Tuesday, November 18, 2014
The Longyou Grottoes, located in Longyou area in Zhejiang province, have been reported by many news media ever since they were first found in 1992. They have been draped with mysterious colors and have attracted the attention of archaeologists, tourists and many others.
It will take about one hour to get to the destination from Jinhua City, traveling about 70 kilometer per hour. Shiyanbei is small village within Yazhou region in the middle of Zhejing province, this village, sitting at the foot of the mountain on the North and facing the water to the south, has been regarded as the treasure place with geomantic omen since olden times. Looking over from one end of the village, you can see a wide field of vision with Qujiang River revolving around and passing by the village, which gives you a sense of enchanting illusion. There is a temple in a bamboo forest on one side of the river close to the village; the temple is full of the burning incense and Buddha sound.
On June 9,1992, Grandma Wu with three other villagers, after 17 days pumping using four pumping machines, revealed to the whole world such a mystery that could match with the discovery of a UFO. Grandma Wu took the lead entering into the mysterious underground world full of magnificence and complicated confusions. The grottoes won peoples admiration and also left people confused. Groping for half a day in the grottoes was an unforgettable experience of a life. An introduction of preliminary points of view from individual observation is reported here as a reference.
I. Scale and characteristics of Longyou Grottoes:
Longyou Grottoes have been asserted as the ninth miracles in China after Great Wall and The Tomb of the Emperor of the Qing Dynasty. From a preliminary observation, the author thought that Longyou Grottoes surpass the Great Wall in terms of the causation, scale as well as the artistic value. It was summed up as the following eight points:
1). Longyou Grottos are huge and extensive in scale.
Judging from the 7 unearthed grottoes, the Longyou Grottoes were huge projects and the model was consistent with others. The model, pattern and the style are extremely similar. On the whole, the distribution is very reasonable, the No.1 grotto, the smallest, covers an area of 300 square meters, No.2 to No.5 grottoes covers an area of 900 square meters, 1,200 square meters, 2,000 square meters and 700 square meters respectively. The whole covering area of the 5 grottoes reaches 5,100 square meters. It is understood that there are 23 similar grottoes underground within the circumference of 1 square kilometer of the Shiyanbei village. There are about 50 to 70 similar grottoes under the ground in the Longyou area within circumference of 2.88 square kilometer. Calculated at a covering area of 1,000 square meters per grotto, one grotto will need to dig out 20,000 square meter of soil. Calculated according to 50 grottoes, it will need to dig out 1,000,000 square meter of soil. If we calculate the digging rate of 0.3 square meters per day per person, it will take 2,000,000 days to finish. According to the statistics. It will take 1,000 persons six years to work day and night without break to finish this project. Since the model was consistent, the technology was particular and delicate with the care and precision of a sculptor, the actual workload would far surpass the theoretic estimation.
2). The design of Longyou Grottoes is delicate and scientific.
The scale of the Longyou Grottoes is magnificent and momentous, the design was delicate and scientific, the construction was standard and sophisticated, and it had the glamour of superlative craftsmanship. Every grotto itself is a grand hall, presenting a shape of an inverted Carpenters Square with a small outlet and larger bottom. One side is steep and another side is 45% inclined. Four walls are straight; the edges and corners are clearly demarcated. The chiseling marks are arranged orderly on the roof and the walls of the grottoes, the chiseling line was uniform, the straight line is straight line and the curve line is curve line. The widths are all about 1 foot as if the same person made them. They looked as if they were made by machine. There are stairs leading up and down along the wall in the shape of a saw-tooth. There is distance of three meters between saw-teeth. It is four meters long from the platform to the outlet. Every grotto has huge stone pillars ranging from four at most to one at least to support the roof, the perimeters are 10 meters at most and 5 meters at least. Every Grotto is in a shape of triangle with the peak pointing inside and the base facing front. Every grotto was well separated and there was no connection between grottoes. There is a huge square pool 5 meters deep with a area of 20 square meters that was half-carved and half-laid. A clear rock picture was seen at a point of 10 meters high in No.1 grotto containing three animals a horse, bird and fish. This was the only rock picture found in the seven grottoes. The line and pattern are simple and vigorous, straightforward and uninhibited, full of artistic conceptions.
3). The construction marks of Longyou Grottoes are still fresh.
