Homework #0
Humphrey Geology 4880 Fall 2015
This is due next
Thursday (Sept 8).
Notes on all homework:
This course
deviates from most courses in that it recognizes that the world around us is
complex, and that questions and answers must only be approximations. Learning to answer approximate questions in a
reasonable way is fundamental in learning how to ask questions about how our
world works.
Try to couch your
answers at the appropriate level of accuracy that is implied by the question.
You are free to use data from any source or to make reasonable assumptions, but state what you
assume, or show
the data you use and give the source of the data. Be aware that data and ideas from the Web are
of highly variable quality, so if you use web sources you must include the
URLs. To do the homework you will have
to take 4 steps:
·
figure
out how to do the problem,
·
decide
on the data you need (if any),
·
collect
the necessary information,
·
and finally produce an answer, or more
likely, a discussion of a possible answer.
Note for these questions I expect an answer based on your thinking. If by chance you actually find an answer to a
question on the Web, I will expect you to explain the answer.
Your work must be neat, legible, and organized. I am not willing to wade through a mess and I will just give it back to you to re-do. You can work with others, but be aware that you will have to do similar questions on exams and quizzes, by yourself.
Often the homework
will include one or more questions that are quite hard. Warning, usually the last one(s)
are virtually impossible; however I expect an attempt, since I want to see how
you approach a difficult question. (Homework #0 does not have an impossible
last question, but all the questions should make you think). Note that these questions are mostly just to
get you thinking in the wide ranging style that is needed to solve a lot of
geomorphic type questions. Actual answers only need to be (or for that matter can
only be) approximate. Since it is early
in the course, these questions do not require deep geomorphic knowledge, but do
introduce several concepts in geomorphology and environmental Geology.
Now the actual
homework
1
·
Part 1
How much rock is in Medicine Bow Peak? To make it more precise: what is the mass in kilograms
of Medicine Bow peak, above the elevation of Gap Lake (the lake between
Medicine Bow Peak and Browns Peak)? You
will need a topo map. TopoQuest on the web is a good place to
look. For other views Google Earth is a fantastic tool. [You will have to decide how accurately you
want to make this estimate. A general
rule of thumb: there is no point in making any measurement that is
significantly more accurate than any other variable in the problem. Part 2 asks
you to think about this a bit more]
·
Part 2 Now include an
educated comment on the likely size of the error in your estimate. Again, to be precise, answer these questions:
i.
What
are the 3 largest potential sources of error in your estimate, in order of importance. (Note
this is a straightforward question, but introduces the difficulty of answering
real world problems. Include your
working so I can follow your method)
ii.
Based on your answer to
the previous, put a % value on the potential size of the error. And look at
your answer to part 1, and decide how many significant digits should be in your
answer.
2 Afternoon thunderstorms are common
at this time of year in Laramie. How
many raindrops hit the Geology building (both wings) during a typical Laramie
thunderstorm? List the assumptions you
had to make. (This is an exercise in reasonable assumptions)
3 Close to ˝ the surface of the earth
has been transformed by human activity.
One of the spatially largest activities is deforestation. Removing a forest tends to raise the albedo
of the land and thus more sunlight is reflected from the earth, which in turn
should cool the global climate. So could we reverse our current global warming
trend by cutting down trees?
Write a comment on
this idea: is it true (Note, please don’t talk about the ethics of this, I am
asking for a science answer)? Part of
the reason for asking this question is that you will probably find several well
written but opposite viewpoints in the literature and especially on the
web. I want to illustrate that many
simple questions do not have a single ‘correct’ answer. Note that there really is an answer; if we
did cut down all the trees, the temperature will either go up or down. (But can we really know the answer now,
without cutting down trees?)
4 An interesting little factoid is
that tire dust is a notable source of air pollution (mainly because it is
chemically reactive). It is mainly a
problem in urban environments. But a lot
of vehicles drive on I-80. How many
metric tons (1000kg) of tire dust is produced in the Wyoming segment of I-80 in
a year, just by the 18 wheel trucks?
5 Sand sized particles are common in
the weathered surface material of our planet. Sand is common everywhere that
physical (as opposed to chemical) weathering occurs, such as in rivers, beaches
and deserts. Indeed, virtually all
surficial deposits, that are not marine, have a strong peak in the sand size of
the distribution. Laramie overlies a
large indurated pile of sand, the Casper sandstone. Why is sand so common? (or why isn’t there
a continuum or smooth distribution of sizes from big to tiny, instead of this
preponderance of sand, and as it turns out another peak in abundance in the
silt/clay sizes?). Hint, note I said that
sand is common where physical erosion processes dominate.