Q. How deep is the sand on a typical beach?
A. There are so many variables in the evolving natural history of a sandy beach that it would be virtually impossible to identify a typical beach. The depth of the sand can range from a few inches to many feet and can change noticeably with each season, each storm, each tide or even each wave.
Often, underneath the loose sand of a beach is a layer of hard, compacted sand, which could be on its way to becoming sandstone if the necessary cement, pressure and heat ever appear — and if is not eroded by severe storms.
Among the variables in beach depth are the shape and angle of the area where sand accumulates; the materials that lie under the sand, whether mud, rocks, rubble or more sand; the source of the sand, as well as its size and texture; and wave and current patterns.
Human intervention is often futile. Repeated studies have found that sand pumped onto beaches in order to protect coastal property may be washed out by a storm or two. These beaches commonly lose all the new sand in five years or so.
For example, 3.5 million cubic yards of sand were used to restore beaches in the Rockaways in Queens, beginning in 2014 after Hurricane Sandy. As of this summer, the ocean had already eaten its way to the dunes and boardwalk in certain areas.
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