The role of engineering-geologic factors in the early settlement and expansion of the conterminous United States

Geologic factors that are favorable or unfavorable for land use and construction strongly influenced the early history and expansion of the United States. Many Indian settlements in the American west were built on natural plateaus, near the rims of canyons, or in recesses in canyon walls where they could be defended easily. After 1492, European settlers built communities along the seacoasts, where there were natural harbors, or along lakes and rivers that were transportation routes. Many of these places were low and swampy, so that construction difficulties were common when the early settlements began to expand. Early roads and canals were laid out and built with little or no benefit of geologic knowledge. The Appalachians were a barrier to westward expansion until the first part of the 19th century, when settlers began moving into the interior. In the 1850's the War Department engineers made exploratory surveys to determine the best routes for railroads that were to cross the country from the Mississippi to the Pacific Coast. Most of their geologic reports described the fossils, topography, lithology, and the natural resources of the country they explored, but dealt very little with the geological problems that might be encountered during construction of the railroads. In 1868 the burgeoning town of San Francisco was damaged by an earthquake, but the scientific report that was prepared after the disaster was never published. During the late 1800's four great geological exploratory surveys examined the natural resources of the west, and in 1879 the U.S. Geological Survey was established as a government agency. At first the work of the Geological Survey emphasized mining geology, but the scope of their studies gradually broadened. In 1890 they published an account of the earthquake at Charleston, South Carolina. In 1894 the application of geologic information to construction was discussed in a Geological Survey publication dealing with roads of the United States. A similar report was published by the New York Geological Survey in 1897. However, it was not until the end of the 19th century and the beginning of the 20th, that the clear relationship between geology and civil engineering was well established, and the location of roads and structures was influenced by studies of the geologic conditions of the routes or sites.