The Great Leap Forward and soil erosion

"dal letame nascono i fiori,
dai diamanti non nasce niente"
"from dirt flowers are born,
from diamonds nothing comes"
"Via del Campo" by Fabrizio de André (Italian poet-musician)

In Geology soils are defined as the uppermost layer or substratum of earth, it supports most of the plant life and is therefore also essential for all heterotrophic life. Soils are the results of complex interactions between the biosphere-atmosphere-lithosphere and hydrosphere over long periods of time - oversimplifying the remains of the weathering of rocks enriched by organic debris.

Soil degradation and erosion was and still is one of the major threats to soil quality and function. Erosion is a natural process; however human influence and mismanagement can significantly increase the velocity and extent of this process. Unprotected soil can be rapidly eroded by wind or washed away by running water - logging, overexploitation, monocultures can damage, even destroy the plant cover protecting the soil. Irrigation and processing can condense the soil or modify its chemistry. The collapse of many civilisations in the past was triggered by the erosion and degradation of soil, followed by decrease in the agricultural production and widespread famine and death. Even in the 20th century humans - mainly politicians - made such errors leading to terrible consequences for the entire population.

The areas of China covered with Loess are characterized by very fertile soils. For millennia such soils were cultivated by farmers. However, this yellowish, fine-grained, carbonate-rich aeolian sediment is very vulnerable to erosion by wind and water.
Near the small village of Westeregeln (Thuringia, Germany) past quarrying activity has exposed Mesozoic gypsum and limestone formations, covered by Pleistocene sediments. The uppermost part of the stratigraphy is represented by a postglacial soil developed on Loess - a sediment deposited during the last glacial period. Note the secondary infillings of the burrows of animals and the different colors of the horizons of the soil.

The rise of the communistic party under the leadership of Mao Zedong in China after 1966 had a profound impact on society and the environment - it caused one of the greatest humanitarian catastrophes in modern times and effects are still visible in modern China. Inspired by the apparent success of the U.d.S.S.R. under Stalin the Chinese party intended to transform in only few years the rural agriculture economy into a socialistic power - The Great Leap Forward - (as envisaged in the propaganda poster at the top of this post, displaying the production of grains skyrocketing) - following a strange mix of science, personal opinions and pseudoscientific claims, like these formulated by Trofim Denissowitsch Lyssenko, one of the leading agriculture scientists of Stalin's regime.

A preliminary 5-year plan was adopted in the years 1953 to 1957, consisting of a complex pattern of logging and reforestation - in only few months estimated 10% of China's forests were transformed into farmland. To increase the production of iron simple backyard furnaces were constructed, the increased demand for fire-wood led to an even faster deforestation and subsequent soil erosion. Heavy equipment, as used on the cultivated fields in the Russian plains, lead to tillage erosion on the slopes and in the soft soils of the Loess Plateau.

In the years 1957/1958 a second, even more ambitious plan for the next 12-years was adopted - with even more catastrophic effects.
Farmers should plant 12 to 15 million plants per hectare instead of the previous 1.5 million, Mao thought that plants would grow better in a large collective - as results of this overexploitation and the concurrence for light and nourishments most plants in fact died. Plant species ill-suited to the local soils and climate were planted on large areas - especially maize (Zea mays mays). The dense root system of this grass species tends to seal off the soil, water can no longer infiltrate and the upper part of the soils get cloaked by mud particles, limiting the diffusion of oxygen into the soil and finally heavily damaging the growing plants.
The construction of dams and canals modified the catchments of rivers and the hydrology of entire regions; this lead to widespread erosion of the fertile soil and reservoirs became clogged with sediments and could no longer provide water.

