De La Beche's Awful Changes

Caricatures are exaggerated sketches of a person or human behavior. However, such cartoons appear only at a superficial glance as simple drawings, as they contain deep and complex insight in our culture and society. This consideration is also true for scientific caricatures, dealing with subjects or persons involved in science and research.

For a long time, the caricature by British geologist Henry De la Beche (1796-1855) "Awful Changes. Man Found only in a Fossil State - Reappearance of Ichthyosauri" was considered a caricature of fellow geologist and paleontologist William Buckland (1784-1856). The sketch was widely publicized in Francis Buckland's (1826 - 1880, son of William) book-series "Curiosities of Natural History" (1857-72), including a biography of his father.

"A lecture, - 'You will at once perceive,' continued Professor Ichthyosaurus, 'that the skull before us belonged to some of the lower order of animals; the teeth are very insignificant, the power of the jaws trifling, and altogether it seems wonderful how the creature could have procured food."

However, geologist and earth-science historian Martin J.S. Rudwick realized the connection of this scene with some drawings produced before 1831 by De la Beche in his diary, where he ridiculed the approach adopted by Charles Lyell. In the unpublished drawings, a lawyer (the reference to Lyell, who actually was a lawyer, seems obvious) is carrying a bag with "his" theory around the world, or he is shown wearing particular glasses (like Professor Ichthyosaurus), and offering his "view" and the resulting "theoretical approach" to a geologist carrying a hammer and collecting bag, a reference to the geologist actually working in the field. De la Beche never completed the sketch, because he abandoned this design in order to try out others, including the now famous "Awful Changes."

De la Beche believed that Lyell injected too much of his lawyer profession into the emerging field of geology, focusing too much on theories than real research. "Awful Changes" does lampoon one crucial part of Lyell's uniformitarianism - theory, the concept of time repeating itself, as prehistoric animals are behaving much like Victorian scholars. In a second cartoon De la Beche is mocking another idea of Lyell, the effects of present causes operating at the same slow magnitude throughout geologic history. The cartoon shows a vast U-shaped valley, in the foreground a nurse with a child, presumably the son of William Buckland, can be spotted. The child is peeing into the huge valley and in the caption De la Beche has his nurse exclaiming, "Bless the baby! What a valley he have made!!!"

The caricature was inspired by the ongoing debate of river-erosion at the time. The glacial theory wasn't still accepted to explain the formation of large valleys and the shape of many valleys in Europe was hard to explain only based on, as proposed by Lyell's uniformitarianism, slow fluvial erosion.

Carl Friedrich Christian Mohs's Mineralogical Legacy

Carl Friedrich Christian Mohs, lithography by Joseph Kriehuber (1832).

Talc – Gypsum – Calcite – Fluorite – Apatite – Feldspar – Quartz – Topaz – Corundum – Diamond - the Mohs Scale of Mineral Hardness is familiar to rock-hounds and earth-science students alike. The ten-point hardness scales lists common minerals in the order of the relative hardness, with talc being the softest and diamond the hardest mineral found in nature.

The Mohs scale is named after German mineralogist Carl Friedrich Christian Mohs, born January 29, 1773, in the town of Genrode, at the time part of the principality of Anhalt-Bernburgs. After attending school, he worked in his father's business as a merchant, but in 1796 he went to the University of Halle to study there mathematics, physics and chemistry. He continued his studies at the famous Royal Saxon Mining Academy of Freiberg, where he studied under the renowned geognost Abraham Gottlob Werner. Werner published in 1787 a »Kurze Klassifikation und Beschreibung der verschiedenen Gesteinsarten« - Short classification and description of the various rock types - as a guide for identifying and classifying rocks and minerals. Unlike other mineralogists at the time, mostly using chemical analysis, Werner uses easily recognizable features, like color or crystal shape, to classify minerals and rocks. Mohs is impressed by Werner's approach. In 1804, he publishes himself a “student-friendly” classification chart for minerals, based on his experience in the mining district of the Harz mountain and as a consultant for wealthy mineral-collectors. In his book »Über die oryktognostische Classification nebst Versuchen eines auf blossen äußeren Kennzeichen gegründeten Mineraliensystems« - The genetic-geological classification and an attempt to introduce a mineral-system based on outer properties - Mohs combines various physical properties of minerals, like color, hardness and density, with six classes of crystal shapes, to identify 183 different minerals.

