I am building a volcano scene, and I am at the stage where I wanted to make cracks on the ground, and have a very large plane sitting just underneath the ground that is bright orange to simulate the light coming from lava. But my surfaces seemed to be brighter than before. So I disabled everything except the terrain, the plane and a light source, and did a render with the plane enabled (unhidden) and disabled (hidden). Now I know it's been mentioned that translucency is not available in the technology preview, but it sure looks like some sort of translucency or subsurface scattering to me.
While this is a cool effect for other situations, I do not want the plane to affect the terrain surface in anyway. How do I stop this?
[Edit] the third image is exactly the same settings, only I inserted a Default Shader on top of the base colours because I thought it might reset the shader on the terrian, but it only increased the effect.