The resulting decrease in agricultural production lead to a terrible period of starvation in the years 1958 to 1961, estimated 40 to 30 million people died in this period. Extremist Mao Zedong and many of the leadership of the communistic party ignored, however, the facts and affirmed instead that the famine was the result of saboteurs or opposing political forces - a fiercely which-hunt to find a scapegoat was initiated. Only in 1962, the reformations were taken back and the situation improved.
Despite the disastrous results other communistic countries, like Cambodia, Ethiopia and North Korea, adopted questionable agricultural methods during the 20th century, with similar results.

Soil degradation and erosion are still major problems in modern China., Nineteen percent of the area of the country is still affected, but also in many other industrialized countries of the world soil has become a valuable resource on the global market. China and India are buying or renting large areas in underdeveloped countries. This solution is however problematic, considering that the food production in many of the involved countries is not capable to sustain even their own population.

China´s today politics is an example of a conflict of interests similar to all developed countries. It invests in reforestation, conservation areas and environmental protection. However, at the same time, industry and the increasing population demands for further land use and resources.


BORK, H.-R. (2006): Landschaften der Erde unter dem Einfluss des Menschen. Wissenschaftliche Buchgesellschaft, Darmstadt: 207

John "Jack" Walter Gregory and the Great Rift Valley

John "Jack" Walter Gregory was born in London in the year 1864. Already in early age his interest in natural sciences and travels emerged - during his later career he will visit Europe, Africa, Australia, India, North- and South America, even the remote island of Spitsbergen.
His interest in geology spawned from the practical need to know where he actually was:

"… my attention was first directed to geology in order to understand the geography of the districts through which I rambled, and the, often, apparently erratic course of the rivers … and to understand local topography'."
Gregory in 1906

He studied natural sciences, working during day as wool merchant and studying at night - he even became accustomed to sleep only 4 hours per day. After graduation he found work at the British Museum for Natural History, where he worked on the collection of rocks, fossil echinoderms and corals.
In October 1892 Gregory was asked if he would take on an expedition to East Africa, comprising the area of today Kenya, Ethiopia and Somalia - regions at the time still poorly known or mapped, but geopolitically important.

Gregory however showed interest in the geology of Africa long before the possibility to join the expedition, impressed by the hypothesis of Austrian geologist Eduard Suess.
The origin of the mountains and depressions of the African continent were fiercely discussed by geologist, Suess summarized in 1891 the results of an expedition leading to Lake Rudolf, carried out by Count Samuel Teleki (de Szek) (1845-1916), and suggested that the depressions starting at the coasts of the Red Sea were the results of periodic tectonic movements.

Fig.1. "The Great Rift Valley: some associated fractions are marked by broken lines." The part of the valley system explored by Gregory in 1892-1893 (located east of Lake Victoria) is today also referred as Gregory Rift (GREGORY 1920).

20, November 1892 the ship of the expedition unloaded 300 tons of equipment in the harbour of Lamu, 110 camels and 40 donkeys were acquired to transport the material and 300 soldiers were hired to protect the caravan - planned destination of the expedition was Lake Rudolf, a destination that they however would never reach.
Despite the 300 tons of equipment soon problems arouse - food went bad and cooking pots and tents were missing or unsuitable. Fever and various diseases spread among the expedition members, Gregory was first plagued by ulcers on the legs that immobilized him for weeks and on 17, January 1893 he fell sick with malaria. He recovered only after days with very high fever - arrived to Mombasa the expedition was officially cancelled.
Gregory, still interested to see for himself the depressions of Central Africa, decided to take advantage of the situation. He was already in Africa and the equipment of the abandoned expedition could still be usefull - with the financial help of his family and the British Museum he organized a new expedition. On 23, March 1893 the expedition comprising this time 41 men left Mombasa. Gregory's old peculiarities emerged; he loved to walk alone for kilometres, collecting specimens of plants, animals and rocks, for most of the time he didn't sleep at night, sneaking trough the camp controlling if the sentries were on duty.