Mohs scale of hardness sets from the 19th century, Mohs's geological hammer, and a letter to his wife.

Mohs continues to travel, collect material and improve his mineral classification system. He visits Štiavnica in Slovakia, famous for the local Mining Academy, and the mining district of Bleiberg in Carinthia. He visits and studies mines in Hungary, Transylvania and Scotland, and quarries in Germany and Austria.

In 1812, now a professor in the Austrian city of Graz, he creates a preliminary hardness scale and continues to publish guidelines for mineral identification. In 1818 he returns to Freiberg and between 1822-1824 Mohs publishes his final version of the hardness scale in the book »Grund-Riß der Mineralogie« - Essentials of Mineralogy.

The Mohs scale of mineral hardness is based on the ability of one natural sample to scratch another sample visibly. The samples of matter used by Mohs are readily available to a student or miner. Minerals with a hardness of 1 or 2 can be scratched with a fingernail. A coin will scratch minerals with a hardness of 3, the blade of a pocket knife scratches minerals of the hardness 5 and 6. Glass will scratch minerals with a hardness of 7, and harder minerals scratch each other.

Calcite crystals, example of a common mineral with hardness 3.

Artist M.C. Escher and his Crystal-inspired Artwork

“There is something breathtaking about the basic laws of crystals. They are in no sense a discovery of the human mind; they just “are” – they exist quite independently of us. The most that man can do is become aware, in a moment of clarity, that they are there, and take them into account. Long before there were people on the earth, crystals were already growing in the earth's crust. On one day or another, a human being first came across such a sparkling morsel of regularity lying on the ground or hit one with his stone tool and it broke off and fell at his feet, and he picked it up and regarded it in his open hand, and he was amazed.” 

- M. C. Escher (1898-1972)

Dutch artist Maurits Cornelis Escher was fascinated, or maybe even obsessed by "the systematic compartimentalization of space." Many of his illustrations show symmetrical shapes repeated into infinity, completely occupying all the available space. It is not a coincidence that Escher's work reseambles the molecular lattice structure and resulting crystal structure of minerals. Some of his surreal illustrations are even clearly based on crystals.

Spessartine-Garnet on Feldspar, Shigar Valley, Pakistan, and artwork by Escher.

Escher's half brother Berend Escher (1885-1967) was a professor of geology at Leiden University in the Netherlands, whose specialization was crystallography, mineralogy and vulcanology. It is likely that the artist Escher was introduced into the world of crystals by the mineralogist Escher.

Maria Matilda Ogilvie Gordon - A Women Geoscientist In The Dolomites

The Scottish Maria Matilda Ogilvie Gordon (1864-1939), or May as she was called, was the oldest daughter of a pastoral family composed of eight children, five boys and three girls. Maria Ogilvie entered Merchant Company Schools' Ladies College in Edinburgh at the age of nine. Already in these early years, she showed a profound interest in nature. During holidays she enjoyed exploring the landscape of the Scottish Highlands accompanied by her elder brother, the later geologist Sir Francis Ogilvie. Maria Ogilvie aspired to become a musician and at age of eighteen she went to London to study music, becoming a promising pianist, but already in the first year her interests into the natural world prevailed and she went for a career in science.

Studying both in London and Edinburgh she obtained her degree in geology, botany and zoology in 1890. Maria Ogilvie hoped to follow-up their studies in Germany, but in 1891, despite a recommendation even by the famous geologist Baron Ferdinand Freiherr von Richthofen (pioneer geologist of the Dolomites), she was rejected at the University of Berlin - women were still not permitted to enroll for higher education in England and Germany. She went to Munich, where she was welcomed friendly by eminent paleontologist Karl von Zittel (1839-1904) and zoologist Richard von Hertwig (1850-1927). However, she was not allowed to join male students. Sitting in a separate room she listened through the half-open doors to the lectures.

In July 1891, Richthofen invited her to join a five-week trip to the nearby Dolomites Mountains, visiting the Gröden-Valley. From the very first day, Maria Ogilvie was immensely impressed by the landscape and learned rock climbing to better explore the mountains. Richthofen introduced Maria Ogilvie to alpine geology and they visited the pastures of Stuores in the Gader-Valley. At the time Maria Ogilvie was studying modern corals to become a zoologist, but Richthofen, showing her the beautifully preserved fossil corals found here in the Triassic sediments, convinced her to become rather a geologist.

