Field of Science

How 19th Century Climbing Books Reveal Clues About Climate Change

For the stone from the top for geologists…” answered mountaineer George Mallory once when asked why he’d climb Mount Everest (he and his friend Sandy Irvine perished there on June 6, 1924). 
Geologists nowadays study how climate change weakens the mountains based on observations made by such pioneering mountaineers. Continue reading...

Dante´s Inferno - The Geology of Hell

"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

"The Gates of Hell", by Jehan Froissart, 15th century.

For a long time the inner earth was a mysterious place, supposedly the reign of demons and place of eternal damnation. Italian poet Dante Alighieri (1265-1321) imagined an especially elaborate version of hell in the “Divine Comedy”. Like later authors he used in part his contemporary knowledge as inspiration and included in the description of the nine circles of hell, with Lucifer residing in the lowest, real landscapes. Dante mentions earthquakes, rivers, the shape of mountains and landslides, a desert of hot sand and some types of rocks (like the marble of Carrara).
The circles gradually become smaller with less circumference, as hell is depicted like an inverted cone in a sphere, protruding towards earth´s core. This image is based on calculations of Greek philosophers (like Eratosthenes of Cyrene, 276-194BC or Claudius Ptolemy, 100-170AD), Dante even gives an exact value of earth´s radius of 3.250 miles (5.230km, actual radius is 6.371km). 

Dante´s Inferno by Jan van der Straet, 1587.

The cone formed when Lucifer, the fallen angel, fell on earth, the impact was so great that it even shaped earth´s surface, with continents formed on the northern hemisphere and the southern hemisphere covered by the sea (Dante didn't know of the existence of the southern continents of Australia and Antarctica). 

"The fallen angels" by Vincent of Beauvais (1463).

In the south we will find only the mountain of Purgatory. Purgatory, together with the holy city of Jerusalem, forms an axis passing earth, with Lucifer´s belly as center of earth. An allegoric image, as Lucifer is damned as far as possible away from the sun and divine light.
Illustration to Dante's "The Divine Comedy" from the "Codice Urbinate Latino 365" (1480) showing the frozen center of earth with Lucifer trapped in eternal ice. Dante imagined this part of hell as frozen wasteland, as it was as farest away from the warm sun as possible in his geocentric universe (earth as center of the cosmos, with sun, moon and stars around it).

Dante when entering hell is guided by the shadow of ancient Roman poet Publius Vergilius Maro (70-19BC), better known as Virgil. During his pilgrimage from hell to purgatory and 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.

Dante describes in these verses the sight of a 3.000 years old landslide near the Italian city of Trento, even arguing that the cause of this ancient landslide was erosion or an earthquake. Dante maybe visited this site, as he lived for a time in the nearby city of Verona. For sure he used German naturalist Albertus Magnus (1200-1280) as reference, who argued that by the river eroding the base of the mountain it collapsed, forming the ruined landscape of the landslide. Dante also experiences an earthquake at the shores of the river Acheron, caused by winds or vapors blowing inside the caverns of earth and igniting from time to time.

It´s curios to note that Dante didn't describe hell filled by fire, despite Mount Etna and Vesuvius were regarded in ancient times as gates to hell and both mountains seem to be filled by the liquid “lava-fire”.... not to mention hellish volcanic eruptions. However Etna is mentioned when referring to the island of Sicily, as 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.

The Icelandic volcano Hekla as gateway to hell, from "Historiae de gentibus septentrionalibus" by Olaus Magnus (1490-1557), Archbishop of Uppsala.

There is may a simple explanation why Dante didn't include volcanoes more prominent in his work. Both Etna and Vesuvius were at the time relatively calm (Vesuvius erupted only in 1321-1323) and so of no real interest to the poet.

Geology plays even 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 was he sees:

“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 chalcedony variety) was since ancient times a gemstone much valued for its magical properties, like to protect from the venom of snakes. 

After Inferno Dante finally reaches the slopes of Mount 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 poets begin their laborious climb up the Mount of Purgatory, illustration by Gustave Doré (1861).

The Divine Comedy is nowadays appreciated for it´s role in the development of literature and Italian language, but it is also valuable source to better understand the natural sciences and the understanding of earth in the 14th century. 

KROONENBERG, S. (2013): Why Hell Stinks of Sulfur: Mythology and Geology of the Underworld. University of Chicago Press: 352
ROMANO, M. (2016): Per tremoto o per sostegno manco”: The Geology of Dante Alighieri’s Inferno. Italian Journal of Geosciences, 135(1): 95-108

Darwin´s first botanizing steps followed the geological ones

I collected every plant, which I could see in flower, & as it was the flowering season I hope my collection may be of some interest to you."
Darwin in a letter to Henslow, 1836
Darwin´s interests in the natural world were widespread. He enjoyed hunting, later also taxidermy. With his cousin William Darwin Fox he hunted for bugs. He collected rocks and minerals and later geologized around the world during the voyage of the Beagle (1831-1836). His mentor and friend John Stevens Henslow was professor of Mineralogy and later for Botany, introducing the student Darwin in both disciplines. Darwin attended Henslow´s botany lectures, labs and field trips each year during his three years at Cambridge, visiting also private science meetings at Henslow´s home. During the geological field trip in summer of 1831 with Adam Sedgwick he also collected and preserved some plant specimens.

