Brain terrain, also called knobs-brain coral and brain coral terrain, is a feature of the Martian surface, consisting of complex ridges found on lobate debris aprons, lineated valley fill and concentric crater fill.
The upper plains unit fell from the sky as snow and as ice coated dust.
Glacier-like forms in valleys and cirque-like alcoves may coalesce with others to produce lobate debris aprons.
When opposing lobate debris aprons converge, linear valley fill results.
Many of these features are found in the Northern hemisphere in parts of a boundary called the Martian dichotomy, mostly between 0 and 70 E longitudes.