Changes

Linear cross sections are preferably oriented perpendicular to the major structural trends (dip or transverse sections). Bends in the section can be introduced to accommodate variable structural trends or to show different features. In a straight section, much of the data will usually be projected into the plane of section. Accomplishing this projection requires detailed knowledge of the strike direction. If the structural trend is variable so that the cross section is not everywhere perpendicular to strike, data should be projected along strike onto the section. To fully represent the structure, several transverse sections may be linked by a longitudinal or strike section running parallel to the strike. Strike sections may also be important in showing the plunge of a structure, culminations in a fold, or the importance of secondary structures (for example, normal faults across a fold axis).

Linear cross sections are preferably oriented perpendicular to the major structural trends (dip or transverse sections). Bends in the section can be introduced to accommodate variable structural trends or to show different features. In a straight section, much of the data will usually be projected into the plane of section. Accomplishing this projection requires detailed knowledge of the strike direction. If the structural trend is variable so that the cross section is not everywhere perpendicular to strike, data should be projected along strike onto the section. To fully represent the structure, several transverse sections may be linked by a longitudinal or strike section running parallel to the strike. Strike sections may also be important in showing the plunge of a structure, culminations in a fold, or the importance of secondary structures (for example, normal faults across a fold axis).

Some structures plunge steeply (>30°), producing distortion of the geometry in a vertical cross section, so that it may be preferable to construct a profile section in which the plane of section is perpendicular to the plunge of the structure rather than being vertical. This section will be important for understanding geological history and of less importance for understanding the relationship of fluids in the associated reservoirs. However, one type of nonvertical section may be crucial to understanding the filling of reservoirs. This is the ''fault plane section'',<ref name=pt06r3>Allan, V. S. 1989, [http://archives.datapages.com/data/bulletns/1988-89/data/pg/0073/0007/0800/0803.htm Model for hydrocarbon migration and entrapment within faulted structures]: AAPG Bulletin, v. 73, p. 803–811.</ref> which is constructed from well or seismic data to represent the surface of a fault with the trace of units that intersect the fault on either side.

Some structures plunge steeply (>30°), producing distortion of the geometry in a vertical cross section, so that it may be preferable to construct a profile section in which the plane of section is perpendicular to the plunge of the structure rather than being vertical. This section will be important for understanding geological history and of less importance for understanding the relationship of fluids in the associated reservoirs. However, one type of nonvertical section may be crucial to understanding the filling of reservoirs. This is the ''fault plane section'',<ref name=pt06r3>Allan, V. S., 1989, [http://archives.datapages.com/data/bulletns/1988-89/data/pg/0073/0007/0800/0803.htm Model for hydrocarbon migration and entrapment within faulted structures]: AAPG Bulletin, v. 73, p. 803–811.</ref> which is constructed from well or seismic data to represent the surface of a fault with the trace of units that intersect the fault on either side.

===Selection of data===

===Selection of data===