I think that can happen naturally, unless they are dumping rocks on my hometown California beach. There is a layer of rocks below the summer sand level that are

I think that can happen naturally, unless they are dumping rocks on my hometown California beach. There is a layer of rocks below the summer sand level that are exposed in winter. I guess they could have dumped rocks years ago when erosion was problem. My hometown beach was fixed by restoring connection to lagoon behind it and allowing the sand to be dumped in the ocean not the lagoon. Restoring the lagoon and digging a channel helped but what really helped was building new bridge that didn’t block the flow. They used to dredge sand to have enough in summer. Now there is plenty in summer but can get rocky in winter after storm.