Volcanism, the Chicxulub impact and the K-Pg event.

The Deccan traps

It was the best of times. It was the worst of times. The end of the Mesozoic era at ca. 66 million years ago (Ma) is marked by one of the most severe biotic crisis in Earth’s history: the Cretaceous-Paleogene (K-Pg) mass extinction. During the event, three-quarters of the plant and animal species on Earth disappeared, including non-avian dinosaurs, other vertebrates, marine reptiles and invertebrates, planktonic foraminifera and ammonites. Marine ecosystems lost about half of their species while freshwater environments shows low extinction rates, about 10% to 22% of genera.

Two events were linked to this mass extinction: the eruption of the Deccan Traps large igneous province, and the Chicxulub meteorite impact. Early work speculated that the Chicxulub impact triggered large-scale mantle melting and initiated the Deccan flood basalt eruption. Precise dating of both, the impact and the flood basalts, show that the earliest eruptions of the Deccan Traps predate the impact. But, the Chicxulub impact, and the enormous Wai Subgroup lava flows of the Deccan Traps continental flood basalts appear to have occurred very close together in time. Recent studies suggest a possible association between the Chicxulub impact and variations in the progression of Deccan Traps eruptions. Seismic modeling indicates that the impact could have generated seismic energy densities of order 0.1–1.0 J/m3 throughout the upper ∼200 km of Earth’s mantle, sufficient to trigger volcanic eruptions worldwide.

Gravity anomaly map of the Chicxulub impact structure (From Wikimedia Commons)

The oceanic crust records the history of temporal variations in seafloor magmatism continuously and at high resolution through geologic time. Around the time of the Chicxulub impact, 23,000 to 230,000 cubic miles of magma erupted out of the mid-ocean ridges, all over the globe. One of the largest eruptive events in Earth’s history. This pulse of global marine volcanism played an important role in the environmental crisis at the end of the Cretaceous, through magmatism by extruding large volumes of basalt and releasing volcanic gases or through enhanced hydrothermal venting driven by magmatic intrusion. Marine volcanism also provides a potential source of oceanic acidification.

The Chicxulub impact released an estimated energy equivalent of 100 teratonnes of TNT and produced high concentrations of dust, soot, and sulfate aerosols in the atmosphere. The decrease of sunlight caused a drastic short-term global reduction in temperature (15 °C on a global average, 11 °C over the ocean, and 28 °C over land). While the surface and lower atmosphere cooled, the tropopause became much warmer, eliminate the tropical cold trap and allow water vapor mixing ratios to increase to well over 1,000 ppmv in the stratosphere. Those events accelerated the destruction of the ozone layer. During this period, UV light was able to reach the surface at highly elevated and harmful levels.

 

References:

Joseph S. Byrnes and Leif Karlstrom, Anomalous K-Pg–aged seafloor attributed to impact-induced mid-ocean ridge magmatism, Sci Adv 4 (2), eaao2994, DOI: 10.1126/sciadv.aao2994

Charles G. Bardeen, Rolando R. Garcia, Owen B. Toon, and Andrew J. Conley, On transient climate change at the Cretaceous−Paleogene boundary due to atmospheric soot injections, PNAS 2017 ; published ahead of print August 21, 2017 DOI: 10.1073/pnas.1708980114

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Christmas edition: Geologizing with Dickens, part II.

dickens_by_watkins_1858

Charles Dickens at his desk, by George Herbert Watkins (National Portrait Gallery. From Wikimedia Commons)

Charles Dickens (1812- 1870) revitalized the traditions of Christmas, and to Victorian England, Dickens was Christmas. He had only 31, when began to write A Christmas Carol. The novella tells the story of  Ebenezer Scrooge, a bitter old man who finds salvation through the visits of the three Ghosts of Christmas (Ghost of Christmas Past, Ghost of Christmas Present, and Ghost of Christmas Yet to Come). But Dickens also contributed to the popularity of geology in the nineteenth century. Among his friends were Richard Owen and Sir Roderick Murchison. For Dickens, the ideal science is Geology. In his review of Hunt’s Poetry of Science, he wrote: “Science has gone down into the mines and coal-pits, and before the safety-lamp the Gnomes and Genii of those dark regions have disappeared … Sirens, mermaids, shining cities glittering at the bottom of quiet seas and in deep lakes, exist no longer; but in their place, Science, their destroyer, shows us whole coasts of coral reef constructed by the labours of minute creatures; points to our own chalk cliffs and limestone rocks as made of the dust of myriads of generations of infinitesimal beings that have passed away; reduces the very element of water into its constituent airs, and re-creates it at her pleasure…” (London Examiner, 1848).

In 1846, Dickens visited Naples and climbed the Mount Vesuvius. He described that experience in Pictures from Italy. He wrote: “Stand at the bottom of the great market-place of Pompeii, and look up the silent streets, through the ruined temples of Jupiter and Isis, over the broken houses with their inmost sanctuaries open to the day, away to Mount Vesuvius, bright and snowy in the peaceful distance; and lose all count of time, and heed of other things, in the strange and melancholy sensation of seeing the Destroyed and the Destroyer making this quiet picture in the sun.”

An eruption of Vesuvius circa 1845. Credit: Enrico La Pira.

An eruption of Vesuvius circa 1845. Credit: Enrico La Pira.

