Long trenchlike valleys running through the bedrock of lunar maria are called Rilles.

Here's a breakdown:

* Rilles: These are long, narrow, winding depressions that are typically found on the lunar surface. They can be formed by several processes, including:

* Lava channels: These rilles formed as molten lava flowed across the surface, carving out channels.

* Graben: These rilles form when the lunar crust stretches and cracks, creating depressions.

* Impact craters: Some rilles can form as a result of the ejecta from impact craters.

Let me know if you have any other questions about lunar features!