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shingle (roof, or rocky 'sand bar' (UK)) are from the same root word (these too are gravelly!)




Interestingly, the online etymology dictionary says that that the roof shingle and the gravel shingle have different origins:
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shingle (1) Look up shingle at Dictionary.com
"thin piece of wood," c.1200, scincle, from L.L. scindula, altered (by influence of Gk. schidax "lath" or schindalmos "splinter") from L. scandula "roof tile," from scindere "to cleave, split," from PIE base *sked- "to split." Meaning "small signboard" is first attested 1842; that of "woman's short haircut" is from 1924. The verb meaning "to cut the hair so as to give the impression of overlapping shingles" is from 1857.
shingle (2) Look up shingle at Dictionary.com
"loose stones on seashore," 1513, probably related to Norw. singl "small stones," or N.Fris. singel "gravel," both said to be echoic of the sound of water running over pebbles.