Mount Vesuvius is a stratovolcano, consisting of an external truncated cone, the extinct Mt. Somma,  a smaller cone represented by Vesuvius. For this reason, the volcano is also called Somma-Vesuvio. It was formed by the collision of two tectonic plates, the African and the Eurasian. When Mount Vesuvius erupted in 79 AD released deadly cloud of ash and molten rocks, and lasted eight days, burying and destroying the cities of Pompeya, Herculaneum and Stabiae. Vesuvius has the world’s oldest volcano observatory, established in 1845, and Dickens’s own magazine Household Words, frequently ran travel pieces describing the ascent and descent of Vesuvius, alongside trips to Pompei.

The same year, Dickens began to to write Dombey and Son, using his experiences in Italy to describe a violent eruption: “Hot springs and fiery eruptions, the usual attendants upon earthquakes, lent their contributions of confusion to the scene. Boiling water hissed and heaved within dilapidated walls; whence, also, the glare and roar of flames came issuing forth; and mounds of ashes blocked up rights of way, and wholly changed the law and custom of the neighbourhood”. 

Benjamin Waterhouse Hawkins unveiled the first ever sculptures of Iguanodons.

Benjamin Waterhouse Hawkins unveiled the first ever sculptures of Iguanodons.

It was an exciting time full of discoveries and the concept of an ancient Earth became part of the public understanding. The study of the Earth was central to the economic and cultural life of the Victorian Society and Literature influenced the pervasiveness of geological thinking. So when the Crystal Palace was reconstructed at Sydenham in 1854, Dickens and his Household Words were very enthusiastic. Megalosaurus became so popular that is mentioned in his novel Bleak House. In this novel the dinosaurs uncovered by the railway in Dombey and Son move centre stage: “Implacable November weather. As much mud in the streets as if the waters had but newly retired from the face of the earth, and it would not be wonderful to meet a Megalosaurus, forty feet long or so, waddling like an elephantine lizard up Holborn Hill.”  

In Bleak House and Dombey and Son, Dickens encourage reader to perceive the scene of the city as a geological fragment of a much broader spatial and temporal vision. In his last novel Our Mutual Friend (1864–65), Mr Venus, the taxidermist was slightly based on Richard Owen. By the time when Dickens wrote this novel, Owen was the curator of the Hunterian Museum of the Royal College of Surgeons. Our Mutual Friend, also exhibits  traces of the work of Lyell, Jean-Baptiste Lamarck, and Darwin.

References:

A. BUCKLAND, ‘“The Poetry of Science”: Charles Dickens, Geology and Visual and Material Culture in Victorian London’, Victorian Literature and Culture, 35 (2007), 679–94 (p. 680).

A. BUCKLAND. Novel Science: Fiction and the Invention of Nineteenth-Century Geology. Chicago, IL and London: University of Chicago Press, 2013. 400 pp. 9 plts. $45.00. ISBN 978-0-226-07968-4

Unlocking the secrets of the Crater of Doom.

Luis and Walter Alvarez at the K-T Boundary in Gubbio, Italy, 1981 (From Wikimedia Commons)

Luis and Walter Alvarez at the K-T Boundary in Gubbio, Italy, 1981 (From Wikimedia Commons)

The noble and ancient city of Gubbio laid out along the ridges of Mount Ingino in Umbria, was founded by Etruscans between the second and first centuries B.C. The city has an exceptional artistic and monumental heritage which includes marvelous examples of Gothic architecture, like the Palazzo dei Consoli and the Palazzo del Bargello. The rich history of the city is recorded in those buildings. Outside the city, there are exposures of pelagic sedimentary rocks that recorded more than 50 million years of Earth’s history. In the 1970s it was recognized that these pelagic limestones carry a record of the reversals of the magnetic field. The  K-Pg boundary occurs within a portion of the sequence formed by pink limestone containing a variable amount of clay. This limestone, know as the “Scaglia rossa”, is composed by calcareous nannofossils and planktonic foraminifera.

In 1977, Walter Alvarez – an associate professor of geology University of California, Berkeley – was collecting samples of the limestone rock for a paleomagnetism study. He found that the foraminifera from the Upper Cretaceous (notably the genus Globotruncana) disappear abruptly and are replaced by Tertiary foraminifera. The extinction of most of the nannoplankton was simultaneus with the disappearance of the foraminifera (Alvarez et al., 1980).

Forams from the Upper Cretaceous vs. the post-impact foraminifera from the Paleogene. (Images from the Smithsonian Museum of Natural History)

Forams from the Upper Cretaceous vs. the post-impact foraminifera from the Paleogene. (Images from the Smithsonian Museum of Natural History)

At Caravaca on the southeast coast of Spain, Jan Smith, a Dutch geologist, had noticed a similar pattern of changes in forams in rocks around the K-T boundary. Looking for clues, Smith contacted to Jan Hertogen who found high iridium values at the clay boundary. At the same time, Walter Alvarez  gave his father, Luis Alvarez – an American physicist who won the  Nobel Prize in Physics in 1968 – a small polished cross-section of Gubbio  K-Pg boundary rock. The Alvarez gave some samples to Frank Asaro and Helen Michel, who had developed a new technique called neutron activation analysis (NAA). They also discovered the same iridium anomaly. The sea cliff of Stevns Klint, about 50 km south of Copenhagen, shows the same pattern of extinction and iridium anomaly. Another sample from New Zeland also exhibits a spike of iridium. The phenomenon was global.