The pastures of Stuores in the Gader-Valley with outcrops of Triassic marl.

Richthofen was over sixty years old and therefore he couldn't provide much support in the field. Maria Ogilvie remembers later the challenge and danger of field work, sometimes accompanied by a local rock climber named Josef Kostner:

"When I began my fieldwork, I was not under the eye of any Professor. There was no one to include me in his official round of visits among the young geologists in the field, and to subject my maps and sections to tough criticism on the ground. The lack of supervision at the outset was undoubtedly a serious handicap."

For two summers she hiked, climbed and studied various areas in the Dolomites and instructed local collectors to carefully record and describe their fossil sites. In 1893 she published "Contributions to the geology of the Wengen and St. Cassian Strata in southern Tyrol". In the paper she included detailed figures of the landscape, geological maps and stratigraphic charts of the Dolomites, establishing fossil marker horizons and describing the ecology of various fossil corals associations. She described 345 species from the today 1,400 known species of mollusks and corals of the local Wengen- and St. Cassian-Formations.
The published paper, a summary of her thesis "The geology of the Wengen and Saint Cassian Strata in southern Tyrol", finally earned her respect by the scientific community. In 1893 she became the first female doctor of science in the United Kingdom. The same year she returned into the Dolomites to continue with her geological and paleontological research. In 1894 she published the important "Coral in the Dolomites of South Tyrol." Maria Ogilvie argued that the systematic classification of corals must be based on microscopic examination and characteristics, not as usually done at the time, on superficial similarities.

Fossil corals from the pastures of Stuores, plate from LAUBE (1865).

In 1895 she returned to Aberdeen, where she married a longstanding admirer. Dr. John Gordon respected and encouraged her passion for the Dolomites. He and their four children accompanied Maria Ogilvie on various excursions into the Dolomites.

In 1900 she returned to Munich, becoming the first woman to obtain a Ph.D. She helped her old mentor, paleontologist von Zittel, to translate his extensive German research on the "Geschichte der Geologie und Palaeontologie" - "The History of Geology and Palaeontology."

Maria Ogilvie continued her studies and continued to publish. In 1913 she was preparing another important work about the geology and geomorphology of the Dolomites, to be published in Germany, but in 1914 with the onset of World War I. and the death of the publisher, the finished maps, plates and manuscripts were lost in the general chaos.
In 1922 she returned into the Dolomites, where she encountered the young paleontologist Julius Pia, who, during the war, had carried out research in the Dolomites. Together they explored many times the Dolomites.

Landscape profile of the Langkofel-massif after GORDON & PIA (1939): Zur Geologie der Langkofelgruppe in den Südtiroler Dolomiten. Maria Matilda included hand-drawn sketches in her research.

Apart from scientific papers, Maria Matilda published also one of the first examples of geological guide books for the Dolomites. To honor her contributions to earth sciences in 2000 a new fossil fern genus, discovered in Triassic sediments, was named Gordonopteris lorigae.

Interested in reading more? Try:

WACHTLER, M. & BUREK, C.V. (2007): Maria Matilda Ogilvie Gordon (1864-1939): a Scottish researcher in the Alps. In BUREK, C. V. & HIGGS, B. (eds): The Role of Women in the History of Geology. Geological Society: 305-317

Darwin's First Botanizing Steps Followed His 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." - Charles Darwin in a letter to his friend and mentor John Stevens Henslow, 1836.

Charles Robert Darwin's interest in the natural world was widespread. As a student, he loved to hunt animals and collected bugs and minerals. His mentor and friend John Stevens Henslow, mineralogist and professor of botany, introduced the young Darwin to both disciplines. Darwin attended Henslow's botany lectures and field trips each year during his three years at Cambridge, visiting also private meetings at Henslow's home. Here he met with Adam Sedgwick, president of the newly formed Geological Society of London. During a geological field trip in the summer of 1831 with Sedgwick, Darwin collected and preserved also some plant specimens.

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.

During the five-year-long voyage of the Beagle Darwin collected plants or seeds on the Cape Verde Islands, in Argentina, in Uruguay, in Chile, in Brazil and 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 limited himself to remote or poorly studied localities.

Darwin had prepared several thousand labels in different colors before the voyage to be applied to every dried plant (the labels including species, locality, date and his signature). Wet specimens, conserved in "spirits of wine", were tagged with a small, metallic plate. Henslow, who back in England managed Darwin's collection, however, removed most labels when including Darwin's specimens into the herbarium. Unlike the collected rocks and animals Darwin didn't number the plant specimens, 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 plants.

