This is a film steeped in metaphor
Yes the film is set around an unsolved mystery, but the film is more about the metaphors than anything else.
The whole concept is the clash between the wild, vast, untamed nature of the Australian landscape and the stifling British aristocratic mindset.
One of the most poignant images in the film can be largely skipped over. There is a shot where the beautiful light, fluffy cake that the girls have been eating for St Valentine's day is covered in ants, who are devouring what is left over. This is Australia, so far removed from Britain and aristocracy. It is wild and the landscape is indifferent to our wants and needs. It also takes what it wants and needs.
Similarly, we have the image of the garden party taking place on the rugged shoreline of a watering hole. The women in their big heavy dresses and the men in their heavy suits and big hats...yet you cut to the 'Aussie' sitting in his shack with a beer in his hand, a sensible hat (for the conditions) and his shirt open and breathing; far more suited to the landscape than this absurd British aristocratic garishness. He says "that's the difference between you and me...".
The images of the girls in their lace and heavy stockings lying at the base of the rock is at odds with the rugged, scorched landscape; they look out of place. Why would you cover your entire body in heavy fabrics, corsets and gloves when the landscape is so dry, rugged, hot and unforgiving?
You see the girls begin to strip off their stockings and walk in their bare feet as they climb the rock. You also see the girls start to lose their inhibitions and to embrace the environment around them; to become one with the wild, untamed nature of their environment. They fall asleep on the rock and the lizard moves past them without even a second glance, as if they are just part of the rock. The lizard cares nothing for them but merely continues on with his search for food and shelter. This land has not been conquered and goes on as it always has even with human contact.
The whole film is a metaphor for the stripping away of Victorian values/British culture and the embracing of the wild nature of the Australian landscape...the new world.
The film is set in 1900 because it signifies a new era, and the birth of a new century and a new country.
Australia was federated in 1901 and became a country rather than a group of separate colonies. This film is one giant metaphor for the movement of Australia away from British aristocracy, and the embracing of a completely different way of living and relating to the world around us.
Watch the film with these goggles on, and I promise it will make more sense.
As for what happened to the girls? It is of no consequence, they were absorbed by the landscape and would never be seen again. If they were dead? The animals would feast on their remains (just as the ants feasted on the remains of the cake), and life would go on, and the landscape would be completely indifferent to what had happened.
Hence the fact that the British gentleman almost kills himself trying to find the girls, but only finds a small square of fabric from one of the girl's dresses..the rest would never be found.
The whole point is that the landscape swallows them up, and all of their rituals and aristocratic ways mean nothing in that context. The girls probably weren't raped or attacked, they simply disappeared never to be seen again...absorbed by the landscape.
The line "if the cop...can't find them, then nobody can, and that's the stone cold end of it". He's right! That is the 'stone cold end of it"; they will never be found, and that is the nature of the world these people now inhabit; that is the nature of the Australian landscape.
The Australian landscape will just swallow you up, this is the reality of this new world. The same is true today, Australia still swallows people up, never to be seen again. It is still vast and untamed in many parts, and no matter how much Britain tried to tame Australia, it was never 'tamable', and thus a new culture was born.
It's a beautiful film and will always be one of my favorites, simply because of the poignant metaphors.