The gravel

In[9]:=
  Needs["fBm`"]
  Needs["Graphics`Graphics`"]
  Needs["Graphics`ParametricPlot3D`"]
  SetOptions[{SurfaceGraphics, Plot3D},
  	MeshStyle -> Thickness[0], Mesh -> False];
  SetOptions[{ContourGraphics, ContourPlot},
  	ContourStyle -> Thickness[0]];
  SetOptions[ListPlot, PlotStyle -> Thickness[0] ];
  bottom = Plot3D[ .4(1-x) + .05,
          {x, -0, 1}, {y, 0, 4}, PlotPoints -> 8 ];
  gravel = fBmRA[bottom, 32, 0.8];

In[10]:=

  Show[gravel];

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