Alternating rock, colored by impurities, is called Marble. The main appearance of this function is given by an underlying Perlin Noise, which distorts stripes to gain the typical look of marble.

The roughness of that underlying noise is increased with the Octaves and Persistence parameters. Increase the Resolution value to replace big distortions by smaller, finer ones.

Use the Tiling values to control the number of stripes in either horizontal or vertical direction.

The direction of the stripes is set by the Dimensions switch. Use Both directions to create diagonal stripes.

You can adjust the strength of distortion, that is caused to the stripes by the Perlin Noise, with the Amplify value.