The accurate starting date of the huge and delicately designed Longyou Grottoes was nowhere to be found. The records of the human studies of Longyou started in the Han dynasty. There were no traceable records before. From historic information of Zhou and Qin dynasties and the documents from Tang dynasty, Hanyu wrote The Monumental to Xuyuan Emperor. There was the record showing "to make the room by chiseling to set a memorial temple for Emperor Yuan". Emperor Yuan was the fifth emperor in the West Zhou (eleventh century BC to 77 year BC.). There is no record of how huge the "room" is. In chiseling the stone to make the room, and the association with the grottoes in Longyou still is questionable. If it was, the grottoes were built at least 2,500 or 3,000 years ago. They have gone through numerous floods and calamities and wars in such a long period, the mountains have changed their appearance and the exposed stones have been weathered, but the shape, patterns and marks are still fresh, as if it were made yesterday.
II. The dissection and question about the Longyou Grottoes;
After on the spot investigation plus quotation of the works of classics, scientists and scholars have put forward many explanations for the Grottoes, but most of them could not justify themselves so they were unconvincing
1) Theory of the tomb (including the theory of emperor palace and theory of storage)
According to The Monumental to Xuyuan Emperor written by Hanyu, many archaeologists have put forward that the grottoes were the tombs of the old emperors, or the emperor halls or place for storage. This interpretation is undoubtedly far-fetched.
First: if it was the emperor halls for the members of the emperor to live, why there were no trace of the funeral objects and things left behind by the deceased.
Second: if it were the emperor place, it would be separated into different halls, such as the hall for morning meeting, the palace for sleeping and the place for the guards to live, etc. The grottoes were empty and nothing for blocking could be seen.
Third: if it were an emperor palace, it would have traces of the people living there, but the walls of the grottoes were still very clear and fresh.
Fourth: The distance between of the stairs is very long; it was difficult to transport the goods in and out of the grottoes. Wouldnt they consider the disasters caused by the flood, fire, earthquake and other nature calamities?
2) Theory of mining (including digging other mineral resources)
Some experts held that Longyou Grottoes were the abandoned caves left by digging the stones, it could justify itself.
First: The safest and the most economic approach is to do the work outside, it is both safe and convenient for digging, why did they design deliberately such a way to do so.
Second: the stones in the grottoes belong to the stones formed by the red soil deposits, judging from appearance, the stones are easy to get weathered, why take such huge and painstaking project to dig the stones that could easily get weathered.
Third: the underground operation would need a lot of equipment and apparatus, such as equipment for digging, illumination, transportation, etc. How did they get these problems solved? Why were no marks left at all?
Fourth: If these caves were abandoned caves for digging stones, why did they make such delicate and regular decorations.
3) The troop station theory:
Some experts held that the grottoes were the places of troop stations of emperor Yue to revenge, the explanation was that he was afraid of the leakage of the information, he dug this underground grottoes for war preparations. This interpretation also has many points to be doubted.
First: it was not a work to do in short period of time, if you spent so many years to dig and then many years to prepare, should you lose and abuse the power already weak and small?
Second: if they worried about the leakage of the information, didnt they worry about the collapse caused by sabotage from the enemy because of the leakage of the information?
Third, in the grottoes, it is impossible to use the nature illumination and there were no trace left by the artificial lighting, how all this could be explained?
Fourth: troop station should be characteristic of smooth road, promptly getting in and out, this is the common knowledge of the military, but the grotto had only one way with three meter distance between the stairs, how could they embody the strategy of the fast movement.
Fifth: if it were for the troop station, they should have left some trace of fighting and exercise.
4) The theory of the alien civilization
UFO experts made on the spot investigation and analysis. They raised the theory of civilization left by the alien. It is to some extent convincing, but still there are many questionable points as follows.
First: How many aliens and equipment are needed to fulfill such a huge project? Could so many aliens land on the earth?
Second: on the whole, the digging of the grottoes was very regular, the chiseling marks were standard and sophisticated, aliens must have used sophisticated equipment to operate. But under careful observations, the chiseling marks also displayed fine differences. We would say that this was done by skilled craftsman rather than done by powerful equipment.
Third: what was the purpose of the aliens digging these grottoes. If they dug these grottoes to live in, it was better and more economic to build an earth observation station with their materials. If the dug these grottoes for gleaning the elements from earth, why did they do such a delicate and careful work? If they dug these as presents to earth, to dig so many grottoes is no better than to dig only one or two grottoes and put one or two civilized products from the other space, which could carry more meaning.
