Changes

===Fault plane===

===Fault plane===

The fault plane technique is used to model surfaces cut by nonvertical faults when enough data are available to model fault faces and structural surfaces on either side of those faults. Separate models are built for each surface on each side of each fault and for each fault plane. Baselap (maximum) and truncation (minimum) operations are used to prevent surface models from projecting through faults that bound them and to merge faults that intersect one another properly ([[:file:using-and-improving-surface-models-built-by-computer_fig14.png|Figure 14]]). The faults are treated as if they were unconformities and the surfaces between faults as if they were sequences, thus the previously described techniques apply. For more than a few faults (three or four), the ordering of the operations becomes complex. Both normal and reverse faults can be modeled.

The fault plane technique is used to model surfaces cut by nonvertical faults when enough data are available to model fault faces and structural surfaces on either side of those faults. Separate models are built for each surface on each side of each fault and for each fault plane. Baselap (maximum) and truncation (minimum) operations are used to prevent surface models from projecting through faults that bound them and to merge faults that intersect one another properly ([[:file:using-and-improving-surface-models-built-by-computer_fig14.png|Figure 14]]). The faults are treated as if they were [[Unconformity|unconformities]] and the surfaces between faults as if they were sequences, thus the previously described techniques apply. For more than a few faults (three or four), the ordering of the operations becomes complex. Both normal and reverse faults can be modeled.

If this technique is used, then creating displays and volumes for a surface or zone requires careful manipulation of a large number of surface models. This is because each surface is represented by a suite of surface models, one for each fault block. Also, much care is required to model surfaces cut by faults that fade out in the map area.

If this technique is used, then creating displays and volumes for a surface or zone requires careful manipulation of a large number of surface models. This is because each surface is represented by a suite of surface models, one for each fault block. Also, much care is required to model surfaces cut by faults that fade out in the map area.