeable proponents of all points of view.
o Arguments from authority carry little weight (in science there are no "authorities").
o Spin more than one hypothesis - don't simply run with the first idea that caught your fancy.
o Try not to get overly attached to a hypothesis just because it's yours.
o Quantify, wherever possible.
o If there is a chain of argument every link in the chain must work.
o "Occam's razor" - if there are two hypothesis that explain the data equally well choose the simpler.
o Ask whether the hypothesis can, at least in principle, be falsified (shown to be false by some unambiguous test). In other words, it is testable? Can others duplicate the experiment and get the same result?
Additional issues are
o Conduct control experiments - especially
"double blind" experiments where the person taking measurements
is not aware of the test and control subjects.
o Check for confounding factors - separate the variables.
Common fallacies of logic and rhetoric
o Ad hominem - attacking the arguer and not the argument.
o Argument from "authority".
o Argument from adverse consequences (putting pressure on the decision maker by pointing out dire consequences of an "unfavorable" decision).
o Appeal to ignorance (absence of evidence is not evidence of absence).
o Special pleading (typically referring to god's will).
o Begging the question (assuming an answer in the way the question is phrased).
o Observational selection (counting the hits and forgetting the misses).
o Statistics of small numbers (such as drawing conclusions from inadequate sample sizes).
o Misunderstanding the nature of statistics (President Eisenhower expressing astonishment and alarm on discovering that fully half of all Americans have below average intelligence!)
o Inconsistency (e.g. military expenditures based on worst case scenarios but scientific projections on environmental dangers thriftily ignored because they are not "proved").
o Non sequitur - "it does not follow" - the logic falls down.
o Post hoc, ergo propter hoc - "it happened after so it was caused by" - confusion of cause and effect.
o Meaningless question ("what happens when an irresistible force meets an immovable object?).
o Excluded middle - considering only the two extremes in a range of possibilities (making the "other side" look worse than it really is).
o Short-term v. long-term - a subset of excluded middle ("why pursue fundamental science when we have so huge a budget deficit?").
o Slippery slope - a subset of excluded middle - unwarranted extrapolation of the effects (give an inch and they will take a mile).
o Confusion of correlation and causation.
o Straw man - caricaturing (or stereotyping) a position to make it easier to attack..
o Suppressed evidence or half-truths.
o Weasel words - for example, use of euphemisms for war such as "police action" to get around limitations on Presidential powers. "An important art of politicians is to find new names for institutions which under old names have become odious to the public"
Some of the above items are much more useful than others, and the details of application of others can be argued, but many have found them a useful information screening device. Below are two examples where you can try to identify some of the above components.
Example 1: R. T. Chamberlin, a well known American geologist said the following of the idea of continental drift as proposed by Alfred Wegener in the 1920s. Continental drift was the then revolutionary concept that continents move large distances with respect to each other, splitting and colliding.
"Wegener's hypothesis in general is of the foot-loose type, in that it takes considerable liberty with our globe, and is less bound by restrictions or tied down by awkward, ugly facts than most of its rival theories. His appeal seems to lie in the fact that it plays a game in which there are few of the restrictive rules and no sharply drawn code of conduct." (quote taken from Hallam, 1983).
Which of the above fallacies (if any) does the above quote utilize?
Example 2: The following example is taken from Hallam, 1983, Great Geologic Controversies, Oxford Press, p. 73, and is a quote from a well known geologist in 1838, when a debate was raging about whether a host of features were formed by glaciers and the Ice Age, or by a Noachian style flood.
" Could scratches and polish just be due to ice? If we apply it to any as the necessary cause, the day will come when we shall apply it to all ..."
Which of the above fallacies (if any) does the above quote utilize?
Example 3: The following example is taken from http://www.pathlights.com/ce_encyclopedia/05agee3.htm#Evidence%20from%20Beneath
"EVIDENCE FROM ON THE SURFACE OF THE EARTH
1 - Topsoil. It has been calculated that 300 to 1,000 years is required to build one inch [2.54 cm] of topsoil. Yet the average depth of topsoil is about eight inches. On this basis, the earth could only be a few thousand years old.-p. 27. "
Which of the above fallacies (if any) does the above quote utilize?
Last exercise: Consider the material you researched and read last week on surface features on Mars in preparation. Find any of the above fallacies that can be identified in the one you chose to read. Quote the relevant section and indicate what type of fallacy it is.