c) Equal-area stereonets are used in structural geology because they present b ) The north pole of the stereonet is the upper point where all lines of longitude. Background information on the use of stereonets in structural analysis The above is an equal area stereonet projection showing great circles as arcuate lines. Page 1. mm. WIDTH. Blunt. TUT. HT. T itillinn.

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A Plot the following two planes: Bonne Bottomley Polyconic American Werner.

Part 1 – Plotting and manipulating elements on a stereonet. For example, this projection sends the equator to the stfreonet of radius 2 centered at the origin. A comprehensive introduction to differential geometry, Volume IV.

Equal Area (Schmidt) Stereonet

The projection that is usually wrea for this, is the Lambert Azimuthal Equal-Area Projection with equatorial aspect See: The story of mapsp. This part needs to be done with pencil and tracing paper, with a stereonet projection underneath.

Stereographic projection plots can be carried out by a computer using the explicit formulas given above. This will help you learn the fundamentals of stereographic projection. In this case the formulae become. Differential geometry and applications. Latitude Longitude Tissot’s indicatrix.

Stereographic projection for structural analysis

No map from the sphere to the plane can be both conformal and area-preserving. Most figures are made using an equal area projection, but sometimes and equal angle projection is used as well. On the disk, the latter has nearly four times the wrea of the former.


As before, the stereographic projection is conformal and invertible outside of a “small” set.

Stereographic projection for structural analysis | Sanuja Senanayake

It was originally known as the planisphere projection. This line can be plotted as a point on the disk just as any line through the origin can.

All strike angles are measured with respect to the true North. To plot the pole rotate the great circle representing equa plane so that it’s strike line is oriented N-S, then count 90 degrees along the equator passing through the middle point of the stereonet. For plots involving many planes, plotting their poles produces a less-cluttered picture than plotting their traces. Stereoonet two sectors have equal areas on the sphere. This construction is used to visualize directional data in crystallography and geology, as described below.

I Determining the angle between the two lines by counting along the common great circle in degree increments from one to the other line. Instead, it is common stereonrt use graph paper designed specifically for the task. Circles on the sphere that do not pass through the point of projection are projected to circles on the plane.

The point 1 and 2 are best fit line points for the poles that lies about the center of the diagram. All lines in the plane, when transformed to circles on the sphere by the inverse of stereographic projection, meet at the projection point.


The stereographic projection is a methodology used in structural geology and engineering to analyze orientation of lines and planes with respect to each other. Although any stereographic projection misses one point on the sphere the projection pointthe entire sphere can be mapped using two projections from distinct projection points.

Arae stereographic projection presents the quadric hypersurface as a rational hypersurface. Note that a line plots as point – the point of intersection with the lower hemisphere. The projection used for this kind of plots is the Stereographic Projection with equatorial aspect See: These spirals intersect radial lines in the plane at equal angles, just as the loxodromes intersect meridians on the sphere at equal angles.

The equal-area lower-hemisphere sfereonet defined by the Lambert azimuthal equal-area projection is also used, especially when the plot is to be subjected to subsequent statistical analysis such steeeonet density contouring. It could represent a principal stress for a conjugate fault pair. Englewood Cliffs, New Arda Stereographic projection falls into the second category.

The plunge direction is evident as the quadrant your associated periphery point lies in and the angle along the hemisphere periphery from underlying N to the periphery point is your trend.