"… the geology was so tempting that I went off alone. By this time the men were accustomed to my going by myself, for I did so whenever the country was safe and the next camping-place easy to find. These solitary rambles were to me the most delightful incidents in the expedition. Free from the bother of the caravan, I could climb a mountain, track a river, visit a neighbouring lake, chase butterflies, and collect plants as careless as a schoolboy."
Gregory 1896

The main geological work was carried out from the village of Njemps on the shores of Lake Baringo, where they mapped the geology of the western wall of the Kamasin Scrap - today recognized as part of the Great Rift Valley. Gregory confirmed Suess interpretation of the tectonic origin of this valley and deduced from the weak erosion seen on the mapped faults that this process must have been very recent. He described his discoveries in an article published in the journal of the Royal Geographical Society in 1920, where he coined also the modern term of Rift Valley and connected it to tectonic movement of the earth (a controversial hypothesis at the time, when most landscapes were regarded as results of erosion).

Fig.2. Geological sketch map of British East Africa (Kenya) showing the locations of Lamu Island, Witu, Mombasa, Lake Baringo and Mount Kenya, all visited by Gregory in 1892 and 1893, plus an outline of the Rift Valley (GREGORY 1896).

Fig.3. Section across the Rift Valley (GREGORY 1896), F=faults, Gregory suggested that the faults, forming the characteristic elements in the section of the rift valley, were due to vertical movements - apparently also Scar from "Lion King" is singing in an area with active tectonic uplift…




"For this type of valley I suggested the term Rift Valley, not implying that the whole valley was formed by the two sides being simply pulled apart, but as a breach due to a subsidence between two series of rents."
GREGORY 1920

Gregory connected the African Rift Valley with the similar Red Sea in the north - the dimensions of this feature surprised him, clearly that was a mayor element of earth's crust, connected to mountain ranges and similar basins found around the globe. He proposed that the magmatic rocks filling the African rift erupted during the Tertiary from the lateral shear zones, evidence of vertical, rather than horizontal movements - before the advent of continental drift a common model for global tectonics.

Gregory visited also Mount Kenya, even if - despite his alpine climbing experience - he was not able to reach the summit. Here he mapped the moraines of the glaciers and noted that they had retreated previously to 1893 to their "actual" position. Mount Kenya was conquered by Sir Halford Mackinder in 1899, who also named one of the glaciers found on the mountain - Gregory Glacier.

Fig.4. Reproduction from his 1896 book of a view of Gregory and an African climbing on Mount Kenya.

Bibliography:

GREGORY, J. W. (1920): The African rift valleys. The Geographical Journal, Vol. 56 (1): 13-41
GREGORY, J. W. (1896): The Great Rift Valley: being the narrative of a journey to Mount Kenya and Lake Baringo : with some account of the geology, natural history, anthropology and future prospects of British East Africa. John Murray, London: 500
LEAKE, B.E. (2011): The Life and Work of Professor J.W. Gregory FRS (1864-1932). Geological Society Memoir, No. 34: 234

A geologist riddle #20

A new riddle - this following engraving shows a particular place visited during an expedition, the leader of this particular expedition coined also a term that today all geologists and anthropologist know well - who was this leader?

P.S. try also your keen sense of deduction on this georiddle...

Geology of Beer

There were some major changes on this blog latterly - not only now it displays a very professional layout, but more importantly "History of Geology" is now part of the awesome "Field of Science Blog Network" - many thanks to Edward Michaud for the invitation and the possibility to join.

This event has to be celebrated by combing two of the most important topics dear to geologists, one of them also appreciated by all non-geologists and essential for almost all celebrations.

It is considered one of the oldest foods and most appreciated beverages of the world - chemical remains were found on fragments of a more than 4.000 old jar, the Mesopotamians guaranteed its purity with a law that threatened with death whoever manipulated the traditional recipes and the old Egyptian considered it an essential part of the afterlife, it was the beverage of the gods of the Vikings - and today of geologist - known also as beer.



The quality of a beer, produced by the fermentation of an extract of cereal grains, comprises five factors: the flavour, alcohol content, colour, head retention, and clarity. These factors depend strongly from the used ingredients - one of the most important is water and the quality of water depends strongly from the geology and hydrology of the tapped spring.

