Here's why:
* Formation: Rilles are long, narrow depressions that are thought to be formed by lava flows. As the lunar maria were formed by massive volcanic eruptions, the lava flows created these channels as they flowed across the surface.
* Location: Most rilles are found within the maria, indicating their close relationship with volcanic activity.
* Types: There are two main types of rilles:
* Sinuous rilles: These are winding channels that resemble riverbeds, likely formed by flowing lava.
* Straight rilles: These are more linear and often associated with tectonic activity, possibly formed by the collapse of underground lava tubes.
While some rilles might be found near other lunar features like craters, their association with maria is the most prominent.
