Kategorie: Geology

Geomythology: The Beast of Gévaudan

On the last day of June 1764, the 14-year-old Jeanne Boulet was killed near the village of Saint-Étienne-de-Lugdarès, at the time located in the county of Gévaudan, a highland region in the middle of southern France. Only some remains of the young shepherdess were ever recovered. Just a month later, a 15-year-old girl was attacked near Puylaurent. Deadly wounded, she managed with her last breath to describe the attacker as “a horrible beast.”

Animal attacks were common at the time. However, now authorities started to note an unsettling pattern. Already on September 8, 1762, a boy from the village of Laval was killed by an unknown creature. One month before Jeanne Boulet, another shepherdess was attacked near the city of Saint-Flour in the Auvergne. Her herd formed a defensive ring against the attacker, saving the girl in the end. Notable enough, the creature seemed to be less interested in the cattle than in the girl. And now, more and more children and women were killed by the unknown creature – the Beast of Gèvaudan.

“Figure of the ferocious Beast”, one of the first depictions of the Beast published in November 1764.

Overwhelmed by the developing disaster, authorities asked for military support. Jean-Baptiste Duhamel, the captain of the local infantry, organized a hunt involving, as he claims, 30.000 men. But even as the Beast was finally spotted and shot, it escaped unharmed by the bullets into the woods. A local newspaper wrote at the end of the first year:

» … a ferocious beast of unknown type, coming from who knows where, attacks the human species, killing individuals, drinking their blood, feasting on their flesh, and multiplying its carnage from day to day…hunters who are in pursuit have neither been able to stop it, because it is more agile than they, nor lure it into their traps, because it surpasses them in cunning, nor engage in combat when it presents itself to them, because its terrifying appearance weakens their courage, disturbs their vision, sets their hands shaking, and neutralizes their skill. «

The Gévaudan and Auvergne were rural areas, characterized by a rugged and mountainous landscape. Just some years before the killings, physician Jean-Etienne Guettard visited the region. During his visit of Vichy, a city in northern Auvergne, he noted some strange dark rocks, used by locals to make bricks and roofing shingles (“roche tuiliére” in French).

Stone wall made from sections of basalt columns. Town of Murat, Massif Cantal.

Guettard was also interested in geology, offering his skills to rich collectors, helping them classify their rock samples. He noted that the roche tuiliére were very similar to samples of lava coming from Mount Etna in Sicily and hosted in the collection of the Count Of Orléans. Guettard correctly concluded that large parts of the Auvergne and some parts of the Gévaudan were formed by lava flows of ancient, now extinct, volcanoes.

The Francois Pasumot and Nicolas Desmarest volcano-geomorphological map of part of Auvergne, 1774, showing lava flows and volcanic cones.

Various types of rock characterize the area where the Beast of Gévaudan preyed on its victims. The central highlands of Margeride are composed mainly of old metamorphic granitoids (rocks of magmatic origin) and gneiss. The mountain massifs of Cantal, Aubrac and Velay, surrounding the Gévaudan, are composed mainly of younger basaltic lava. Some sedimentary rocks are found in the south.

Simplified geological map of the Gévaudan with recorded attacks by the Beast.

The metamorphic rocks forming the highlands are impermeable to water, the landscape here is characterized by gentle rolling hills, covered by a mosaic of meadows, forests, and swamps. The surrounding volcanic rocks are very resistant to weathering, the landscape here is characterized by a more rugged terrain. Lakes formed by volcanic explosions, volcanic cones and many rocky outcrops of basalt and tephra prevail.

Swamp landscape with eroded volcanic cones in the moor of Narse.

It was extremely difficult to hunt on such a terrain. The hunter D´Enneval de Vaumesle noted after a first survey of the area that “this Beast will not be an easy catch.” Horses could not be used in the swamps, and the creature could easily escape in the forests, hide between the rocky outcrops, or find shelter in caves and crevasses.

Outcrop of volcanic rocks in the extinct volcano of Puy de l’Enfer.

The Cantal Massif, with some peaks over 1.500 meters high, also acts as a barrier for clouds. The weather in the Gévaudan was notoriously bad, with cold and long winters and wet summers. Again and again the Beast escaped into the mist or hunters gave up the pursuit because of heavy rain.

View from the Puy Mary in the Cantal Massif, a large and ancient volcanic edifice.