Iridium is rare in the Earth’s crust but metal meteorites are often rich in iridium. Ten years before the iridium discovery, physicist Wallace Tucker and paleontologist Dale Russell proposed  that a supernova caused the mass extinction at the K-Pg boundary. Luis Alvarez realised that  a supernova would have also released plutonium-244, but there was no plutonium in the sample at all. They concluded that the anomalous iridium concentration at the K-Pg boundary is best interpreted as the result of an asteroid impact, which would explain the iridium and the lack of plutonium. In 1980, they published their seminal paper on Science, along with Asaro and Michel, and ignited a huge controversy. They even calculated the size of the asteroid (about 7 km in diameter) and the crater that this body might have caused (about 100–200 km across).

A paleogeographic map of the Gulf of Mexico at the end of the Cretaceous (From Vellekoop, 2014)

A paleogeographic map of the Gulf of Mexico at the end of the Cretaceous (From Vellekoop, 2014)

In 1981, Pemex (a Mexican oil company) identified Chicxulub as the site of a massive asteroid impact. In 1991, Alan Hildebrand, William Boynton, Glen Penfield and Antonio Camargo, published a paper entitled “Chicxulub crater: a possible Cretaceous/Tertiary boundary impact crater on the Yucatan Peninsula, Mexico.” They had found the long-sought K/Pg impact crater.

The crater is more than 180 km (110 miles) in diameter and 20 km (10 miles) in depth, making the feature one of the largest confirmed impact structures on Earth. The  Chicxulub impact released an estimated energy equivalent of 100 teratonnes of TNT and produced high concentrations of dust, soot, and sulfate aerosols in the atmosphere. Model simulations suggest that the amount of sunlight that reached Earth’s surface was reduced by approximately 20%.This decrease of sunlight caused a drastic short-term global reduction in temperature. This phenomenon is called “impact winter”. Cold and darkness lasted for a period of months to years.  Photosynthesis stopped and the food chain collapsed. This period of reduced solar radiation may only have lasted several months to decades. Three-quarters of the plant and animal species on Earth disappeared. Marine ecosystems lost about half of their species while freshwater environments shows low extinction rates, about 10% to 22% of genera. Additionally, the vapour produced by the impact  could have led to global acid rain and a dramatic acidification of marine surface waters.

The Chicxulub asteroid impact was the final straw that pushed Earth past the tipping point.  The K-Pg extinction that followed the impact was one of the five great Phanerozoic  mass extinctions. Currently about 170 impact craters are known on Earth; about one third of those structures are not exposed on the surface and can only be studied by geophysics or drilling. Now, a new drilling platform in the the Gulf of Mexico, sponsored by the International Ocean Discovery Program (IODP) and the International Continental Scientific Drilling Program, will looking rock cores from the site of the impact. The main object is learn more about the scale of the impact, and the environmental catastrophe that ensued.

References:

Alvarez, L., W. Alvarez, F. Asaro, and H.V. Michel. 1980. Extraterrestrial cause for the Cretaceous-Tertiary extinction: Experimental results and theoretical interpretation. Science 208:1095–1108.

Alvarez, W. (1997) T. rex and the Crater of Doom. Princeton University Press, Princeton, NJ.

Hildebrand, A.R., G.T. Penfield, D.A. Kring, M. Pilkington, A. Camargo, S.B. Jacobsen, and W.V. Boynton. 1991. Chicxulub crater: A possible Cretaceous/Tertiary boundary impact crater on the Yucatán Peninsula, Mexico. Geology 19:867–71.

 

 

Application of diatoms to tsunami studies.

Lisbon earthquake and tsunami in 1755 (From Wikipedia Commons)

Lisbon earthquake and tsunami in 1755 (From Wikipedia Commons)

Diatoms are unicellular algae with golden-brown photosynthetic pigments with a fossil record that extends back to Early Jurassic. The most distinctive feature of diatoms is their siliceous skeleton known as frustule that comprise two valves. They live in aquatic environments, soils, ice, attached to trees or anywhere with humidity and their remains accumulates forming diatomite, a type of soft sedimentary rock. Diatoms are the dominant marine primary producers in the oceans and play a key role in the carbon cycle and in the removal of biogenic silica from surface waters. But diatoms are also a valuable tool in reconstructing paleoenvironmental changes because of their sensitivity to environmental factors including salinity, tidal exposure, substrate, vegetation, pH, nutrient supply, and temperature found in specific coastal wetland environments. Through years, diatoms become part of the coastal sediments, resulting in buried assemblages that represent an environmental history that can span thousands of years. Diatoms alone cannot differentiate tsunami deposits from other kinds of coastal deposits, but they can provide valuable evidence for the validity of proposed tsunami deposits (Dura et al., 2015).

Electron microscope image of Diatoms from high altitude aquatic environments of Catamarca Province, Argentina (From Maidana and Seeligmann, 2006)

Electron microscope image of Diatoms from high altitude aquatic environments of Catamarca Province, Argentina (From Maidana and Seeligmann, 2006)

Tsunami deposits can be identify by finding anomalous sand deposits in low-energy environments such as coastal ponds, lakes, and marshes. Those anomalous deposits are diagnosed using several criteria such as floral (e.g. diatoms) and faunal fossils within the deposits. The delicate valves of numerous diatom species may be unusually well preserved when removed from surface deposits and rapidly buried by a tsunami.

