Coroner Sheriff Payne told the hearing that Miss Blackman's death could not have been predicted.
He said the National Trust, which owns a stretch of the beach where the tragedy happened, appeared to be doing all it could to warn visitors of the dangers presented by the 100ft cliffs.
"Sadly, Charlotte Blackman died as a result of an accident. It was a sudden act of nature that nobody could have predicted at that time."
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Into the evening it will remain dry with the best of the clear spells in the west.
Some evening sunshine, although low cloud will spread from the coast into many areas early in the night.
Mr Parnell, from Sileby in Leicestershire, was celebrating his first wedding anniversary.