A cross section is a profile showing geological features in a vertical plane through the earth. Some geologists prefer the term "section" for this type of diagram, reserving "cross section" to denote a section made perpendicular to structural strike. In practice, relatively few of these diagrams can be constructed strictly perpendicular to strike. Also, the word "section" used alone could be misconstrued to mean seismic Section, columnar section, or even thin section. in petrology, a section is a lithologic sequence which can be viewed in outcrop. In paleontology, a section is an important division of a genus. On public lands, a section is a smaller division of a township. To avoid ambiguity, many geologists have come to use the term "cross section" to describe a geological profile made across the earth, i.e., along any vertical plane through the earth, regardless of its orientation to structural strike. The term "dip section" is used to indicate cross sections made perpendicular to strike. we have adopted this more general definition of "cross section" since we believe that any practical study guide should reflect the most common and current usage of terms.
[...] Used wisely, vertical exaggeration is an effective tool in the construction of cross sections. The decision to employ vertical exaggeration is based on what the cross section is intended to illustrate and on how one can most effectively achieve that illustration. An exaggerated cross section should be clearly labeled with bar scales and the value of v. For quick reference, it may also be helpful to include a small inset with an unexaggerated view of the cross section ( Figure 2 Practical considerations also affect the choice of scale. [...]
[...] Many rough cross sections can be constructed in this manner while the geologist begins to visualize the geology of the area. The first step in drafting a cross section is to determine what the diagram is intended to illustrate. Keeping this purpose in mind, the geologist chooses a line of section, scales, and a datum. Beyond this point, the procedure for plotting data will vary depending on whether the diagram is a structural or a stratigraphic cross section and, to a certain extent, on the type of data to be used. [...]
[...] Cross Section Diagrams In Three Dimensions Fence Diagrams In petroleum exploration, the development of a prospect is a three- dimensional problem. One of the drawbacks of cross sections is that they are limited to two dimensions. How can we illustrate the three-dimensional geology of an area? The most common type of diagram showing geological relationships in three dimensions is a fence diagram ( Figure 1 Fence diagrams consist of a three-dimensional network of geological cross sections drawn in two dimensions. [...]
[...] The Elements of a Cross Section The geologist must answer a number of fundamental questions and must make a number of important decisions before a cross section is constructed. What will the cross section illustrate? Will it be a structural or a stratigraphic cross section? Will it be used to communicate broad relationships or to illustrate great detail? Is it for problem-solving or for display? What are the geological features of interest? What data will be used? How should the scale be chosen? [...]
[...] Scale After the line of section and data points have been chosen, the geologist must decide on the scale of the cross section. There are actually two scales to consider: one horizontal and one vertical. For convenience in construction and cross reference, the horizontal scale is often taken to be equal to the scale of corresponding geological maps. The vertical scale may or may not be equal to the horizontal scale, depending on what the cross section is intended to illustrate. [...]
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