Lighting Banding Artifact

I am doing some procedural terrain generation by generating meshes at run-time. (Note that I'm NOT using the built-in terrain engine). I am currently using a single directional light and I am seeing some strange banding artifacts. I am using the mesh object's RecalculateNormals function.

The first two images show a scene with multiple meshes at a distance with and without textures. Adding a texture doesn't help much. The last image shows a close-up of a single mesh and drawing normals to demonstrate that it's not a problem with my normals.

Any ideas?