FIFTY years ago this week a writer called Joan Lindsay published a mystery book about a group of schoolgirls who vanished on St Valentines Day 1900.
The place where the girls disappeared was one of Australia's most eerie locations, Hanging Rock.
Often shrouded in mist, it's also shrouded in mystery with baffling and unexplained incidents happening close to the rock.
The six million year old rare volcanic formation rises up on a plain between two tiny townships 70km northwest of Melbourne.
Less commonly known as Mount Diogenes, it comprises several distinctive outcrops including the 'Hanging Rock', a boulder suspended between other boulders under which is the main entrance path. Close by are other rock formations - the Colonnade, the Eagle and the UFO.
It was a sacred Aboriginal site for the Wurundjeri people and well-known to Lindsay who reportedly felt it had a mystical power.
Her book Picnic at Hanging Rock was published on April 3, 1967, and was made into Peter Weir's award-winning 1975 film.
According to a new book to be published this week to mark the 50th anniversary of Lindsay's novel, when Weir's crew went to the rock to shoot the film strange things happened.
The next day they travelled to Hanging Rock, getting lost en route and approaching from the wrong side where the formation loomed in front of them beneath a cloud.
"Immediately, they sensed the eeriness of the place," McCullough writes. "Lovell was immediately uneasy.
"The rock 'seemed so alien to the rest of the countryside'.
"At the picnic grounds at the base of the rock, her watch inexplicably stopped.
"It was the first of many times this would happen, either at Hanging Rock or around Joan herself."
A place known locally in the town of Woodend, near Hanging Rock, as "Anti-Gravity Hill" purports to feature a strange and baffling phenomenon.
Mountmacedon.org.au claims that if a person stands on Straws Lane facing up the hill and tips water onto the road it flows "up the hill" not downhill A ball placed on the road will do the same thing and roll up the hill.
During filming at Hanging Rock itself, Weir described the effect where the light that streamed down through the trees was only visible for one hour of the day, when the sun was in the exact spot.
Lindsay, who was occasionally on set during filming, would only say when asked about her book's plot, "some of it is true and some of it isn't".
Despite many attempts to find a historic account of the disappearing schoolgirls, no-one has succeeded and it seems that only the locations are real.
There is one record of a young man falling and dying from Hanging Rock in the early 1900s, but this was recorded and solved and had no connection to the Hanging Rock story.
In 1907, a 19-year-old man murdered another man near the rock and was caught by police.
Joan Lindsay's Picnic at Hanging Rock is the story of schoolgirls from the fictional Appleyard College for Young Ladies' school near the real town of Woodend.
In the film, the formidable actor Rachel Roberts plays Miss Appleyard, with Anne Louise Lambert in the leading role of the ethereal schoolgirl Miranda.
On February 14, 1900 the girls prepare for a picnic at nearby Hanging Rock with their mathematics mistress Greta McCraw, and French mistress Mlle. de Poitiers played by Helen Morse.
As their buggy gets closer to the rock, the driver's watch stops on the stroke of twelve.
At the rock Miranda and three other girls, Irma, Mario and Edith, decide to explore.
They are observed by picnicking English tourist Michael Fitzhubert to lie dazed on the ground before moving, in a trance, into a recess in the rock face.
One of the girls, Edith screams and flees down the rock and a depleted and hysterical group returns to Appleyard College.
Missing are Miss McCraw, Miranda, Marion and Irma.
A police search party fails to find them, a Miranda-obsessed Fitzhubert sets out but is found near-delirious and clutching a piece of lace from Miranda's dress.
Only Irma is found, unconscious and missing her corset but alive. She cannot remember what happened.
The incident spooks Woodend and Appleyard College, two more die and the girls' disappearance is never solved.
Weir's film is set to haunting pan flute music and was a critical success before being nominated for a raft of awards, but winning only a BAFTA for Best Cinematography.
The film created renewed interest by visitors to Hanging Rock, which is now a popular tourist destination and retains its reputation for being a "haunted" site.
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