Diatoms within the tsunami deposits are generally composed of mixed assemblages, because tsunamis inundated coastal and inland areas, eroding, transporting, and depositing brackish and freshwater taxa. Nonetheless, problems differentiating autochthonous (in situ) and allochthonous (transported) diatoms complicates reconstructions. In general, planktonic diatoms are considered allochthonous components in modern and fossil coastal wetland assemblages, while benthic taxa can be considered as autochthonous. Diatoms can also be used to estimate tsunami run-up  by mapping the landward limit of diatom taxa transported by the tsunami.

 

References:

Hemphill-Haley, E., 1996. Diatoms as an aid in identifying late Holocene tsunami deposits. The Holocene 6, 439–448.

Tina Dura, Eileen Hemphill-Haley, Yuki Sawai, Benjamin P. Horton, The application of diatoms to reconstruct the history of subduction zone earthquakes and tsunamis, Earth-Science Reviews 152 (2016) 181–197. DOI: 10.1016/j.earscirev.2015.11.017

Armstrong, H. A., Brasier, M. D., 2005. Microfossils (2nd Ed). Blackwell, Oxford.

Barron, J.A. (2003). Appearance and extinction of planktonic diatoms during the past 18 m.y. in the Pacific and Southern oceans. “Diatom Research” 18, 203-224

The geological observations of Robert Hooke.

Ammonite fossil illustrations drawn by Robert Hooke (‘Discourse on Earthquakes’ from 1703).

Ammonite fossil illustrations drawn by Robert Hooke (‘Discourse on Earthquakes’ from 1703).

At the beginning of the sixteenth century and throughout the seventeenth century a great debate about the true nature of fossils started in Italy and extended to Europe. There was two hypothesis in dispute: the first one postulated an inorganic origin for the fossils (directly formed within rocks) and the second, which contemplated an organic origin. The court doctor to the Grand Duke of Tuscany, Nicola Steno argued that the stones called Glossopetrae or “tongue stones” looked like shark teeth because they were shark teeth deposited a long time ago. In 1667, Henry Oldenburg, the secretary of the Royal Society included an abstract of ‘The head of a shark dissected’ (Canis Carchariae Dissectum Caput) by Nicolas Steno in one of the early issues of the Philosophical Transactions. Robert Hooke (1635-1703), Curator of Experiments of the Royal Society, expressed similar ideas two years before Steno. In ‘Micrographia’ (1665) he  argued that the micro-structure of petrified wood were identical to those seen in normal wood. He also described the ‘serpentine stones’ and concluded that these stones were not formed due any ‘plastic virtue’, but were due to shells of shellfish that became filled with mud or clay or petrifying water and had over time rotted away, leaving their impressions ‘both on the containing and contained substances’ (Kusukawa, 2013).

Between 1667 and 1700, Hooke delivered a series of at least 27 lectures or ‘Discourses’ to the Royal Society on the generic subject of ‘Earthquakes’, or earth-forming processes, published in his Posthumous works (1705), and accompanied by some of Hooke’s drawings that survived among the papers of Sir Hans Sloane.

Hooke's drawing of fossil bivalves, brachiopods, belemnites, shark teeth and possibly a reptilian tooth (Copyright © The Royal Society)

Hooke’s drawing of fossil bivalves, brachiopods, belemnites, shark teeth and possibly a reptilian tooth (Copyright © The Royal Society)

Hooke’s ‘wandering poles’ theory was the first dynamic explanation of continent formation in the history of science. ‘The Earth’s rotation, he proposed, caused a bulge and thus greater altitude at the equator versus a flattening at the poles. He maintained that over time, a change in the positions of the poles on the Earth surface due to a change in the moment of inertia would cause different areas of bulging and flattening with the creation of new land or sea areas’ (Drake, 2007).

By the time that he delivered his third series of ‘Discourses’ in 1687, Hooke had arrived to three remarkable conclusions. First, that fossils were the petrified remains of once living creatures (he called ‘medals of Nature’ and part of ‘Nature’s Grammar’, to be collected like coins and read like texts) and not just twists in the rock. Second, that there had been radical changes of sea level. Third, that hill-tops in England had once formed the beds of tropical oceans as indicated by the discovered of gigantic sea shells.

Hooke’s writings were intimately connected to his birthplace: the town of Freshwater near the western edge of the Isle of Wight. Throughout his Discourses he mentioned the cliffs around Freshwater Bay from which he collected fossils. Unfortunately, many of the fossils that he collected for the Royal Society, along with his portrait as Secretary of the Society, many papers and several scientific instruments and models designed by Hooke are lost, but Hooke’s ideas were transmitted by later writers, demonstrating the continuity of the development of geological thought. Arthur Percival Rossiter even nominated him in 1935 as ‘The First English Geologist’.

Reference:

E. T. Drake, The geological observations of Robert Hooke (1635-1703) on the Isle of Wight; p19-30. Geological Society, London, Special Publications 2007, v.287; doi: 10.1144/SP287.3

Sachiko Kusukawa, Drawings of fossils by Robert Hooke and Richard Waller, Notes Rec. R. Soc. 2013 67 123-138; DOI: 10.1098/rsnr.2013.0013. Published 3 April 2013

M. J. S. Rudwick, The meaning of fossils: episodes in the history of palaeontology(University of Chicago Press, 1985)

 

The Great Acceleration.

