Spread is the ratio of half the base of a ridge to its elevation. It is set for each side of the ridge. Extremely large spread values can yield odd results. Spread values can be applied both to the entire ridge and to individual nodes. Due to minimum values needed to create the ridge, a vertical cliff is not created with a spread of 0.
Cliffs
The cliff setting will remove any part of the ridge beyond the cliff location. Cliff settings can be applied to either or both sides of the ridge.