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.

From the Contracting Earth to early Supercontinents

“What are they? Creations of mind?- 
The mind can make Substance, and people planets of its own  
With beings brighter than have been, and give  
A breath to forms which can outlive all flesh.”
“The Dream“, Lord Byron (1788-1824)

Already when the first maps of America were published (1507 and after), geographers and naturalists alike noted the similar shape of the west-coast of Africa and the east-coast of South America.

In 1620 the English philosopher Francis Bacon claimed in his “Novum Organum” that “it’s more then a curiosity”. In 1658 the cleric Francois Placet published a small booklet entitled “The break up of large and small world’s, as being demonstrated that America was connected before the flood with the other parts of the world.” He argued that the two continents were once connected by the continent of “Atlantis”, submerged and lost forever during the biblical flood.

The idea of a flood to explain the shape of continents will remain very popular for the next 250 years.

Fig.1. Illustration from Thomas Burnet´s book “The Sacred Theory of the Earth“, published in 1684, where he tries to explain the shapes of the continents by the biblical flood. The homogenous primordial crust of earth is shattered (first drawing) releasing water from the underground. This water covers the entire planet (second drawing) and finally flows back in the fissures, leaving behind fragments of the crust that now forms the modern islands and continents (last drawing).

The great French palaeontologist Buffon in his “Les Epoques de la Nature” (1717) not only addresses the age of earth, but also speculates about a former land bridge connecting Ireland and America to explain the distribution of fossil shells found on both sides of the Atlantic Ocean.

The American president (of the Academy and College of Philadelphia) and naturalist Benjamin Franklin explained marine fossils found on mountains in a letter to French geologist Abbé J. L. Giraud-Soulavie in 1782 as follows:

“Such changes in the superficial parts of the globe seemed to me unlikely to happen if the earth were solid to the center. I therefore imagined that the internal parts might be a fluid more dense, and of greater specific gravity than any of the solids we are acquainted with, which therefore might swim in or upon that fluid. Thus the surface of the earth would be a shell, capable of being broken and disordered by the violent movements of the fluid on which it rested.“

The great German naturalist and geographer Alexander von Humboldt explored South America in 1799-1804 and observed that the similitudes between the two coastlines were not only restricted to a morphological pattern, but also to the geological features: mountain ranges that seemed to end on one continent continued on the other, the Brazilian highland is similar to the landscape of the Congo, the Amazonian basin has it’s counterpart in the lowlands of Guinea, the mountain ranges of North America are – geologically – very similar to the old European mountains and rocks in Mexico resemble those found in Ireland.

Fig.2. Columnar Jointing in the basalts of Regla, Mexico, as depicted in Alexander von Humboldts (1810) “Pittoreske Ansichten der Cordilleren und Monumente amerikanischer Völker.” (image in public domain), the accompanying text explains: “The basalts of Regla, which are presented on this copper plate, are an incontrovertible proof of this identity of forms, which is noted on the rocks of different climates. Travelled mineralogist need only to look at this drawing to recognize the basalt forms in Vivarais, in the Euganean Mountains or in the foothills of Antrim, in Ireland. The smallest coincidences observed in the European rock-pillars are also found in this group of Mexican basalts. Such a great analogy let us assume a similar principle of formation acting under all climates in various temporal epochs, the basalts covered by compact limestone and clay-slate must be of different age than those who are resting on layers of coal and boulders.”

But even Humboldt still argued that the Atlantic Ocean represents a large and ancient river bed, flooded subsequently by the biblical catastrophe.

The French zoologist Jean-Baptiste Lamarck developed a surprisingly new hypothesis. To explain the discovery of fossil marine animals on dry land he proposed that the continents “move” slowly around the globe in a very peculiar manner. The eastern coastlines of the single continents are eroded by the sea, but in the same time new sediments were deposited on the western coasts, so the continents apparently move around the globe and the sea becomes land.
Unfortunately, also for the lack of evidence for his theory, Lamarck was not able to find a publisher for his “Hydrogéologie” and printed in 1802 on his own behalf 1.025 copies, but only a small number of books were sold.

In the early 19th century another hypothesis was proposed to explain the shape of Earth: the Contracting Earth theory formulated by the American geologist James Dwigth Dana explained mountains and continents as products of a cooling and subsequently shrinking earth. Like an old and dry apple the shrinking surface of earth would develop fissures (basins) and wrinkles (mountains).

Austrian Geologist Eduard Suess published in his multi-volume work “Das Antlitz der Erde” (1883-1909) this hand coloured map, showing the supposed remains of the primordial continents – preserved “cores of crust” surrounded by younger basins today filled with oceans. Curiously he suggested also that the deep-sea trenches, found along the borders of the Pacific, are zones where the ocean floor was pushed under the continents (!).

Fig.3. Hand coloured map showing the primordial continent -”cores” according to the Austrian geologist Eduard Suess, published in “Das Antlitz der Erde” (The Face of the Earth) 1883 to 1909 (image in public domain).

But the Contracting Earth theory couldn’t explain the irregular distribution of mountains on earth and why there are regions with strong tectonic movements and earthquakes and also “quiet” areas. According to this theory, such features and events should to be distributed randomly on the surface of a homogenous cooling and shrinking planet.

Already in 1858 the French naturalist Antonio Snider-Pellegrini (1802–1885) published a reconstruction of America and Africa forming a single continent on a planet with a fixed volume. But Snider-Pellegrini couldn’t propose a convincing mechanism, apart the great flood described in the Bible, to explain the forces needed to move entire continents.

Fig.4. This 1858 reconstruction by Antonio Snider-Pellegrini is the first map showing a former supercontinent.

