Random Landscapes

Clear[landscape];
landscape[n_] := landscape[n] = Module[{pts},
   pts = GaussianFilter[
      Accumulate@
       Table[RandomReal[NormalDistribution[0, 1], n], {i, n}],
      Floor[n/4]] +
     Transpose@
      GaussianFilter[
       Accumulate@
        Table[RandomReal[NormalDistribution[0, 1], n], {i, n}],
       Floor[n/4]];
   pts = Flatten[
     Table[{(i - 1)/(n - 1), (j - 1)/(n - 1), pts[[i, j]]}, {i,
       n}, {j, n}], 1];
   Interpolation[pts]
   ];
Manipulate[
 ContourPlot[
  Sum[(\[Alpha])^-n landscape[2^n][x, y], {n, 2, 11}], {x, 0.2,
   0.8}, {y, 0.2, 0.8}, Axes -> None, PlotRange -> All,
  Contours -> Table[i, {i, -3, 3, 0.1}],
  ColorFunction -> "GreenBrownTerrain", Frame -> None]
 , {\[Alpha], 1.2, 2}]