During the appropriate lecture, I will call on students to answer questions such as these. Occasionally I will ask for all the papers of a particular day to be turned in to be graded as quizzes. The questions are usually from the textbook, our class notes, or our webpage and its links.
Wednesday, August 27, 2003
1. Please briefly describe the nebular hypothesis for the origin of the Sun and the Solar System.
2. Why is the interior of the Earth so hot?
3. Why is the distribution of fossils in the Earth's crust important for the development of the geologic time scale?
Friday, August 29, 2003
1. What is the definition of a mineral? (Sorry for such an easy question. A critical one, though.)
2. What is it about the atomic structure of some minerals that gives them the property of cleavage?
3. How is specific gravity defined?
September 1, 2003 (Monday)
1. Consider the wonders of Bowen’s Reaction Series. Why does the remaining liquid of a crystallizing magma increase in silica content with decreasing temperature? (Think of which minerals form first, which last, and why.)
2. Why do intrusive igneous rocks tend to have coarse crystals (phaneritic texture) and extrusive igneous rocks tend to have fine crystals (aphanitic texture)?
September 5, 2003 (Friday)
1. What is decompression melting and how is it a factor at mid-ocean ridges?
2. Rhyolitic magmas, when erupted, are much more explosive than basaltic magmas. Why is this? In your answer, please mention an area where rhyolitic eruptions occur and one where you expect to find basaltic eruptions.
3. When a granite is melted, can you predict which minerals will melt first? If so, please list them in the order they will melt.
September 8, 2003 (Monday)
1. Why are sediment accumulations thinner on the ocean floors than on the continents if all sediment is eventually destined to erode off the continents into the sea?
2. What is a sedimentary facies? You may need to use the Web or a geological dictionary to answer this one.
September 10, 2003 (Wednesday)
1. Why do mudcracks appear in sediments which dry out?
2. What is graded bedding? How does it form?
3. What is the quickest way to make sea level rise? How about to make it fall?
September 15, 2003 (Monday)
1. How do geologists define a metamorphic rock?
2. What is the difference between lithostatic pressure and differential pressure? How can these differences be manifested in metamorphic rocks?
3. What are index minerals and how are they used to classify metamorphic rocks?
September 17, 2003 (Wednesday)
1. I’ll assume you already know the Geological Time Scale, but I’ll print it on the back of this page anyway. You’ll also be able to easily tell me here the difference between relative and absolute time:
2. What error did the physicist Lord Kelvin make when he miscalculated the age of the Earth?
3. What is the Principle of Fossil Succession?
September 19, 2003 (Friday)
1. Please see the diagram on page 497 of your textbook. Your task before Friday’s class is to develop a similar geological history for the block of crust printed below. Follow the procedures outlined in Chapter 17 and used in class. Remember that a history starts with the oldest events and proceeds to the youngest.
September 22, 2003 (Monday)
1. What is the definition of a fossil? (Yes, those of you in Invertebrate Paleontology – or who have already had it – are at a considerable advantage here!)
2. Some fossils are preserved by carbonization. What is the process of carbonization?
3. Why (not how) are fossils useful for dating rocks?
September 24, 2003 (Wednesday)
1. What is the geological technique of stratigraphic correlation?
2. How can the fossil record be useful in correlating between different sedimentary facies?
3. Let’s say you have found a stratigraphic sequence with a disconformity which you cannot actually see. (These are sometimes called paraconformities.) How can the fossil record tell you it is there?
September 29, 2003 (Monday)
1. We return to some earlier reading for this lecture on absolute dating techniques. Let’s start with a review of our most useful term: isotope. Please define an isotope below and give an example.
2. What is the difference between alpha decay and beta decay?
3. You want to radiometrically date a piece of wood approximately 25,000 years old. What will be your most useful technique?
October 1, 2003 (Wednesday)
1. Radiocarbon dating (using carbon-14) has an effective range of only about 40,000 years under ordinary conditions. Why can’t we use it for older materials?
2. What is the difference between stress and strain in geological terminology?
3. For that matter, what is the difference between brittle and ductile in geological terms?
October 3, 2003 (Friday)
1. The concept of strike and dip of rock units is fundamental to an understanding of geological structures. Let’s start with the first term: please define strike below. This will be very difficult to do without a little drawing!
2. OK, now what is dip?
3. While we’re on these basics, please draw little labeled diagrams showing a normal fault and then a reverse fault. What forces (tension or compression) are involved in each?
October 8, 2003 (Wednesday)
1. What was the contribution of the German meteorologist Alfred Wegener to the eventual Theory of Plate Tectonics?
2. How is Permian glaciation used to demonstrate the past existence of Gondwana?
3. What is the Curie Point?
October 10, 2003 (Friday)
We’re ahead a bit on our Preparation Questions, so I have a chance to ask you what sort of special project you would like to pursue in this course. Remember that this is not a term paper. You will choose an activity which involves some geological material or technique, and then briefly report on what you learned and discovered to the class at the end of the semester.
