  Although geographic features, such as mountains and coastlines, are fractal,
some studies have claimed that the fractal property is not universal. This
claim, which is false, is mainly attributed to the strict definition of fractal
dimension as a measure or index for characterizing the complexity of fractals.
In this paper, we propose an alternative, the ht-index, to quantify the fractal
or scaling structure of geographic features. A geographic feature has ht-index
h if the pattern of far more small things than large ones recurs (h-1) times at
different scales. The higher the ht-index, the more complex the geographic
feature. We conduct three case studies to illustrate how the computed
ht-indices capture the complexity of different geographic features. We further
discuss how the ht-index is complementary to fractal dimension, and elaborate
on a dynamic view behind the ht-index that enables better understanding of
geographic forms and processes.
  Keywords: Scaling of geographic space, fractal dimension, Richardson plot,
nested rank-size plots, and head/tail breaks