Bibliography:

FRISCH, W.; MESCHEDE, M. & BLAKEY, R. (2011): Plate Tectonics – Continental Drift and Mountain Building. Springer-Publisher: 212
MILLER, R. & ATWATER, T. (1983): Continents in Collision. Time-life books, Amsterdam: 176

The End of the Mayan World

According to the popcorn-movie "2012" (2009) the end of the world will come due increased solar activity that will overheat earth and cause catastrophic volcanic and tectonic storms on December 21, 2012. This premise is so dumb that even NASA declared "2012" as the most "absurd science-fiction movie" of all times, not only because the science is so bad, but the movie exploits also the fear mongering story of the supposed end of the Mayan calendar, first proposed by artist and author José Argüelles in 1987. Almost all of the supposed end of the world tale is nonsense, the various proposed mechanism to explain the destruction of the planet, like solar eruptions, pole shift or the impact of an invisible planet, are unrealistic, as it is unrealistic to claim that the end of a arbitrary time period has any significance for earth.

Fig.1. The goddess Chakchell, with her terrifying snake headdress, is flooding earth with the waters coming from the jar of the gods. She is helped in this task by the dark god of the underworld, with an owl as symbol of his power, and the divine crocodile - even the holy hieroglyphs are crying and the world will soon drown (after the "Codex Dresdensis", ca. 1200-1250, plate 47 "The flood").

However in the last years the Maya Civilization arouse the interest not only of crackpots, but also serious historians and even climate scientists. This ancient society possessed advanced knowledge of astronomy, mathematics and architecture, but 1.200 years ago (750-950 A.D.) the various city-states on the Yucatan peninsula suffered a sudden collapse. Various hypotheses tried to explain this demise: internal warfare, foreign invasions, diseases, overpopulation in combination with environmental degradation and climate change.
The Yucatan peninsula is characterized by a heterogenic spatial distribution of precipitation and seasonal droughts, especially during the beginning of the year (January- May). The climate is influenced by the position of the Intertropical Convergence Zone (ITCZ), wind systems that shift position due the seasons and bring moisture to the land. The Maya had to deal with these variations and in response build large artificial reservoirs. The limestone of the Yucatan peninsula is highly permeable and the groundwater is almost inaccessible, if not by naturally occurring caves or cenotes, and there are virtually no rivers.
It was in these cenotes that geologists of the University of Florida collected sediment cores and discovered in the isotope variations of shells a pronounced drought period between 800 and 1000 A.D., coincident with the collapse of Classic Maya civilization. A even more detailed reconstruction of the climate of the region was possibly by the research done on sediments from the Cariaco Basin, a basin with limited deep water mixing and anoxic conditions on the ground (and therefore perfect sedimentation conditions) offshore Venezuela. Depending from the position of the ITCZ fossil-rich or clastic-rich layers are deposited, so by studying and counting these layers the former variation of the ITCZ and the amount of precipitation can be estimated.
Also this record shows a climate shift and cyclic multi-year droughts from 910 to 760 A.D.

According to the proposed scenario a population at the margin of environmental sustainability experienced repeated droughts and a demise of agricultural production. The various city-states, chronically involved in wars for power and sacrifice victims, consumed the last reserves in a desperate struggle for survive.

However like in the case of Easter Island considering both evidence from natural sciences and historical and cultural circumstances the scenario could become more complicated. The Mayan Civilization was characterized by religious violence and war was less aimed to destroy the enemy than to catch (and sacrifice) the political elite. This society had also survived previous droughts or phases of increased soil erosion, when in A.D. 550-830 the population reached high densities. The power became concentrated in few city-states, which struggled for power and replaced small military expeditions with great wars. The crumbling central government could no longer guarantee the safety of peasants, when the society was further weakened by climate changes.

In the end the city-states were replaced by a most decentralized kind of society, whit the descendants still living today.

Bibliography:

ANSELMETTI, F.S.; HODELL, D.A.; ARIZTEGUI, D.; BRENNER, M. & ROSENMEIER, M.F. (2007): Quantification of soil erosion rates related to ancient Maya deforestation. Geology Vol. 35(10): 915-918
GILL, R.B. (2000): The Great Maya Droughts - Water, Life, and Death. Univ. New Mexico Press: 464
PETERON, L.C. & HAUG, G.H. (2005): Climate and the Collapse of Maya Civilization. American Scientist, Vol. 93: 322-329

In Megalonyx We Trust: Jefferson's patriotic monsters

During the transition of the 18th to the 19th century earth sciences experienced a major revolution - the principles of the modern identification of rocks was introduced and sediments subdivided by the content of embedded fossils. Animals of the past apparently differed from modern ones in their abundance and in their diversity (so they could be used to subdivide the stratigraphic column) and some organisms were completely unknown to modern scholars. These observations led to a major problem: if these organisms are today unknown, are they surviving in remote regions of the globe and yet not discovered?
Classic monsters, like sea serpents along the shores of North America, the giant kraken along the shores of Africa and even sirens in the sea surrounding the United Kingdom, were spotted and depicted in books for centuries (and still today), but now naturalists responded with scepticism and reluctance to these stories - reports coming from America were soon considered as "Yankee Humbug" by European scholars.

In 1812 Georges Cuvier proclaimed that there was little hope to discover new species of large tetrapods and regarding the efforts of explorers to track down mythical animals he noted:

"…we hope that nobody thinks to search them for real, it would be like searching the animals of Daniel or the beasts of the apocalypse. Let us not even search for the mythical animals of the Persians, results of an even greater imagination."

In 1796 the third president of the United States, also president of the American Philosophical Society and naturalist Thomas Jefferson (1743-1826) studied some fossil bones and a giant claw discovered during mining activities in a cave.
March 10, 1797 he presented the results to the Philosophical Society under the title "A Memoir on the Discovery of Certain Bones of a Quadruped of the Clawed Kind in the Western Parts of Virginia" and concluded that these remains belong to a giant felid " three times as large as the lion" which he named "Megalonyx" (great claw).

Fig.1. Engraving of the bones of the foot, toe, and claw of Megalonyx, as published in a paper by Caspar Wistar "A description of the Bones deposited by the President, in the Museum of the Society, and represented in the annexed plates." (1799). Jefferson's Megalonyx paper, which had no illustrations of the bones, was published in the same volume of American Philosophical Society Transactions.