Fig.1. Herbarium sheet by J. S. Henslow with three plants collected by Charles Darwin in 1831 at Barmouth, North Wales. This is the earliest-known herbarium specimen collected by Darwin (image source).
During the voyage of the Beagle Darwin collected plants or seeds on the Cape Verde Islands (the first stop of the Beagle), then Argentina, Uruguay, Chile, Brazil, later also on some of the visited islands, like the Falkland, Galápagos and Cocos islands. As Darwin had limited space on the Beagle, most occupied by rocks and animals, he concentrated on remote or less well studied localities.
Darwin had prepared several thousand labels in different colors before the voyage to be applied to every dried plant (the labels including plant name, locality, date and his signature). Wet specimens, conserved in "spirits of wine", were tagged with a metal tag. Henslow, who back in England managed Darwin´s collection, removed however most labels when putting Darwin´s specimens into the herbarium. Unlike the collected rocks and animals Darwin didn´t number the plants, so it seems a bit confusion sneaked into the collection. Another friend of Darwin, botanist Joseph Dalton Hooker, lamented to Darwin that not all notes could be attributed to the preserved plant specimens.
Darwin´s plant collection is especially interesting as it includes many species from the – at the time – less visited islands of Galápagos and Cocos islands. Darwin was intrigued about the relationship of the island species to nearby continents, he will do some experiments with seeds showing that some can survive salt water for months and so be dispersed over the sea. Despite Darwin´s first plans he didn't publish the collected plants in his description of “The Voyage of the Beagle” (published in 1839), as a very busy Henslow didn't meet the deadlines for publication.

Darwin collected 756 different species, subspecies or varieties of vascular plants during his voyage around the world, 220 species were new to science. Darwin was especially surprised by the variability of plants, one collected grass species was divided by Henslow into 15 different groups! This was an intriguing observation, important for his later theory of evolution, as variability is where natural selection acts on. Also the relationship of plant species on islands to nearby continents was an important observation. The plants from the Galápagos islands showed, according to Hooker, a remarkable variability between the single islands, however some even more remarkable similarities to species from North America and Brazil. Would a divine creator not be able to create distinct, unique species on remote islands as he pleased? However if seeds could disperse with marine currents and islands be colonized by plants from nearby continents, couldn't they also evolve there in new species?
PORTER, D.M. (2010): Darwin: the Botanist on the Beagle. Proceedings of the California Academy of Sciences, Vol.61(4): 117-156

Bone and blood is the price of coal - Animals in Mines

"Humanity’s genius is to have always had a sense of its weakness. The physical energy and strength, with which nature insufficiently endowed humans, is found in animals that help them to discover new territories."
From the movie "Home" (2009)
Since prehistoric times humans searched for rocks and minerals hidden deep inside earth. First for silex and quartz, used for stone tools, later for metals and finally for coal and oil to fuel the industrial revolution.
In antiquity the work in mines was done by prisoners or slaves. In the middle ages miners became professional workers. The demand was so high that miners were members of a privileged social class, often freed from direct taxes, living in villages with own independent jurisdiction. The price for the privileges was nevertheless high. The work in the mines was dangerous, rock-fall and sudden flooding of the tunnels, wet and cold conditions for hours, poisoned air and dust causing sickness and death.

But not only humans, also animals had to suffer. In the middle ages animals, like horses, were not yet used directly in the mines, but to move large machines, like pumps, cranes and conveyor belts. Only after 1750 pit ponies were introduced for the first time in coal mines to pull mine tubs.

Fig.1. & 2. A horse as engine, image from Georgius Agricola "De re metallica libri XII" (1556). Apart horses or mules, in alpine regions also dogs were used to help in the transport of the ore, here carrying empty bags up the mountain.

Fig.3. A pit pony in a subterranean railway tunnel.

Apart infrastructure, animals played also a role in the security and hygiene of a mine. To detect poisonous and highly explosive methane-gas, called also grisú, miners relied on canary birds. As birds however have a poorly developed sense of smell they were more useful to detect carbon monoxide, as this gas would suffocate first the birds, warning so the miners.

Fig.4. Miners using a canary.

To control rats and mice in the Yorkshire mines terrier dogs were used, the Yorkshire was breed for size and agility, to catch rats even in the narrowest of tunnels and galleries.
Cats were used as living detectors. Able to see in near darkness and thanks to their keen hearing, entrapped miners could be more quickly found and may rescued in time.
Modern mines nowadays use powerful machinery and sensors have replaced the cats, but it´s still hard work. Also still in many less developed countries, working in small mines, humans and animals risk their health and lives to extract the precious metals, essential to run our modern electronic gadgets.
Famous physician Philippus Theophrastus Aureolus Bombastus von Hohenheim (1493-1541), better known as Paracelsus, interested both in mines and diseases, once wrote:

...nothing good can be acquired without a price.“