From this high promontory, the landforms of the Sonoran Des­ ert take on awesome proportions. The mesas, buttes, cinder cones, basalt flows, mountains, and valleys, all carved and modi­ fied by water in this dry place, must be measured in kilometers and millions of years. Even the colors are dazzling. The volcanic rocks, altered by ancient hydrothermal activity, glow a warm orange and yellow in the October sun. The bright, clear light illuminates each tiny crevice etched by weathering and erosion in the cliffs. Several hundred meters below and about a kilo­ meter away the river rolls, a brown silt-laden ribbon on the floor of the gorge. The water rustles so quietly that I can hear it only when the wind dies. In the distance, sharp mountain peaks rake the bottom of the ocean of air where streamers of clouds stretch over the horizon to the ocean of water. The field is a fitting place to write the preface for a book on geomorphology because of the importance of the field experi­ ence in the development of the science. Dramatic landforms and processes, especially in drylands, have excited the imagination and intellect of artists, writers, and scientists. Each observer has explored a different route to knowing and understanding this thin envelope that is the contact between sky and earth. De­ scriptions of these striking landscapes have appealed to cataclys­ mic forces, operation of machine-like processes, and even ran­ dom occurrences governed by happenstance.