1. Please tell me below what sort of project you have in mind. It could be the thin-section analysis of a rock, the interpretation of the rings in the Kauke/Old Main trees, the study of a fossil collection, etc. Feel free to just tell me what you’d like to do. This document does not obligate you to anything – it is the start of a discussion.
October 15, 2003 (Wednesday)
This one is different in honor of our upcoming Fall Break. I wouldn’t want you to leave without something to do! (And I don’t want to give you anything too onerous, either.) Attached to this page is a web article from the creationist group “Answers In Genesis”. It is an attempt to answer the question why there are no human fossils intermingled throughout the fossil record, which would be expected if most fossil-bearing strata is from Noah’s Flood (the standard premise of modern creationism). Since this article makes several statements about geology which you can now understand, I’d like you to read it and simply make comments about it in the space below. We will use these comments to start a class discussion of creationism and geology. Lest you think this is a sideline issue, remember that about 45% of Americans believe that the Earth is less than 10,000 years old and the Flood of Noah really happened on a global scale.
October 17, 2003 (Friday)
1. What is the Benioff Zone? A nice little drawing will be useful.
2. Might as well define another convergent-margin term. What is a mélange? (Love that word.)
3. What type of magma can be melted by simply adding water? (Interesting concept.)
October 22, 2003 (Wednesday)
1. Please name below three mountain ranges which have formed by collisions between two continental plates, and then name the two plates for each.
2. What is a microplate? These are sometimes called allochthonous terranes.
October 24, 2003 (Friday)
1. On Thursday (tomorrow) at 11:00 a.m. in Scovel 205, Ethan Skinner will be giving a talk entitled: “Taphonomy of some exceptionally preserved organisms from the Lower Cambrian of Laurentia”. This will be a required lecture for this class, and I have some questions in advance. First, what is “Laurentia”?
2. What is unusual about the preservation of these Cambrian fossils?
3. What conditions may have led to this type of preservation, according to Mr. Skinner?
October 27, 2003 (Monday)
1. Here’s one to look up somewhere other than your book: What is the Red Shift of light coming from distant galaxies, and what does it tell us about the dynamics of the Universe? The Web is a good place to start on this one.
2. The universe today consists mostly of hydrogen (75%), followed by helium (24%); the other elements make up the remaining 1%. Soon after the beginning it was entirely hydrogen. What happened to all that hydrogen?
October 29, 2003 (Wednesday)
1. What is the present composition of the atmosphere?
2. Our atmosphere could have as much carbon dioxide in it as the atmosphere of Venus, but it doesn’t. Why?
3. For that matter, what would it be like on the surface of the Earth if we did have all that CO2 in our atmosphere?
November 10, 2003 (Monday)
1. Almost 60% of Proterozoic rocks are quartzites, limestones and shale. What does this tell us about Proterozoic depositional environments? (Especially in comparison to the Archean and Phanerozoic.)
2. How do we define the Proterozoic/Phanerozoic boundary?
3. What was the Grenville Orogeny? How did it affect the region we now call Ohio?
November 12, 2003 (Wednesday)
1. What is a mobile belt in terms of continental architecture?
2. For that matter, what are epeiric seas?
3. OK, one more definition. I don’t think you’ll find this one in your book, so to the web or a geological dictionary for you! What is an aulacogen?
November 14, 2003 (Friday)
1. What was the primary cause of the Taconic Orogeny in eastern North America?
2. For that matter, what caused the Acadian Orogeny? Again, in simple terms.
3. The large clastic wedge formed from the Acadian Highlands in eastern North America is called the Catskill Delta. What was its equivalent from the Caledonian Highlands in Baltica?
November 17, 2003 (Monday)
1. What do you think the climate was like in the interior of the supercontinent Pangaea in the Late Permian? Why?
2. The many orogenic uplifts associated with the development of Pangaea may have led to a decrease in the amount of carbon dioxide in the atmosphere. How can mountains affect atmospheric composition?
3. Name and briefly describe (one sentence) three groups of organisms which went extinct at the end of the Permian.
November 19, 2003 (Wednesday)
1. The Web will be most useful for this: Please describe either the Sevier Orogeny or the Laramide Orogeny in western North America, including labeled diagrams. (And yes, you must find your own links!)
November 21, 2003 (Friday)
1. Earlier this semester we looked at the Hawaiian Islands and Emperor Seamounts chain of hotspot volcanoes in the Pacific Ocean. Why does this chain make an abrupt bend about 40 million years ago?
2. How did the San Andreas Fault in California originate?
November 24, 2003 (Monday)
1. Since so many of you have had the History of Life course, I don’t want to repeat significant amounts of that material. However, the Cretaceous extinction story is dramatic and dynamic, so it won’t hurt anyone to hear the latest version. The first question: Why is the element iridium significant for our catastrophic explanation of the Cretaceous extinctions?
2. What evidence do we have that the Chicxulub structure in Yucatan is really a buried impact crater from the latest Cretaceous?