Or you can use an infinite plane with Anything Grooves, if you have that... Or a different technique using planes with Anything Grooves, and an infinite plane with the same noise function for bump as the planes use for their height maps... It requires that the edges of the ordinary planes are slowly faded out to have no height, and a bump map or alpha channel working in the opposite direction, if you get what I mean... It's hard to get this technique to work properly though, mostly due to reflections acting differently as there is an actual height distortion on one, while the other only has different normals.