"The enjoyment of a glass of beer may be received by many senses: the sight may be attracted first by the clarity of a pale ale or the rich creamy head of a stout.
As the glass is raised to the lips the aroma of the bever age, possibly the bouquet of the essential oils of the hops, may excite the nostrils. Then, as the liquid flows over the taste buds at the back of the mouth, and further volatile products diffuse into the back of the nose, the flavour of the beverage is perceived. Finally, the beer enters the body, where the alcohol is rapidly absorbed into the bloodstream and exerts its well known physiological and psychological effects."
Anonymous source

The brewing process involves great quantities of water and many breweries possess or profit from private springs or wells, referring even to the water quality or purity in their advertisements. In medieval times beer was a more trusted beverage than river water.

Natural waters contain mainly four cations particularly significant for the brewing process, calcium, magnesium, sodium and potassium.
Calcium stabilize the enzymes used by the yeast to breakdown the starch, it also precipitates phosphate - also present in water - correcting the acidity of the water and supporting microbial activity.
Magnesium has a similar effect and also controls the phosphate content of the mash - however to much Magnesium will give the beer a bitter taste.
Sodium and potassium in to great concentration can ruin the taste of the beer, and more importantly have a laxative effect on the heavy drinker.

In areas dominated by Carbonate rocks - with springs high in content of calcium and magnesium - the control of the pH of the water and mash is one of the major problems. The low pH resulting makes only relatively sweet beers possible, even if by selecting carefully other ingredients still variation is possible - one bad luck of the Irish, with an island dominated by Carboniferous limestone. However the chemistry of the water made it possible to brew a particular porter and a well-known stout of Dublin

Also the content of anions of the water influence the final product.
Sulphate, deriving from evaporitic rocks, can give a beer a desired bitter flavour by supporting the release of bitter oils from the used hops and reacting with magnesium to produce magnesium sulphate - a bitter tasting salt.
Also springs with high contents of chloride and sodium (deriving from salt deposits) give a salty to bitter flavour - however in the correct proportions the sweetness of the chloride ion can prevail - causing the taste of the unique classic ale.

Regions dominated by sandstone and Palaeozoic or Precambrian metamorphic rocks have waters with low contents of dissolved minerals and ions, this causes often a less distinct flavour, therefore the beer has to be ferment for longer time, this also increments the alcoholic content of a beer.
Pils and lager, classic beers from Central Europe, received their name from the traditional storage and fermentation of the beer in cold caves.

Today, with the advent of effective water pumps and transfer of water over long distances, the role of local geologic conditions is less important than in the past. Many wells or springs - especially in industrialized areas or regions with intense agriculture, are today also contaminated with pollutants or overexploit. Some modern breweries are using water that was previously deionized and subsequently customized to a desired chemical composition- with the advantage of hygiene and better quality control.

So in the end - enjoy your beer like a geologist and remember: Now that you know how complicated it is to brew a good beer, do not waste it and drink with moderation - especially don't Drink and Drive!

Bibliography:

CRIBB, S.J. (2005): Geology of Beer. In Selley, R.C.; COCKS, L.R.M. & PLIMER, I.R.: Encyclopedia of Geology: Elsevier Academic Press: 78-81

It’s sedimentary, my dear Watson

On February 20, 1949 Mrs. Henrietta Helen Olivia Roberts Durand-Deacon, a sixty-nine-year-old wealthy widow, disappeared from the Onslow Court Hotel located in South Kensington, London. The police interviewed the residents and soon forty year-old John George Haigh became a suspect, as he was the last person to have seen the woman alive and was known already to the police for crimes of fraud and thievery. 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.
“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 did ignore one important fact in his euphoria – that the law doesn’t require a body to incriminate him – it requires a corpus delicti- the evidence that a murder happened - as for example a strange pebble.

