sulcation

A channel or furrow.

Markings resembling channels or furrows, especially in shells, fossils, etc.

The ornamentation of the shell is a character of considerable palaeontological importance. . . . The types of ornamentation are two; longitudinal striation, and transverse sulcation conformable to the shape of the aperture.

[T]he presence of sulcation in the brow horns of all the Arrhinoceratops specimens known at the present time suggests a certain constancy in this genus.

The development of or resulting formations of sulci in a brain cortex.

Lissencephaly refers to a diffusely smooth-surfaced cerebral hemisphere without sulcation.

Since the appearance and development of sulci in the fetal brain follows a predictable pattern, the degree of sulcation may be used as an indicator of gestational age-related cortical development, both at autopsy and in vivo with fetal MRI.