Sleeping Beauty (1959)

Why did the animators depict the land with sheer cliffs and uneven spots, as if there was an earthquake?

Aurora and Prince Philip dancing in the forest

According to the The Making of Disney's Sleeping Beauty (around 9:32-14:00), the background artist, Eyvind Earle, studied and mimicked medieval, Gothic, proto-Rennaisance art because of the temporal setting of the story itself. One of the principal influences Earle cited in his artistic direction for the film was the Book of Hours. Earle channeled those influences into a modern style with "strong verticals" (12:30), which actually carried over even into how the animation team portrayed the film's characters (i.e., Aurora, King Stephan, Maleficent).