Despite all efforts, the Beast continued to kill. King Louis XV. was even forced to replace Duhamel, sending his own gun-bearer François Antoine from Paris to the Gévaudan. But also Antoine, despite his experience, had difficulties with the terrain. Only in September 1765, he shot and killed an extraordinarily large wolf near the town of Murat in the Cantal Massif. The king himself announced the death of the Beast.

The town of Murat today, with outcrop of magmatic rocks and a volcanic cone in the background.

But just two brief months later the attacks resumed.

The mysterious killings continued until July 1767, when the local hunter Jean Chastel shot another large wolf in the forest of Teynazére, on the highlands of the Margeride. Until its final demise, the Beast (or maybe a pack of wolves) had killed at least 116 children and women and wounded many more.

References:

  • SMITH, J.M. (2011): Monsters of the Gévaudan – the Making of a Beast. Harvard University Press:378
  • TAYLOR, K.L. (2007): Geological travellers in Auvergne, 1751 –1800. From: WYSE JACKSON , P. N. (ed.): Four Centuries of Geological Travel: The Search for Knowledge on Foot, Bicycle, Sledge and Camel. Geological Society, London, Special Publications, 287: 73–96

The Geology Of Star Wars

Geology is strong in the successful Star Wars franchise, be it in the movies or behind the scenes.

Spectacular landscapes, like salt-plains in the Andes, an active volcano in Sicily, the dolo- and limestone peaks of the Dolomites, and the sand dunes of Tunisia act as a background for the struggles of our heroes against the dark side.

The famous lightsaber battle on Mustafar in the 2005 film Star Wars Episode III: Revenge of the Sith, was done by combining computer graphics with real footage of Mount Etna. The crew was filming in 2002 in Italy when just by chance Mount Etna erupted with spectacular lava fountains and flows, so they decided to film there.

In the movie, the fictional planet Mustafar displays a landscape covered entirely in dark rocks, igneous in origin as the many active lava flows and eruptions suggest. Likely the early Earth – some 4,5 billion years ago – was pretty much a lava planet, with a thin crust of basalt covering a fiery ocean of molten magma. Only later, when plate tectonics and erosion by water started, other rocks formed. Planets like Mars and Venus are still today covered mostly by basalt, even if it is not clear if there are active volcanoes to be found.

One of the most recent episodes of Star Wars, The Last Jedi (2017), features some spectacular landscapes, like the Salar de Uyuni, a dry salt-plain located in the Andes. In the movie, Crait is a small planet covered entirely with salty minerals. During a battle scene, it is shown that beneath the white crust of salt lays a red mineral. Halite, the mineralogical name for salt (NaCl), can become dark red/brown when exposed to radioactive radiation. Sylvite, a potassium chloride (KCl), has a reddish color that can become purple if exposed to radiation, but it is a rare mineral on Earth. Later our heroes escape through a cave filled with gigantic red crystals, likely crystallized over millions of years.

In the 2018 spin-off movie Solo: A Star Wars Story, scenes of a train heist on the planet Vandor-1 were filmed in the Dolomites, near the peaks of the Tofane, the Langkofel, Sella Pass and the Drei Zinnen. The base of those mountains are composed of the Cassian-Dolomit, the dolostone cores of former Triassic reefs. The relative plain summits – as seen in some scenes – are formed by erodible marl deposits of the Heiligkreuz- and Travenanzes-Formation, and the plane-bedded Hauptdolomit-Formation.

The fictional desert city of Mos Espa, the hometown of Anakin Skywalker, was built in 1997 for the movie Star Wars Episode I: The Phantom Menace and then abandoned in the Tunisian desert. Over the years it has become a tourist attraction. The dry climate preserves the buildings very well and the only menace for the site comes from the slowly moving barchan dunes, up to 6 meter high windblown accumulations of sand and gypsum grains. The set of Mos Espa, consisting of twenty buildings made of wood and plaster, was built on a flat, clay-rich pan and the city later expanded digitally in size, with dunes only barely visible in the background of some scenes.

However the prevailing wind, blowing from east to west, constantly moves the sand. The dunes are migrating with the wind eastwards, just in the direction of the remains of the abandoned site. Using the buildings as a fixed reference point in a quite featureless landscape, and comparing a series of satellite images from 2002 to 2009 and pictures taken by Star Wars fans over the years, researchers were able to calculate the migration rate of three larger dunes. With 4,8 to 15 meter per year, the dunes move with an average speed. The study notes that the dune located nearest to the film set slowed down in recent years, possibly influenced by changes in the wind pattern caused by the encountered obstacles. Even so, Mos Espa will be buried completely in estimated 80 years by the sand. The slow destruction of his home may also explain why Darth „Anakin“ Vader doesn’t really like sand (as revealed in the 2002 film Star Wars Episode II: Attack of the Clones).

