Pyroclastic Flow Unit
A pyroclastic flow unit is a tongue-like pyroclastic flow deposit that forms in a volcanic eruption. It is generally composed of various types of ignimbrites and other volcaniclastic rocks. The unit can be related to a single eruption or to several consecutive eruptions that form a composite volcanic pyroclastic flow unit made up of multiple accumulated pyroclastic flow units. The rock structure and formation of a pyroclastic flow unit can be divided into longitudinal or transverse banding and can have different degrees of melting. Therefore, the landform of pyroclastic flows (which are generally known as ignimbrite strata) is controlled by the lithological variations inside the unit, which cause many varieties of landscapes.