After years of spot erosion accumulating on Field 5 of Robert Moses State Park, the beach's deterioration has been so severe this spring that half of the popular Babylon site and its parking area are going to be closed down for the summer. Off-shore storms and possibly the ghost of Jane Jacobs have left the beach in a state where at high tide, the surf goes right up to the dunes, which have now been replaced by an eight-foot cliff. A state parks director told Newsday, "The surf cut into the dunes and at high tide there is no beach for people to put their blankets on. This is the worst erosion at that section of Robert Moses that we have seen since at least two decades." Field 5 can usually play host to up to 10,000 sunbathers and its parking lot holds 1,200 spaces. In order to accommodate, Field 4 has begun taking on some of its lifeguards and will now be open on Thursdays and Fridays starting in July. Just last summer the Suffolk park celebrated its 100th anniversary.