Geology, sort of, was also involved behind the scenes of Star Wars. Forty years ago the Death Star was blown up by the rebels in the 1977 sequel Star Wars: A New Hope. The computer animation for the simulated attack on the Moon-sized battle station was done using computers of the University of Illinois. At the time only a few computers were powerful enough to calculate the vector graphics as shown in the scene. Geologist Christopher Scotese had to share his spare computer time, used for simulations of how plate tectonics shapes Earth, with the special effects artists at work.

Nicolas Steno and the Nature Of Fossils

In October 1666, a large shark was captured by a fishing boat in the sea of Livorno (at the time part of the reign of Tuscany). The animal was pulled onto the shore, beaten to death and dismembered. As the body was too heavy to be transported, only the head was saved. It was brought to Florence, where famous Danish anatomist and naturalist Niels Stensen (latinized Nicolas Steno) was asked to dissect the specimen.

Steno later published a detailed anatomical description of the shark, which included a chapter where he compared the shark’s teeth with fossils commonly found in the hills of Tuscany. The fossils of unknown origin were simply referred to as Glossopetrae or tongue stones.

Steno was not the first to speculate about an organic origin of fossils. In his 1565 book De Rerum fossilium, Lapidum et Gemmarum maxime, figuris et similitudinis Liber (On Fossil Objects), Swiss naturalist Conrad Gesner compared fossil sea urchins with living specimens, and argued that some fossils are petrified organisms. In 1616, the Italian naturalist Fabio Colonna argued that glossopetrae were shark teeth.

However, there was a big problem – they couldn’t explain how the supposed remains of sea animals could be embedded in rocks now parts of inland mountains. So most naturalists preferred to explain fossils just as curiously shaped inorganic features growing inside rocks.

Steno was the first to explain why fossilized teeth of a creature from the sea could be found inside rocks that were far distant from the modern sea.  Before dissecting the shark in Florence, Steno had visited the Royal Danish Kunstkammer in Copenhagen and the fossils on display there. He wrote in a private note:

Snails, shells, oysters, fish, etc., found petrified on places far remote from the sea. Either they have remained there after an ancient flood or because the bed of the seas has slowly been changed. On the change of the surface of the earth I plan a book, etc.

During his travels in Tuscany, Steno had studied outcrops of layered rocks, and he had recognized that the sedimentary layers were petrified shores and marine sediment of an ancient, now vanished sea.

He also noted that fossils are found only in layered rocks and never in recent soils. If fossils were of inorganic nature, like many naturalists argued at the time, we should find them in every kind of soil and rock. By combining his observations in the field and the results of the shark’s dissection, Steno formulated a surprisingly modern geo-theory:

  • The layers were formed by deposition in water. The now hard rock was once a soft mud.
  • An animal living in the sea would, after its death, sink slowly into the soft mud. Mud and water would petrify the animal and preserve it.
  • Collapsing cavities in earth´s crust would tilt layers along the borders of the forming crater upwards. Exposed to air the mud – with the fossils still inside – dries and becomes hard rock.
  • Eventually the crater fills with water and a new layer is deposited above the old ones.

In the end, Steno argued, all the layers were uplifted again, this time high enough to form a mountain, where a curious naturalist can find the fossils eroding from the rocks. Unfortunately Steno’s work, like the work of many others before him, was soon forgotten and ignored.

In 1695, amateur physician and naturalist John Woodward published An Essay toward a Natural History of the Earth. This book, intended to prove the veracity of the Biblical account of a large ancient flood, was not well written and mostly based on work copied from other naturalists. Woodward argued that fossils are the remains of animals killed by a flood, and cited Steno to support this idea. However, reading Steno’s original considerations makes it clear that a single flood was not sufficient to explain the thick layers of sedimentary rocks found everywhere.  Woodward’s book was therefore mostly dismissed by contemporary scientists, but it made Steno’s ideas popular again. Scientists then began to actively study and discuss sedimentary rocks and fossils – and the rest is history.

Used References:

KARDEL, T. & MAQUET, P. (eds.) (2013): Nicolaus Steno – Biography and Original Papers of a 17th Century Scientist. Springer Publishing: 739

The Geology Of Jules Verne’s Journey To The Center of the Earth

Figure from the novel „Journey to the Center of the Earth“ published by Jules Verne in 1864.

