Introduction
Course objectives
The objective of this course is to show how it is possible to reconstruct the past history of the Earth from our present observation of the rocks.
It will differ from other textbooks in that it will place a strong emphasis on asking and answering the question: "How do we know?" Most textbooks report certain aspects of geological knowledge simply as things that are known: for example, that granite is an igneous rock, or that sandstone with certain properties is aeolian; or that the Earth's core is iron; but without addressing, or at least without
systematically addressing, the question of how these things are known in such a way as to satisfy the doubts of the skeptical or the inquisitiveness of the curious.
As a result, the average geology textbook does fairly poor service to the skeptical, or to those who wish to debate and convince the skeptical. It also, in my view, does a disservice to the science of geology itself: for the story of geology is in effect the world's longest-running detective story, and it is more interesting if geology is presented as such than as a collection of facts handed down from on high.
Course outline
Finding the right order in which to structure a course in geology is perhaps the most perplexing decision facing its author. No solution is ideal, because (with the exception of the definition of basic terms, which clearly should come first) it would be best if every topic could be discussed last, so that the reader can come to it with the rest of the course as context. As this is impossible, some sort of compromise has to be made.
The contents of the course will be as follows:
(1) Rocks and minerals: in which I explain what is a mineral, what is a rock, what are sedimentary, igneous, and metamorphic rocks.
(2) Weathering and erosion: a look at mechanical weathering, chemical weathering, and erosion.
(3) Sedimentology: a systematic look at all the different types of sediment and their corresponding sedimentary rocks --- peat and coal; glacial till and tillite; deserts and aeolian sandstone; coccoliths and chalk; etc, etc, etc.
(4) Plate tectonics: in which we describe how it is known that plates move, what is know of the mechanisms, and what effects this has in terms of faulting, folding, orogeny, ophiolites, terranes, etc.
(5) Stratigraphy: a discussion of actualism, of Steno's principles, of way-up marks, of cross-cutting relationships, of the geological column, of index fossils, and so forth. This may also be a good place to discuss paleoclimatology.
(6) Absolute dating: those dating methods other than the relative methods of stratigraphy. This will include a look at some of the methods of more doubtful value, such as fluoride dating and racemization.
At that point I shall have done what I set out to do, in that the reader will then have a grasp of the principles of historical geology. However, it may be that the readership will have further questions. In particular, the reader may want to see some historical geology actually done, or in other words to see some case studies. It may be possible to continue the discussion along these lines.
Note on sources
It will not be necessary to give references for notions which are the common property of geologists, such as the definition of a mineral or the fact that granite is felsic. However, I shall provide references to the more abstruse or particular facts to which I allude.
Acknowledgments
Thanks are due to Pressie for volunteering to review the material. Any remaining errors are, of course, my fault.
Edited by Dr Adequate, : No reason given.
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