Schematic plot of field size versus number of fields showing the population of discovered fields (red area) fit with lognormal and fractal distributions. The number of undiscovered fields estimated under the lognormal curve (yellow area) is less than the number of undiscovered fields estimated under the fractal curve (yellow area + green area). Estimations can be made to any arbitrary lower limit, even to crustal abundance, depending on the user's needs.
This USGS Fact Sheet can be found at <URL:http://energy.usgs.gov/factsheets/HydroRes/fig5.html>
Maintained by L. Friedrich Last updated 24-Sept-1997