In an equal area stereonet, the small circles are equal size but instead of being true circles they are fourth order quadrics that are less distorted near the center, and more distorted towards the edges of the net fig. The schmidt net is a manual drafting method for the lambert azimuthal equal area projection using graph paper. Planisphaerium by ptolemy is the oldest surviving document that describes it. Select a format and navigate to the folder where you wish to save the file. In addition to contouring pole densities, dips allows you to contour the magnitude of other quantitative directional variables on the stereonet e. Georose is a rose diagram and stereonet plotting program, which can plot structural geology rose diagram, equal area and equal angle stereonet diagram. The program can produce various types of plots such as scatter plots, great circle plots, contour. The great circles represent northsouth striking planes with dips in 10 degree increments. Stereonets are used in many different branches of geology and. For a map the grid represents the meridians and parallels, whereas in structural geology the grid is generally not shown. The macintosh version is being made available here for those users who need binary file compatibility with the windows version. More in detail, you can project in equal area, or you can choose to project in equeal projection. You cannot download datasets already uploaded to strabospot.
Blank equal angle and area stereonet 1 thumbtack tracing paper take extra sheets work in pencil and erase errors stereonet program. Equalarea stereonets are used in structural geology because they present no. To do this, click on the stereonet in the shape list and then select from its inputs in the move to list. This distortion of area is a problem when manually contouring data on the wulff net. Stereonet analysis of data from arbuckle mountains near. Joaqu n cort es july 16, 2017 1 introduction although there are many amazing programmes to plot data on equal area stereonets my. At the same time, polar area diagram is ruled out in this release. Basic methods of structural geology download ebook pdf. It was originally known as the planisphere projection. Other common uses for stereonets calculating rake we use rake to describe the angle between a plane and lineations on that plane. Workbook 2 stereonets school of earth and environment. The software is written in python, a highlevel, crossplatform programming language and the gui is designed with wxpython, which provide a consistent look regardless the os. Undeformed and deformed strain marker reference used for derivation of formulae.
One of its most important uses was the representation of celestial charts. This website is best viewed with browser version of up to microsoft internet explorer 3343 or firefox 3. An online stereonet application that allows you to create and view all of your geologic stereonet information in 3d. Equalangle wulff b equalangle stereonets are used in crystallography because the plotted angular relationships are preserved, and can be measured directly from the stereonet plot. The correct answer is shown together with common plotting errors. A tick mark coinciding with the 0 degree mark is labeled n, with e, s and w marked at. Data is entered either by pasting from the clipboard from other applications, or from ascii text files, in a wide range of file formats, and using a range of orientation conventions. A users manual for stereonet 9 is available within the lab materials folder at the geol305 sakai site. Part i covers basic geometric techniques and the use of equal angle and equalarea nets. Stereonet 9 for macintosh uses the modern mac os x cocoa architecture. Pdf implementation of stereographic and spherical projection in.
Geologic mapping regional tournament science olympiad. Go to eps116 links webpage for allmendinger software download. You can change the title and axes labels and select between schmidt equal area and wulff equal angle plot types. Equal angle stereonets have distorted areas and so a symmetrical, bullseye data population will appear distorted. Spherical projections include equalarea schmidt net, stereographic wulff net or stereonet, orthographic, and equidistant projections. The stereographic projection was known to hipparchus, ptolemy and probably earlier to the egyptians.
In python, stereonet are veeery simple to do thanks to joe kington a geologist. The stereonet used for the exercises is an equal area stereonet. Georient plots orientation diagrams equal area, or equal angle stereographic projections, and rose diagrams as shown in the composite image above or this screenshot. Structural geology laboratory manual third edition david t. An online stereonet program that allows you to create and view all of your geologic stereonet information in 3d.
The parallels and meridians intersect at right angles in an equalangle projection and they are equally spaced. Innstereo is a stereographic projection program or stereonet program for. Spherical projections with osxstereonet sciencedirect. Geologists use this type of programs for stereographic projection and structural geology analysis. Stereonet equal area schmidt net and equal angle wulff net stereographic.
A wuff net stereonet uses the stereographic equalangle projection, whereas schmidt net uses the lambert azimuthal equalarea projection. Stereonet equal area schmidt net and equal angle wulff net stereographic projections great circles poles linears rotation around axis contours rose diagram dynamic rendering drawing features on stereonet with mouse csv import and export finding bestfitting plane for lineations calculating bestfitting intersection for. Point distributions are analyzed by contouring, and by computing eigenvectors or vector means. Joe created a stereonet module for matplotlib called mplstereonet. Most figures are made using an equal area projection, but sometimes and equal angle projection is used as well. Stereonet equatorial equalarea net polar equalarea net kalsbeek counting net orthographic net. En 38343 pdf purchase your copy of bs en iso as a pdf download or hard copy directly from the official bsi shop. If you are dealing with planar data, plot it as poles since you can not contour great.
You can make further edits by clicking the edit button in the stereonet window. These exercises explore concepts from chapter 2 including the gnomonic and mercator projections, 2 and 3dimensional transformation of coordinates, and use of the equal angle stereonet to plot the orientations of planar and linear structural elements. Request pdf mathematica code for leastsquares cone fitting and equalarea stereonet representation in structural geology it is often assumed that folds are cylindrical. This lab will give you practical experience using stereonets to plot your structural data. First, we will familiarize ourselves with plotting lines on a stereonet remember that. The orientations of lines and planes can be plotted relative to the center of a sphere, called the projection sphere, as shown at the top of fig. We are going to explore this module in this tutorial. Visible geology runs in the browser so there is no need to download anything, just click to add lines and double click to add planes. Stereonets and rose diagrams in python geology and python. Answers to the plotting exercises can be found by clicking on a reading. Contents school of earth and environment 4 introduction to stereonets a stereonet is a lower hemisphere graph on to which a variety of geological data can be plotted. Implementation of stereographic and spherical projection in. The stereonet or stereographic projection is the most important visualization tool for orientation data in structural geology. Structural geology with javascript and the web through svgnet.
Stereonets can be exported in the following formats. Allison associate professor of geology department of geology and geography university of south alabama. The projection that is usually chosen for this, is the lambert azimuthal equal area projection with equatorial aspect see. A stereographic projection, or more simply a stereonet, is a powerful method for displaying and manipulating the 3dimensional geometry of lines and planes davis and reynolds 1996. Generate strike, dip direction and dip rose diagrams, and equal area and equal angle stereonet diagrams. They are also used as map projections, and for maps of the sky in astronomy or the satellites your gps is tracking. Equal area net schmidt net university of california. A couple of years ago i wrote an article about stereonet programs. The spreadsheets for calculating apparent dip solutions may be downloaded. The term planisphere is still used to refer to such charts. Contents scoo o t n nvironent 4 introduction to stereonets a stereonet is a lower hemisphere graph on to which a variety of geological data can be plotted. Intended as a learning reference and an exercise manual. Osxstereonet plots lines and planes in a stereographic, equal angle or equal area, projection. The above is an equal area stereonet projection showing great circles as arcuate lines connecting the north and south points and small circles as arcuate lines in a latitudinal type position.
Part ii addresses specialized topics written by specialists in the field. Each team must have a protractor, ruler, nonprogrammable calculator, colored pencils, and an equal. Users can fully control the style of the diagram as in rose diagram plotting mode. It is one of the most powerful tools we have, a few weeks ago, through the comments of this article, i got to know another piece of software which, being at least as good as the well known suites as far. These can be plotted on either hemisphere, or transparency can be used to display both hemispheres.