"Surface" is a very general term. It can refer to many things, and the answer to whether a surface is rocky or flat depends on what surface you're talking about. Here are some examples:

Rocky surfaces:

* Mountains: The surface of a mountain is often rocky.

* Canyons: The sides of canyons are often rocky.

* Planets: Some planets, like Mars, have rocky surfaces.

* The Moon: The surface of the moon is covered in rocks and craters.

Flat surfaces:

* Tables: A table is a flat surface.

* Floors: Most floors are flat surfaces.

* Mirrors: Mirrors have flat surfaces.

* Water: The surface of still water is usually flat.

Other surfaces:

* Grass: The surface of a grassy field is neither strictly rocky nor flat, but a mixture of blades of grass and soil.

* Sand: The surface of a beach is covered in sand, which is neither rocky nor flat.

To get a more specific answer, please tell me what surface you are referring to.