Field of Science

Fantastic Rocks and Where to Find Them – High Pressure Metamorphites

Only a small part of rocks are stable on earth´s surface, as widespread erosion and alteration shows. Magmatic rocks, like granite, crumble and minerals composing these rocks, like feldspar and mica, react with water to become soft clay. Similar things happen to metamorphic rocks, eroding under atmospheric conditions. Often metamorphites, formed deep within earth, quickly start to decay already during uplift. Especially unstable are metamorphic rocks formed under very high pressure (25-30 kbar) and temperature (650-700°C), conditions as found in earth´s crust in a depth ranging from 56 to 186miles (90-300km). One locality where such Ultra-High-Pressure (UHP) rocks are partially preserved are the Western Alps between Italy and France, in particular the Dora-Maira Massif.
Fig.1. Geological map of the Western Alps DM=Dora-Maira-Massif, by Phil Mair 85, source Wikipedia.

Here whiteschists, named after the white-greyish color, are embedded as large lenses in a thick layer of gneiss. The whiteschists are geologically speaking not true schist, as this term refers to low grade metamorphic rocks, but pyrope-quartzites. This rock is composed mostly of quartz with large garnets (pyrope) embedded within, also some other typical metamorphic  minerals, like kyanite (an aluminum bearing silicate), talc (a magnesium bearing silicate), phengite (a mica variety) and rutile (a titanium dioxide), can be found. 

Especially interesting is the presence of the high-pressure modification of quartz, called coesite, and the pink mineral ellenbergerite. Ellenbergerite is a complex magnesium-aluminum-titanium-silicate known only from the Dora-Maira-Massif and described for the first time as typical UHP mineral 30 years ago. The minerals are preserved as grains in large garnet crystals, the crystals acted like a pressure chamber preserving these unstable minerals. Both ellenbergerite, coesite and garnets formed when parts of the oceanic crust of the Penninic Ocean were subducted into a depth of at least 186miles. During the later uplift forming the Alps minerals like ellenbergerite and coesite adjusted to changes in pressure and temperature by decaying into other minerals, coesite becomes for example common quartz. However mineral grains entrapped in the larger garnets remained, like in a closed pressure chamber, under high pressure conditions and were also protected from circulating fluids. 

Fig.2. Outcrop of pyrope-quartzite. Some of the garnets embedded in the white quartz-phengite matrix are more than 10 inches in diameter, unfortunately very requested by mineral collectors only the casts remain here (geologist is sadly looking at the hole...)..

Fig.3. UHP rocks are rare even in the Dora-Maira Massif, as most decayed during uplift, adjusting to lower pressure and temperature. Evidence for medium-grade metamorphism during uplift is the presence of blueschists, here with blue glaucophane-amphibole and alterated garnets.

At the time of the discovery an unique find in the Alps, similar UHP rocks are nowadays described also from China and the German Erzgebirge.

Would You Kindly Help To Expand A Rock Collection

If you eventually enjoy my blogging or like the historic titbits I share on social networks and would show some gratitude - I´m not asking for money but rather some samples to expand a rock collection used for teaching purpose. If by chance you got some smaller samples (6x8x4cm/8x8x4cm or smaller would be enough) with basic info (where, when, who, what) to share, drop me a mail at HistoryGeology"add" to discuss details, direct contact and refund.


David Bressan

Of Love and Lava: A Geomythological Tale of Kilauea

The first colonists arrived on Hawai´i probably in the years 800-1.000. Lacking a written history their nevertheless developed a rich oral tradition, inspired in part by past events. 
One of the most important stories involves the volcano goddess Pele and her youngest sister Hi‘iaka. Once, so the myth, they arrived on Hawai´i and after a long search Pele decided to settle on the summit of Kilauea, since then also named Kalua o Pele, the pit of Pele. She send her youngest sister  Hi‘iaka‘aikapoliopele (generally shortened to Hi‘iaka) to search for Lohi‘au, a man Pele loved. The sister promised to bring him back to her and Pele promised as reward to her sister to spare the beloved forest of Hi‘iaka from fire and lava. Hi‘iaka had to overcome many obstacles, but finally she managed to bring Lohi‘au back to  Kilauea. However Pele had grown tired in the meanwhile and in a moment of anger she burned the entire forest.  Hi‘iaka for revenge take Lohi‘au and Pele, seeing the two together, became so envious that she killed Lohi‘au during a furious eruption. Hi‘iaka desperately searched for many weeks the corpse of Lohi‘au between the lava and rocks send by Pele.