Jefferson, in accordance to the naturalistic knowledge of the time, believed that in nature no species could became extinct, so he continued in his report:

"In the present interior of our continent there is surely space and range enough for elephants and lions, if in that climate they could subsist; and for the mammoth and megalonyxes who may subsist there. Our entire ignorance of the immense country to the West and North-West, and of its contents, does not authorise us so say what is does not contain."

Jefferson based this conclusion in part on anecdotes of woodsmen being terrorized by a large cat-like animal in the wilderness and the presumed representations of lions in Indian rock paintings (possibly the American lion Panthera atrox ?).

However the most important argument for Jefferson was a theological one: if a species can become extinct in a perfect divine creation such a creation can't possibly be so perfect all along, the continuous loss of species would inevitable lead to the end of this imperfect creation.

"The movements of nature are in a never ending circle. The animal species which has once been put into a train of motion, is still probably moving in that train. For if one link in nature's chain might be lost, another and another might be lost, till this whole system of things should be evanish by piece-meal; a conclusion not warranted by the local disappearance of one or two species of animals, and opposed by the thousands and thousands of instances of the renovating power constantly exercised by nature for the reproduction of all her subjects, animal, vegetable, and mineral."

Fig.2. Sketch of the so called "Madrid skeleton" sent to Jefferson by tradesman William Carmichael in 1789. A large skeleton was found near Buenos Aires, in his letter Carmichael notes "I also inclose…a discription of the Skeleton of an Animal discovered lately in Spanish America. I supposed these to be objects of Curiosity to you,…" Jefferson recognized that the bones and claw he had attributed to his large cat Megalonyx were comparable to these of this animal, described in 1796 by Cuvier as Megatherium.
Jefferson also collected all sorts of information about large mammals and bones to support his view of the new continent as populated with fascinating animals as the old continent and rest of the world.

Jefferson also had some political motives to support the existence of large and ferocious animals in the U.S.
In his works the eminent France naturalist Georges-Louis Leclerc, Comte de Buffon (1707-1788) proposed a theory to explain the worldwide distribution of animal species: from environmental optimal centres species would spread all over the globe, however degenerating in areas with less favourable climate or environment - and according to Buffon the fauna of America was an perfect example of such a degenerated European and African fauna.
This worldview not only offended Jefferson's personal feelings, but also seriously damaged the reputation of the young United States of America. The U.S. needed the political and financial support of France during the Revolutionary Wars (1775-1783), Buffon was however popularizing the perception that "America is an excessively cold and humid continent where big animals cannot survive, domestic animals become scrawny, and men become stupid and lose their sexual vigor" (ROWLAND 2009)

In spring 1785 Jefferson published anonymous his "Notes on the State of Virginia", where he discussed naturalistic and also political facts of this state. In various lists he compared the mammals of the new continent to the mammals of the old continent, concluding that the body mass and diversity of American animals was far superior then envisaged by Buffon. He also reaffirmed his view on the impossibility of extinction:

"The bones of the Mammoth which have been found in America, are as large as those found in the old world. It may be asked, why I insert the Mammoth, as if it still existed? I ask in return, why I should omit it, as if it did not exist?
Such is the economy of nature, that no instance can be produced of her having permitted any one race of her animals to become extinct; of her having formed any link in her great work so weak as to be broken. To add to this, the traditionary testimony of the Indians, that this animal still exists in the northern and western parts of America, would be adding the light of a taper to that of the meridian sun. Those parts still remain in their aboriginal state, unexplored and undisturbed by us, or by others for us. He may as well exist there now, as he did formerly where we find his bones."

In 1803 Jefferson organized the famous Lewis and Clark expedition; apart political important tasks, like the geographical exploration of Louisiana and the search for a navigable passage to the Pacific, this expedition should also dig for fossils and search for the supposed unknown large tetrapods of North America.

Jefferson in his lifetime never really embraced the theory of extinction, probably as a results of personal religious beliefs and political agenda - only in the mid 19th century extinction will become a scientific fact.

Bibliography:

ROWLAND, S.M. (2009): Thomas Jefferson, extinction, and the evolving view of Earth history in the late eighteenth and early nineteenth centuries. In ROSENBERG, G.D., ed., The Revolution in Geology from the Renaissance to the Enlightenment: Geological Society of America Memoir 203: 225-246

Online Resources:

MURPHY, D.C. (): Fossils and Extinction. The Academy of Natural Sciences. (Accessed 15.08.2011)
MURPHY, D.C. (): Discovering The Great Claw: Part 1 - The Giant Cat. The Academy of Natural Sciences. (Accessed 15.08.2011)

May 8, 1902: La Pelée

"My Dear Sister: This morning the whole population of the city is on the alert and every eye is directed toward Mont Pelee, an extinct volcano. Everybody is afraid that the volcano has taken into its heart to burst forth and destroy the whole island."

Mrs. Thomas T. Prentis, wife of the United States Consul at St. Pierre, to her sister in Melrose (Boston). After May 8, rescuers would find the charred corpses of both the consul and his wife, sitting in chairs in front of a window that faced Pelée. The bodies of their children would never be found.

Despite recognized as volcano, Mount Pelée, - the bald headed mountain - owning possibly its name to the devastation of an eruption occurred in 1635 before the European colonization, on the island of Martinique was considered extinct since an eruption in 1767 that killed more than 16.000 people living on its slope. In 1856 the mountain however gave signs of activity with minor eruptions of steam and single mudflows descending the slopes, however the rich city of St. Pierre was not affected.

Fig.1. A relief map of Mount Pelée showing the area affected by the eruptions of 8 May and 3 August, 1902, after Lacrox 1904. Note on the summit of the volcano two depressions - L´Etang Sec, a temporary lake, and the Lac de Palmistes.