„Well gentlemen, at one point at least I agree … the materials of the geologists are not charts, chalk and chatter, but the earth itself. We should never know the truth until we are able to make that journey and see for ourselves.“ 

from „Where Time Began,“ a 1976 film based on Jules Verne’s novel Journey to the Center of the Earth.

Novelist Jules Verne was born on February 8, 1828, in the French city of Nantes. Today he is known as a pioneer of the science-fiction genre, imagining a submarine traveling twenty thousand leagues under the sea, a space projectile heading to the moon and a fantastic journey into the depths of our world. One hundred and fifty years after Verne’s visions, humans have walked on the moon, nuclear submarines can travel under the sea and we have started to explore the mysteries of the deep earth.

Journey to the Center of the Earth was published in 1864 and was immediately a critical success, and has remained in publication in both French and English to this day. In the opening chapters of the novel, the German Professor Otto Lidenbrock and his nephew Axel discover an ancient document, written by Snorri Sturluson. This (fictional) 16th-century alchemist described a journey into a large system of volcanic conduits, accessible from the crater of the Icelandic volcano Snæfellsjökull. So Lindenbrock and his nephew traveled to Iceland, employed a local guide, and following the document’s coded directions, entered the volcanic crater.

There, they descended through the sedimentary layers of the crust into its foundation. About 140 kilometers beneath the surface they discovered an underground sea occupying a cavern, roughly the size of Europe, hollowed in the granite of the lower crust. The travelers ventured upon the „Lidenbrock Sea“, as they name the newly discovered ocean, in a raft built out of the logs of “great palm-trees of species no longer existing” growing along the shores.

At sea, they witnessed a battle between Jurassic sea monsters and disembarked on an island with a geyser. Venturing inland they discovered living mastodons and primitive hominids. Verne’s bestseller was a product of rich imagination and research. He likely based his fictional travel account on the works of geologists like Alcide d’Orbigny, who classified rock strata by their fossil content, Elie de Beaumont, who worked on the origin of mountain ranges, and Charles Sainte-Claire Deville, who studied volcanoes.

Geological section, published by German geophysicist August Sieberg in 1914, showing the anatomy of a stratovolcano, with a main conduit, various lateral dikes and a large sill connected to the magma reservoir. In contrast to the sketch, the conduits for magma are in reality only a few meters wide.

An important source of inspiration to Verne were the books by the French scientist and writer Louis Figuier. In 1864 Figuier published La Terre avant le déluge, a popular science book discussing geology and paleontology. From Verne’s surviving correspondence with his publisher, we know that he started to work on his novel sometimes between January to August 1864. Some passages and scenes in Verne’s novel, like the battle between an ichthyosaur and a plesiosaur witnessed by the travelers, was likely inspired by an illustration in Figuier’s book. Verne’s imaginary forest growing along the „Lidenbrock Sea“ was similar to the fossil forests of the Carboniferous period. The heat necessary to keep the forest alive comes from „the excessive heat of the globe. The Earth was still so hot in itself that its innate temperature dominated“ as Figuier writes in his textbook. Before the discovery of radioactive decay, geologists believed that earth’s inner heat was the residual heat of its formation from a molten ball. Over time earth cooled down and a solid crust formed.

Verne’s explorers used the hollow volcanic conduit of Snæfellsjökull as a gateway to earth’s interior. Many geologists at the time believed that volcanic conduits, empty once the volcano erupted, connected a volcanic crater to magma chambers deep underground. Today we know that such conduits are far too small (and obstructed by solid rock) for humans to move through.

However, Verne was right when he described a chamber full of gigantic crystals found deep underground. For crystals to grow, they need the right conditions and a lot of time. In theory, there are no limits to how large a crystal can become, however, perfect conditions for crystal growth are rarely met. That said, such perfect conditions are found in the Cueva de los Cristales, located in the Naica Mine, Chihuahua, Mexico.

The mine of Naica was opened in 1828 to mine for lead, zinc and silver ore. In 1910 a natural cave was discovered, named later Cueva de las Espadas. The name derives from the three-foot long blade-like gypsum (calcium-sulfate) crystals covering the walls of the cave. However, what the miners discovered almost 90 years later, during the construction of a tunnel 0.2 mile below ground, is even more astounding. The Cueva de los Cristales hosts the most incredible crystals ever discovered, mirroring Verne’s fantastic description. Almost perfect conditions made it possible to grow gypsum crystals more than 10-meters in length and with an estimated weight of 40 to 50 tons.

