Geostatistics aims at providing quantitative descriptions of natural variables distributed in space or in time and space. Examples of such variables are 

Ore grades in a mineral deposit 

Depth and thickness of a geological layer 

Porosity and permeability in a porous medium 

Density of trees of a certain species in a forest 

Soil properties in a region 

Rainfall over a catchment area 

Pressure, temperature, and wind velocity in the atmosphere
Concentrations of pollutants in a contaminated site

The objective of this paper is to show how well known the structure is for a particular uranium deposit. After presenting the average vertical variogram for all the holes, some of the individual variograms will be studied and we will show the influence of a few very rich holes on the overall variogram. This turns out to be poorly defined. The first order variogram, which also has been considered, is curiously similar to the usual variogram, whereas the structure of the translated logarithm proves to be better known. <...>

The intention of this paper is to provide the user with a few essential and handy hints for variogram analysis. So often one is faced with the task of analysing the spatial continuity of a data set or with the task of generating a resource model using geostatistical techniques. However, practical guidelines for completing these tasks are few and far between and, even though one may attend a geostatistics course, time lapses between exposure to geostatistical techniques and actual application of the techniques to real situations is generally large enough for the handy hints of variography to be lost in the never-never land of memories. <...>

Most of the natural phenomena we study are variable both in space and time. Considering a topographic surface or a groundwater contamination one can observe high variability within small distances. The variability is a result of natural processes, thus deterministic. As most of these processes are sensitive and the conditions under which the they took place are not fully known, it is not possible to describe them based on physical and chemical laws completely. <...>