These are Electron Microscope images of record grooves from Chris Supranowitz, a researcher at The Insitute of Optics at the University of Rochester.
⇑ Vinyl Grooves Magnified 200x: Darkest area is top of groove (uncut material)
⇑ Vinyl Grooves Magnified 500x
⇑ A Single Vinyl Groove Magnified 1000x
⇑ CD Pits Magnified 20,000x