Strike
Dip
App. dip
Pole
Stereographic projection in structural geology is a 2D graphical technique used to represent and analyze 3D orientation data of geological features, such as planar bedding planes, fault surfaces, and linear fold axes or lineations on a two-dimensional circular diagram called a stereo net.
Select one of the three learning options to explore stereographic construction. Use the controls in the left panel to change the orientation or input values. The 2D stereonet and 3D View update to reflect the current geometry.
Set the Strike and True Dip of the plane using the sliders. The 3D View provides a three-dimensional representation of the plane and its orientation.
Press Next → Stereonet to start the construction. The stereonet shows the corresponding great-circle representation of the plane.
Enter two apparent-dip observations using Amount/Angle and Direction. The two apparent dips provide the information required to determine the true orientation of the plane.
The 2D stereonet shows the geometric construction, while the 3D View displays the resulting plane. Use the Plane Transparency slider to adjust the visibility of the plane surface.
Set the orientation of Plane 1 and Plane 2. Their planes are displayed in the 3D View as outlines while the construction is being prepared.
Start the stereonet construction to plot the two planes. When the construction of each plane is completed, its corresponding 3D surface is filled. At the end of the construction, the line of intersection is displayed in the 3D View.
Use Speed to cycle through the available construction speeds. A slower speed can be useful when following individual geometric constructions.
The 3D View provides a spatial representation of the geological geometry. The reference hemisphere and orientation graphics help relate the 2D stereonet construction to the three-dimensional plane or planes.
Use Reset to return the current learning activity to its initial state and clear the construction.
In Manual mode, the controls allow you to Draw Tick, Draw Line, Draw Arc, and Rotate the stereonet overlay. The manual controls are intended for direct graphical construction on the stereonet.