Darwin's plant collection is especially interesting as it includes many species from less visited islands of the Galápagos and the Cocos archipelago. Darwin was intrigued about the relationship of the isolated species found on the islands to the species found on nearby continents. Later Darwin conducted experiments with seeds, showing that some can survive salty water for months and so be dispersed by marine currents. Despite Darwin's plans, he didn't publish the collected plants in “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 five years long voyage around the world, 220 species were new to science. Darwin was especially surprised by the variability displayed by plants. A collected grass species was divided by Henslow into fifteen different varieties! This was an intriguing observation, important for his later formulated theory of evolution, how one species can split over time in various new ones. 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 can be dispersed with marine currents and islands be colonized by plants from nearby continents, couldn't they also evolve there in new species?

Radioactivity and Earth's Age

In the 19th century, the discrepancy between the age of Earth and the age of the cosmos posed a great problem to scientists. Geologists had calculated, using methods like erosion or sedimentation rates, ages for Earth spanning from three million to fifteen billion years. Physicists and astronomers, based mostly on the energy output of stars, calculated an age for the universe spanning from twenty million to ten billion years - so in many models of the cosmos, Earth seemed to be too young or too old to fit in. In August 1893, during a meeting of the American Association for the Advancement of Science, geologist Charles D. Walcott (1850-1927) summarized the debate as follows:

"Of all subjects of speculative geology, few are more attractive or more uncertain in positive results than geological time. The physicists have drawn the lines closer and closer until the geologist is told that he must bring his estimates of the age of the earth within a limit of from ten to thirty millions of years. The geologist masses his observations and replies that more time is required, and suggests to the physicist that there may be an error somewhere in his data or the method of his treatment."

In 1896 the French physicist Henri Becquerel (1852-1908), based on Conrad Röntgen's (1845-1923) research, discovered that naturally occurring elements, like uranium, also emit X-rays and in 1897 Polish physicist Marie Curie (1867-1934) coined the term radioactivity to describe this energy of unknown origin. Her husband, Pierre Curie (1859-1906), realized that this energy from radioactive decay must be considered when calculating the age of Earth. Physicists supporting a young Earth based their calculations on a quickly cooling Earth. However, radioactive decay in Earth's interior provided a continuous source of energy and heat, therefore Earth was cooling slowly and so could be quite old.

Radioactive decay or another similar long-lasting and high-energy source (nuclear fusion was discovered later) could also explain how stars could produce light and heat for very long periods of time. The notion that stars or the sun had to be young (in most calculations younger than Earth) could also be dismissed.

But even better - the discovery of radioactivity provided not only indirect evidence of an old Earth but by measuring the constant decay it was also possible to calculate the exact age of a mineral, a rock and even of Earth.

High-energy rays, derived from radioactive decay, form a halo of alteration around a mineral grain in the larger biotite-crystal, image from J. JOYLE (1909): Radioactivity and geology, an account of the influence of radioactive energy on terrestrial history.

It’s sedimentary, my dear Watson

February 20, 1949 Mrs. Henrietta Helen Olivia Roberts Durand-Deacon, a wealthy widow, disappeared from the Onslow Court Hotel located in South Kensington, London. The police interviewed the residents and soon John George Haigh became a suspect, as he was the last person to have be seen together with the woman. He led the police to an old storeroom on Leopold Road in Sussex, where they discovered strange and suspicious tools – a revolver, some rubber protective clothing and three containers filled with sulphuric acid.

During the interrogation Haigh suddenly confessed to an incredible crime, “Mrs. Durand-Deacon no longer exists. She has disappeared completely, and no trace of her can ever be found again. I have destroyed her with acid. You will find the sludge which remains on Leopold Road. But you can’t prove murder without a body.” 

Fortunately, Haigh ignored one important fact in his euphoria: the law doesn’t require a body to incriminate him – it requires a corpus delicti - the evidence that a murder happened. Forensic pathologist Keith Simpson examined carefully the ground at the supposed crime scene. He noted something unusual, a small pebble which he described as follows: “It was about the size of a cherry, and looked very much like the other stones, except it had polished facets.“ Simpson realized that he had found the evidence to prove the murder. The pebble was a gallstone from poor Mrs. Durand-Deacon. Gallstone can form from calcium-salts and organic substances in the gallbladder. A thin layer of organic matter protected the pebbles from being dissolved in the acid. John George Haigh, who was ultimately suspected of committing an entire series of murders, was sentenced later to death.

