Now we are beginning to find these buried lake floor sediments themselves beneath the uppermost till sheet
in Huron County (Campbell 1955), and Seneca County (Coash personal communication).
This will allow the source of anomalous radioactivity encountered in the drill holes to be identified, and a distinction between thorium, potassium and uranium sources in the till sheet
(glacial overburden) will be made.
Similarity in the properties of diamictons in a single till sheet
separated by over 150 km suggests that provenance and genetic processes were the same on both sides of Lake Michigan.
The till sheet
averages 3 m in thickness but can be up to 20 m thick in drumlins.
These data indicate that a single till sheet was deposited as the dominant ice-flow direction fluctuated between east, south-southwest, and east-southeast across the study area.
A single till sheet was found, although its colour and composition changes with variations in underlying bedrock.
Ballantyne and Matthews (1983) documented polygonal fracture development on a newly exposed till sheet
in the periglacial environment in front of a retreating glacier where the mean annual temperature was -1 [degrees] to -2 [degrees] C (30-28 [degrees] F).
These data indicate that a single till sheet
, 1-4 m thick, was deposited as the dominant ice-flow direction fluctuated between southeastward, eastward, and northward over the study area.
The Wisconsinan till sheet
of central and western Ohio south of the Powell and Union City moraines is considered relatively uniform in chemical and physical properties.
As many as eight or nine distinct till sheets
overlap in western Indiana.