A GEOGRAPHICAL ANALYSIS OF
The first part of this book is a geographical description of the portion of western America which was still unexplored in 1800. Regional divisions have been used, where possible, as a means of description. The area has been divided into physiographic regions, climatic regions, drainage basins, vegetation regions, and regions which differentiate the cultures of the Indian tribes. Only in the chapter on animals was it found unnecessary to attempt a regional treatment. This regional analysis has been made in the light of modern geographical knowledge, but the actual words of the explorers themselves have been used to explain the positive statements of modern geographers.
The influence which geography exerts on the course of history can be most clearly seen in the earliest stages of the historical development of a region. In the "old" continents, human development has become so complex that it is very difficult to disentangle the geographical factors which most closely concern their organisation at the present day. The history of exploration has, therefore, a peculiar value to the geographer, because it reveals a vivid picture of man when nature's influence over his movement and settlement is most obvious. Unfortunately for the geographer, it is almost impossible to draw such a picture for some regions of the world at certain periods of history, because the documentary and other evidence is so scanty. In the case of North America in the nineteenth century, however, the student is overwhelmed by a mass of geographical material which exists in the journals of traders and explorers. Extracts from the writings of men such as Lewis and Clark, Pike and Frémont have been used in the