Since the advent of Mandelbrot's fractal geometry in 1975, many geolog
ical and geophysical patterns have been characterized by their fractal
scaling properties. The purpose of this paper is to present and compa
re standard and new methods used to estimate the fractal dimension of
random (natural) fractals. Examples demonstrate the relative limitatio
ns of the techniques, and the modifications necessary to more accurate
ly estimate the scaling properties of certain types of fractals. Discu
ssion and examples include branching diffusion-limited aggregates, fra
cture surfaces, and fractional Brownian surfaces.