Schuylkill Valley Paper - Areal Work of the United States Geological Survey

Most nations and states have conducted geological surveys, generally with the view of discovering and developing natural resources, sometimes with the aim of promoting science. In some cases, as in the first survey of Pennsylvania, the official geologist so far preceded the prospector and miner as to guide the discovery and exploitation of the commoner ores, mineral fuels and structural materials; but in most instances statesmen have only been awakened to the need of such a survey by the successful extraction of minerals;