 

Iron and Coal, 1855–60, by William Bell Scott illustrates the central place of coal and iron working in the industrial revolution (From Wikimedia Commons)

Iron and Coal, 1855–60, by William Bell Scott illustrates the central place of coal and iron working in the industrial revolution (From Wikimedia Commons)

During a meeting of the International Geosphere-Biosphere Programme (IGBP) celebrated in Mexico, in 2000, the Vice-Chair of IGBP, Paul Crutzen, proposed the use of the term Anthropocene to designate the last three centuries of human domination of earth’s ecosystems, and to mark the end of the current Holocene geological epoch. He suggested that the start date of the Anthropocene must be placed near the end of the 18th century, about the time that the industrial revolution began, and noted that such a start date would coincide with the invention of the steam engine by James Watt in 1784.

Although there is no agreement on when the Anthropocene started, researchers accept that the Anthropocene is a time span marked by human interaction with Earth’s biophysical system. It has been defined, primarily, by significant and measurable increases in anthropogenic greenhouse gas emissions from ice cores, and other geologic features including synthetic organic compounds and radionuclides. Eugene Stoermer, in an interview in 2012, proposed that the geological mark for the Anthropocene was the isotopic signature of the first atomic bomb tests. Hence,  Anthropocene deposits would be those that may include the globally distributed primary artificial radionuclide signal (Zalasiewicz et al, 2015).

 

anthropocene

Alternative temporal boundaries for the Holocene–Anthropocene boundary (calibrated in thousand of years before present) From Smith 2013

 

Human activity is a major driver of the dynamics of Earth system. After the World War II, the impact of human activity on the global environment dramatically increased. This period associated with very rapid growth in human population, resource consumption, energy use and pollution, has been called the Great Acceleration.

During the Great Acceleration, the atmospheric CO2 concentration grew, from 311 ppm in 1950 to 369 ppm in 2000 (W. Steffen et al., 2011). About one third of the carbon dioxide released by anthropogenic activity is absorbed by the oceans. When CO2 dissolves in seawater, it produce carbonic acid. The carbonic acid dissociates in the water releasing hydrogen ions and bicarbonate. Then, the formation of bicarbonate removes carbonate ions from the water, making them less available for use by organisms. Ocean acidification affects the biogeochemical dynamics of calcium carbonate, organic carbon, nitrogen, and phosphorus in the ocean, and will directly impact in a wide range of marine organisms that build shells from calcium carbonate, like planktonic coccolithophores, molluscs,  echinoderms, corals, and coralline algae.

Clastic plastiglomerate containing molten plastic and basalt and coral fragments (Image adapted from P. Corcoran et al., 2014)

Clastic plastiglomerate containing molten plastic and basalt and coral fragments (Image adapted from P. Corcoran et al., 2013)

One important marker for the future geological record is a new type of rock formed by anthropogenically derived materials. This type of rock has been named plastiglomerate, and has been originally described on Kamilo Beach, Hawaii. This anthropogenically influenced material has great potential to form a marker horizon of human pollution, signaling the occurrence of the Anthropocene epoch (Corcoran et al., 2013).

Climate change, shifts in oceanic pH, loss of biodiversity and widespread pollution have all been identified as potential planetary tipping point. Since the industrial revolution, the wave of animal and plant extinctions that began with the late Quaternary has accelerated. Calculations suggest that the current rates of extinction are 100–1000 times above normal, or background levels. We are in the midst of  the so called “Sixth Mass Extinction”.

Dealing with the transition into the Anthropocene requires careful consideration of its social, economic and biotic effects. In his master book L’Evolution Créatrice (1907), French philosopher Henri Bergson, wrote:  “A century has elapsed since the invention of the steam engine, and we are only just beginning to feel the depths of the shock it gave us.”

 

References:

Will Steffen, Wendy Broadgate, Lisa Deutsch, Owen Gaffney, and Cornelia Ludwig. The trajectory of the Anthropocene: The Great Acceleration. The Anthropocene Review, January 16, 2015 DOI: 10.1177/2053019614564785

Jan Zalasiewicz et al. When did the Anthropocene begin? A mid-twentieth century boundary level is stratigraphically optimal. Quaternary International, published online January 12, 2015; doi: 10.1016/j.quaint.2014.11.045

Smith, B.D., Zeder, M.A., The onset of the Anthropocene. Anthropocene (2013),http://dx.doi.org/10.1016/j.ancene.2013.05.001

Ellis, E.C., 2011. Anthropogenic transformation of the terrestrial biosphere. Philosophical Transactions of the Royal Society A 369, 1010–1035.

 

A Christmas Carol: Dickens and the Little Ice Age

Scrooge's third visitor,  by John Leech. London: Chapman & Hall, 1843. First edition. (From Wikimedia Commons)

Scrooge’s third visitor, by John Leech, 1843. (From Wikimedia Commons)

Charles Dickens was born on 7 February 1812. He had only 31, when began to write A Christmas Carol in September 1843. The book was published on 19 December 1843. The novella tells the story of  Ebenezer Scrooge, a bitter old man who finds salvation through the visits of the three Ghosts of Christmas (Ghost of Christmas Past, Ghost of Christmas Present, and Ghost of Christmas Yet to Come). Dickens divided the story in five “staves”, where he describes the brutal winter and the horrors of social inequality. Scrooge is considered to be the very embodiment of winter: “No wind that blew was bitterer than he, no falling snow was more intent upon its purpose, no pelting rain less open to entreaty.”

Dickens describe the severe weather in many parts of the book: “…and they stood in the city streets on Christmas morning, where (for the weather was severe) the people made a rough, but brisk and not unpleasant kind of music in scraping the snow from the pavement in front of their dwellings, and from the tops of their houses, whence it was mad delight to the boys to see it come plumping down into the road below, and splitting into artificial little snow-storms.

