Lava channels that appear to have been incised into the underlying substrate are commonly ascribed to thermal or thermomechanical erosion. Here we show that where the associated lava flow moves on a hot and soft substrate, the channel may also be ascribed to viscoplastic indentation of the substrate. A simple model of viscoplastic indentation leads to distinct predictions that can be readily tested in the field. For example, two broad, wedge-shaped, levee-like features should rise from the substrate during indentation. Such features appear to have risen alongside of a channel that was incised into a hot and soft, recently emplaced basaltic substrate during the 2001 eruption on Mount Etna.