Thermal weathering is caused by temperature changes causing small portions of the material to
crumble and pile up on the bottom of an incline. The thermal weathering erosion ends the slopes of uniform
angles. Thermal erosion is a relaxation process and is very easy to implement. At each time step the difference
between the altitude of each vertices of terrain and theirs neighbors to the defined constant talus angle
*T* is compared (see Figure 9).

**Figure 9:** One possible step of thermo erosion.

If the topical slope between vertex *v* and its neighbors *u* is greater than *T* then some part
of material is moved from *v* to *u*. Amount of moved material specifies the constant

In the same way as in the case of the hydraulic erosion mentioned above we should care to the distribution to the all lower neighbors. The amount of moved material to one neighbor is proportional to the corresponding slope.

Ivo Marak - marak@sgi.felk.cvut.cz