Our coastal bluffs were exposed to erosion long before humans impacted the sand budgets. The biggest man-made monkey wrench is probably the Oceanside Harbor. It is important to note that it opened in the early 60s.
Here is a historic photo from Solana Beach. It was taken long before the harbor opened.
Notice the seaweed up to the bluff's toe (the high tide line?) and the two caves carved out by erosion.
See Also: Historic Encinitas Beaches and Bluffs