Fig.1. On the rim of Pele´s pit, painting by P. Hurd, 1824.

It maybe is possible to interpret this myth in a geomythological way, linking it with features really found in the landscape and the geological history behind the formation of such features. The caldera of Kilauea is dated to 1470-1500 and also the Aila‘au flow (named after another Hawaiian deity), a large lava flow covering the north side of Kilauea, formed around 1470. Morphology and a well developed network of lava tubes suggest it formed during a single, prolonged volcanic eruption of Kilauea. The historic date makes it seems reasonable to assume that the event was watched by the locals and possibly the event was recorded and passed from generation to generation in form of a myth. The destruction of Hi‘iaka´s forest by the furious Pele could describe the lava burning down the vegetation around the crater, suggesting also that before this eruption enough time passed from the previous eruption to grow a dense forest. Also the last part of the myth is interesting.  Hi‘iaka moves and throws rocks into air during her search, maybe the description of an explosive eruption or explosions resulting from the lava coming into contact with groundwater or the sea.


The interpretation of myths in geological light helps also to better evaluate the risk, as eruption style of former volcanic events and the impact on the society can be reconstructed in more detail than just from studying the volcanic deposits.

Interested in reading more? Try: 

SWANSON. D.A. (2008): Hawaiian oral tradition describes 400 years of volcanic activity at Kilauea. Journal of Volcanology and Geothermal Research 176: 427–431

From Rocks to Angels

Fig.1. Medieval engraving of a scala naturae showing the "ladder" concept. The words on the steps read: rocks, flame (as a chemical reaction), plants, beasts, humans, heaven, angels, god.
The scala naturae or great chain of being placed all natural objects in a supposedly divine order and can be traced back to the ancient Greek Aristotelian philosophy. A common scala naturae in the 18th century started with less complex objects, like the (supposed) elements air, water, earth, to proceed towards metals, salts, rocks, corals (as half plants, half rock), lichens, higher plants, animals and finally Homo sapiens (just outclassed on the highest steps of the scala naturae by angels). 
Until the 19th century also science reflected this chain, as it was divided in physics, chemistry and natural history, the latter including the study of animal, plants and rocks. Still in the various disciplines a certain order, from the inanimated to animated, is present. Around 1800 for the first time it was suggested that the science of “biology”, or the philosophy of life forms, should study the laws that rule and circumstances that enable life as we know it and, more important, be distinguished from geology as the study of earth and its lifeless matter. However the idea didn´t at first attract much interest and still in 1842 German botanist Matthias Jacob considered the proposed distinction between the animated an inanimated world an absurdity, as there could be found a gradual transition between every single object. However Jacob was among the last opponents, as indeed biology had started to become an own, distinct scientific discipline. 

However still some interdisciplinary ideas survived. Like in crystallography, many biologists believed at the time that there exists, like for crystals, a smallest possible unit of life, a physiological unit or like Darwin proposed in 1867, a “gemmules”. Ernst Haeckel even named this supposed smallest entity (even smaller as a cell, at the time the smallest observable organic structure) Kristalloid” in 1876. Like a crystal forms and can grow by putting together the basic unit cells, an organism was composed of smallest units, each possessing the “lifeforce” and so giving life to the entire being. 

Only at the beginning of the 20th century and discovery of cellular organelles and DNA the idea of such "living basic units" was abandoned.

The Early Exploration and Geology of the Chamois Mountains

Su le dentate scintillanti vette, 
salta il camoscio, 
tuona la valanga da' ghiacci immani
rotolando per le selve scroscianti; 

ma da i silenzi de l'effuso azzurro esce nel sole l'aquila,
e distende in tarde ruote digradanti il nero volo solenne.

