Astronomy/Geology 1070: Earth: Its Physical Environment

Written Homework 4, Due October 6, 2011
20 points

Please submit your work to me by the beginning of class.

These questions are for you to combine different ideas and apply them to situations not directly addressed in class or in the textbook. Think about the situation, and about the science that applies to it. See me for help if you are stuck.

This assignment has four parts. The first three parts each give you two choices of which question to answer. Answer one question each from parts A, B, and C. Part D is for your own good.

Part A: Rocks (5 points)

Rock types.

Most of the rocks of the Earth’s crust are igneous, but most of the rocks found at Earth’s surface are sedimentary. Explain why this is so.

Sediment and rock.

What is the difference between sediment and sedimentary rock?
What is the difference between sedimentary and metamorphic rock?
Why isn’t sedimentary rock considered metamorphic?

Part B: Topographic maps (10 points)

Telling things apart.

On a topographic map, how can you distinguish the following pairs of features?

A hill from a depression?
A U-shaped valley from a V-shaped valley?
A steep slope from a gradual slope?
A ridge from a valley?
A level valley from a plunging valley? (“Plunging” means that it has a tilted axis. An example is a stream running downhill.)

Explain the maps.

You have a topographic map of an area where you plan to hike. Your roommate, who has never seen a topographic map before, asks you about it. What does it show? How do you read it? Write the script of the dialogue between you and your roommate as you teach how to read the map. Be sure to explain to your roommate how you can tell what the shapes of the landscape features are, how big they are, and how steep they are. Make sure your roommate understands you!

Part C: Glaciers and streams (5 points)

Valleys.

Explain why glacier-eroded valeys are U-shaped but river-eroded valleys are V-shaped. What characteristics and features of rivers and glaciers cause these cross-sectional different profiles? What different processes occur in these two settings to produce these different results? Explain your reasoning.

You may not be able to find the answer to this question in your book or notes. The point here is for you to think about what is going on and propose a reasonable explanation. Your answer will receive full credit if it shows evidence of careful thought, even if it is not fully “correct.”

Sediments.

Glacier-deposited sediments, known as till, are unsorted (pieces of all sizes occur together), but river-deposited sediments are highly sorted (pieces near each other tend to be of very similar sizes). Why is this? Explain your reasoning.

As with the previous question, the answer to this question may not be in your book or notes. Here as well, your answer will receive full credit if it shows evidence of careful thought, even if it is not fully “correct.”

Warning: Do not turn in paper that has ragged edges! If you write your work in a spiral-bound notebook, trim the edge before submitting it. Papers with ragged edges will be returned unmarked.

You may also submit your answer using the “Assignments” tool in WyoSakai.

Part D: HTML (0 points)

That’s right. This is for your own good, not for a grade.

I have written a series of tutorials explaining HTML and posted them to my web site. You may consult them to learn how to make web pages. (You want to know how to make HTML web pages because your third project will be an HTML web page.)

Read the first one, which explains what HTML is and steps you through making and displaying a simple HTML file (web page) of your own. Then, actually make your HTML file and upload it to the “Assignments” tool on Sakai.

If you choose, you may consult other HTML tutorials on the web as well, or you may rely entirely on other sources and ignore mine. But I do want you to be able to make HTML files.

Here is the gateway to my HTML tutorials.
Here is the first tutorial in the series.