Geomorphology is the study of the shape of the Earth. In this book we take this quite literally, and address the shape of the Earth at many scales. We ask why it is spherical, or not quite spherical, why it has a distribution of elevations that is bimodal, one mode characterizing a quite well-organized set of ocean basins, another the terrestrial landscape. At smaller scales, we address why hilltops are convex, why glacial troughs are U-shaped, why rivers are concave up. At yet smaller scales, sand is rippled, beaches are cusped, hillslopes are striped, and mud is cracked. These are some of nature’s most remarkable and visible examples of self-organizing systems. Each cries out for both explanation and appreciation. <...>

Every researcher in the applied sciences who has analyzed  data has practiced inverse theory. Inverse theory is simply the set of methods used to extract useful inferences about the world from physical measurements. The fitting of a straight line to data involves a simple application of inverse theory. Tomography, popularized by the physician’s CT and MRI scanners, uses it on a more sophisticated level.

We make discoveries about reality by examining the dierence between theory and practice. There is a well-developed theory about the dierence between theory and practice, and it is called \geophysical inverse theory". In this book we investigate the practice of the dierence between theory and practice. As the folklore tells us, there is a big dierence. There are already many books on the theory, and often as not, they end in only one or a few applications in the author's specialty. In this book on practice, we examine data and results from many diverse applications. I have adopted the discipline of suppressing theoretical curiosities until I nd data that requires it (except for a few concepts at chapter ends). <...>

In this and in Part C, I describe the behavior of electromagnetic fields applied in geophysical methods. As is well known, these fields are used in many areas of geophysics, such as
1. Delineation of conductive zones inside the earth's crust
2. Tracing the boundary between different parts of a collector saturated by highly mineralized water and oil or gas
3. Mining prospecting, mainly for detecting good conductors
4. Engineering and groundwater geophysics
5. Borehole geophysics