III. Preliminary points of view of author.
According to the careful on the spot observations in the grottoes and comprehensive analysis from all materials by myself. I think it was too early to come to any conclusion with the currently collected information. The accurate answers need complete unearthing and more comprehensive observations. But some points are certain:
1) The grottoes were not formed naturally.
The area in the middle of Zhejiang is hilly land. According to the quotation from the classics, about 300 to 250 million years before. In the geologic age, this area was an ocean. Times brought about great changes of the world. Great orogeny came about in the earths crust in this region. The earths crust raised and became bulged and formed many folds and crease. This region became an area with many caves, such as the double-dragon cave, ice-pot cave and Chaozhen cave in Jinhau City, and also the underground cave in Lanxi City. All these caves were obviously different from the Longyou Grottoes.
2) The grottoes were not built by modern technology:
The development of the production power has offered more and more advanced underground digging machines to humans. It makes the underground operation safer and more efficient, such as the digging of coal and the excavation for underground transportation, etc. But the modern human starts from the safe, economic and beautiful points of view. Underground digging was in a straight line. Once it takes shapes, it would be reinforced and begins to make it beautiful instead of decorating original-digging models directly. In addition, if it was a product of the modern technology, it should be a project built after the industrial revolution in 18 century. Such a huge project, if I was built after 18 century, must have left detailed records in history.
3) The ancients did not build the grottoes:
Huge projects and backward production methods form striking contrasts. It was not possibly built by an individual or common person. Only the emperor and the leaders could have organized such a huge project and the digging capacity. Like the construction of the Great Wall, which was built to defend against invasion from the outside. It was really unnecessary to spend so much manpower and so much time to dig these grottoes without any purpose. Therefore, the Longyou grottoes were not the product of the poor and backward ancients out of leisure and for enjoyment.
While the Longyou Grottoes shows simplicity and magnificence, it also is an immeasurable mystery to the world. Longyou Grottoes could compare with the Pyramids in Egypt, and also could match the mysteriousness of the UFO. It deserves the efforts of all the men of insight to investigate and to disclose this worldly mystery close to us.
Wednesday, November 12, 2014
Our consciousness sets us apart from all other life. Yet, its evolutionary appearance highlights the accidental nature of our origins, writes Darren Curnoe
The beginning of our species is one of the most significant events in the Earth's — some say the universe's — history. At its centre is answering big questions like the beginnings of consciousness.
The 20th century luminary of biology, Julian Huxley, believed the evolutionary arrival of humans was so profound an event in Earth's history that he dubbed the geological period when it occurred the "Psychozoic Era".
That is, the geological era of the soul or mind.
Contemporary cosmologists like Paul Davies have even argued that the evolution of humans gave the universe self-awareness.
We humans have always thought of ourselves as rather unique in the natural world — even special — a vast intellectual gulf seemingly separating us from all other life.
To reinforce this, we have constructed cosmologies placing humans at the centre of the cosmos: the Sun orbiting the Earth — as seen for example in Ptolemy's geocentric model of the universe.
This view changed of course with Copernicus who showed some 1,300 years later that the Sun was at the centre of universe; well the solar system more accurately, the Earth being just one of several celestial or extraterrestrial bodies orbiting the Sun.
Four hundred years later came the space race. Humans, through the Apollo missions, ventured beyond our Earthly — our evolutionary — home, setting foot on our extraterrestrial neighbour.
We were struck by our seeming aloneness and insignificance in the universe: our pale blue dot of a home set against the vast black expanse of the universe.
This event also marked the serious search for life in outer space, and there's something rather poignant about our desire to see just whether we ARE actually alone in the universe.
So far we seem to be one of a kind. Yet, it hasn't always been this way, being alone I mean.
Living with the cousinsOur ancestors shared the planet with other intelligent life not so long ago — the blink of an eye in evolutionary time — with creatures a lot like us.
Our ancestors shared their world with them for most of our evolutionary history stretching back to around eight million years ago, to the beginning of two-footed apes.
Being alone, as we are today, is the unusual state of affairs.
You've undoubtedly heard of the Neanderthals, Homo neanderthalensis? They lived up until just 40,000 years ago.
The so-called 'Hobbit' — or Homo floresiensis — from the island of Flores. It lived up until around 17,000 years ago.
Or, the Red Deer Cave people, one of my own discoveries with my colleague Ji Xueping, from southwest China. Cousins that lived even more recently, up until about 10,000 years ago.
