equal area stereonet with small circles showing consistent size. Small circles Angles are slightly distorted and make the circles appear as ellipses. The x-axis. This is a printable 2 degree equal angle (Wulff) stereonet in PDF format. Equal angle versus Equal area nets. Two projections used in structural geology. They are also used as map projections, and for maps of the sky in astronomy (or .

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There are absolutely no differences between the interpretations made using manual drawing and software-based drawing of datasets. In order to do this, rotate the two pole points until they fall on the same great circle.

Part 1 – Plotting and manipulating elements on a stereonet. You anble need the following materials in order to proceed with this and the subsequent stereonet exercises: This is the bisector. Equal angle projection 2.

The strike and dip of that great circle is that of the common plane. Cardinal directions are shown. For someone who is starting in geology or structural geology, it is highly recommended to use paper and pencil over software.

Stereographic projection for structural analysis

There are different methods by which the points of intersection with the lower hemisphere are projected onto the stereonet.

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The blue plane position is where North has been rotated so that the great circles all have a strike of N45W The stereographic projection is a methodology used in structural geology and engineering to xngle orientation of lines and planes with respect to each other.

In most cases it is preferable to use a projection that optimises equal area, because it makes it easier to assess the spatial distribution of structures. Read the Docs v: That great circle is the bisecting plane. They are equal area stereonet and equal angle stereonets.

2. Stereonet — InnStereo 0 documentation

G On a new sheet of paper plot the following two lines. It could represent a principal stress for a conjugate fault pair. A Plot the following two planes: A line is drawn from that projection point to the lower hemisphere intersection point light green dashed lines. It is the true North which is denoted by the azimuthal angle of degrees on the primitive. An zngle of such a plane is shown in red here.

Equal Angle (Wulff) Stereonet

We can now consider how two lines the ones in green plot. These could be though of as the apparent dips of the red plane in a N-S and E-W vertical cross section respectively. If you have understand how 3D vectors work, this should be a no-brainer.

Hence, most educational institutions prefer equal area steronets for their students over the equal stereohet stereonets.


Then count along that great circle in degree increments moving from one point pole to the other. It is the outer most circle is the primitive. In this case the North position is designated in blue.

What is plotted on the stereonet is a projection of where a given line or plane intersects the lower hemisphere surface.

That is the angle desired. This is because the equal angle stereonets preserves the true relationships between stratigraphic and structural features. If it is less than 90 degrees it is the acute angle, otherwise it is dtereonet obtuse angle. Planes plot as great circle traces. It may take some timeand focus to understand the geometry.

Angles are slightly distorted and make the circles appear as ellipses. The point 1 sterdonet 2 are best fit line points for the poles that lies about the center of the diagram. The steeper the dip the less curved the great circle is and the closer to the center, and the shallower the dip of the plane the more equxl and the closer to the outside margin of the stereonet plot the great circle is.