This diagram was created using the software program Trishear 4.5 by Richard Allmendinger (1997-2000), to whom we are grateful for making this and other software so widely and easily accessible to the geocommunity. The algorithm used in the software is described in the following two references:

- Allmendinger, R. W., 1998, Inverse and Forward numerical modeling of trishear fault-propagation folds. Tectonics, v. 17, 640-656.
- Zehnder, A. T. & Allmendinger, R. W., 2000, Velocity field for the trishear model: Journal of Structural Geology, v. 22, p. 1009-1014.

Here is the geometry after 250 meters of slip. Note how the distance between cutoff points along the faults decreases for the successively higher beds. Click on the image to see what happens with 250 meters of slip on the decollement. It should be emphasized that the geometry show here is just one of many possibilities. Changing the input parameters will change the specific appearance of the fold quite a bit.