Arrival of the mindOur species evolved only about 200,000 years ago: probably the newest arrival on the evolutionary scene.
Yet, if we look at the evidence for the behavior our ancestors — the archaeological record — we can scarcely distinguish the behaviour of sapiens-humans from our cousins.
That is, until somewhere in the geological window of time around 50, 60 or 70 thousand years ago. Roughly three quarters of the way through our species' evolution.
At this time, we saw a major event which archaeologists have dubbed the 'Human Revolution'.
At this time we saw the first examples of jewellery being made.
Also at this time, humans took their first steps out of Africa — the humans who went on to the found the world's living populations across the globe.
People lived for the first time in previously unoccupied areas; like rainforests, intensely arid zones including deserts, high mountain ranges, and they quickly settled the Arctic region.
East Asia was also settled about 50,000 years ago for the first time by humans, as was the island continent of Australia.
All of this occurred about the time our kind left Africa. Not earlier, and sometimes a little later. And despite the fact we had existed as an unremarkable species for around 150,000 years.
We saw the first cave paintings at this time, in Europe, Asia and Australia. Symbolic representations of the internal and external world through vivid paintings of cave and rock shelter walls.
And we saw a much wider range of tools being made, with rapid innovation in tool form and use.
Tools called 'microliths': tiny tools that replaced in many places the bigger, chunkier tools made by our earlier ancestors and relatives.
In short, we saw humans in all of our glory: with our vivid internal world and imagination, and living in virtually every nook and cranny the planet has to offer.
Gift from a departing relativeSo, why the 'Human Revolution' then and not some other time during the 200,000-year span of our species?
We can piece together the evidence to develop a rather surprising scenario: a truly remarkable narrative of our origins, based on the latest science.
At about 60,000 years ago, when our human ancestors were beginning to make their journey to settle new parts of Africa and the rest the Old World the planet was a very different place to today.
It was a world inhabited by our close relatives: cousins living in parts of Africa, and in Asia and Europe.
Now, something rather extraordinary seems to have occurred about this time, as has been shown by the work of some very clever geneticists.
When our ancestors moved into these new places they did something that seems to be a first in human evolution — they mated with the locals.
Now our genome, it turns out, is like a patchwork quilt. It's estimated that up to five per cent of the DNA of people living in North Africa and outside of Africa today comprises Neanderthal genes.
And a similar value also for the Denisovans — a mysterious species from Siberia we know from a single tooth and finger bone, but also its genome.
It might strike you as odd that different species interbreed. But, in fact, between species mating is common in nature and is actually an important source of evolutionary innovation right across life.
The Denisovans, for example, probably gave us a raft of genes associated with immune function and genes that allowed people living today in the Himalayas to survive at high altitude.
Accidental origin of usThere's another really fascinating and potentially profound genetic gift they gave us on their way out: a variant of the microcephalin gene.
This gene plays a key role in brain size in humans and there is ample evidence it has been under strong selection in recent evolution.
Now, genetic studies suggest this gene may actually have been added to our genome through interspecies interbreeding with a close cousin. Maybe even with the Neanderthals.
I don't wish to suggest this is THE gene for consciousness, for without doubt something as complex as the human mind or consciousness must involve multiple genes or even networks of genes.
But, the microcephalin gene is likely to be a key gene, without which consciousness might not exist.
So, it could be that the psychozoic of Huxley, or the universal consciousness of Davies, resulted from the incorporation of a gene we received from a close evolutionary relative.
Isn't this the ultimate irony? We get the gene, send them to extinction, and claim universal consciousness while we're at it!
Science constantly updates and knowledge progresses. And, without doubt, this story will change as well. But, in the end, this doesn't really matter because it highlights one really important aspect of our evolution.
It is clear that we humans, and our remarkable consciousness, were not planned, nor inevitable, and not built into some design for the universe or the fabric of the cosmos.
Instead we were accidental, our evolution contingent.
The very feature we hold so dearly may in fact result from a chance encounter in a dark alley, even an evolutionary one-night stand.
This article is based on a TEDX Brisbane talk given on 5 October 2014. A longer version is available on Walking on Two Feet.
Associate Professor Darren Curnoe is an evolutionary biologist at the University of New South Wales. He writes about all aspects of evolution on his blog blog. His work with colleague Ji Xueping is featured in the documentary Enigma Man: A Stone Age History. He also appears regularly on ABC 702.