This forensic case was an unusual example of how rocks can help solve a crime. However already in the mid of the 19th century people realized that rocks, soils and the science of geology could be used to reconstruct a crime and provide circumstantial evidence to connect a suspect with the crime scene. An 1856 one issue of the magazine “Scientific American” reported the “Curious Use of the Microscope” to help clarify a case of thievery:

“Recently, on one of the Prussian railroads, a barrel which should have contained silver coin, was found, on arrival at its destination, to have been emptied of its precious contents, and refilled with sand. On Professor Ehrenberg, of Berlin [1795-1896, famous zoologist and geologist] from Leipzig in, being consulted on the subject, he sent for samples of sand from all the stations along the different lines of railway that the specie had passed, and by means of his microscope, identified the station from which the interpolated sand must have been taken. The station once fixed upon, it was not difficult to hit upon the culprit in the small number of employees on duty there.“

Influenced by the rapid development of science, the British author Sir Arthur Conan Doyle introduced in 1887 a new kind of detective, who based his crime solving abilities on the scientific and forensic clues that everybody acquired or left behind by touching objects, or simply walking on muddy ground: “Knowledge of Geology. – Practical, but limited. Tells at a glance different soils from each other. After walks has shown me splashes upon his trousers, and told me by their colour and consistence in what part of London he had received them."

About at the same time as Doyle published his fictional adventures, the Austrian professor of criminology Hans Gross (1847-1915) published various textbooks dealing with forensic investigations methods. In his “System der Kriminalistik” (Criminal Investigation, published in 1891) he proposed that the police should carefully study geomorphological maps, to infer possible sites where criminals could commit crimes or hide bodies – like forests, ponds, streams or sites with a well. In 1893 Gross published his “Handbuch für Untersuchungsrichter” (Handbook for Examining Magistrates), where he explained how the petrographic composition of dirt found on shoes could indicate where a suspect went previously. Based on these ideas, in 1910 the French physician Edmund Locard (1877-1966) established the basic exchange principle of environmental profiling:

“Whenever two objects come into contact, there is always a transfer of material. The methods of detection may not be sensitive enough to demonstrate this, or the decay rate may be so rapid that all evidence of transfer has vanished after a given time. Nonetheless, the transfer has taken place.“

The German chemist Georg Popp (1867-1928) was the first investigator to solve a murder case by adopting the principles of Gross and Locard and considering soil as reliable evidence. In the spring of 1908 Margarethe Filbert was murdered near Rockenhausen in Bavaria. The local attorney had read Hans Gross’s handbook and know Popp from an earlier case, where Popp connected a strangled woman to the suspect by mineral grains of hornblende found in the mucus of the victim’s nose and under the fingernails of the suspect.
In the Filbert case a local factory worker named Andreas Schlicher was suspected, however he claimed that on the day of the murder he was working in the fields.

Popp reconstructed the movements of the suspect by analyzing the dirt found on his shoes. The uppermost layer, thus the oldest, contained goose droppings and earth from the courtyard of the suspect’s home. A second layer contained red sandstone fragments and other particles of a soil found also where the body of the victim was discovered. The last layer contained brick fragments, coal dust, cement and a whole series of other materials also found on the site where the suspect’s gun and clothing had been found. However, there were no mineral grains – fragments of porphyry, quartz and mica- on the shoes. Since these were found in the soils of the field where Schlicher supposedly worked the very same day, he was obviously lying.

In the last two decades, the significance of forensic geology increased steadily. It is applied not only to connect single suspects to criminal cases, but also to trace the provenience of explosive, drugs or smuggled goods, including wildlife, not to mention the possible applications to detect cases against the environmental law. Forensic geology also proved valuable to reconstruct and uncover modern war crimes.