A Frost Fair on the Thames at Temple Stairs by Abraham Danielsz Hondius (Abraham de Hondt), circa 1684 (From Wikimedia Commons)

Dickens grew up during the coldest years of the Little Ice Age, between 1805 to 1820. Many of the Christmas stories that are popular today were written during that period and winter landscapes were commonly depicted by artists like Pieter Bruegel, Hendrick Avercamp,  and Abraham Hondius.

The Little Ice Age (LIA) was a period that extends from the early 14th century through the mid-19th century, during which the Northern Hemisphere suffered from severe and prolonged cold winters. The period between 1600 and 1800 marks the height of the Little Ice Age.

Volcanoes are a possible cause for the LIA. The Tambora eruption on April 10, 1815, released two million tons of debris and  sulphur components into the atmosphere.  The following year was known as “the year without summer”. Charles Lyell describes the eruption in his Principles of Geology: “Great tracts of land were covered by lava, several streams of which, issuing from the crater of the Tomboro Mountain, reached the sea. So heavy was the fall of ashes, that they broke into the Resident’s house at Bima, forty miles east of the volcano, and rendered it, as well as many other dwellings… The darkness occasioned in the daytime by the ashes in Java was so profound, that nothing equal to it was ever witnessed in the darkest night.”

Reconstructed depth of the Little Ice Age varies between different studies  (From Wikimedia Commons)

Reconstructed depth of the Little Ice Age varies between different studies (From Wikimedia Commons)

Dickens revitalized the traditions of Christmas and to Victorian England, Dickens was Christmas. But he also contributed to the popularity of geology with the creation of ideas and images for public consumption, such as he did in Bleak House, with the description of the streets of London where ancient lizards roamed, and volcanoes and quakes shocked the earth.

 

References:

Charles Dickens, A Christmas Carol, Chapman & Hall, 1843.

BOER, de J.Z. & SANDERS, D.T. (2002): Volcanoes in Human History: The Far-Reaching Effects of Major Eruptions. Princeton University Press: 295

Brian M. Fagan, The Little Ice Age: How Climate Made History 1300-1850 (2001), Basic Books.

Buckland, Adelene , ‘“The Poetry of Science”: Charles Dickens, Geology and Visual and Material Culture in Victorian London’, Victorian Literature and Culture, 35 (2007), 679–94 (p. 680).

 

Mignon Talbot and the forgotten women of Paleontology.

 

Sin título

Mignon Talbot  (From Turner et al, 2010)

 

The nineteenth century was the “golden age” of Geology, and women began to play an important role in the advance of this field of science. They collected fossils and mineral specimens, and were allowed to attend scientific lectures, but they were barred from membership in scientific societies. It was common for male scientists to have women assistants, often their own wives and daughters. A good example of that was Mary Lyell (1808–1873), daughter of the geologist Leonard Horner and the wife of eminent geologist Charles Lyell. But for most of men, the participation of women in geology and paleontology was perceived as a hobby.

Mary Anning (1799-1847), was a special case. She was the most famous woman paleontologist of her time, and found the first specimens of what would later be recognized as Ichthyosaurus, the first complete Plesiosaurus, the first pterosaur skeleton outside Germany and suggested that the “Bezoar stones” were fossilized feces. Scientists like William Buckland or Henry de la Beche owe their achievements to Mary’s work. William Buckland himself, persuaded the British Association for the Advancement of Science and the British government to award her an annuity of £25, in return for her many contributions to the science of geology.

Thanks to the pioneer work of these women,the twenty century saw the slow but firm advance of women from the periphery of science towards the center of it. Unfortunately, most of these early female scientists were forgotten and none of them reached the fame of their most illustrious predecessor, Miss Mary Anning.

Podokesaurus holyokensis holotype (From Wikimedia Commons)

Podokesaurus holyokensis holotype (From Wikimedia Commons)

Mignon Talbot was born in Iowa, on August 16, 1869. She studied geology at Ohio State University. In 1904 she received a Ph.D. from Yale and then joined at Mount Holyoke College, where she became Professor of Geology and Geography until her retirement in 1935. During her years at the faculty, she amassed a large collection of invertebrates fossil, but published few technical papers. In 1910, she became the first woman to find and describe a dinosaur: Podokesaurus holyokensis (swift-footed saurian). In 1911, she published a scientific description of the fossil. She wrote: “In a bowlder of Triassic sandstone which the glacier carried two or three miles, possibly, and deposited not far from the site of Mount Holyoke College, the writer recently found an excellently preserved skeleton of a small dinosaur the length of whose body is about 18 cm. The bowlder was split along the plane in which the fossil lies and part of the bones are in o half and part in the other. These bones are hollow and the whole  framework is very light and delicate“.  At the time, she was mentored in her investigation by Richard Swan Lull, who suggested that this dinosaur was insectivorous (although, Talbot identified it as a herbivore at a meeting of the Paleontological Society in December 1910). Unfortunately, in 1916, a fire destroyed the science hall and the only specimen of Podokesaurus holyokensis. She died on July 18, 1950.

