The illustration shows a canyon-like crack through the epidermis and into the dermis. In contrast to an excoriation, there is no substance of the skin missing from being scratched away. Lateral pressure on this lesion would make the skin appear whole again. The same maneuver would not close an excoriation.
This deep fissure in the thick cornified cell layer of the heel epidermis is caused by xerosis and hyperkeratosis. These lesions are often quite disabling when they occur in weight-bearing skin or in areas subject to repeated flexion.