In 1997 the United Nations International Criminal Tribune for the Former Yugoslavia (UN ICTY) began exhuming five mass graves in north-eastern Bosnia associated with the massacre of civilians in and around the town of Srebrenica in July 1995. Intelligence reports showed that 3 months after the initial executions of civilians, the primary mass graves had been exhumed and the bodies transported over a 1-3 day period to a number of unknown (but at least 19) secondary grave sites. To prosecute the suspects, it was necessary to prove that the now recovered bodies came without doubt from Srebrenica, and that therefore the later dislocation of the graves was intentionally to hide these war crimes. Two grave sites were intensively studied and samples of the grave fills and surrounding soils and bedrock collected. Soil samples can be screened by their content of minerals and rocks, the size and form of single mineral or rock grains, biochemistry of organic substances, microbiology, remains of invertebrates and plants and pollen and spores preserved in it. These various parameters can vary in so many ways, every soil can be regarded as unique. Comparing the parameters between samples recovered from the victim or the suspect and collected at the crime sites it is possible to establish a unique connection between them.
During the investigations in Bosnia a clast of serpentinite found in one of the secondary gravesites proved to be the decisive evidence. This greenish rock connected one secondary grave site with only one primary site – only there an outcrop with a serpentinite dyke could be found. Similarity, the presence or absence of particular clay minerals, depending on the surrounding geology of the primary burial site, connected or excluded the primary to the secondary sites.

The list of fascinating or strange cases solved thanks to forensic geology would surprise even Sherlock Holmes himself.

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.

Charles Darwin in Rio de Janeiro and the Geology Of Sugarloaf Mountain

The Sugarloaf Mountain (aka: Pão de Açúcar) rising almost 400m above Rio de Janeiro is composed of granitoid rock – a plutonic rock formed by the slow cooling from magma and composed mostly of the minerals quartz, feldspar and mica.
 

Charles Darwin, visiting Rio de Janeiro in 1832, describes in details this rock “- This whole district is almost exclusively formed of gneiss, abounding with garnets, and porphyritic with large crystals, even three and four inches in length, of orthoclase feldspar: in these crystals, mica and garnets are often enclosed.”
 

Fig.1. View of Rio de Janeiro with Sugarloaf Mountain as seen from the Corcovado by HMS Beagle artist Augustus Earle. 

Granite shows commonly no preferred orientation of the minerals, however Darwin noted that the granite of Rio de Janeiro seems to be more of a gneiss with a weak developed “stratification and foliation” of minerals, as he continues “The mountains of gneiss-granite are to a remarkable degree abruptly conical, which seems caused by the rock tending to exfoliate in thick, conically concentric layers: ...”
 

Indeed the Sugarloaf is, as correctly described by Darwin, composed mostly of augen-gneiss, a metamorphic rock with single large, often elongated, crystals, resembling eyes in a finer matrix of smaller crystals, therefore the name as auge means eye in German.

Fig.2. Simplified geological map of the Sugarloaf and surrounding bornhardts, from MIGON 2010.

The Sugorloaf is also evidence for plate tectonics. 560 million years ago, when the ancient supercontinent of Gondwana started slowly to break apart, large magmatic bodies intruded into the weakened crust, feed from below by the Tristan da Cunha hotspot. 

Fig.3. Large Igneous Provinces (LIP) and correlated hotspots. Magmatic rocks of the same type can be found on both sides of the Atlantic Ocean, showing that South America and Africa once were one single continent.

Slowly cooling in the upper crust these magmatic bodies formed a large granitic pluton. During the movement of the continents parts of the pluton broke apart, as we find the same type of rock along the coasts of South-America and of Africa, also some metamorphism and deformation of the rocks occurred and the cleavage of the gneiss formed. Later finally the metamorphic pluton was pushed upwards and erosion started to form the modern landscape of Rio with the hard augen-gneiss towering above weaker and more erodible rocks.

The Dog´s Cave, Animal Cruelty and an unseen Volcanic Killer

The Grotta del Cane (the Dog´s Cave) is a short, 9m deep, artificial gallery located on the rim or the basin of Agnano near Naples. The basin is in reality the remains of an 8.000-4.000 year old collapsed volcano, just one smaller caldera of the Phlegraean Fields.

 

Fig.1. The Phlegraean Fields with the caldera of Agnano located almost at the center, from SUESS, E. "Das Antlitz der Erde" (1892).

Since antiquity the area is known for it´s volcanic activity, like hot springs and fumaroles, called mofettes.
It´s also famous because inside the dog´s cave small animals like dogs and bird will slowly suffocate. Already the Roman poet Vergil (70-19 BC) writes of the nearby lake of Averno:

"There was a deep stony cave, huge and gaping wide,
sheltered by a dark lake and shadowy woods,
over which nothing could extend its wings in safe flight,
since such a breath flowed from those black jaws,
and was carried to the over-arching sky, that the Greeks
called it by the name Aornos, that is Avernus, or the Bird-less."