Tilly Edinger (Photo,Museum of Comparative Zoology, Harvard University, Cambridge, MA)

Tilly Edinger (Photo,Museum of Comparative Zoology, Harvard University, Cambridge, MA)

Johanna Gabrielle Ottilie  “Tilly” Edinger was born on November 13, 1897 in Frankfurt, Germany. She was the youngest daughter of the eminent neurologist Ludwig Edinger and Dora Goldschmidt. She studied at Universities of Heidelberg, Frankfurt, and Munich. In 1921, she received her Ph. D at the University of Frankfurt. When she was preparing her doctoral dissertation about the palate of the Mesozoic marine reptile Nothosaurus, Edinger encountered a skull with a natural brain cast. Her early research was mostly descriptive and she was influenced by the work of Louis Dollo and Friedrich von Huene. In 1929,  she published Die fossilen Gehirne (Fossil Brains), the book that established Edinger’s membership in the German and international paleontological communities. She briefly worked at British Museum of Natural History after the events that followed the infamous “Kristallnacht” (Night of the Broken Glass). In 1940, with the support of Alfred S. Romer, she moved to Massachusetts to take a position at the Harvard Museum of Comparative Zoology. Shortly after, she was the first and only woman who attend the founding meeting of the Society of Vertebrate Paleontology (SVP). By the early 1950s, she was not only the major contributor to the field of paleoneurology but also the mentor to a younger generation that was following in her footsteps. She died on 27 May 1967 in Cambridge, Massachusetts.

References:

Susan Turner, Cynthia V. Burek and Richard T. J. Moody, Forgotten women in an extinct saurian (man’s) world, Geological Society, London, Special Publications 2010, v. 343, p. 111-153

Buchholtz, Emily A.; Seyfarth, Ernst-August (August 2001), “The Study of “Fossil Brains”: Tilly Edinger (1897–1967) and the Beginnings of Paleoneurology”, Bioscience 51 (8)

Kass-Simon, Gabrielle; Farnes, Patricia; Nash, Deborah, eds. (1999). Women of science : righting the record. Bloomington, Indiana: Indiana Univ. Press.

Talbot, M., 1911, Podokesaurus holyokensis, a new dinosaur of the Connecticut Valley: American Journal of Science, v. 31, p. 469-479

 

The Poetry of the Ice Age.

Joseph Mallord William Turner Source of the Arveron in the Valley of Chamouni Savoy 1816 (Image from The Tate Gallery)

Joseph Mallord William Turner
Source of the Arveron in the Valley of Chamouni Savoy
1816 (Image from The Tate Gallery)

Glaciers occupy a privileged site between narrative and science. Percy Shelley’s “Mont Blanc: Lines Written in the Vale of Chamonix“ (1816) used the landscape as a metaphor to analyze the relationship between the human mind and the universe.

Far, far above, piercing the infinite sky,
Mont Blanc appears,— still, snowy, and serene —
Its subject mountains their unearthly forms
Pile around it, ice and rock; broad vales between
Of frozen floods, unfathomable deeps,
Blue as the overhanging heaven, that spread
And wind among the accumulated steeps.

And of course, Mer de Glace, on the slope of the mountain, is where Victor Frankenstein reunited with his Creature: “…From the side where I now stood Montenvers was exactly opposite, at the distance of a league; and above it rose Mont Blanc, in awful majesty…. The sea, or rather the vast river of ice, wound among its dependant mountains, whose aerial summits hung over its recess….” (Mary Shelley, Frankenstein, 1818)

Johann Wolfgang von Goethe,  one of the world’s greatest poets, was also a great naturalist. More important, he was the very first to believe in an ice age. Jean de Charpentier (1786- 1855)  in Essai sur les glaciers presented Goethe’s theories of glacial transport (Charpentier, 1841, p . v).

Jean Louis Agassiz in 1870 (From Wikimedia Commons)

Jean Louis Agassiz in 1870 (From Wikimedia Commons)

In 1837, Karl Friedrich Schimper, a  German botanist and geologist, wrote a poem to commemorate Galileo’s birthday, Die Eiszeit: fur Freunde gedruckt am Geburtstage Galilei.  The expression Eiszeit—“ice age”— appeared for the first time in this poem. One of its stanzas says:

Last vestige of the primal ice,
more ancient than the Alps!
Primal ice of yore, when the might of frost
buried mountain high even the South,
enveloped mountain and sea alike!

Karl Schimper was born in Mannheim, Germany, on February 15th, 1803. During the summer of 1835, he was studying mosses which were growing on erratic boulders in the alpine upland of Bavaria and came to the conclusion that ice must have been the means of transport for the boulders.

Based on the works of Schimper and de Charpentier,  Louis Agassiz (1801–1873) presented his “Discours de Neuchatel,” at the annual meeting of the Swiss Society of Natural Sciences on July 24, 1837. In this seminal work, he proposed that the Earth had been subject to a past ice age.

References:

Kate Flint, The Victorians and the Visual Imagination, Cambridge University Press, 2000.

Tobias Krüger, Discovering the Ice Ages: International Reception and Consequences for a Historical Understanding of Climate, BRILL, 2013.

Women in the Golden Age of Geology in Britain.

A sketch of a Plesiosaur by Mary Anning, 1824.

A sketch of a Plesiosaur by Mary Anning, 1824. From original manuscripts held at the Natural History Museum, London. © The Natural History Museum, London

The nineteen century was the “golden age” of Geology. The Industrial Revolution ushered a period of canal digging and major quarrying operations for building stone. These activities exposed sedimentary strata and fossils. So, the concept of an ancient Earth became part of the public understanding and Literature influenced the pervasiveness of geological thinking. The study of the Earth became central to the economic and cultural life of the nation and in 1807, the Geological Society of London is founded with the purpose of making that geologists become familiar with each other, adopting one nomenclature and  facilitating the communications of new facts.

