Geology of Boulder, Colorado, United States of America

Abstract

The Executive Council and Board of Directors of the Association are pleased to provide the membership with a new series in the Bulletin, Geology of The World9s Cities. Cities are the irrevocable focus of all that drives civilization forward; cities are the cauldrons that produce the pressures of cooperation and confrontation between peoples and nations; cities have been the birthplace of culture; cities have been the depletors of natural resources; cities have been the generators of immense quantities of wastes that now peril the environment. Cities, for all of their good and bad, are the fundamental aspect of human life on the planet. The Association recognizes that each city was originally established for reasons of geologic influence. These same geologic influences are still present, both in the city9s shape and structure and as constraints on what can and should be accomplished to prepare the cities for continued service in the coming centuries. In offering this series of papers, the Association hopes to discover elements of geologic influence and impact, so that the whole spectrum of practitioners can better control the renovation and rebirth of cities. By example of this series, peoples of various regions and nations will come to recognize that innovations of others have been applied to overcome some of the stresses on the people and resources of cities. To this end, we recognize the long-time influence of our distinguished Canadian colleague and native Briton, Dr. Robert F. Legget, who has labored in speech, text, and example for more than 45 years to bring this message to us all. In this premier paper of the series, John E. Costa, an educator, and Sally W. Bilodeau, a practitioner, have presented the Geology of Denver, an American boomtown, grown large and commanding. Its presence, lodged at the eastern edge of the continent9s greatest mountain range, marks the real transition from east to west in cosmopolitan America. Denver is the great North American city of our resource-conscious times. The great energies of Denver are people-generated and people-oriented. Denver runs on a 24-hour day, because it is the great sociologic magnet of the continent. Little of its humble frontier beginnings remain for detection by the casual visitor, but its origins are tied to its geologic setting: its development has been controlled by its geology; and its future will be guided by such influences. Founded in 1858, on the site of placer gold discoveries, Denver has always served as a resource-oriented supply and operations center. Today the city serves a vast area of the central United States as a financial, engineering, scientific, governmental, educational and resource extraction center. The city that was born of resource extraction remains a key element in that activity today. Denver9s very existence, on the fringe of a great mountain range, displays the effect of the natural environment on the development of a city. Its near-region topography varies by nearly 8,000 ft (2,400 m); it lies on a sedimentary basin some 13,000 ft (3,960 m) thick; it consumes ground water and surface water at a phenomenal rate; it demands construction aggregates in alarming quantities; and it produces burdensome quantities of waste. Denver is affected by significant geologic constraints: both collapse-prone and swelling soils, hillslope instability, induced seismicity, flooding, and some areas of rising ground water. Denver is a city of the age and of the decade. The citizens and builders of Denver have learned to respect its geologic setting! Papers in this series will be the result of cooperation between engineering geologists, geotechnical engineers, hydrogeologists, environmental engineers, seismologists, urban planners, and other allied technical specialists. Most of the papers will be released in the Bulletin along with other papers. Occasionally a group of cities in regional areas or nations will be printed in a single Bulletin issue. We welcome your continued interest in the series, both as concerned readers and as concerned authors.