In April 1902 the old father - as the mountain was referred by the locals- awoke again with violent explosions and on the summit a depression became filed with boiling water - the L'Etang Sec (the dry lake). End of April ash fall on St. Pierre were reported by the local newspaper "Les Colonies":

"The rain of ashes never ceases. At about half-past nine the sun shone forth timidly. The passing of carriages in the streets is no longer heard. The wheels are muffled [in the ashes]. Puffs of wind sweep the ashes from the roofs and awnings, and blow them into rooms of which the windows have imprudently been left open."

The population of St. Pierre became anxious, many of the residents left the city, but they became immediately replaced by refugees from the area surrounding the volcano and many non-residents coming to town for the election of the new island governor on May 10.

On May 5, heavy rain occurred and the dam holding back the boiling water of L´Etang Sec collapsed, a gigantic mudflow rushed down the slopes of Pelée and buried completely a sugar mill on the base of the mountain, 150 people were killed, the waves generated in the sea reached even the harbour of St. Pierre - people begun to panic.
In an effort to tranquillize the public and hold the voters in the city the French governor appointed a commission to investigate the danger from the volcano. "Les Colonies" stated:

"[Professor Landes of the Lycée concludes that] Mt. Pelée presents no more danger to the inhabitants of Saint Pierre than does Vesuvius to those of Naples."

Fig. 2. The newspaper "Les Colonies" May 7, 1902 with the statement that La Pelée "presents no danger", 24 hours later all journalists and editor were dead.

Ironically the Italian Marino Leboffe, Capitan of the freighter Orsolina anchoring in the harbour, complained on May 2, to the local authorities:

"I know nothing about Mount Pelée, but if Vesuvius were looking the way your volcano looks this morning, I'd get out of Naples."

On May 7, the volcano La Soufriére on the island of St. Vincent, 145 km distant, exploded, people hoped that the violent eruption released enough pressure of the earth to prevent the eruption of old father, the residents settled down.

May 8, would became a sunny day, a column of steam was rising above the old father, but otherwise the activity of the volcano seemed unchanged.
At 7:50 in the morning the Pelée blew itself to pieces. For hours after the four explosions the city burned, and for days it was unapproachable by the great heat emanating from the ruins.
Estimated 28.000 to 40.000 people died, only three survivors were reported. The young shoemaker Léon Compère-Léandre (1874-1936) escaped from the border of St. Pierre into the village of Fonds-Saint-Denis, the girl Havivra Da Ifrile tried to escape to a cave near the coast and was washed onto the sea, where she was rescued days later. To Da Ifrile we owe one or the rare eyewitnesses accounts of the eruption:

"But before I got there, I looked back-and the whole side of the mountain which was near the town seemed to open and boil down on the screaming people. I was burned a good deal by the stones and ashes that came flying about the boat, but I got to the cave,…"

One of the most well-know survivor was the 25-year-old stevedore Louis-Auguste Cyparis (1875-1929), who survived in his small prison cell and became known as the "Samson of St. Pierre" in the Barnum & Bailey Circus where he worked and told his story after his rescue.

Fig.3. The "Samson of St. Pierre".

Fig.4. and 5. Photograph of St. Pierre, Martinique, in the 19th century long before the eruption, and photograph by Angelo Heilprin of St. Pierre after the eruption of Mount Pelée on May 8, 1902. The monstrous blast and subsequent pyroclastic flows wiped out the entire city, only four locals survived this day of the final eruption, one was staying outside the city, the other three escaped or survived by mere chance.

On May 20, Pelée exploded again investing the ruins of the city and killing 2.000 rescuers, engineers, and mariners bringing relief supplies to the island.

The devastation experienced in St. Pierre was unexplainable at the time when volcanology was still regarded only as a minor branch of geology. However May 21, the first scientists arrived to the island to study the volcano. They noted the signs of an unknown and deadly phenomenon - the "nueé ardente" or pyroclastic flows, a dense "cloud" of ash, hot gases, fragments of magma and superheated steam moving downhill generated by the collapse of volcanic domes.

Fig.6. Pyroclastic flows December 16, 1902 at La Pelée documented by Lacroix 1904. Lacroux will propose the first modern classification of volcanic activity - one explosive type will be known as Pelean type.

This particular kind of eruption was first studied at Pelée and gave since then its name to this kind of volcanic activity: the Pelean type is common on convergent plate margins and characterized by its explosive character and dangerous pyroclastic density currents.

Fig.7. From October 1902 to September 1903 (when it collapsed) a 300m high obelisk like dome of lava grow from the crater of L´Etang Sec, the American scientist Angel Heilprin noted that is seemed as if ". . . nature's monument dedicated to the 30,000 dead who lay in the silent city below."

Bibliography:

DAVIS, L. (2008): Natural Disasters. Facts on File Sience Library. Infobase Publishing: 464
HEILPRIN, A.(1903): Mont Pelée and the Tragedy of Martinique. J.B. Lippincott Company, Philadelphia and London: 335.
LACROIX, A. (1904) : La Montagne Pelée et ses éruptions. Masson et Cie, Paris.
MORRIS, C. (2006): The San Francisco Calamity by Earthquake and Fire. Librivox.

Online Resources:

ALEAN, J. ; CARNIEL, R. & FULLE, M. (15.05.2007): La Montagne Pelée und Saint Pierre - September 2005. (Accessed 08.05.2011)
Cerimes (01.01.1974): Eruption de la montagne Pelée - 8 mai 1902. (Accessed 08.05.2011)

Tsunamis in the geological record

Tsunami deposits are well documented in the Holocene and the Pleistocene, in part by the good accessibility in outcrops to rocks of these epochs or when historic records help to identify areas subjected to tsunamis.

Modern databases list more than 2.000 tsunami events for the lat 4.000 years, most of them recorded in documents and chronologies and others inferred by their geological evidence.
It seems also possible that tsunamis in historic times (after 1700) have found place in myths and oral tradition of the local Indian tribes of the Cascade Range. Based on these stories geologists tried to establish a chronology of events, backed by geological evidence.