The enormous gypsum crystals of Naica. Note person at bottom right for scale. Credit: Wikipedia/Alexander Van Driessche. CC BY 3.0. Van Driessche

Maybe Verne was right in even a more spectacular way. The largest crystal possible on earth could be indeed found at its center. Earth’s core is a solid ball of superhot iron and nickel alloy about 760 miles in diameter. Modern research suggests that it displays a crystalline structure. Unfortunately, at the moment, there is no way to be sure and visit this place as Verne imagined.

Carl Linnaeus’s Systema Naturae And An Early Attempt of Mineral Classification

18th Century Swedish physician, botanist, and zoologist Carl von Linné – latinized Carl Linnaeus – is today famous for his binomial nomenclature, a hierarchical classification scheme for every living organism.

But he was also interested in mineralogy and tried to include minerals in his system. Curiously enough, fossils, now recognized as the petrified remains of ancient organisms, were of no interest to Linné.

During his early travels in Sweden and Norway, Linné became interested in mining activities. During his time, mineral identification and classification were quite a messy thing. Only the most common minerals, like feldspar and quartz, and minerals of some economic value, like ore minerals or gemstones, even had specific names.

Basic mineral identification often relied on easy to observe properties, like color, adding to the general confusion. For example, distinct minerals like ruby and garnet were classified based on the same red color as one mineral, but color variations of the same mineral – like quartz – were all seen as different minerals.

Linné classified plants (and later animals) based on their sexual reproduction organs. The system worked, so he also adopted the idea of sexual reproduction for the classification of minerals.

Of course, minerals don’t mate or have genitals, but Linné imagined that minerals formed by the mixing of various salty fluids, acting as male parts, with different kinds of rocks, acting as female parts. His more practical approach included minerals classified by the shape of the crystal, number of crystal faces, and the observed behavior if exposed to great heat.

The 1770 edition of Linné’s Systema Naturae.

In contrast to his biological classification system, Linné’s mineralogical system never really became popular.

Today, minerals are defined by a specific mineralogical composition and their regular crystalline structure. Linné lacked the technology to accurately identify the chemical composition of a given mineral, and also lacked the knowledge of the physical laws that control the symmetry of crystals.

It wasn’t until the beginning of the 19th century that the first modern mineral classification books were published, such as naturalist Abraham Gottlob Werner’s Short classification and description of the various rock types and The genetic-geological classification and an attempt to introduce a mineral-system based on superficial properties by mineralogist Carl Friedrich Christian Mohs.

Geological Star Trek Review – “Arena”

Captain Kirk fights a Gorn in the 1967 TOS episode „Arena“ – you can see Vasquez Rocks in the background.

Sulfur, niter (saltpeter) and carbon, as coal and as crystalline diamond, save Captain Kirk’s life in the 1967 TOS episode „Arena.“

When a remote outpost of the Federation is attacked by an unknown enemy, the Enterprise pursues the fleeing vessel, inadvertently entering a sector of space controlled by the Metrons, a race with powerful psychic powers. Kirk, transported by the Metrons to a desolate planetoid, is forced into a battle against the captain of the Gorn ship – a reptile-like creature protected by an almost indestructible armored skin.

The planetoid displays a rich geologic diversity. Kirk mentions finding ruby corundum. He uses niter (saltpeter), sulfur, and coal he finds to make gunpowder for use in a primitive cannon, and diamonds as projectiles (here – judging from the crystal shape – likely quartz was used as film prop). After injuring the Gorn, Kirk spares his life to the surprise of the Metrons.

There are almost 5.000 known mineral species, yet the vast majority of rocks are formed from combinations of a few common minerals, like feldspars, quartz, amphiboles, micas, olivine, garnet, calcite, and pyroxenes. We still know little about other worlds. Over 300 minerals have been identified in meteorites, 130 minerals were discovered so far on Mars and 80 on Earth’s Moon.

By convention, the names of terrestrial minerals (a crystalline combination of one or various elements) end with the suffix -ite, the denominations of elements with the suffix – ium, -um, -on, -gen, or -ine. This nomenclature is not always applied in Star Trek.