Giosuè Carducci (1835-1907)

In medieval times the Alps, especially the alpine regions above the tree line, were simply referred as Gamsgebirg - the chamois mountains.

Fig.1. The Livre de chasse is a medieval book on hunting, written between 1387 and 1391 by Gaston III, Count of Foix and dedicated to Philip the Bold, Duke of Burgundy. One figure shows an alpine hunt with ibex and chamois hiding between the peaks.

Only, as a guide from 1917 describes, fools would venture there. However the Alps since ancient times were a traveled region. Shepherds, merchants, collectors of plants and minerals and hunters populated the valleys, high-altitude pastures and maybe sometimes also climbed a peak.
The first person to climb a mountain just "because it´s there" was supposedly Italian poet Francesco Petrarca (1304-1374), as he describes an ascent on Mount Ventoux in France. 

Italian author Valerius Faventies in 1561 publishes “De montium origine”, wherein he collects all the contemporary theories explaining the formation of mountains. An important role was given to celestial influences. But only later authors like cartographer Sebastian Münster (1489-1552), cartographer Johannes Stumpf (1500-1566),  naturalist Konrad Gessner (1516-1565)  and especially naturalist Johann Jakob Scheuchzer (1672-1733) describe mountains in great details, including plants, animals and the geology.

Fig.2. The chamois in Konrad Gessner´s „Allgemeines Thierbuch“ (1565).

Scheuchzer used examples of large-scale folds observed in the Swiss Alps as evidence for the veracity of the Biblical account of a flood in remote times. Only a large flood, a deluge, could twist, break and fold the sedimentary rocks.

Fig.3. "Views of Chamonix, as seen [during the expedition] in 1742", apart glaciers the drawing shows also typical animals, like the ibex, the chamois and the marmot. Figure from a report to the Royal Society in London by William Windham.

Also English theologian and naturalist Thomas Burnet in his book “The Sacred Theory of the Earth“, published in 1684, tries to explain the mountains and shapes of the continents by the biblical flood. The homogenous primordial crust of earth was shattered, releasing water from the underground. The water covers the entire planet and finally flows back in the fissures, leaving behind fragments of the crust that now forms the modern islands and continents. Mountains, so Burnet, were fragments of the primordial crust of earth stacked atop, ruins of the former perfect paradisic world.

Fig.4. The chamois hunter's hunting ground, by Johann Baptist Zwecker (1814–1876).

Still for a long time the Alps were seen as haunted, dangerous and most important unholy territory. One there was "in company of the devil,..." as Swiss naturalist Horace-Bénédict de Saussure (1740-1799) refers to the chamois when writing about the Alps. De Saussure was also the first naturalist to describe the geology of one of the highest peaks in the Alps (mostly composed of granite), the 4,808.73m high Mont Blanc, climbed by his expedition in July 1789.

Interested in reading more? Try: 

BEATTIE, A. (2006): The Alps: A Cultural History. Oxford University Press: 246
BRIDLE, B. (2011): Mountaineers. Royal Geographical Society,The Alpine Club: 359
MacFARLANE, R. (2003): Mountains of the Mind - Adevntures in Reaching the Summit. Random House Publishing, New York: 324

The true Geology behind The X-Files: Darkness Falls

Many of the threats encountered on the X-Files are not of this world, but even aliens seem normal when compared to some of our world´s insect species. 

In the episode "Darkness Falls" (season 1, episode 20) special agents Fox Mulder and Dana Scully are called in to investigate the mysterious disappearance of a team of loggers somewhere in the Cascade Range. Initially suspecting bigfoot (Mulder´s suspect) and eco-terrorists (Scully´s favourite), soon the agents find themselves isolated and trapped by a seemingly ancient menace lurking in the dark of the woods. Filming was done in the Seymour Demonstration Forest, north of Vancouver, a difficult to reach location even for the real film-crew.  

