Gasman,
The mud slides definately did happen and not just on the coast highway. That highway has been a problem along the coast for many years as the land keeps shifting. A beautiful drive, but they have installed huge steel nets in many places to catch the rocks to keep them from knocking cars into the ocean. Topanga Canyon is famous for it's slides and they had a huge boulder about the size of a small pick up right in the middle of it getting ready to blast it into smaller pieces to remove. Just remember, when driving along the coast highway, and especially near Carmel and that area, drive fast and avoid the rolling rocks.
Ron