Online Ressources:

CHESELDEN, W. (1733): Osteographia, or The anatomy of the bones. - Fig.1.Frontispiece

Dorothea Bate: the great lady of island palaeontology

"Outside the harbour of the country, neither very near it nor very far from it, there is a small well-wooded isle . . . it remains unploughed and unsown perpetually, empty of men, only a home for bleating goats. For the Kyklopes possess no ships; they build no vessels to serve their needs, to visit foreign towns and townsfolk as men elsewhere do in their voyages."
The "Odyssey" after Homer (800 BC), translation after Walter Shewring (1980)

Dorothea Bate was born in Carmarthen in South Wales in 1878, the second of three children in a family of a rural countryside. Her father encouraged her interest in the collection of natural artefacts and she absolved the regular school, but despite their enthusiasm there was not the possibility of higher education. In 1898, at age 19 the family of Dorothea moved to Gloucestershire, a region with many caves in the surrounding limestone formation. At this time in Dorothea emerged also an interest in palaeontology.

Fig. 1. Dorothea Bate, drawing by her sister Leila Luddington probably in 1906. It was probably painted during the 5 years when her parents refused to allow her to travel abroad, from SHINDLER 2007.

Dorothea decided to approach the British Museum in London and to ask for a job. Surprised by such ardour she was taken to the curator of the collection of birds. Dr. Richard Bowdler Sharpe was at first not too enthusiastic of this decision, not only he mistrusted the young women, but especially women were not employed at all by the British Museum. But her knowledge of bird taxonomy soon impressed him and doubts vanished.

In one of the caves of Gloucestershire she discovered, during a private excursion and helped by local miners, cave deposits with a large quantity of small bones. She extracted the bones from the sediments and contacted the vertebrate palaeontologist at the British Museum.
The fossils of small rodents from the last ice age discovered in "Merlin's Cave" was considered so exceptional that she was encouraged to publish her research "A short account of a bone cave in the Carboniferous limestone of the Wye Valley" (1901) in the prestigious Geological Magazine.

In the same year another exceptional occasion arose, she was invited to pass some time by friends on the British controlled island of Cyprus, in 1904 she visited also Crete. Despite fossils were already known to occur on these islands, little was known about the animals these remains represent.
In 1528 the Italian astronomer and cartographer Benedetto Bordone mentions in his "Isolario", a book describing all the islands and their peculiarities known at the time, entire mountains made of bones of animals and humans.
In his "Chronicle of Cyprus", written previously of 1555 by the Cypriot historian Leontios Machairas, he mentions petrified bones, supposedly from ancient catholic martyr.
Cuvier described in 1804 and 1824 various fossil hippopotami, one species was a pigmy hippopotamus named Phanourios minor, thought to come from French deposits it was later recognized to be identical to "pig" material send from Cyprus by Dorothea Bates to Charles Forsyth Major at the museum of Paris.
In the second half of the 19th century various expeditions were financed to collect fossils on the various islands of the Mediterranean Sea.

Apart these information's, the fossil sites described by previous researchers were still difficult to reach in the early 20th century - there were for example no harbours for larger ships in Cyprus, streets were rare and much rarer were accommodations for the few tourists venturing inland.
But Dorothea was not afraid of obstacles; walking, riding and swimming she visited various previously described caves and managed to discover new fossil bearing caves with a rich fossil fauna: various strange endemic species, bones of elephants, various deer (in 1904 Bate will also discover in a cave on Crete the fossil bones of an endemic Cretan deer Candiacervus) and rodents (Mus minotaurus, also from Crete).
Most intriguing were species resembling animals of the mainland, but significantly different in their size - like dwarf elephants new to science - Elephas cypriotes and Elephas creticus - or the dwarf Hippopotamus minutus and a extinct dormouse Hypnomys morpheus much larger than the specimen previously known. Dorothea recognized this trait of size differentiation was peculiar to island faunas and that it had affected various, very different groups of mammals.