References:

  • De FOURESTIER, J. (2005): The Mineralogy of Star Trek. Axis, Vol.1(3): 1-24

Giovanni Arduino And The Geology Of The Dolomites

» [I worked] still young in the mines of Klausen and elsewhere in Tyrol, in order to learn Metallurgy; I went there by chance, and I was urged to stay by my natural very strong inclination for the universal Mineralogy, and for all the matters concerning the Science of the Fossil Kingdom. «

Venetian scientist Giovanni Arduino worked at an early age as a mining assistant in the iron mines of Klausen in South Tyrol.

Italian mining engineer Giovanni Arduino (1714-1795) is considered nowadays the spiritual father of the modern chronostratigraphic chart. Based on his observations in the Venetian Dolomites and Tuscany in 1759 Arduino proposed „a series of layers forming the visible crust of earth … “ subdivided „in four generalized units following each other.“ He named them primary, secondary, tertiary, and quaternary, speculating that they formed at various times and under different environments.

Arduino used a section of rocks exposed in the Val dell´Agno (Venetian Dolomites) to explain his classification. The numbers refer to the thickness of the strata, the letters to the description in the accompanying text. The extremely tattered state of the original drawing suggests that Arduino showed it repeatedly to the many naturalists who visited him.
  • Primary Layer: Pebbles formed by the erosion of underlying “primitive or primeval” – considered to be the earliest – rocks. Fossils were rare, if not absent. This unit includes unstratified or poorly stratified rocks, like porphyry, granite and schist, of the crystalline basement of the Dolomites. Arduino’s rock unit survives into modern chronostratigraphic charts as the Paleozoic Era (rocks older than 252 million years) and Precambrian Eon (541 million years to about 4.6 billion years ago).
Mica shist as crystalline basement rock of the Dolomites, Arduino’s Primary Rocks.
  • Secondary Layer: A well-stratified succession of marl- and calcareous rocks with marine fossils, making up the characteristic peaks of the Dolomites. In 1841, English geologist John Phillips, based on the correlation of fossils in rock strata worldwide, renamed this sedimentary succession the Mesozoic Era (252 to 66 million years ago).
Sas de Pütia showing Arduino’s Secondary Rocks, the well-stratified red Gröden-Sandstone, grey Bellerophon limestone and fossil-rich reef limestone.
  • Tertiary Layer: Poorly consolidated sediments like gravel, clay, fossiliferous sand, and also younger volcanic rocks. Our modern Cenozoic Era (66 to 2 million years ago).
A conglomerate of the Tagliamento catchment, dating into the Pleistocene to Miocene according to our modern stratigraphic system (2-23 million years). Similar deposits were Arduino’s Tertiary Rocks.
  • Quaternary Layers: Unconsolidated sediments found in valleys. Our modern Quaternary Period (2 million years ago to modern age).

Geological Movie Review – „Alien“

When the movie “Alien” was released in 1979, it quickly terrified audiences worldwide. Its unexpected mix of classic horror and science-fiction elements got at first mixed reviews, however, over the years Alien had come to be regarded as one of the best horror-science-fiction films ever made.“Alien“ screenwriters Dan O’Bannon and Ronald Shusett based parts of their script on various older science-fiction movies and tales, like „At the Mountains of Madness“, a science-fiction/horror story published by American author H.P. Lovecraft in 1936. In the story, a team of scientists is hunted and killed by ancient creatures resembling fossil animals. Lovecraft apparently based this part of his story on the real discovery of fossil archaeocyathids in Antarctica made in 1920 by geologist William Thomas Gordon. Archaeocyathids are an extinct group of sponge-like creatures believed to be among the oldest animals ever to live on Earth.

Hans Rudolf Giger, Swiss surrealist artist, architect and industrial designer, was hired to create all forms of the Alien featuring in the film, from the egg to the adult. Giger created various versions of the alien life-cycle, like a gigantic egg nest, replaced in the final movie with an egg silo inside a derelict spaceship. The eggs were directly inspired by female reproductive organs, slightly modified to avoid censorship. The facehugger, a parasite attaching to the head of its victim to incubate an embryo, is based on the bones and muscles of a human hand and male genitalia, its springlike tail was added to emphasize its quick movements. The parasitic life-form was an idea of Ronald Shusett. Shusett suggested that one of the crew members be implanted with an alien parasite to explain how the alien life-form, discovered at first as an egg in a derelict alien spaceship, came on board of the mining spacecraft Nostromo. The parasite bursts from the chest of its victim and soon the crew has to deal with the fast-growing life-form hiding in the air vents of the spaceship. The design of the chestburster and the full-grown xenomorph (alien-shaped thing) is based on Giger’s „Necronom IV„, an artwork created in 1976. The surrealist drawing shows a female figure composed of different parts of insects, parts of vertebrates and even fossils. Giger used the fossils of 300 million-year-old crinoids, commonly called sea lilies, on display in the Aathal dinosaur museum as a source of inspiration.