Sunday, November 9, 2014
A brinicle (brine icicle, also known as ice stalactite) forms beneath sea ice when a flow of extremely cold, saline water is introduced to an area of ocean water, being the undersea equivalent of a hollow stalactite or icicle.
Known since the 1960s, the generally accepted model of their formation was proposed by the US oceanographer Seelye Martin in 1974. The formation of a brinicle was first filmed in 2011 by producer Kathryn Jeffs and cameramen Hugh Miller and Doug Anderson for the BBC series Frozen Planet.
At the time of its creation, a brinicle resembles a pipe of ice reaching down from the underside of a layer of sea ice. Inside the pipe is the supercold, supersaline water being produced by the growth of the sea ice above, accumulated through brine channels. At first, a brinicle is very fragile; its walls are thin and it is largely the constant flow of colder brine that sustains its growth and hinders its melt that would be caused by the contact with the less cold surrounding water. However, as ice accumulates and becomes thicker, the brinicle becomes more stable.
A brinicle can, under the proper conditions, reach down to the seafloor. To do so, the flow of supercold brine from the pack ice overhead must continue, the surrounding water must be significantly less saline than the brine, the water cannot be very deep, the overhead sea ice pack must be still, and currents in the area must be minimal or still. If the surrounding water is too saline, its freezing point will be too low to create a significant amount of ice around the brine plume. If the water is too deep, the brinicle is likely to break free under its own weight before reaching the seafloor. If the icepack is mobile or currents too strong, strain will break the brinicle.
Under the right conditions, including favorable ocean floor topography, a brine pool may be created. However, unlike brine pools created by cold seeps, brinicle brine pools are likely to be very transient as the brine supply will eventually cease.
On reaching the seafloor, it will continue to accumulate ice as surrounding water freezes. The brine will travel along the seafloor in a down-slope direction until it reaches the lowest possible point, where it will pool. Any bottom-dwelling sea creatures, such as starfish or sea urchins can be caught in this expanding web of ice and be trapped, ultimately freezing to death.
The formation of ice from salt water produces marked changes in the composition of the unfrozen water. When water freezes, most impurities are forced out of solution; even ice from seawater is relatively fresh compared with the seawater it is formed from. As a result of forcing the impurities out, sea ice is very porous and spongelike, quite different from the solid ice produced when fresh water freezes.
As the seawater freezes and salt is forced out of the pure ice crystal lattice, the surrounding water becomes more saline. This lowers its freezing temperature and increases its density. The lower freezing temperature means that the surrounding water does not freeze to the ice immediately, and the higher density means that it sinks. Thus tiny tunnels called brine channels are created all through the ice as this supersaline, supercooled water sinks away from the frozen pure water. The stage is now set for the creation of a brinicle.
As this supercooled saline water reaches unfrozen seawater below the ice, it will cause the creation of additional ice. If the brine channels are relatively evenly distributed, the ice pack grows downward evenly. However, if brine channels are concentrated in one small area, the downward flow of the cold water, now so saline that it cannot freeze at its normal freezing point, begins to interact with unfrozen seawater as a flow. Just as hot air from a fire rises as a plume, this cold water descends as a plume. Its outer edges begin to accumulate a layer of ice as the surrounding water, cooled by this jet to below its freezing point, ices up. This is a brinicle: an inverted "chimney" of ice enclosing a downward flow of this supercold, supersaline water.
When the brinicle becomes thick enough, it becomes self-sustaining. As ice accumulates around the down-flowing cold jet, it forms an insulating layer that prevents the cold, saline water from diffusing and warming. As a result, the ice jacket surrounding the jet grows downward with the flow. It is like an icicle turned inside-out; rather than cold air freezing liquid water into layers, down-rushing cold water is freezing the surrounding water, enabling it to descend even deeper. As it does, it creates more ice, and the brinicle grows longer.
A brinicle is limited in size by the depth of the water, the growth of the overlying sea ice fueling its flow, and the surrounding water itself. In 2011, brinicle formation was filmed for the first time.
Tsingy de Bemaraha Strict Nature Reserve comprises karstic landscapes and limestone uplands cut into impressive 'tsingy' peaks and a 'forest' of limestone needles, the spectacular canyon of the Manambolo river, rolling hills and high peaks. The undisturbed forests, lakes and mangrove swamps are the habitat for rare and endangered lemurs and birds.
