"Through me the way is to the city dolent;
[...]
Through me the way is to eternal dole;
Through me the way among the people lost.
Before me there were no created things,
Only eterne, and I eternal last.
All hope abandon, ye who enter in!"
- Canto III of Dante's Inferno, translated by Mark Musa
For a long time, the inner earth was a mysterious place - supposedly the reign of demons, home to ancient gods (like Pluto) and place of eternal damnation. Italian poet Dante Alighieri imagined an especially elaborate version of Hell in his Divine Comedy. He included in his description the nine circles of Hell, with Lucifer residing in the lowest, real landscapes and geological features. According to author Marco Romano, in the description of Dante's Inferno we find earthquakes, rivers, mountains, landslides, a desert of scorching sand and even some types of rocks (like the famous marble of Carrara).
Dante imagined Hell like an inverted cone, with its circles gradually becoming smaller nearer to Earth's core. Each circle was dedicated to a sin and the sin's related punishment. This image is based on calculations of Greek philosophers, like Eratosthenes of Cyrene or Claudius Ptolemy, who argued that Earth is a sphere. Hell, as part of earth, would have to be cone-shaped. Dante even gives an exact value of Earth's radius of 3,250 miles (it's actually 3,959 miles).
Dante's Inferno as imagined by artist Jan van der Straet in 1587 (image in public domain).
The cone, according to Dante, formed when Lucifer, the fallen angel, fell to Earth. The impact of the Fall was so great that it even reshaped Earth's surface. Continents were uplifted on the northern hemisphere and the southern hemisphere lowered and was covered by the sea (Dante didn't know about Australia and Antarctica).
In Dante's writing, only Mount Purgatory can be found in the south. Purgatory, together with the holy city of Jerusalem, forms an axis passing through Earth, with Lucifer's belly as center of Earth and the universe. This is an allegoric image, showing Lucifer is damned as far as possible away from the sun and the divine light.
When entering Hell, Dante is guided by the shadow of the ancient Roman poet Publius Vergilius Maro, better known as Virgil. During his pilgrimage from Hell to purgatory to paradise, the way is obstructed by ruins, destroyed, as one demon reveals to Virgil, by an ancient earthquake.
Like the ruins this side of Trent left by the landslide
an earthquake or erosion must have caused it
that hit the Adige on its left bank,
when, form the mountain’s top where the slide began
to the plain below, the shattered rocks slipped down,
shaping a path for a difficult descent
so was the slope of our ravine’s formation.
Here, Dante describes a 3,000 years old landslide in the Adige valley, even arguing that the cause of this ancient landslide was erosion or an earthquake. Dante may have visited this site, as he lived for a time in the nearby city of Verona. It's certain he used German naturalist Albertus Magnus as a reference, as Magnus argued that by the river eroding the base of the mountain it had collapsed, forming the ruined landscape of the landslide.
Dante also experiences an earthquake at the shores of the river Acheron, one of the rivers flowing in Hell. Dante, following in part contemporary explanations of earthquakes, mentions that vapors blowing inside the caverns of Earth and exploding from time to time are shaking the entire earth.
It's curious to note that Dante didn't describe Hell filled by fire, even though Mount Etna and Vesuvius were regarded in ancient times as gates to Hell and both mountains seem to be filled by liquid fire. However, Etna is mentioned when referring to the island of Sicily, as a site with sulfur vapors. The Phlegethon and some minor rivers are described as rivers of boiling blood with "lithified" margins, like - so Dante writes - the hot springs of Bullicame near the city of Viterbo in the Lazio region.
There may be a simple explanation why Dante didn't include volcanoes more prominently in his work. Both Etna and Vesuvius were at the time relatively calm (Vesuvius erupted only in 1321-1323) and so may have been of no real interest to the poet.
In Dante's Inferno, geology even plays a role in the punishment of the sinners. In the third circle, the simonists (people who sold holy artifacts for profit) are driven upside down into the ground and "squeezed tightly in the fissures of the rock."
The robbers are punished in a circle filled with poisonous snakes. Dante describes looking down into the pit:
Within this cruel and bitterest abundance
people ran terrified and naked, hopeless
of finding hiding-holes or heliotrope.
Their hands were tied behind their backs with serpents.
Heliotrope (a variety of chalcedony) was a gemstone much valued for its magical properties in ancient times, and one use was to protect from the venom of snakes. As the gate to Hell promised, there is no hope for the sinners to find such a talisman here and escape, even only temporarily, their punishment.
After the Inferno, Dante finally reaches the mountainous landscape of Purgatory, leaving Hell behind:
The climb had sapped my last strength when I cried:
“Sweet Father, turn to me: unless you pause
I shall be left here on the mountainside!”
He pointed to a ledge a little ahead
that wound around the whole face of the slope.
“Pull yourself that much higher, my son,” he said.
His words so spurred me that I forced myself
to push on after him on hands and knees
until at last my feet were on that shelf.
The Divine Comedy is appreciated today as a masterpiece of world poetry. But Dante also included a lot of his contemporary knowledge, providing an important source to better understand the earth sciences in the 14th century.
Geology from Hell - dikes in the Dolomites. Once molten, these rocks cooled deep within earth... [+]
Interested in reading more? Try:
KROONENBERG, S. (2013): Why Hell Stinks of Sulfur: Mythology and Geology of the Underworld. University of Chicago Press: 352