A petrified crinoid. Similar fossils inspired the creature featured in the successful „Alien“ saga.

The earliest known crinoids date back to the Ordovician (some 450 million years ago). Their remains are very common in the fossil record, forming rocks like limestone or dolostone. The skin of echinoderms, including sea cucumbers, sea urchins, crinoids, brittle stars and starfish, is covered with tiny ossicles made of calcium carbonate forming a protective, yet flexible, outer shell. In a similar way, Giger’s Alien is protected by a silicon-based external skeleton. This outer shell is also very useful to contain the acid blood of the creature. Concept artist Ron Cobb added the acid blood as a defense mechanism, making it impossible to kill the Alien without damage to the crew or the spaceship.

In the sequel „Aliens“ a team of space marines enters an Alien hive, the walls resembling Goethite, Grube Eisekaute, Bad Marienberg, Germany.

The life-cycle of the Alien from egg to queen (as introduced in the sequel) resembles the life-cycle of real animals, the Ichneumonidae. The Ichneumonidae is a wasp family preying on insects. An adult female wasp will lay her eggs within a host through a process known as ovipositing. The eggs will grow and develop into larvae, which will feed on their host from the inside-out. Somewhere along the way the host will actually die or be kept in a state very near death until, finally, the little wasp spins a cocoon around and-or within its host, eventually emerging as an adult wasp. A horrified Charles Darwin famously mentions in a letter sent in 1860 to his friend, the botanist Asa Gray, the parasitoid wasp:

» I cannot persuade myself that a beneficent and omnipotent God would have designedly created the Ichneumonidae with the express intention of their feeding within the living bodies of caterpillars… «

In their natural environment, these wasps play important roles in regulating the populations of their insect hosts, and have been used in agricultural crops to control caterpillar pests. Dolichogenidae xenomorph is a parasitoid wasp species named in 2018 after the xenomorph, as „the wasp is also black and shiny like the Alien.“

The graphic representation of the „perfect organism“ earned the visual effects team of „Alien“ a well-deserved Academy Award.

Geological Observations Revolutionized Renaissance Art

» It is their art to stop at every stone and carry out an investigation at every layer of earth! «

Swiss author Rodolphe Toepffer describing geologists

During the Renaissance, the study of common rocks inspired great artists and revolutionized artistic techniques. Italian artist Leonardo da Vinci was one of the first naturalists to both understand the origin of sedimentary rocks and recognize fossils as petrified remains of former living animals. He used his geological insights to improve his paintings and in doing so inspired an entire generation of artists.

The Alps, ca. 1513, red chalk drawing by Leonardo da Vinci. He was fascinated by mountains and called them the “bones of the earth.”

This approach can be seen in da Vinci´s earliest recognized works, dating to 1473. In „The Hills of Tuscany“ or „Landscape with River“, we are apparently standing on the borders of the Apennines, looking down onto a waterfall and the larger valley of the Arno.

The layers of the earth, visible above the waterfall, are depicted in a geologically correct way – thin at the bottom and thick on the top, like the Turbidite sequences found in the Apennines. Together with the lines used to draw the cultivated fields in the Arno valley, the sedimentary layers help to create an three-dimensional effect giving to this landscape a realistic „depth.“ This effect is also helped by the waterfall, which is shown flowing away from the observer in a hydrologically correct manner down the slopes of the mountains into the Arno valley.

Leonardo da Vinci’s sketch of an outcrop.
Outcrop with sedimentary layers as spotted in the Apennines.

Leonardo’s technique was soon adopted by other artists. German painter Albrecht Dürer visited Italy twice to study the perspectival paintings of contemporary Italian architects and artists. Traveling back home, he tried to apply this revolutionary method to his own paintings. One of his drawings shows a quarry, maybe somewhere near his hometown of Nürnberg, displaying horizontal layers of sandstone and thinner layers of marl in a manner similar to da Vinci’s. Using the tectonic fractures as vertical construction lines, Dürer tried here to subdivide the picture like da Vinci and create the illusion of depth along the steep cliff.

„The Quarry“ by Albrecht Dürer, probably painted in 1495.

