Shading issues with procedural landmass generation

Hey guys! Experimenting with using perlin noise to generate a landmass. I've just been fiddling about trying to get collision to work, but after adding a collider, my landmass now looks like this:

With no texture,
and this:

With a texture. As you can see, it's as if lighting and shading are having no effect on it whatsoever, and it's really strange. The shader of my material is set to standard, and even removing the collider has no effect on this strange behaviour. Increasing/decreasing my directional light intensity has no effect, though oddly it seems to light up the scene more brightly when pointed slightly left than it does when pointed slightly right. No clue what's going on here, but clearly I'm having some shading issues. Any ideas?
Many thanks.

 

Nevermind! I had to recalculate the mesh normals on generation. My bad, all fixed now.

 

You might also want to call:

https://docs.unity3d.com/ScriptReference/Mesh.RecalculateBounds.html

But if your last call was to assign something to .triangles (as opposed to .vertices), bounds should be fine.