Florida Geological Survey - Geologic Topics
Earth’s rocks are basically classified as igneous, metamorphic, and sedimentary. In this application we deal only with the sedimentary class of rocks or deposits. Sediments may be either indurated (i.e., cemented as rocks) or unconsolidated (i.e., deposits). If indurated sedimentary rocks can be disaggregated, they can be analyzed by the tools described in this application.
There are many reasons to study sedimentary deposits including reconstructing and identifying the transportation mechanisms and depositional environments. This application provides the opportunity to do so by plotting the results of grain-size analyses (granulometry). This application is comprehensive enough that almost all of the typical granulometric objectives will be satisfied.
Two-dimensional plotting tools have been widely used in the analysis and interpretation of granulometric data. Arithmetic-arithmetic, log-log, arithmetic-log (semi-log), and other types of plots have been proposed to display analytical results. The use of arithmetic probability paper (APP), however, has far more useful capabilities. Natural data plotted on APP may, in many applications, be made up of multiple straight-line segments or components. These segments are often attributable to some identifiable natural cause or process. Most statistical computer applications do not allow for the generation of APP plots, because of non-linearity of the percentile (or probability) axis of the plot. This problem has been solved in the present application by the derivation of equation(s) for quantifying plotting positions of Gaussian percentiles (or probabilities), so that APP plots can be easily computer generated.
Programmed EXCEL application templates are provided here (click on the appropriate links) for automatically-produced, complete granulometric analyses. The EXCEL application is designed for use with classified data, such as sieve data. For unclassified data, such as that from settling tube analysis, the settling tube data will need to be transformed to classified format in order to use the EXCEL application. The file includes a README spreadsheet that provides information about how to use the workbooks. An enhanced version of GRANPLOTS (release 4.0) has recently been added to the application. It allows the user the ability to identify and fit signatures reflecting transportation and deposition to plotted results and to produce publication-quality figures.
Additional material is currently being prepared for this application including a comprehensive compilation of granulometry protocols, including field sampling, lab procedures, analytical/statistical determinations and interpretation. This documentation is particularly useful because these topics are not typically addressed in sedimentary texts.
Based on monthly “hit” data and user feedback, it appears that there has been significant use of this website application; however, actual use is not quantified. We would appreciate hearing from you if you use this application so that we can maintain and continuously improve this website.
The original version of this program appeared in the following publication: Balsillie, J.H., Donoghue, J.F., Butler, K.M., and Koch, J.L., 2002, Plotting equation for Gaussian percentiles and a spreadsheet program for generating probability plots: Journal of Sedimentary Research, v. 72, p. 929-933. Subsequent revisions have been made by Jim Balsillie and Joe Donoghue. Any questions or comments on the application can be addressed to Joe Donoghue at email@example.com. The form below can also be used for feedback. Any information you provide is purely voluntary. The form is NOT required in order to use this application.
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Last updated: December 08, 2009
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