The terrain on the right is affected by the tfThermalWeathering, displaying a much smoother surface.
This is set to Thermal Weathering, by default.
The other Modes settings are: Hydraulic (2D Particles), Hydraulic (X-Particles), Coastal and Snow.
These other modes are dealt with in more detail in their own dedicated pages.
This mode simulates the natural phenomenon of rocks and landscapes changing with heat, causing crumbling and cracking and the displacement of sediment downhill, causing further erosion through abrasion.
The erosion simulation is run multiple times on the terrain.
Each run will erode the terrain a little more. This is set to five times, by default.
This parameter is the most important one, regarding erosion strength and calculation time.
Larger values will erode more but take longer to calculate.
Iterations set at the default 5 on the left, compared to 30 times, on the right-hand terrain.
Dictates at what slope angle the erosion will take place.
Smaller values will erode the terrain more equally, while larger values will only affect steeper slopes.