Soon it is discovered that an unknown species of insects was freed when the loggers illegally cut down old-grown trees. Mulder speculates that the insects, forming a sort of green-glowing swarm in the night, are a mutation caused by radioactive gases released from the underground, but extinct in the wild. However a swarm of the creatures, in close-up stock-footage of mites was used (mites are not insects, but related to spiders and can´t fly), survived hiding in the pores of a tree-ring, but now the swarm is free, very, very hungry and ready to build a nest. X-Files producer Chris Carter was inspired to write this episode based on his interest in dendrochronology – the study of tree-rings. 

Fig.1. The truth is in the tree-rings of this Douglas-fir - dendrology is used to reconstruct climate change in the past and was used in 1937 by R.H. Finch for the first time to date the activity of the Cinder Cones volcanic field in California.

But what about strange behavior of the supposed insects, are there similar real cases to be found? 

Ants are a common insect group, forming swarms with a complicated social structure and are successfully used as bioindicators - maybe even for gases coming from the underground.

 Fig.2. Alien ants...

Faults can be pathways for liquids and gases and some research tries to map faults by measuring the concentration of gases like radon. The permeability of a fault is also influenced by its activity, anomalous gas concentration could be signs of increased tectonic activity. During investigations in 2002 of the structural geology of the Rhenish Massif in Germany, it was noted that anthills of the species Formica rufa, F. polyctena and F. sanguinea display a peculiar linear trend. The locations coincided with active, gas-permeable fault zones. That ants could choose a site for their nest based on the bedrock is not impossible and was noted already 70 years ago, as the bedrock can influence if the soil is wet or dry and ants prefer dry conditions. However no correlation with faults or nests was known. In the 2002 research more than 1000 anthills were mapped, almost 700 of them running parallel to vertical fault lines. It´s not clear what effects the ants, as faults can imply a sudden change of bedrock, topography and gases. The case remains unsolved at the moment...

Fig.3. Ant may take some advantages by building their nests on gas-permeable faults, as the warm gases from the underground can act as sort of natural heating, figure from BERBERICH et al. 2013.

Interested in reading more? Try: 

BERBERICH, G. et al. (2013): Early Results of Three-Year Monitoring of Red Wood Ants’Behavioral Changes and Their Possible Correlation with Earthquake Events. Animals, 3: 63-84
BRENNHOLT, N. (2008): Geologische Störungszonen als Kriterium der Standortwahl Hügel bauender Waldameisen unter Berücksichtigung spezieller mikrobieller Gemeinschaften. Dissertation Universität Duisburg-Essen: 239
SCHREIBER, U.; BRENNHOLT, N. & SIMON, J. (2009): Gas permeable deep reaching fracure zones encourage site selection of ants. Ecological Indicators, 9: 508-517

The true Geology behind The X-Files: The Jersey Devil

Mulder: "But, but what if through some fluke of nature, a human was born, who reverted to it's most animal instincts, a kind of carnivorous neanderthal. Wouldn't he occupy a space above us on the food chain?"

In the X-Files episode "The Jersey Devil" (season 1, episode 5) special agents Fox Mulder and Dana Scully investigate a supposed serial killer with cannibalistic tendencies hiding in the woods of New Jersey. Strange drawings let Mulder speculate about a surviving population of prehistoric man-beasts..
The idea of the missing link, an intermediary creature between apes and man, was introduced by Victorian geologist Charles Lyell in 1837 but still it´s very popular in our imagination.

On a cold morning in 1969 local residents of Colville  (Washington, U.S.A.) found more than 1.000 tracks of an unknown creature in the snow. Strangely the tracks resembled a gigantic human foot, one track showed even a malformation, caused supposedly by a severe injury. Casts were made of the more unusual tracks and send to anthropologist Grover Sanders Krantz (1931-2002), who soon was convinced that no trickster could fake such tracks – the creature was surely bigfoot, a supposed giant ape living in the forests of North America.
Fig.1. Reconstruction of Neanderthal man as ape-man for a newspaper, art by Frantisek Kupka (1909).

