Wisconsin tills from northeastern Ohio were studied under the electron microscope as fragments from less than 1 to several microns and on surfaces as large as 1/4 inch, using carbon replica techniques. Subhedral "grains" are composed of illite and chlorite; anhedral "grains" are kaolinite. Kaolinite is absent from "late" Cary (just pre-Defiance) till. Nonclay minerals, quartz, feldspar, and calcite, are either absent or exceedingly rare in less than 2 micron sizes, but increase in amount in larger sizes and are common in larger than 4 micron grain sizes. The platy clay minerals are oriented more or less parallel to the horizontal plane of the till in place.

First Page Preview

First page PDF preview
You do not currently have access to this article.