Geology 102, Fall 2007

Mid-term #1 study reference

General statement. I take questions from my lecture notes to make up the exam. Much of my lecture material comes from the book, but not all. Reading the book thoroughly and reviewing my lecture notes should be sufficient preparation for the exam.

The following chapters will be covered on Mid-term #1

1: Introduction

2: Minerals

3: Rocks: Materials of the Solid Earth

4: Weathering and soil sections only!

11: Geologic Time

12: Earth’s History: A brief summary

Comments about my exams

I expect you to have a thorough understanding of those subjects listed here. I try very hard to construct questions that are on the major topics covered in lecture; in most cases these subjects are also covered in the book.  Note: I double-check the review sheet after I construct the exam to be sure that I only have asked questions on the subjects that I have listed for study.

A note about my questions: I have been accused of asking “tricky” multiple-choice questions.  By “tricky” what is meant is that answers may all seem like reasonable answers to the question, particularly if you have not studied. To that I say, “Guilty as charged!”   I will give you questions that require you to think through each answer before deciding which one is right.  I will do my best not to ask you factoid questions as they do little to satisfy you (or me!) that we are getting a worthwhile education.  Facts slip from memory quickly, but understanding the processes that govern our world are harder to forget once you’ve learned them.  These will stay with you even when there are no more classes.

The exam questions will be based on the following topics, which I have talked about in class and mostly are covered in the book. I strongly urge you to review your notes and read the text carefully before the exam.  I will formulate the questions from this pool of topics. Questions will be multiple-choice, fill in the blank, sketch a diagram, and a one-paragraph essay (you choose from one of three topics).

Big Bang- how long ago, what elements did it create?

Nucleosynthesis in the center of stars- responsible for creating the heavier elements up through iron.

Supernovae- exploding stars.  What evidence is there that one led to the creation of our Solar System?

Nebular Hypothesis: Sun, Earth, Moon formation: When? How?

Earth’s internal heat: what are the four sources?

What are the primary compositional layers in Earth’s interior and on its exterior?

What are the primary layers of Earth based on physical properties (solid vs. liquid)?

Planetary model for the atom: protons, neutrons, and electrons

Periodic Table- What do rows equate to in the planetary model of an atom? What do the columns mean in terms of electrons in outermost shell (ring)?

Why do elements chemically bond with other elements, particularly is the elements are electrically neutral before bonding?

Chemical bonding- covalent and ionic- which is strong? Which is weak?

What’s mineral cleavage?  What is crystal form?

Silica tetrahedron- what’s its importance in silicate mineral cleavage?  Note how silica tetrahedral join together to form ifferent groups of silicate minerals (isolated tetrahedral, chains, double chains, sheets, frameworks).

What’s  Bowen’s Reactions series and how does the structure of the silica tetrahedra relate to a mineral’s position within the series?

Mineral stability- why is quartz so abundant at Earth’s surface, whereas olivine and clinopyroxene are not? (hint: study Bowen’s Reaction series, and consider where Earth’s surface would plot on this diagram)

Igneous, sedimentary, and metamorphic rocks- why does each form?  Recall that all three types of rocks are named based on rock texure.  Know those texture classifications.

How are rocks decomposed by weathering?

What are the two main types of weathering?

Why doesn’t quartz have cleavage?

Igneous rocks.  How does magma form in the mantle (recall P, T, volatiles)?  Where, globally speaking, do each of these three controls on magma formation occur? (recall mid-ocean ridges, subduction zones and mantle plumes).

What is crystal settling and how does it affect the magma’s density?

What are the four main constituent of a soil?  What does the soil profile look like for a humid environment? How about an arid environment?

Chapter 11: Geologic Time

Catastrophism vs. Uniformitarianism

Laws of: Superposition, cross cutting relationships, original horizontality, inclusions, faunal (or fossil) succession

Unconformities: Angular, dis-, non-

Radioactive dating- half life, exponential decay, parent and daughter isotopes

What happens to an element that undergoes radioactive decay (they change into different elements)

Geologic Time Scale

Precambrian Eon- 88% of Geologic history

How did Precambrian atmosphere differ from the modern atmosphere?

Banded Iron Formations- How long ago?  W what does their presence tell us about the Earth?

Snowball Earth- how does it compare to the ice age that ended 12,000 years ago?

Evolution of life on earth- what’s the general progression of life from earliest invertebrates to mammals (i.e. the "Ages")?

What are the main subdivisions of the Phanerozoic Eon? What are the ages of the Paleozoic-Mesozoic, and Mesozoic-Cenozoic Boundaries?

In a general way, how has the continent of North America changed position on Earth over the last 700 Myr?