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Earth of fire

Actualité volcanique, Articles de fond sur étude de volcan, tectonique, récits et photos de voyage

Publié le par Bernard Duyck
Publié dans : #Mythes et légendes.
Lake Agnano. - Colored engraving by Pietro Fabris, 1776. - a click to enlarge

Lake Agnano. - Colored engraving by Pietro Fabris, 1776. - a click to enlarge

The Agnano Basin is the oldest crater of the third eruptive period of the Phlegraean Fields, dated from 8,000 to 3,900 years ago. With a circumference of 6.5 km, it collapsed on its west and north sides because of the subsequent formation of the Solfatara craters and the Astroni; it ends in the southwest at Mount Spina and east at Monte Sant'Angelo.

The site has been known since antiquity, and ruins of Roman baths are visible on the slopes of Mount Spina.

Lago d'Agnano (Napoli) - Lake view in the 1860s - photo Giorgio Sommer - one click to enlarge

Lago d'Agnano (Napoli) - Lake view in the 1860s - photo Giorgio Sommer - one click to enlarge

The gates of hell -2 : Grotta del Cane and lago d'Agnano.

Until 1870, the Agnano basin hosted a lake, appeared in the eleventh century, following seismic phenomena called bradyseism, which means a rise or a slow decline in the ground level of volcanic origin. The basin is fed by 75 thermo-mineral sources, with a temperature of up to 75 ° C, which has been used for retting flax, polluting and smelly. It was emptied artificially and dried in 1870.

Antique engraving of Lake Agnano and the Grotto of the Dog - 1572 / Braun & Hogenberg - to notice: the dog immersed in the waters of the lake. - a click to enlarge

Antique engraving of Lake Agnano and the Grotto of the Dog - 1572 / Braun & Hogenberg - to notice: the dog immersed in the waters of the lake. - a click to enlarge

Lake Agnano and Grotta del Cane - watercolor  Sieur Rogissart (18 ° s) - one click to enlarge

Lake Agnano and Grotta del Cane - watercolor Sieur Rogissart (18 ° s) - one click to enlarge

This setting not at all enchanting did not prevent it from being visited by foreigners and travelers of the "Grand tour" attracted by the "Grotta del Cane". For a few coins, a small dog was placed on the ground of the cave and showed in a few seconds signs of asphyxiation; Quickly released in the open air, or immersed in the waters of Lake Agnano, he "resuscitated" ... much to the astonishment of the tourists of the time, including Goethe, Alexander Dumas Sr. and Mark Twain.

Grotta del Cane - a guide shows a dog asphyxiated to a couple of tourists - drawing Arthur Mangin 1865

Grotta del Cane - a guide shows a dog asphyxiated to a couple of tourists - drawing Arthur Mangin 1865

Grotta del Cane - Agnano - 1920s postcard

Grotta del Cane - Agnano - 1920s postcard

The dog was intoxicated with volcanic carbon dioxide, which was denser than air and stagnant in the deep parts. The local guides, who held the animal for a moment, were unaffected as they protruded from the stale air layer.

The Cave of the Dog has been described and illustrated many times in the 19th century. It has recently been visited by Italian speleologists, who interpreted it as a cavity created by man in antiquity to serve as a sudatorium. The carbon dioxide level was measured at 9.9%. Prolonged exposure in an atmosphere with 5% CO2 can induce irreversible health effects, and above 6% lead to unconsciousness and death.

Alfred Swaine Taylor Diagram 1832 / The London Medical and Physical Journal, explaining the principle used at the Cave of the Dog

Alfred Swaine Taylor Diagram 1832 / The London Medical and Physical Journal, explaining the principle used at the Cave of the Dog

 Grotta del Cane - surveys carried out in 2001 by the speological research center.

Grotta del Cane - surveys carried out in 2001 by the speological research center.

Sources:
- Napoli Underground - The Ancient Thermal Baths of Agnano & the Grotto of the Dog
- Napoli Underground - Il mistero del lago di Agnano
- Volcanic Gases May Explain The Deadly Effects Of Ancient Sacrificial Chambers - Bressan D

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