Geomorphology and Quarternary Geologic History of the Lower Mississippi Valley.Volume 2

摘要

This comprehensive, two-volume synthesis, the first in 50 years, is aimed at amultidisciplinary audience concerned with multiple aspects of water resources engineering and natural and cultural resources management. It presents, at a scale of 1:250,000, the distribution of environments of deposition as compiled from more than 30 years of detailed geologic mapping, as well as a new interpretation and delineation of the eroded suballuvial surface. A detailed interpretation of the evolution of the alluvial valley and deltaic plain is presented and illustrated by a series of 13 paleogeographic reconstructions. The chronology of valley events is based on stratigraphic relationships and radiometric age determinations but relies heavily on archeological evidence. The geologic processes and controls that affect the entire region include continental glaciations, climate, sea level variations, tectonics and diapirism, and subsidence. Both erosional and depositional landscapes are represented, and the lithology, soils, and geotechnical properties of the latter are presented in narrative and tabular form for the principal fluvial, lacustrine, eclian, deltaic, and deltaic-marine environments. Discussions of neotectonics in the region focus on the New Madrid Seismic Zone, and a section of the synthesis addresses special engineering considerations such as groundwater occurrence, mass movements, river meandering, and long-term stability. (AN).