Fig.1. Temporal distribution of 2341 tsunami events listed in the database of the National Geophysical Data Center, USA. The database contains the events of the past 4000 years until 2001 AD, from SCHEFFERS & KELLETAT 2003.

However such a database has to be very incomplete, tsunami without greater damage or loss of life are likely to be underrepresented in historic documents, tsunamis with disastrous effects can in contrary became overemphasized and tsunamis occurring in uninhabited regions will not even be noted by humans. With the age of colonization and exploration the known and inhabited zones grow rapidly, and so also the record of large, destructive tsunamis apparently experienced a mayor increase.
However it can be assumed that the actual number, frequency and power of tsunami in such a compilation are still inaccurate and probably underestimated in the past and emphasized in the present the occurrence of strong tsunamis.
In the geologic record examples of ancient tsunamis are however quite rare. The coastal environment, like flood plains or the estuary of a river, are subject to continues reworking, erosion and deposition, a single event like a tsunami can got destroyed even before it's deposits or traces can became fossilized.
Also in such a complex environment single events tend to became homogenized and amalgamated with the "background" sedimentation, like deposits of the tides or storm events.

In theory a tsunami can produce various geologic evidences in four phases: it can both deposit sediments and erode them during generation, propagation, run up on land and backwash current. The sedimentologic record of the run up by a tsunami on land is well described by this post at "Trough The Sandglass", especially sand layers, and it´s environmental effects at "paleoseismicity" - however tsunamis can transport and deposits giant boulders (like reef debris thrown on land), these boulders are unlikely to be reworked by normal processes of a coastal environment and have a great potential to become fossilized.
Liquefaction phenomena like sand dikes and intrusion during the earthquake are preserved in the sediments underlying the soil and tsunami deposits.

Fig.2.Worldwide published distribution of coastal boulders thrown on land as evidence for tsunamis. Historical tsunami and storm wave boulders were defined here as those purporting to show clear depositional evidence based on historical descriptions, direct observations, and analyses of aerial photographs during the historical age (from GOTO et al.2010).

There is also indirect biological evidence to infer the occurrence of a tsunami.

A strong earthquake can cause a displacement of great parts of a coastal area and the land can become inundated by the sea. The salt water soon will kill trees and plants growing on this land. Because dead trees will survive for quite a while as "Ghost forests" the tree stumps can became buried in the sediments of the tidal flat. After the displacement the land can rise upward by the continuing tectonic movements and again became dry.
These changes can be observed in the stratigraphic succession: layers of peat or soil with tree stumps will change suddenly to sand and silt layers deposited by the tsunami and the tides. The plant remains can be dated by the radiocarbon method and are used to produce a chronology of the changes.

Fig.3. Summer in the ghost forest in Alaska and the remains of the town of Portage after the earthquake of 1964 and in the year 1998. In the background of the old photo spruce trees are dying and the high tide covers recently subsided land. In the modern photo still few trunks are standing and shrubs cover the land rebuilt by tidal silt (after BOLT 1995 and ATWATER et al. 2005).
The 1964 Alaska earthquake was a megathrust earthquake that began at 5:36 P.M. on Good Friday, March 27,.1964. Across south-central Alaska, ground fissures, collapsing buildings, and tsunamis resulting from the earthquake caused about 131 deaths.

The remains of the trees provide even a more accurate chronology: The sudden occurrence of the event is proved by the tree rings, a gradual subsidence of the land would produce a different pattern in the rings that the sudden interruption often observed in cedar trees along the North American coast.

Bibliography:

ATWATER, B.F.; SATOKO, M.-R.; KENJI, S.; YOSHINOBU, T.; KAZUE, U. YAMAGUCHI, D.K. (2005): The Orphan Tsunami of 1700 Japanese Clues to a Parent Earthquake in North America. U.S.G.S. - University of Washington Press: 144
BOLT, B.A. (1995): Erdbeben - Schlüssel zur Geodynamik. Spektrum Akademischer Verlag, Berlin: 219
DAWSON, A.G. & STEWART, I. (2007): Tsunami deposits in the geological record. Sedimentary Geology 200: 166-183
GOTO, K.; KAWANA, T. & INAMURA, F. (2010): Historical and geological evidence of boulders deposited by tsunamis, southern Ryukyu Islands, Japan. Earth-Science Reviews 102: 77-99
SCHEFFERS, A. & KELLETAT, D. (2003): Sedimentologic and geomorphologic tsunami imprints worldwide-a review. Earth-Science Reviews 63: 83-92

Historic tsunamis in Japan

Fig.1. Kanagawa Oki Uranami - "The Hollow of the Deep-Sea Wave off Kanagawa", coloured woodcut from the collection of "Thirty-Six Views of Fuji" (1831) by Japanese artist Katsushika Hokusai. The contrast between the various elements reflects the harmonic order between Ying and Yang and the necessity of solidarity of men in case of natural disasters.

The destructive power of water from the sea - Ying- contrasts with the calmness of the fishermen - Yang- the symmetric symbol is also formed by the wave and the sky. The similar colour of the volcano in the background and the wave emphasise the harmony between mountain (symbol for the body) and wave (symbol for the soul).
Many books describe this wave as a tsunami, but it's shape, characterized by a deep leading through and a very peaked crest, reveals it's origin from the wind. Only some tsunamis resemble such a wave and only near the shore.

The words "tsu-nami" in Japanese means "wave in the harbour", the name derives from the experience of fishermen that only when they returned from the sea into the supposed secure harbour they discovered the terrible destruction that these waves can cause on the shore. Tsunamis are generated by the rapid dislocation of large quantities of water by displacement of the seafloor triggered by earthquakes or landslides, also by explosions caused by volcanic eruption or meteoric impacts. The Pacific Ocean is surrounded by tectonic active borders of the lithospheric plates; nearly 53% of tsunamis worldwide occur here and 82% of them are caused by earthquakes.

