World War II and the stress of war-time economics from 1940 to 1945 placed new demands on all phases of industry. These elements of change, combined with the effects of postwar economic expansion, were manifested in many geology-related problems. For example, (1) the need for increased supplies of industrial water in some coastal areas led to an excessive drawdown of the ground-water level and allowed sea-water encroachment; (2) construction of the Alaskan Highway in early 1940s for defense of territory led to an in-depth realization of the permafrost phenomenon and its impact on construction in arctic terrain; (3) the need for large underground storage and bombproof military facilities by the mid-1940s led to pioneering research in rock mechanics and the dynamic stress phenomenon of large-scale explosions (McCutchen, 1949; Kiersch, 1951); (4) the demands for terrain analysis to serve military actions resulted in several new aerial exploration and interpretive techniques that were later available for civil projects; and (5) more recently, geology was a major factor and was investigated extensively during the planning and construction of the Alaskan pipeline in the 1960s and 1970s (Pewe, Chapter 14, this volume).
The large reservoirs built in the 1920s and 1930s increased sediment-filling to the status of a serious geological problem; then, ironically, the cleansed reservoir water created leakage problems downstream in the very canals that were formerly self-sealed by the natural silt. Each difficulty ultimately provided an improved state of knowledge and progress in engineering geology.
By the 1950s, international interest was keen on a distinction between an artificial, underground nuclear explosion (test) signal and a natural seismic event; the “detectability of seismic signals” became the focus of major seismological research by the U.S. Air Force and experiments by the Terrestrial Sciences Laboratory (Haskell, 1957).