Dorothea returned to England, where she, not entirely voluntarily, stayed for the next 5 years, as unmarried daughter she had to keep company to her parents. After this time-out she travelled to the Balearic Islands and continued her research on island faunas.
Here she discovered and described in 1909 one of the strangest fossil mammals ever to be found - the "mouse goat" Myotragus balearicus (also referred as rat-like goat, cave goat or antelope-gazelle, emphasizing his strange morphology).

Fig.2. Dorothea Bate's photograph of the "Coves dels Coloms" in northeast Majorca, one of the cave sites where she discovered fossil remains of Myotragus, from SHINDLER 2007.

Fig.3. Skeleton of Myotragus balearicus.

Myotragus was a bulky animal, with legs situated wide apart, the eyes were directed more to the front, not as usual in artiodactyls to the side - probably all adoptions to better climb steep cliffs and jump distances. But the most peculiar characteristic were just two, enormously enlarged and continuously growing rat-like incisors in the lower jaw.

Despite her scientific success, between 1903 and 1914 she published 15 papers dealing with insular faunas, she had to finance her entire research for most time privately and money was always a problem - she couldn't also become a scientific staff member of the museum, as this was forbidden for women until 1928.
Only in 1948, with 70 years, she was given official employment and managerial responsibility of the Natural History Museum at Tring (50km from London). She died on 13, January 1951, working until just before her death.

Various species of fossil island mammals were dedicated to Dorothea Bate:

Cervus dorothensis - Capasso Barbato (1992)
Mus bateae - David Mayhew (1977)
Myotragus batei - Crusafont Pairo and Basilio Angel (1966)

Bibliography:

GEER, A.v.d.; LYRAS, G.; VOS, J.d. & DERMITZAKIS, M. (2010): Evolution of Island Mammals - Adaption and Extinction of Placental Mammals on islands. Wiley-Blackwell: 479+26 plates
SHINDLER, K. (2007): A knowledge unique: the life of the pioneering explorer and palaeontologist, Dorothea Bate (1878-1951). In BUREK, C. V. & HIGGS, B. (eds) The Role of Women in the History of Geology. Geological Society, London, Special Publications 281: 295-303

History of Paleomammology: The sabre-toothed moonrat from the island of the sabre-toothed prongdeer

In 1969 a team of palaeontologists, Cornelis Beets, Hendrik Schalke and Matthijs Freudenthal from the Dutch Rijksmuseum van Geologie en Mineralogie from Leiden, discovered and excavated various fossil lagerstätten in the fissures of the Mesozoic limestone of the Gargano promontory, exposed by the intense quarrying activities in the area. For three summers the team, aided also by other researchers from all over Europe, searched the red clays for bones and teeth of rodents, insectivores and artiodactyls.
One of the most intriguing specimens of the endemic fauna recovered was a large insectivore mammal, described in 1972 by Freudenthal as Deinogalerix and attributed to the family of the Erinaceidae, which includes modern hedgehogs and the moonrats.

Fig.1. The fossil material of Deinogalerix is actually composed by two sub-complete skeletons and hundreds of isolate teeth and bones, the first one was found in 1969 and is hosted today in the Nationaal Natuurhistorisch Museum of Leiden (from VILLIER et al.2009).

Moonrats today include only 7 species found in South-east Asia; they are large, ratlike animals lacking the characteristic spikes of the common hedgehogs - they most probably resemble best how the extinct Deinogalerix look alike.
However Deinogalerix displays the usual unusual characteristics of endemic mammals of islands - in contrasts to related fossil or recent mainland species it was a very large animal - 9 kilograms (this is a 2 kg rat of the the genus Mallomys, endemic to Indonesia) heavy and 60 centimetres long - not including the stumpy tail - with 20 centimetres skull - one of the largest insectivore known and the name emphasize the astonishment of the researchers realizing how large this strange animal was - they named it "terrible mouse".

