La Gruta de las Maravillas, Cave of Wonders, spectacular, beautiful formations in Aracena, Huelva province
In September 1914, La Gruta de las Maravillas in Aracena became the first cave system, in Spain, to be opened to the public. In 1915 the cave was visited by King Alfonso XIII and Queen Victoria Eugenie. The monarchs returned in 1929. Since then millions of visitors have wondered at the spectacular formations within the caves that rank as some of the most beautiful in the world.
Stories of how the caves, the entrance to which is in the town itself, were found, vary. Some say it was a local shepherd, Tio Blas, that found the entrance whilst looking for lost sheep, others say it was miners prospecting for silver during the 18th century who found the cave system. Either way, before long, the local residents were entering and removing the calcite formations. It was the Marquess de Aracena, Francisco Javier Sánchez Dalp and the local mayor, Juan del Cid, that saw the commercial and touristic potential of the caves and they started promoting visits.
All the tours are guided and start at fixed times. The booking office is opposite the cave entrance in Pozo de la Nieve, an ornate arch built by architect Anibal Gonzalez, better known for the Plaza de España in Seville.
The standard tour is about 1.5 kilometres in length and starts at the lower levels of the cave system with the Conch Chamber. More imaginatively named passages and chambers include the Chickpea Chamber, the Great Lake and the Naked Chamber.
The stalagmites (they are the ones that start at the ground and grow upwards), stalactites (they start at a roof or ledge and grow downwards), columns (formed when a stalagmite and stalactite join), calcite curtains and flowstones, calcite pools, helictites (formations that alter their axis from the vertical during growth) and straws (very thin, hollow stalactites), all coloured with different minerals, the most common being copper, lead, and iron, provide a series of awesome spectacles. Pure calcite is white, copper adds green, iron – yellow, orange and red, lead - grey and black.
Cave formations, collectively called speleothems, form when water, containing dissolved calcium from the surrounding limestone rock, finds its way to a chamber. As the water drips from the ceiling, a minute amount of calcium is deposited. When the water droplet hits the floor it leaves a small amount of calcium behind. Over thousands of years stalactites and stalagmites grow, typically at a rate of 10 cms per thousand years, but that does depend on rainfall in the area, the depth of the cave beneath the limestone, air currents and water flow through the cave. If a stalagmite is cut through and polished, you would find ‘annual rings’ just the same as a tree’s growth rings. By studying the thickness of the rings, scientists can deduce the weather from the present day to many thousands of years in the past.