The most popular aspect of geology was  the collecting of fossils and minerals and the nineteenth-century geology, often perceived as the sport of gentlemen,was in fact, “reliant on all classes” (Buckland, 2013). Women were free to take part in collecting fossils and mineral specimens, and they were allowed to attend lectures but they were barred from membership in scientific societies. It was common for male scientists to have women assistants, but most of them went unacknowledged and become lost to history (Davis, 2009). However, some women found the way to cross that line and make a name in Geology.

Mary Elizabeth (née Horner) Lyell, (1808–1873), wife of Sir Charles Lyell, by Horatio Nelson King © National Portrait Gallery, London, and Mary Ann (née Woodhouse) Mantell (1795–1869), wife of Dr. Gideon Mantell, © 2014 The Natural History Museum.

Mary Elizabeth (née Horner) Lyell, (1808–1873), wife of Sir Charles Lyell, by Horatio Nelson King © National Portrait Gallery, London, and Mary Ann (née Woodhouse) Mantell (1795–1869), wife of Dr. Gideon Mantell, © 2014 The Natural History Museum, London.

The early female scientists belonged to wealthy families or they benefited from their associations. In the first group we could find Etheldred Benett of Wilshire (1776–1845), she described the stratigraphic and geographic distribution of fossils of Wiltshire. Although she was not formally published, Benett wrote several manuscripts, which are now in the collections of the Geological Society of London.

Barbara Rawdon (née Yelverton) Hastings (1810–1858), 20th Baroness Grey de Ruthyn and Marchioness of Hastings was known as a fossil collector and a “lady-geologist” . She is also well known for the “Hastings Collection,” consisting of several thousand fossil specimens from England and Europe. She also studied the stratigraphy of England and published her findings in “Description géologique des falaises d’Hordle, et sur la côte de Hampshire, en Angleterre” (Hastings, 1851–52) and “On the tertiary beds of Hordwell, Hampshire” (Hastings, 1853).

The Philpot sisters (Margaret, ?–1845; Mary, 1773?–1838; Elizabeth, 1780–1857) were also well know for their fossil collection and their friendship with Mary Anning. They lived in Lymes Regis and amassed an important collection of fossils from the Jurassic. Elizabeth maintained correspondences with William Buckland, William Conybeare, Henry De la Beche, Richard Owen, James Sowery and Louis Agassiz.

Skull of Crocodilus hastingsiae named by Sir Richard Owen, in honor to Barbara Hastings. Image from Wikimedia Commons.

Skull of Crocodilus hastingsiae named by Sir Richard Owen, in honor to Barbara Hastings. Image from Wikimedia Commons.

In the other group we could find those women who worked with their husbands. The most prominent of these women were Mary (née Moreland) Buckland (1797–1857), wife of Rev. William Buckland; Mary Ann (née Woodhouse) Mantell (1795–1869), wife of Dr. Gideon Mantell; Charlotte (née Hugonin) Murchison (1789–1869) wife of Sir Roderick Murchison; and Mary Elizabeth (née Horner) Lyell (1808–1873), wife of Sir Charles Lyell (Davis, 2009).

Mary Morland (1797–1857) illustrated some of George Cuvier’s work before she became Mrs William Buckland. She made models of fossils for the Oxford museum and repaired broken fossils. She assisted her husband by taking notes of his observations and illustrating his work. After the death of her husband, she continued working on marine zoophytes.

Charlotte Murchinson (1789–1869) was a strong influence for her husband and introduced him in the world of geology. She accompanied him on excursions and spent time sketching the  landscape and outcrops and collecting Jurassic fossil specimens from the beaches.

Mary Mantell (1795–1869) discovered the teeth of Iguanodon, which led to her husband’s publication of an important paper announcing the discovery of a new giant reptile (Creese and Creese, 1994). She also made the illustration of Mantell’s work: “Fossils of the South Downs: or Illustrations of the Geology of Sussex”. Mary Mantell left her husband in 1839 and the children remained with their father as was customary.

Mary Lyell (1808–1873) was daughter of the geologist Leonard Horner. She read both French and German fluently and translated scientific papers for her husband and managed his correspondence. She later specialized in conchology and regularly attended meetings of the London Geological Society.

Megalosaurus' jaw and teeth drawn by Mary Buckland. © Paul D Stewart / Science Photo Library

Megalosaurus’ jaw and teeth drawn by Mary Buckland. © Paul D Stewart / Science Photo Library

Mary Anning (1799-1847), was an special case. Despite her lower social condition and the fact that she was single, Mary became the most famous woman paleontologist of her time. She found the first specimens of what would later be recognized as Ichthyosaurus, the first complete Plesiosaurus, the first pterosaur skeleton outside Germany and suggested that the “Bezoar stones” were fossilized feces.

Fighting in their own way against the difficulties, women had contributed significantly to the development of geology and paleontology. Fortunately, geoscientists and historians are rescuing these woman from oblivion.

References:

BUREK, C. V. & HIGGS, B. (eds) The Role of Women in the History of Geology. Geological Society, London, Special Publications, 281, 1–8. DOI: 10.1144/SP281.1.

Davis, Larry E. (2009) “Mary Anning of Lyme Regis: 19th Century Pioneer in British Palaeontology,” Headwaters: The Faculty Journal of the College of Saint Benedict and Saint John’s University: Vol. 26, 96-126.

Buckland, Adelene: Novel Science : Fiction and the Invention of Nineteenth-Century Geology, University of Chicago Press, 2013.