The long, narrow elevations of rock that crisscross the Moon are called rima (singular: rima). They are often described as lunar rilles or lunar valleys.

These features are thought to be formed by several processes, including:

* Lava flows: Rima are often associated with volcanic areas and are thought to have formed by flowing lava creating channels in the lunar surface.

* Tectonic activity: Some rilles may have been formed by the movement of the Moon's crust, similar to faults on Earth.

* Impact craters: Some rilles may have been formed by the impact of large meteoroids.

Rilles are a fascinating feature of the lunar surface and provide valuable clues about the Moon's geological history.