Naturalists from Antiquity until the Renaissance know of the strange phenomenon and speculated about toxic vapors coming from the underground, killing smaller animals. German polymath Athanasius Kircher (1602-1680) suggested that “Ochre, Sandrak*, Orpiment and Arsenic” compounds, known at the time to be toxic (and very popular as pigments to paint), were to blame.
In the early 19th century naturalists in self-experiments determined that below a certain level in the cave they experienced a strange dizziness and started to lose feelings in their legs. Those were recognized as symptoms of a carbon-dioxide intoxication. The invisible and odorless carbon-dioxide is heavier than normal air and tends to flow to the bottom of wells and caves. 
The gas emanates from the volcanic underground and accumulates in the dog´s cave. At the entrance the layer of carbon-dioxide is just sufficiently thick to suffocate smaller animals, deeper in the cave it can become dangerous also for humans. 

The dog´s cave became a popular and somehow macabre tourist attraction in the 18th-19th century. Visitors could buy a dog from a nearby shelter and observe how it would become unconsciousness and suffocate inside the cave – when not saved in the last moment by throwing it in the nearby lake of Agnano (today dried up). The cold water would revive the poor dog in most of the cases...

 

Fig.2. Demonstrating the deadly effects of the dog´s cave, from “The book of curiosities: containing ten thousand wonders and curiosities of nature and art” (1822). 

*Sandrak is actually a resin used to fix pigments

Literature:

KROONENBERG, S. (2013): Why Hell Stinks of Sulfur: Mythology and Geology of the Underworld. University of Chicago Press: 352

Scrooge McDuck and his geological treasures

Scrooge McDuck, today famous as the richest duck in the world, was born into a poor family of 19th century Glasgow and during a lifetime of adventures he found many geological treasures and made his first fortune with copper and gold – or so imagines Keno Don Hugo Rosa, American comic book author, in a successful series of 12 comic book stories published in 1992-96.  Don Rosa did quite some background research for the series. Scrooge meets real-life based characters or witnessed historic events, like the eruption of the Krakatoa in 1883, and there is also some geology or references to precious gemstones to be found.

In the story “Dreamtime Duck of the Never-Never” Scrooge, yet at the beginning of his career, finds a dreamtime opal in Australia.
He leaves the for the Aborigines sacred relict untouched. Australia is indeed famous for its opals, a noble variety of quartz.
Another sacred crystal reveals to Scrooge, that he should travel into the north, where he will finally make a fortune.

 

During his travels in  the U.S. Scrooge is taught some basic geology by the former prospector Howard Rockerduck when searching for copper in Montana and he temporarily becomes owner of the Anaconda copper mine.

August 1896, gold was discovered in Klondike, found at Bonanza Creek, Alaska by George Carmack. The news will trigger the last great gold-rush in Klondike. In the stories "King of the Klondike", "The Prisoner of White Agony Creek" and "Hearts of the Yukon" we meet Scrooge, after leaving Australia, as a prospector participating to the gold-rush of 1896-97. The gold of the Yukon is found as dust in ancient fluvial sediments – referred as muck by the miners -  as correctly depicted in the comic. Scrooge this time is successful, even finding a goose-egg big gold nugget.

In search of more gold, diamonds and other valuable gemstones he travels the world for years to come -

“There’s gold, and it’s haunting and haunting;
It’s luring me on as of old;
Yet it isn’t the gold that I’m wanting
So much as just finding the gold.“
(“The Spell of the Yukon” by Robert W. Service)
 

In Russia he is informed of the existence of a gigantic striped ruby, finally finding the lost gemstone. 

There are indeed rubies with a phenomenon called asterism. Such star stones display a luminous star-like figure or stripes when seen in light. This optical effects happens due twinning in crystals, small tubular cavities or when fine fibers of another mineral grow into a larger crystal. It's a very rare effect in rubies and for a time this gemstone is Scrooge's greatest treasure.

In one of the last comic stripes finally Scrooge McDuck achieves the goal of a lifetime – he is the richest duck in the world!!! - proving the ancient prophecy of the clan McDuck as true - "Fortuna favet fortibus."

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?
 

References:
 

PORTER, D.M. (2010): Darwin: the Botanist on the Beagle. Proceedings of the California Academy of Sciences, Vol.61(4): 117-156