What's causing horizontal artifacting in my shadows?

I'm working on cooking up a really simple dynamic lighting setup for a game with procedural terrain and a day/night cycle. No enlighten, no baked lighting of any kind, just a simple skybox material, a directional light for shadowcasting, and a flat color for ambient/environmental lighting. It looks pretty okay, but shadows do this weird horizontal banding on every single asset. (You'll note the big gradient at the top of the image, and tons of tiny lines on the bottom- I assume those are caused by the same problem.)



This happens on unity default planes/cubes, so I know it's not an issue with the UVs on my models, but nothing I mess with in the rendering or lighting settings seems to get rid of it- is there something obvious I'm missing?

 

Shadow acne. Tune "bias" settings on a light sources.

 

That fixed it, thank you!