Fig.2. Location of tsunami in the Pacific Ocean region: A) Location of 1.274 tsunami since 47 BC. Size of circle increases proportional to number of events per degree square of latitude and longitude. B) Source of significant distant tsunami - tsunamis generated at the coast of Japan can have effects on the coasts of the American continents and vice versa. Size of circle increases proportional to area affected and magnitude of the event, after BRYANT 2008. Note however that the diagram is biased against well studied coast regions (like U.S.A.) or areas with long written records (Japan).

Recognized Tsunamis sediments in Japan go back nearly for 5.000 years, historic records span for nearly 1.300 years, however the most detailed and precise accounts cover mostly the recent period.

An earthquake offshore the north-eastern coast generated a large-scale tsunami on July 13. in 869, we read in the Nihon Sandai Jitsuroku - the "The True History of Three Reigns of Japan" compiled in the year 901:

"Some time after severe seismic shocks, a gigantic wave [tsunami] reached the coast and invaded entire Sendai plain. Rising seawater flooded an old castle town [Tagajo], causing the loss of 1000 lives."
Inscriptions on up to 600 years old stone marker located near the coastal city of Kesennuma warn descendants:
"Always be prepared for unexpected tsunamis. Choose life over your possessions and valuables."
"If an earthquake comes, beware of tsunamis."
"High dwellings are the peace and harmony of our descendants, remember the calamity of the great tsunamis. Do not build any homes below this point."

In 1596 an earthquake offshore reportedly generated a tsunami that destroyed the island of Uryu-Jima completely and caused more than 4.000 deaths.
An official diary about the life and work of the Japanese warlord Tokugawa Ieyasu in his residence city of Sumpu from 1612 contains what is probably the earliest example of the written word of "tsu-nami". The text contains eyewitness-reports of a tsunami that hit north-eastern Honshu, killing thousands of people on December 2. 1611.

On 26. January 1700 contemporary chronicles describe a surprising tsunami, which caused minor havoc, but was not preceded by an earthquake (that earthquakes can be followed by a tsunami was already a well known fact). Research 300 years later revealed that this "orphan tsunami" was generated by an estimated magnitude 9 earthquake offshore the North American coast.

Possibly one of the largest tsunamis recorded in the history of Japan followed a strong earthquake in 1737. Information is scarce and written records are based mostly on rumours: according to these a 64meter (!) high wave devastated the island of Yezo (modern Hokkaido) and destroyed the coastal city of Kamaishi, thousands of people died.

On June 15. 1896 many villages along the coast of Sanriku were celebrating the return of the soldiers from the war against China, when an earthquake of magnitude 8.5 occurred nearly 145 kilometres offshore of Honshu.
The direct effects of the five minutes long quake were of minor entity, the epicentre was distant enough to reduce catastrophic movements on the main island and earthquakes were nothing unusual in this region.
However 35 minutes after the earthquake the most devastating tsunami experienced until then in modern Japan hit the coast, one of the subsequent waves reached a height of over 30-38 meters. 26.000-27.122 people were killed and 9.000 buildings destroyed, the effects of the Tsunami were observed over the entire Pacific, in Hawaii some houses were swept away and a three meter high wave reached the coast of California.
Fig.3. Drawing by Walter Molino, published in the Italian newspaper "La Domenica del Corriere" January 5, 1947, of a tsunami, probably the tsunami of the Great Tokyo Earthquake of the 1. September 1923. The devastation of the earthquake was caused mainly by the subsequent fire, but it triggered also a 11m high wave - estimated 90.000-130.000 people were killed.

In 1933 another very strong tsunami hit the coast of Sanriku. The earthquake of magnitude 8.4 occurred on March 3. 1933, this time also the quake caused heavy damage and landslides, it was then followed by a 21m high tsunami; In sum more than 6.000 people died.
The dead toll was significantly lesser then in previous events, in the years after the tsunami of 1896 authorities had invested in catastrophe mitigation, escape routes were build and the coast reinforced by special constructions (4m high walls and artificial barriers) and planted trees. Most effort was put into education; booklets warned of the consequences of earthquakes in the sea and explained the signs of danger of a incoming tsunami: a tsunami can be preceded by a loud noise like a thunder, the most important warning sign is however the temporally retreat of the sea before the first wave.

In May 1960 a tsunami generated by an earthquake off the coast of Chile reached the coastline of Hokkaido, causing havoc on the island of Okushiri, 142 people were killed.Okushiri was hit again in more recent years. July 12. 1993 an earthquake of magnitude 7.8 caused an 6-10m high tsunami that hit the small island to the west of Hokkaido (in nearly the same region an earthquake on August 29. 1741 produced a tsunami with a maximum run-up of 90m along the adiacent coast). From 680 buildings in the city of Aonae 550 were destroyed or damaged, more than 200 people were killed.

Tab.1. List of the deadliest tsunamis in Japan's history with date/year, affected region and estimated death toll, adapted from KOZAK & CERMAK 2010.

28.10.1707- Tokaido-Nankaido 30.000
1826- Not specified 27.000
20.09.1498- Nankaido 26.000
27.05.1293- Sagami Bay 23.024
15.06.1896- Sanriku, a wave generated by the Riku-Ugo earthquake killed 20.000-26.000 people
21.05.1792- Southwest Kyushu 14.500-15.030 (tsunami triggered by the eruption of the Unzen)
24.04.1771- Ryukyu 13.486
31.12.1703- Tokaido-Kashima 5.233-6.000
31.01.1605- Nankaido 5.000
02.03.1933- Sanriku 3.000-6.000
20.12.1946- To-Nankai 1.330
07.12.1944- To-Nankai 1.223

Fig.4. The Coastal Engineering Committee of the Japan Society of Civil Engineers released a map (23. March 2011) showing the heigths of the Tsunami on March 11.2011 in Japan. The highest value shown is 30meters with an average height of over 15 meter.