Fig.2. and 3. Fragments of a left maxilla with three molars and of a right mandible with five molars of Deinogalerix compared to the respective bones of a modern hedgehog.

Various species (even if some of dubious taxonomic value and representing a possible sexual dimorphism) are described, all descending from the earliest known genus Parasorex originally of Asiatic origin: D. freudenthali, D. brevirostris, D. minor, D. intermedius and D. koenigswaldi - the last and biggest species of the genus.

Fig.4. The skulls of D. koenigswaldi and D. brevirostris compared to two actual species of insectivores: Echinosores gymnura (moonrat) and Erinaceus europaeus (hedgehog) (from VILLIER et al.2009) - for the size of the largest species - D. koenigswaldi - see also this reconstruction by artist M. Anton and for the impact on pop-culture also this alternative reconstruction...

Based on its size of D. koenigswaldi early research suggested that the dull animal was a scavenger, the dentition suggest however that Deinogalerix was an active predator, hunting insects, and helped by its size, also small vertebrates.
The former of island of Gargano lacked population of large carnivores, with the exception of rare fossil of crocodiles, an otter (Paralutra garganensis) and more common bird of preys no fossil evidence of active predators was discovered. Deinogalerix had therefore little competition to fear and over geologic time occupied the niche as one of the apex predators of the Gargano island environment.

Fig.5. and 6. "The exact nature of the species to which the above mentioned fossil remains belong was at first quite dubious: there are molars which on a superficial view might be attributed to an artiodactyl, premolars that might conceivably indicate a carnivore, and large caniniform incisors, all of them together in a skull over 20 cm long." FREUDENTHAL 1972
Skull reconstruction from VILLIER et al.2009, upper premolar from Deinogalerix from the "Red Clays" of Gargano.

The peculiar fauna of the Gargano was considered an isolated and endemic fauna, however in 1999 a fragmentary maxilla with the characteristic teeth of Deinogalerix freudenthali was found in the ossiferous breccia of Scontrone, a village of today Central Italy. This discovery suggests a paleogeographic connection, maybe trough an episodic land bridge or smaller islands of the island of Gargano to the European mainland.

Bibliography:

AGUSTI, J. & ANTON, M. (2002): Mammoths, Sabertooths, and Hominids - 65 Million Years of Mammalian Evolution in Europe. Columbia University Press: 313
FREUDENTHAL, M., (1972): Deinogalerix koenigswaldi nov. gen., nov. spec., a giant insectivore from the Neogene of Italy. Scripta Geologica 14: 1-19
GEER, A.v.d.; LYRAS, G.; VOS, J.d. & DERMITZAKIS, M. (2010): Evolution of Island Mammals - Adaption and Extinction of Placental Mammals on islands. Wiley-Blackwell: 479+26 plates
VILLIER, B.; OSTENDE, H. & PAVIA, M. (2009): Deinogalerix: a giant hedgehog from the Miocene. Poster-Abstract Giornate di Paleontologia IX Edizione - Apricena (FG), 28-31 maggio 2009.

Online Resources:

Anonymous (): Age of Mammals - Deinogalerix. (Accessed 11.07.2011)
Tupaia (17.01.2011): L’incredibile fauna dell’isola del Gargano, arcipelago Puglia. (Accessed 09.07.2011)

8, July 1836: Darwin on St Helena

The HMS Beagle, with on board the amateur naturalist Charles Darwin, arrived at the remote island of St Helena on July 8, 1836, where it stayed until noon of July 14, afterwards proceeding its journey back to the United Kingdom and setting sails to the nearby island of Ascension.
Darwin used these five days to explore the geology of the island and hired an elderly man as a guide. Since Van Diemen´s Land Darwin's written notes and observations had become more hasty and fragmentary - as a combination of the short stops by the Beagle on the single islands and maybe a bit of homesickness, nevertheless Darwin dedicated later one of his notebooks, written down in September to December 1938, to the island, the "St Helena Model", where he on 15 pages noted observations and thoughts on the general island geology (and also troubles with the laundry).
As already on the island of St. Jago Darwin noted various geological evidence that the island had risen from the sea in an outcrop of basaltic rocks:

