Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Civil, Construction, and Environmental Engineering


Borings in certain loess deposits in the upper midwestern United States reveal the existence of a zone of soft, saturated soil whose natural water content is at or near the soil liquid limit. These soils, which tend to liquify if disturbed, have been called liquid silts;A distribution of loess deposits in which conditions may naturally be favorable for forming and sustaining liquid silts is presented tentatively for the state of Iowa. This distribution essentially shows areas where loess deposits are saturated at relatively shallow depths by groundwater perched on underlying impermeable glacial till or paleosols, and where the saturated loess would be expected to be normally consolidated;The vertical extent and location of the zone of liquid silt within a soil deposit is related to the unique variation of water content with depth exhibited by saturated, normally consolidated clayey sediments. Clay type and amount are significant factors in determining this relationship as shown by the effects of leaching at one site, where removal of carbonates from the upper portion of the deposit has resulted in increased clay content, which contributed to development of liquid silt in a soil where it would not otherwise have occurred. Thickness of the solum may limit the minimum depth at which liquid silts will exist.



Digital Repository @ Iowa State University,

Copyright Owner

Robert Odell Lamb



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99 pages