Ah, the shingly shore…
William McTaggart, A Shingly Shore, oil on canvas, 1904.
The nature of the coast: steep, flat, cliffy, rocky, sandhills, stony, shingly, sandy, mangrove, mud, gravel, coral, breakers, rubble, unsurveyed.
The nautical chart map symbol for a shingly shore is taken from section A of Chart #1, Nautical chart symbols and abbreviations used by U.S. Lake Survey, Corps of Engineers, U.S. Army, Dept. of Defense; U.S. Coast and Geodetic Survey, Dept. of Commerce; U.S. Navy Hydrographic Office, Dept. of Defense (Washington DC, 1957). The entire page A with the rest of the symbols is here (1.2 mb jpg). A contemporary version of these symbols, still Chart #1, is here.