"The successive sheets are either closely united together, or are separated from each other by beds of scoriaceous rock and of laminate tuff, frequently containing well rounded fragments. The interstices of these beds are filled with gypsum and salt; the gypsum also, sometimes occurring in thin layers. From the large quantity of these two substances, from the presence of rounded pebbles in the tuff, and from the abundant amygdaloids, I cannot doubt that these basal volcanic strata flowed beneath the sea."
DARWIN (1844) "Geological Observations on the volcanic islands and parts of South America visited during the Voyage of H.M.S. "Beagle"." 75-76

Fig.1. A section trough the coastline of St Helena by the hands of Charles Darwin (dated 15 September 1838), from CHANCELLOR 1990.

At the time the origin of volcanoes as mountains was under scrutiny, one model - proposed by the eminent German geologist Leopold von Buch (1774-1835) - stated that volcanoes form like a bubble: first geologic forces upraise the ground and form the mountain, the summit collapses, forming the steep crater walls, finally the magma can spout trough the surface, causing an eruption. Lava flows or ash layers where therefore a secondary feature of volcanoes, not the "construction material" of the volcanic complex. This "crater of elevation" hypothesis was very popular at the time and supported by most European geologists. Two French geologists, Armand Dufresnoy (1792-1857) and Léonce Elie de Beaumont (1798-1874), tried even to prove mathematically that continuous lava flows can form only on surfaces with an inclination less than 6°, according to their calculations on steeper surface a flow start to disintegrate, and as most observed lava flows were however steeper, this observations could only be explained by the surface of the volcano steepen over time.

Fig.2. Topographic map of the Canary Island published by von Buch in 1814 in his book "Description physique des lles Canaries, suivie dúne indication des principaux volcans du globe." Von Buch assumed that the radial valleys, descending from the central summit, are fissures caused by the inflation and uprising mountain - in fact these valleys are formed by the erosion of the volcanic rocks.

Darwin did not share entirely this vision of uprising volcanoes; in part the model proposed very fast rates of elevation and Darwin was more inclined to follow the gradual geology as proposed by Charles Lyell - Lyell himself refused the "crater of elevation" hypothesis outright.
Darwin addressed the problem only superficially: he used the observations on St Helena to formulate an intermediate hypothesis, volcanoes rise by slow, gradual and episodic events, he also suggested that more research was necessary to map and determinate the inclination of lava flows.

In 1850 Lyell demonstrated on a lava flow of Mount Etna that the lava solidified on a slope inclined by 35° - the "crater of elevation" hypothesis had lost one of its most important arguments and Darwin left behind the hypothesis of inflating volcanoes.

Bibliography:

CHANCELLOR, G.R. (1990): Charles Darwin's St Helena Model Notebook. Bull. Br .Mus. Nat. Hist. 18(2): 203-228
HERBERT, S. (2005): Charles Darwin, Geologist. Cornell University Press: 485
KRAFFT, M. (1993): I vulcani - il fuoco della terra. Universale Electa-Gallimard: 191

The discovery of the periglacial realm

The term periglacial was introduced by the Polish geologist Walery von Lozinsk in 1910 and 1911 to describe the particular mechanical weathering he had observed in sandstones of the Gorgany Range in the southern Carpathian Mountains - today the reactions of the permafrost to changing temperatures is one of the major fields of research. Read more about the periglacial realm on the American Scientific Blog.

History of Geology is no more...

...only to be found on this Blog.

I am delighted to announce that a new History of Geology Blog is now part of the awesome Blog Network by Scientific American, launched today - lots of science and a bit of geology !

Stay tuned for further developments on both the new and old Blog, there will be many further thoughts on pebbles to be shared !