Despite never really completely mastering the geometrical rules necessary to create a perfect perspective in a painting, Dürer nevertheless popularized this new technique in Europe. Soon, many other artists followed and began painting realistic landscapes, even studying rocks in order to correctly depict them in their art.

References:

  • ROSENBERG, G.D. (2009): The measure of man and landscape in the Renaissance and Scientific Revolution. In Rosenberg, G.D., ed., The Revolution in Geology from the Renaissance to the Enlightenment: Geological Society of America Memoir 203: 13-40

Pyroclastic Flows of the Athesian Volcanic Group

May 8, 1902, began as a sunny day in Martinique, an island in the Caribbean, with only a column of steam rising above Mount Pelée. When the volcano suddenly exploded.

The first rescuers arrived on the site twelve days after the eruption, accompanied by British, French and American geologists. In the city of St. Pierre, almost all of the buildings had been destroyed and an estimated 20.000-40.000 people killed.

» I looked back and the whole side of the mountain, facing towards the town, seemed to open and topple down on the screaming people. I was burned by stones and ashes …, but I got to the cave «

Havivra Da Ifrile, a girl who survived the destruction of St. Pierre hiding inside a cave near the shore.
Photographs of the city of St. Pierre before and after the eruption of Mount Pelée, the volcano is seen in the background (from LACROIX 1904, NHM Paris).

Geologist Edmund Hovey of the American Museum of Natural History, among the first to arrive to the destroyed city, noted that “In many places the limit [of the devastation] passes single trees, one side is dark and burned, the other green as if an eruption never happened.” A lava flow or landslide could not explain the burned trees nor could it explain the sharp boundary between the destroyed and untouched areas.

Two months later, geologists Tempest Anderson and John S. Flett of the Royal Society of London survived a smaller eruption of Mount Pelée.

» The cloud had a spherical form and resembled rounded protuberances amplifying and doubling with terrifying energy. They extended to the sea, in our direction, boiling and changing shape at every moment. It didn’t spread laterally. It didn’t rise up in the atmosphere, but it descended on the sea as a turbulent mass… «

Sequence showing a pyroclastic flow photographed December 1902 by French volcanologist Alfred Lacroix (from LACROIX 1904).
Alfred Lacroix.

For the very first time geologists observed a deadly nueé ardente – an incandescent cloud or glowing avalanche as the phenomenon was first named by French volcanologist Alfred Lacroix in 1904. A nueé ardente, in modern literature referred to as a pyroclastic density current, is a mixture of volcanic material and hot gases. Because its density is greater than air, it sinks downward, flowing like an avalanche along the slopes of a volcano. Pyroclastic flows can originate from the collapse of the eruption column, from a lateral blast or from the partial collapse of a volcano.

Researchers were able to estimate temperatures inside the pyroclastic flow that destroyed St. Pierre based on the observation that bottles melted (glass melts at ~700°C), but copper tubes were not deformed (copper melts at 1.100°C). The geologists, therefore, concluded that temperatures of a pyroclastic flows can range between 700 to 1.000°C. The high temperatures inside a pyroclastic flow also explain why so many people perished in St. Pierre. The heat was so intense that it instantly burnt the outer layers of skin and flesh. As the flesh shrinks due to the loss of water, the inner organs were squeezed out from their cavities. Even those not hit directly by the pyroclastic flow weren’t spared. Inhaling the still 300°C hot gases, their lungs quickly filled with liquid, drowning them.

The photo shows a 200 million-year-old ignimbrite – a name used for lithified deposits of a pyroclastic flow and derived from the Latin word for fire – of the Athesian Volcanic Group. Some of the larger clasts in the photo show an outer rim, indicating that the temperature inside the pyroclastic flow was high enough to alter the mineralogical composition of the rock. The larger rocks are embedded into a matrix of volcanic ash. Pyroclastic flows – a mixture of rocks, overheated gases and vapour – are able to transport even large boulders at a speed of 160km/h. As a result, the impacting mass destroys everything in its path, as happened to the town of St. Pierre.

An exceptional fossil discovered in 1931 in Athesian Volcanic Group deposits – “Tridentinosaurus antiquus by GB Piaz” – The skeletal remains are surrounded by a carbonaceous patina of soft parts, making it the oldest body fossil found in the Southern Alps. It is suggested by some authors, based on the preservation of the fossil, that the animal was killed during a volcanic eruption by a pyroclastic surge.

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