In 1835, while attempting to dig a duck pond, a man named James Newlove and his son Joshua discovered a peculiar hole in the ground. When Joshua crept down inside he entered over 70 feet of winding underground passages at the end of which was a much larger chamber and, within that, something that resembled an altar.
All of the walls were covered in an exquisite tapestry of shells, since found to have been stuck there with an adhesive that is based on gypsum and volcanic elements. Over four million cockle, whelk, mussel and oyster shells formed various patterns of mosaics, with images of the Tree of Life, phalluses, gods and goddesses, the horns or a ram, a three-pointed star, as well as the sun and the moon.
Mr Newlove soon decided to tap into the commercial potential of such a dramatic find, and by 1837 the first paying visitors arrived – and with them the debate commenced as to origin of the caves.
Some people thought they must have been an ancient pagan temple, some the home of a secret sect, while others were entirely convinced that they must be some Regency folly. But such follies were built on wealthy estates and Mr Newlove’s grotto was discovered beneath common farmland. And then, there is also the fact that had the grotto been constructed during the 1700’s then surely some record or map would remain – not least with regard to the enormous industry involved in excavating the long passages and creating all the shell mosaics. And yet, there was no local knowledge regarding the grotto’s existence.
In 1999 English Heritage commissioned an investigation, its only conclusion being that the grotto was unlikely to have been built during the Victorian period. Carbon dating was attempted, but failed owing to the build up of soot on the shells from the use of many oil lamps during Mr Newlove's tours.
Later, in 2001, Mick Twyman of the Margate Historical Society tried to unravel the enigma. He observed that just before the arrival of each spring equinox, the sun enters the underground realm through a dome with a circular opening that acts like a pinhole camera. As the season goes on the ball of light reflected on the temple walls grows larger and continues to move over certain ‘lines’ or bars in the shells, as if a solar calendar. At midday on the summer solstice, the light resembles an egg that glows in the belly of a mosaic snake. At that point it is reflected up into square apertures built above the grotto’s three distinct passages – and that light is then bounced down to shine on the altar that is built within the 'temple' chamber.
By the use of these phenomena and complex mathematical calculations Twyman was able to show that, allowing for a ‘creep’ of 1% in the Equinox angle that occurs every 72 years, the construction date for the grotto would have been around 1141 AD.