Bibliography:
ATWATER, B.F.; SATOKO, M.-R.; KENJI, S.; YOSHINOBU, T.; KAZUE, U. YAMAGUCHI, D.K. (2005): The Orphan Tsunami of 1700 Japanese Clues to a Parent Earthquake in North America. U.S.G.S. - University of Washington Press: 144
BRYANT, E. (2008): Tsunami - The Underrated Hazard. 2.nd edition Springer: 338
GATES, A.E. & RITCHIE, D. (2007): Encyclopedia of earthquakes and Volcanoes. Facts on file science library. 3th ed. New York: 346
GUNN, A.M. (2008): Encyclopedia of Disasters - Environmental Catastrophes and Human Tragedies. Vol.1. Greenwood Press, London: 733
KOZAK, J. & CERMAK, V. (2010): The Illustrated History of Natural Disasters. Springer-Verlag: 203
MINOURA, K.; IMAMURA, F.; SUGAWARA, D.; KONO, Y. & IWASHITA, T. (2001): The 869 Jogan tsunami deposit and recurrence interval of large-scale tsunami on the Pacific coast of northeast Japan. Journal of Natural Disaster Science, Vol. 23 (2): 83-88

De Loys' Ape

Louis François Fernand Hector de Loys, (1892-1935) was a Swiss geologist pioneer of the young science of oil fields prospecting; he travelled extensively and collected experience in Europe, Africa and America during the golden age of oil exploitation.
Unfortunately de Loys is less known for his geological achievements than for a strange story about a strange photography.

Fig.1. François de Loys (1892-1935), photo taken probably before his expeditions to Venezuela in 1917; however de Loys was only 25 when he visited the country, so the general impression of a young, intrepid geologist, probably also larksome, was still valid at the time of his adventures (VILORIA et al. 1998).

In 1920 a handful of exhausted men reached the bank of the Tarra River, a tributary of the Rio Catatumbo in the borderlands of Venezuela and Colombia. They were all what remained of a group of 20 prospectors of the Netherland oil company "Colon Development", which had ventured in the Sierra de Perijeé, a range of mountains, in 1917. In charge of the expedition, intended to geological map and study the region for a planned exploitation of the suspected oil reserves, was de Loys.
The area was not only a dangerous jungle infested with tropical beasts of prey, parasites and diseases, but also inhabited by the hostile Motilones Indians, they decimated one after another the members of the expedition. It seemed already that the expedition was a failure, but in the last part a strange encounter occurred.

One day de Loys spotted at the shores of the Rio Tarra two large, biped monkeys covered with reddish fur and without tails. The two threatening animals walked upright and begun to approach the expedition, visibly irritated, shouting, brandishing with the arms and finally defecating in their own hands and using the excrements as projectiles against the expedition. Finally the frightened men decided to respond to the attack, so they shoot in direction of the two apes and killed was seemed a female, meanwhile the male escaped in the jungle.
Since de Loys and his people had never seen such large monkeys, he tried to preserve the skull and take various photos of the body. However soon the skull begun to decay and during a trip on the river the boat capsized and most of the photos of the animal got lost.
When de Loys finally returned home with the only remaining evidence, a single photography which he treasured in his notebook, he forgot about his annoying encounter with the unknown monkeys. Only years later a friend, the Swiss anthropologist George Alexis Montandon (1879-1944), accidentally rediscovered the photo.

Fig.2. The notoriously photography of de Loys´ ape - Ameranthropoides loysi, from MONTANDON 1929. Note that there exist many versions of the image cropped by the borders, magnifying the impression left by the animal.

Considering the supposed dimension of the box (45-50cm high) visible in the photography the height of the animal was estimated to range from 150 to 160cm.
This seemed to confirm the measurements by Loys (157cm) and based on the dimension and the unusual human-like characteristics, especially the missing tail, in 1929 Montandon published a detailed description of the ape, which he considered a genuine species named "Ameranthropoides loysi", de Loys' American human-like ape.
The animal in the photography displays characteristics that are not found in the monkeys of the new world, like the upright posture, the absence of a tail and 32 teeth (after the description of de Loys). Montandon was fascinated from this sensational discovery of a supposed unknown ape species and began to collect anecdotes and legends of great apes present in remote places of South America (not specifically the region of the supposed encounter).
In two stone statues of the Maya period large, 1,5m high apelike figures are pictured. Among the tribe of the "Caribi" of Guyana there is a widespread belief in the "kanaima", demons which roam the jungle armed with clubs, assaulting whoever dares to enter their reign. In Colombia these creatures are called "didi" and described as half man and half monkey. In Brazil and Venezuela there are legends of the "vastiri".
Author and collector of curious natural history P.H. Gosse reports in 1861:
"It is, however, possible that a great anthropoid ape may exist, as yet unrecognised by zoologists. On the cataracts of the upper Orinoco, Humboldt heard reports of a "hairy man of the woods", which was reputed to build huts, to carry off women, and to devour human flesh [...] Both Indians and missionaries firmly believe in the existence of this dreaded creature, which they call vasitri, or "the great devil." Humboldt suggests that the original of what he boldly calls "the fable", may exist in the person of "one of those large bears, the footsteps of which resemble those of man, and which are believed in every country to attack women;" and he seems to claim credit for being the only person to doubt the existence of the great anthropomorphous monkey of America. But it might be permitted, in return, to ask what "large bear" is known to inhabit Venezuela; and whether it is true that bears´ footsteps have a signal resemblance to those of men; and that bears specially attack women."
In the book "Natural History of Guiana", published by Dr. Edward Bancroft in 1769, there is a description of an encounter with a creature like an "orang-utan", and naturalist George Edwards in "A study of anthropoid life" (1757) depicts a strange ape-like creature resembling the modern photography.