The integral nature reserve of Tsingy of Bemaraha lies 60-80 km inland from the west coast in the northern sector of the Antsingy region of the Bemaraha Plateau, north of the Manambolo River Gorge. The additional forests and lakes nominated include all the remaining native forest, mangrove and lakes between the west coast and the Bemaraha Reserve, lying between the Sohanina and Manambolo rivers.
Much of the reserve integral to Tsingy de Bemaraha comprises limestone karst, delimited to the east by abrupt cliffs which rise some 300-400 m above the Hanambolo River valley and extend several tens of kilometres from north to south. The western slopes rise more gently, and the whole western region of the reserve forms a plateau with rounded hillocks which slope away to the west. To the north undulating hills alternate with limestone extrusions, whereas in the south extensive pinnacle formations make access extremely restricted. The Hanambolo River Gorge is on the southern edge of the reserve. Both seasonal and permanent rivers flow on the plateau (draining to the west), and numerous permanent springs arise at the base of the Tsingy on both sides.
Vegetation is characteristic of the calcareous karst regions of western Madagascar, with dense, dry, deciduous forest, and extensive anthropogenic savannahs.
The fauna of the region has not been studied in any detail. The Tsingy is the only known location for chameleon, and the only western dry forest site known for Madagascar grey-throated rail (only previously known from north-western and eastern Madagascar). The reserve is also the only protected area where the endemic nesomyine rodent is known to occur and there is also an unconfirmed report of aye-aye just outside the reserve. Other notable species include goshawk, which may be threatened, and lemur, all of which are (or may be) threatened.
The entire park is composed of a forest of needle-like rock spires up to 120 meters high in some areas. The rock, formed by water eroding away the limestone, is razor sharp and provides a home to hundreds of species that aren’t found anywhere else on earth.
Visually the place is eerie enough, but it’s also very under-researched. In fact, few scientists ever travel deep into the forest, and only a handful have ever done it more than once.
A journalist for National Geographic describes how difficult it is to travel through the park: “We squeezed through passages, our pack straps catching on fingers of stone. We stemmed narrow ravines and nervously straddled fins that were like fences topped with broken class. The rock pierced our boots, leaving holes in the rubber. Usually we came over needle-sharp rises only to descend onto mats of thin soil covering yet more serrated rock. We’d carefully find our balance, then try to figure out what to do next.”
Atlantis main Island according to the text of Plato in Timaeus & Critias written in 360 BC.
The Richat Structure, also known as the Eye of the Sahara or blue eye of Africa, is a prominent geological circular feature in the Sahara desert in Mauritania near Ouadane. It is nearly 50 kilometers across and very visible from space. Initially interpreted as an asteroid impact structure because of its high degree of circularity, and then as a structure formed by a volcanic eruption that also seems improbable because of the lack of a dome of igneous or volcanic rock, it is now argued to be a highly symmetrical and deeply eroded geologic dome that collapsed. So it is now thought by many to have been caused by uplifted rock sculpted by erosion. But the fact that the "rings", are equidistant to the centre and that the Richat Structure is nearly circular remains a mystery.
And new questions arise. Some people are amazed by the resemblance of this structure with the representation we have of Atlantis by Plato. According to Plato, the island was circular, divided into concentric circles of land and water: "There were 2 of land and 3 of water... Atlantis when sunk by the earthquake became an impossible barrier of mud to voyagers sailing from hence to any part of the ocean..." And he spoke about a mount sheltering the city by North and "and encompassing a great plain of an oblong shape in the south "...etc... Atlantis in Greek means Atlantis, nesos : the island of Atlas. And we get near the geologic eye at the North the Mount Atlas. According to Plato, Atlantis was lying "in front of the Pillars of Hercule", and we are there just in front from South and not beside from East or West as many authors are searching...
Antoine Gigal - April 2012
- Martinez-Frias, J., Rull, F., Martín-Redondo, M.P., Delgado, A., Fernández-Sampedro, M.T., García-Talavera, F., López-Vera, F. and Menor Salván, C.(2011)Multianalytical characterization of silica-rich megabreccias from the proposed natural area of Richat (Sahara desert, Mauritania). Research Journal of Chemistry and Environment v. 15, no. 3, pp. 49-54.
- 2. http://www.youtube.com/watch?feature=player_embedded&v=pTTnYRaZ55A French video with animations by geologists.
- 3. Nemiroff, R., and J. Bonnell (2002) Earth's Richat Structure, Astronomy Picture of the Day, October ...Astronomy Picture of the Day, Michigan Technological University, Houghton, Michigan.
