Fig. 2. Schematic picture of the physical system indicating soil-aggregate sample preparation and used symbols. Cubic or prismatic samples with intact (intact) and cut skins (cut) were prepared out of irregularly shaped (original) soil aggregates leaving the material of the removed skin layer of the cut samples (skin layer). Superscript symbols are used to distinguish between the lengths of the interior and skin parts of intact aggregate samples and the length of the cut samples.