Abstract

A study of the soils in four filled valleys has defined two distinctly different sequences. The upper soil at all sites is a soft, horizontally layered or varved clay. Underlying these soils are stiff, overconsolidated deposits which appear to have been layered or varved clay but are now highly faulted and distorted; their low water content, overconsolidation, and structural distortion indicate glacial overriding.Measurements of preconsolidation stresses of these lower deposits provide data for calculations of overriding ice thickness and surface elevation of the ice. A consistent pattern was found from analysis of four widely separated boreholes. Surficial landforms and topography support the conclusion that parts of the area were overridden by ice.Engineering soil mechanics tests not normally used in geological interpretation are an important part of this analysis.

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