The Devils Postpile formation is a rare sight in the geologic world and ranks as one of the worlds finest examples of columnar basalt. Its columns tower 60 feet high and display an unusual symmetry. Another wonder is in store just downstream from the Postpile at Rainbow Falls, once called a gem unique and worthy of its name. When the sun is overhead, a bright rainbow highlights the spectacular falls.
The monument is also a portal to the High Sierra backcountry; some 75% of the monument is included in the Ansel Adams Wilderness. At 800 acres, Devils Postpile National Monument may be considered small by some, yet its natural and recreational values abound.
Some details of the geologic origin of the Devils Postpile are not completely clear, but enough is known to reconstruct much of the story. Until recently, it was thought to have formed about one million years ago. Current studies suggest that the Postpile was formed less than 100,000 years ago when a cooling lava flow cracked into multi-sided columns. However, to fully understand the geologic setting of the Postpile we must go back millions of years to a time when there was no Sierra Nevada and California was a shallow sea.
The beginning of North America
For nearly 500 million years, what is now Eastern California was a shallow sea. The western edge of North America was several hundred miles east of the present coastline and North America was part of a large super-continent called Pangaea. This super-continent was the land mass from which all of today’s continents were born.
About 200 million years ago, Pangaea began to split and North America began moving to the West while Europe and Asia moved to the East. While all the rifting and moving of Pangaea and North America was taking place, sediments and gravel were steadily eroding from western North American (near present-day Utah and Nevada) and washing out into the shallow sea that covered present-day California.
The stage is set for California to arrive
As North America drifted westward the adjacent oceanic crust was thrust downward and beneath the moving continent. A north-south subduction zone was born, and for millions of years oceanic crust continued to slam into the westward moving North American continent. Most of the crust slid beneath North America, but occasionally a slice of this sedimentary crust would be thrust onto the continent’s edge. Intermittently, North America would get a big chunk of land added to its western margin as volcanic islands, similar to those of Hawaii or Indonesia, were scraped onto the coast, a process called accretion. These pieces of accreted land are called exotic terranes and the addition of each terrane to North America took millions of years. One such terrane, the Smartville complex, contained the gold veins that would bring wealth and people to the state, some 160 million years later. In this fashion the western edge of North America expanded further and further to the west, and the land we know to be California arrived, piece by piece, like waves from the sea.
Mountains begin to rise: The ancestral Sierra Nevada
About 140 million years ago, the friction and pressure between the two plates was so great that the land began to crumple and mountains began to rise east of the subduction zone, the ancestral Sierra Nevada was born. During this period of uplift, the accreted terranes and sedimentary layers were twisted, folded and squeezed together and rocks changed from one form to another, a process called metamorphosis.
As the mountains rose and great pressures metamorphosed California’s rocks, the subducted crust melted below due to pressure and contact with the Earth’s molten mantle layer. The subducted crust slowly melted from hard rock into magma. In some cases, the magma rose upwards into the continental crust forming large underground magma chambers. Wherever this magma cooled underground (over millions of years) granite formed. Millions of years later this granite would be thrust upwards as the mountains we see today. But not all of the magma cooled underground. Some breached the surface creating volcanoes and fissures, spewing lava of varying types onto land. At this time, the Sierra Nevada would have looked more like the present-day Cascade Mountains of Oregon and Washington or the Andes Mountains of South America. Lasting evidence of this volcanic period is common in the area surrounding Devils Postpile. For instance, the dark green rocks of the Minarets and the Ritter Range were created by a caldera that formed during this time. Hornfels near the Minaret Summit and San Joaquin Ridge are likely from this time period as well. Both of these examples have been highly metamorphosed during the millions of years since their original creation. Though the ancestral Sierra Nevada was rising, it was not nearly as high as the mountains we see today. Many millions of years would pass before the Sierra Nevada would rise to its current elevations.
Beginning about 65 million years ago, the ancestral Sierra Nevada began a long period of erosion. The climate was warm and wet at this time, accelerating both chemical and physical erosion processes. Warm shallow seas lapped at the base of the mountains. Rivers carried volcanic and metamorphic rocks and sediments into this shallow sea which is where the Great Central Valley of California lies today.
