PETER H. DANA
THE MAPS that accompany this book are the result of a collaboration between the author of the book and the mapmaker that was so complete as to make us true coauthors of each of these maps. Indeed, the maps would be very different, and we think less effective, without this close working relationship between historian and geographer.
These maps are computer generated. Products of digital technology, their purpose is to illustrate the terrain and waterways of the TransMississippi West and the relationship between landforms and the mountain men who played such a large role in defining the perceptions of the geography of the West during the early nineteenth century. The maps are an attempt to portray, on as realistic and accurate a topographic surface as possible, the routes and places, some real and some imagined, that concerned these explorers.
Most of these maps are shaded relief maps. At one time shaded relief was in many respects more art than science. The cartographer, in attempting to portray terrain surfaces as they might appear from above, makes use of a combination of techniques including contour lines, shading, hachures (lines that follow the steepest slope), and hypsographic tinting (representing elevations with color). Hachures in particular were brought to a true merging of art and science by Swiss mapmakers in the 1940s in their portrayals of the Alps on topographic maps. From the forties through the sixties Erwin Raisz and others incorporated air photographs, satellite imagery, and field data into hand-drawn landform maps of most of the