Spatial variability may be just as complex as vertical variability.
Superimposed upon the natural variability in soilscapes are the variation in
agricultural or forest land use followed by urban constructional features of
buildings, roads, mass transportation and utility networks. In a historical
perspective, several cycles of change and evolution exist, depending upon the
history and geographic location of the site under consideration. The influence
of man is simple or complex but contributes to spatial variability in both cases.
Therefore, it is not uncommon to find a drastic contrast in profiles from one tree
planting pit to another on the same street within the same block. The variability
is illustrated in Figure 5 (Kays, 1982), and necessitates detailed soil sampling
and the production of small-scale maps.