Petrology means the study of rocks.  Because rocks are made of minerals, this course will be very much a continuation of Geology 221a.  Ideally, you will learn how to recognize, describe, and classify many rocks in both hand specimen and thin section.  Your skills of both hand specimen and optical mineralogy will be honed throughout the semester.  In addition you will learn some facts, principles, and tools that should be useful in unraveling the history of igneous and metamorphic rocks. The petrology of sedimentary rocks is considered in Geology 232a, Sedimentology.  Igneous and metamorphic rocks, having formed at elevated temperatures and perhaps elevated pressures, typically contain assemblages of minerals that have approached chemical equilibrium.  These rocks, therefore, are subject to the laws of thermodynamics, which greatly reduce the number of possible mineral assemblages and simplifies our task significantly.  With the petrologic knowledge that certain minerals are commonly found together and that other minerals are never found together, mineral identification in igneous and metamorphic rocks is surprisingly easy.

The major concepts I hope you will learn in petrology are: (1) there is a close relationship between the mineralogy and the chemical composition of a rock (one can calculate the chemical composition from the mineralogy and in some cases the mineralogy from the chemical composition); (2) the relationship mentioned in (1) depends on the physical conditions (temperature, pressure, fH₂O, fCO₂, etc.) under which the minerals grow; (3) the mineralogy and chemistry of a rock, along with the results of laboratory experiments, can be used to constrain the physical conditions that were experienced by that rock; (4) the relationships in (1) and (2) are more easily understood if the data are graphed appropriately; (5) igneous and metamorphic rocks have a tectonic setting and history that can be read in part from (1) and (2) along with field data, textural data, and other geologic information.

The organization of this course will be similar to that of Geology 221a.  Problem sets that explore course material will be assigned regularly.  Lab work, principally the study of rocks in hand sample and thin section, is a major focus of the course and commonly will require individual work outside of the scheduled lab time.  Lab reports are required for most labs.  There is a final lab project.  There are no exams.  Scientists rarely work in a vacuum and seldom work alone.  Two heads are generally better than one and three better than two (there is a limit to this, however!).  I urge you to help one another in the field, in the lab, and in completing problem sets and other assignments (unless an individual effort is specifically requested).  Joint efforts are a problem only if the members of the group are not equal partners in the endeavor.  Don't let other people do your thinking for you. If you do work closely with one or more partners, please acknowledge their assistance in your written work.

There will be two weekend field trips. One is a Sunday trip to some of the igneous rocks along the coast (Cape Ann) north of Boston (01 April).  The other is a full weekend field trip to Vermont  (27-29 April). Field trip participation is required and will be a part of the course grade because so much that is important to petrology can be learned only in the field.  Anyone who has a conflict that prevents them from going on a field trip may turn in a paper summarizing the geology of the region visited (by the start of the lab period the following week) to receive credit.

The text for the course will be An Introduction to Igneous and Metamorphic Petrology by John D. Winter, who teaches at Whitman College. If you cannnot purchase a copy, you can find similar readings available in other petrology texts in Burton 109 or in the libarary. Please do not remove books from B-109; they are there for all to use. Also, chapters of a nearly final draft of the text are available though the Moodle page for this class. Your username and password for Moodle are both your student number. Reading assignments will be given for nearly every class meeting.  Careful reading of these assignments will help you understand class discussions, lab assignments, and the field trips. To encourage you to do the reading before class, there will be a short Moodle quiz on the reading before each class. The quizes will be 1-3 very simple multiple-choice questions that can be answered easily if you do the reading.

Computers will be of considerable use in Petrology and in many other geology courses.  Because some of the software used in this and other geology classes at Smith is specific to Macintosh computers, it is in your interest to become familiar with the Macintosh computer interface. It will also help you to know the basics of software such as Excel (spreadsheets), Word (text), PowerPoint (presentation), and Photoshop (images). Some instruction on the use of Macs and software will be given in class, but you should also watch for Information Systems workshops.

I don't like grades, but evaluation in the form of a grade is required by the College.  Assigned work will include a combination of projects, problem sets, and lab assignments.  You can see a list of planned assignments, but it may change in detail as we proceed so check the list regularly. Each assignment will have a point value (to show their relative importance or the relative effort required). Due dates will be enforced with a 10% decrease in credit for each day late. You can submit assignments electronically through Moodle if you wish. Guidance in thinking about grades can be found in comments by J.H. Williams, modified by C.A. Rigsby.

My office hours will be Th 4-5 and W 10:30-12 (or by appointment if these times are not convenient).  However, I will be happy to talk with you about petrology (and geology in general) most any time I am in my office.

An approximate class schedule is available.  However, you should not be surprised if the course deviates from the details of the planned schedule.