First tales of strange creatures living in the woods were collected by schoolteacher and amateur mythologist John W. Burns in the 1920s, who however described a myth of a giant race of Indians, not apes.  
However the modern story of bigfoot started not in America but in Asia. In 1951 with the discovery by Alpinist  (with a strange sense of humour) Eric Shipton of large tracks in the Himalayas. Eminent zoologist Wladimir Tschernezky was sure that the tracks were made by a large, bipedal and unknown hominid, maybe a descendent of the extinct gigantic ape Gigantopithecus, living during the Pleistocene in Asia. Journalist John W. Green (1927-2016) published in 1968 “On the Track of Sasquatch”, a book where he, even if not claiming that bigfoot is in fact Gigantopithecus, made the argument that if in the past large apes existed it´s not impossible that such animals still exist.
Fig.2. The famous Patterson-Gimli film, showing a supposed encounter with a female bigfoot in California, from 1967 shows bigfoot suspiciously ape-man and Mulder´s supposed culprit in the X-file:

The direct connection between Giganto and anomalous primates was made first by zoologist Bernard Heuvelmans in 1952, based on reconstructions of Gigantophitecus by German palaeontologist Franz Weidenreich (1873-1948) and Ralph Von Koenigswald (1902-1982) as primitive man. Heuvelman writes “this theory, which is utterly hypothetical, provides the only entirely acceptable explanation of the mystery of the Abominable Snowman.” Krantz after reading Green´s book popularized this idea in TV. Krantz argued that migrating groups of Giganto evolved into local populations of anomalous primates, in Asia into the Yeti and in America into the Bigfoot. In 1955 a certain William Roe claimed to have encountered bigfoot, describing it appropriately now as a “giant ape” (Roe´s story was however never verified) - the idea of humans living hidden in the woods was replaced by apes and suddenly people started to talk about strange encounters with hairy ape-man beasts. 
Bigfoot got its name finally in 1958, with an article about alleged bigfoot tracks found at Bluff Creek (California), revealed later to be in fact only fakes.


However the entire Gigntopithecus-hypothesis is based on an outdated reconstructions of the species, as is the idea of a linear evolution of humans.
Franz Weidenreich reconstructed Gigantopithecus, known only from a fragmentary fossil record, as a sort missing link between apes and man - with the appearance of a hairy ape but bipedal locomotion as humans do. However modern reconstructions see it as related more closely to the orangutan than any other large apes or humans. Bigfoot is however rarely (make it never) described as large orangutan.

Mulder muses that his idea of surviving large hominids is highly unlikely, but not outside the realm of extreme possibilities. However as primatologist John Napier (1817-1987) explains, the existence of past species in an entire different ecosystem doesn´t give veracity to modern sightings and misidentifications with no unequivocal physical evidence to back them:

By postulating that a monster is a relic form -  a hangover from the past – monster fans feel absolved from the necessity of explaining how such an outrageous unsuitable creature has evolved in the light of present-day ecology.”

*As for the tracks of Colville. Amateur bigfoot hunter Renè Dahinden (1930-2001) considered the tracks more than suspicious, as no creature was spotted despite thousands of tracks and the first discovery was made by Ivan Marx, a known hoaxer of bigfoot encounters.

Interested in reading more? Try: 

DELISLE, R.G. (2012): Welcome to the Twilight Zone: a forgotten early phase of human evolutionary studies. Endaevour Vol.36 (2): 55- 64
KJAERGAARD, P.C. (2011): 'Hurrah for the missing link!': a history of apes, ancestors and a crucial piece of evidence. Notes Rec. R. Soc. 65: 83-98
LOZIER, J.D.; ANIELLO, P. & HICKERSON, M.J. (2009): Predicting the distribution of Sasquatch in western North America: anything goes with ecological niche modelling. Journal of Biogeography: 1- 5
MELDRUM, J. (2007): Sasquatch: Legend Meets Science. Forge-Publishing: 297
REGAL, B. (2008): Amateur versus professional: the search for Bigfoot. Endaevour Vol.32 (2): 1- 5
REGAL, B. (2009): Entering dubious realms: Grover Krantz, science, and Sasquatch. Ann. Sci. Vol.66(1): 83-102
REGAL, B. (2011): Searching for Sasquatch – Crackpots, Eggheads, and Cryptozoology. Palgrave Macmillian Publisher: 249