One of the enchanting aspects of the natural sciences concerns the roles of observation and generalization. The subject matter of the natural sciences is often complex and, consequently, the source of endless fascination. However, this complexity, which requires documentation through careful observation and analysis, may belie relatively simple principles and symmetries (such as time invariance) which govern the dynamics, and which can only be understood by generalization and abstraction. In many intriguing ways these two different approaches lead in opposing directions and the tension thus created provides the lifeblood of our science. While the different approaches may require very different skills and temperaments, both are important to the development of our science, no one more so than the other. This course fundamentally (and unashamedly) concerns the results and outcomes of the process of generalization (in which the Earth is necessarily considered a very simple beast responding to simple pleasures provided by the laws of nature). However, more than anything else, the questions addressed, and conclusions articulated, here represent the fruits of many hours spent observing at the outcrop scale where geology can appear very complex, indeed. While I believe many benefits accrue from the world-view that results from the process of generalization, I begin with an important disclaimer: careful observation and analysis will always be remembered and used long after once fashionable interpretation has been ridiculed and disbanded. After all, the time-honored tradition of the sciences is that, like biological species, theories have a finite lifespan.

Mike Sandiford, January 1994.