Very fine particles (< 2 microns) adhering to larger particles have been observed by scanning electron microscopy. Such fines, adhering to loess particles, were interpreted by Smalley and Cabrera (1970) as comminution debris, produced in the process of loess-material formation by glacial grinding. This is in contrast to some published information on the nature and composition of glacially produced material, and the subject remains open to debate.
No positive proof was given by Smalley and Cabrera (1970) that the loess material depicted by them was glacially produced. Although these authors may be correct in their interpretation, other additional hypotheses on the origin of loess material cannot as yet be rejected. While there is an obvious connection between glaciation and many loess occurrences, the ultimate origin of much of the loess material has still to be demonstrated.