I combined stepped-fresnel with perlin-noise-driven, screen-space/twirl/tiling UVs, and applied similar stuff to the dark pixels in my texture so that the lines on the continents also wriggle.
By adjusting a few parameters I can ENVELOP THE WORLD IN DARKNESS!!! …And of course, a little displacement just for kicks.
Edit: decided to add adjustable dithering to the take-over layer, I also made sure BOTH sets of lines wriggle now 🙂 Also the colours are now mapped and changeable, hardened normals now optional through the shader 🙂