However this publication of Ameranthropoides became accepted only by the French scientific establishment, in contrast it aroused a violent controversy by scientists from Great Britain and North America, the eminent English naturalist Sir Arthur Keith for example affirmed that the photo showed only a species of spider monkey - Ateles belzebuth native in the region- with the tail deliberately cut off or hidden in the photography.
Spider monkeys are a typical element of the South American fauna; however the largest known species reach 110cm height standing on the hind limbs, De Loys ape was with the estimated 157cm considerable larger. The only known fragmentary remains of such a large spider monkey species (with an estimated weight of 25 kilograms more than twice the weight of modern spider monkeys) are those of Protopithecus brasiliensis, the "primitive monkey of Brazil", a Pleistocene species discovered by the Danish naturalist Peter W. Lund in 1838 in the Brazilian region of Bahia.
In 1990 however an American cryptozoological expedition seemed to confirm Montandon´s ethnobiological research, the locals of Venezuela told the expedition about large red monkeys and recognized the ape in the photo as momo grande, as "big ape", a supposed large unknown spider monkey species. However also this expedition could not provide hard evidence apart rumours of supposed encounters or unrecorded tracks of large monkeys.

The simplest explanation, the possibility that the photo was a fraud was refused on base of the good reputation of De Loys:

"It is sure that Francois de Loys was a man of strict science and responsibility, optimistic and friendly and featuring an intrepid spirit of adventure. It seems unlikely that such a scientist may have perpetuated the fraud of the Ameranthropoides only to gain fame. [...] There are sufficient reasons to affirm that de Loys was not a liar, especially one unimpeachable document as the original photo taken at a time when photography and image manipulation did not exist at all."
VILORIA et al. 1998 & 1999

This statement is surely to optimistic, photo manipulation is as old as the art of photography and the dimension or characteristics of the animal in many cropped versions of the photography can not be compared to other objects apart from the strange box.
De Loys himself was very reluctant promoting the story, in the official publication of 1929 by De Loys himself about the geological expedition there is no mention of the creature or subsequent research, he published only, hustled by Montadon, an article in the Illustrated London News.

In 1998 Pierre Centlivres and Isabelle Girod finally published an article suggesting that the entire story was an idea by anthropologist Montandon.
Montandon was strongly influenced by racist ideas of human evolution popular at the time; he proposed a polyphyletic origin of humans and considered the various human races descending from various local monkey species. He affirmed that Africans evolved from gorillas and Asians from orang-utans. A missing link as the supposed Ameranthropoides was a perfect example of an evolutionary line between spider monkeys and South American Indians and would have confirmed his racist hypothesis.

The most plausible hypothesis that emerges now is a manipulated photo of a common spider monkey of the species Ateles belzebuth, used by Montandon to promote his hypothesis of human evolution. This view is supported by a detail in the complete view of the photo - there are stumps of non-native, cultivated banana trees visible, it is highly improbable that in the middle of the untouched jungle, supposed location of the encounter, banana trees can be found.
In the July-August edition of 1999 the Venezuelan scientific magazine "Interciencia" published a letter send in 1962 from a certain Enrique Tejera to the editor Guillermo José Schael of the magazine "Diario El Universal":

"[...] This monkey is a myth. I will tell you his story. [...]
Mister Montandon said that the monkey had no tail. That is for sure, but he forgot to say something, it has no tail because it was cut off. I can assure you this, gentlemen, because it was before me that the amputations take place.
Who is speaking here in 1917 was working in a camp of the oil exploration industry in the region of Perijá. The geologist was François de Loys, the engineer Dr. Martín Tovar Lange. De Loys was a prankster and often we laughed at his jokes. One day they gave him a monkey with an ill tail, so it was amputated. Since then de Loys called him "el hombre mono" (the monkey man).
Some time later I and Loys went in another region of Venezuela: in an area called Mene Grande. He always walked along the side of his monkey, who died some time later. De Loys decided to take a photo and I believe that Mr. Montandon will not deny it is the same photograph that he presented today. [in 1929 Montandon presented the Ameranthropoides in a public lecture]
More recently during a visit to Paris my astonishment was great visiting the Museum of Man. On top of a monumental scale, filling the back wall, there was a huge photo with the caption: "The first anthropoid ape discovered in America."
It was a photograph of de Loys, beautifully modified. The plants were no longer visible in the background, and it was not possible to understand on which kind of box the monkey was sitting. The trick is done so well that within a few years the monkey will be over two meters high. [...]
Finally, I must warn you: Montandon was not a good person. After the war he was shot because he betrayed France, his homeland.

Sincerely, Your friend Enrique Tejera."

If the myths and rumours of large ape-like creature in South America have a zoological explanation, the photo of de Loys surely has nothing to do with them.
Despite his role in the pranke (he contributed the photo and the story and later never resolved the case), he continued his promising career in the field of exploration geology. In 1926 he engaged in the Turkish Petroleum Company, cultivating contacts with geologists and scientists all over the globe. In 1928 he became a fellow of the Geological Society of London and soon visited the Irak to study the geology and the possible oil reserves of the region. Here he encountered Syphilis, returned to the town of Lausanne in France where he died still to young, on October 16, 1935.

Bibliography:

CENTLIVRES, P. & GIROD, I. (1998): George Montandon et le grand singe américain. L'invention de l'Ameranthropoides loysi. Gradhiva 24: 33-43
GOSSE, P.H. (1861): The Romance of Natural History. 4th ed. Boston, Gould and Lincoln, New York: 280-281
MONTANDON, G. (1929) : Découverte d'un singe d'apparence anthropoïde en Amérique du Sud. Journal de la Société des Américanistes de Paris, 21 (6): 183-195
SHERMER, M. (2002): The Skeptic Encyclopedia of Pseudoscience. ABC-CLIO: 903
VILORIA, A.L.; URBANI, F. & URBANI, B. (1998): François de Loys (1892-1935) y un hallazgo desdenado: La historia de una controversia antropologica. Intercienca Mar.-Apr. Vol.32(2): 94-100
VILORIA, A.L.; URBANI, F.; McCOOK S. & URBANI B. (1999) : De Lausanne aux forêts vénézuéliennes. Mission géologique de François de Loys (1892-1935) et les origines d'une controverse anthropologique. Bulletin de la Société Vaudoise des Sciences Naturelles, 86 (3) : 157-174

Online Resources:

ROSSI, L. (13.12.2004): La Scimmia di Loys. (Accessed 16.01.2011)