Free tool

Online stereonet: plot planes, poles and lines

Plot planes, poles and lines on a lower-hemisphere equal-area (Schmidt) or equal-angle (Wulff) net. Find intersections, angles between planes and lines, rake, apparent dip and fold axes.

Open the interactive stereonet

What it does

• Plots planes as great circles and poles, and lines as points, from right-hand-rule strike/dip, dip direction/dip, or quadrant bearings such as N40E 35SE.
• Finds the line of intersection of two planes, the angle between planes or lines, the plane containing two lines, and the rake of a line in a plane.
• Gives the apparent dip of a plane in any direction.
• Fits a best great circle through bedding poles (a π diagram) and marks the fold axis.
• Accepts pasted columns of field measurements.

Doing it by hand

1. Mark the right-hand-rule strike on the primitive and rotate the overlay so the mark sits at north.
2. Count the dip inward from the east side along the straight E–W line and trace the great circle.
3. For the pole, count the same number of degrees outward from the center toward the west and mark an ×.
4. The line of intersection of two planes is the point where their great circles cross.

Structural geology normally uses a lower-hemisphere equal-area net, which is also the one used for contouring point density.