The Sierra Nevada takes on its present form
A renewal of volcanic activity in the Sierra Nevada and Cascades began some 30 million years ago and continues even today. The whole mountain range began tilting to the southwest some 25 million years ago as the Sierra Nevada slowly evolved into its present shape and form. Still, the Sierra was low enough to allow many rivers beginning in present-day Nevada flowed through the mountains en route to the Pacific. The San Joaquin River was one of these. It is believed that the headwaters of the San Joaquin began further to the east in present-day Nevada. About three million years ago a lava flow filled the northern portion of the San Joaquin River Valley isolating the river to areas west of the Sierran crest. Vestiges of this flow are seen in the dark layered, reddish rocks along the San Joaquin Ridge and above the road near Agnew Meadows. These rocks can be seen from the bridge near Devils Postpile, a ¼ mile walk from the Ranger Station.
By about 2 million years ago, the Sierra Nevada began rising quite rapidly. The range began tilting westward, uplifting peaks along the eastern edge to elevations comparable with those seen today. The climate became cooler and wetter during these times and as the Sierra Nevada rose higher and higher into the colder elevations, precipitation fell as snow instead of rain. During the intermittent ice ages, so much snow would accumulate that large glaciers formed. Beginning high up in the Ritter Range, glaciers flowed down the Reds Meadow Valley repeatedly throughout these centuries, shaping the valley to near its present form. This most recent period has been one of many dramatic and often opposing forces: volcanoes spewing fiery lava east of the Sierra’s crest, mountains growing curtains of ice along the crest itself, earthquakes thrusting mountains higher and higher, and glaciers grinding mountains into domes. It is within this dramatic context that the Devils Postpile formation came to be.
The Postpile begins as a lake of lava
An estimated 80,000 to 100,000 years ago a lava vent began spewing hot basaltic lava into the Reds Meadow Valley near present-day Upper Soda Springs, a few miles north of the Monument. Basalt lava is rich in iron and magnesium and is typically much hotter than other types of lava. Because of these traits, basaltic lava tends to have a lower viscosity and will flow more quickly than other lava types. The lava flowed down the valley like a river until it was blocked by a natural dam, probably a glacial moraine left down-valley by a receding glacier during a previous ice age. The lava began filling the valley behind this dam, creating a lava lake 400 ft. deep in some areas. Such depth is uncommon among lava flows and plays a crucial role in the formation of the long columns we see today.
The lava cools and cracks reach deep into the formation
As the lava flow ceased, the molten rock began cooling into solid rock. Shallow parts of the lava flow would have solidified first, with deeper parts of the lava lake requiring much more time to release the massive amount of stored thermal energy. As the lava lake cooled and solidified from a molten soup to solid rock it began to contract. Contraction stresses developed because the cool solid form of basalt has a lesser volume than the hot liquid form. Cracks, also called joints by geologists, began to form. Jointing releases internal stress created by the cooling and associated contraction. In some locations, such as at the Devils Postpile, the jointing formed columns. Jointing would have begun at the top, bottom and all around the edges of the lava lake where the lava made direct contact with a cooler surface. The cracks would have extended inwards over time as the more insulated locations within the lava lake finally released enough thermal energy to change from a liquid to a solid state.
Powerful forces expose the beauty of the Postpile
The Devils Postpile used to be much taller than what we see today. Powerful erosive forces have been at work during the last 80,000 to 100,000 years carving, shaping and demolishing remnants of the lava flow. Freeze-thaw cycles help break apart the columns. Earthquakes knock columns down into the talus slope below. The river slowly eats away at pieces that fall into the water. But no force has left a greater footprint on the Postpile than that of glaciers. In fact, we wouldn’t even see the beautifully straight hexagonal columns hidden within the depths of the lava flow had glaciers not excavated the formation. Several distinct glacial periods have occurred since the Postpile was formed and each has dug deeper and deeper into the dense, heavy rock known officially as andesitic basalt. The last major glacial period ended about 15,000 years ago. Glacial polish and striations evident on top of the Postpile are from this last glaciation.
Chromium is usually bound up in rocks as chromium III. However, weathering will convert chromium III to chromium VI if there is at least 0.1 per cent oxygen in the atmosphere. This results in a small change in the ratios of chromium isotopes 52 and 53.
"If there's less than 0.1 per cent oxygen in the air, the chromium isotopes don't change," says McGoldrick.
"Our study shows chromium in rocks older than 800 million years hadn't changed, which indicates that atmospheric oxygen levels were less than 0.1 per cent until that time."
Multicellular organisms only diversified after atmospheric oxygen levels increased above 0.1 per cent around 800 million years ago.