Hadeanul nu este o perioada geologica propriu - zisa avand in vedere ca nici o roca de pe Pamant, cu exceptia meteoritilor, nu este atat de veche. In timpul Hadeanului s-a format Sistemul Solar, probabil in interiorul unui nor mare de gaze si praf din jurul soarelui, denumit disc de acretie. Prezenta in cantitate relativ mare a elementelor grele in cadrul Sistemului Solar sugereaza ca gazele si praful au provenit din una sau mai multe supernove (explozia unei stele vechi de dimensiuni mari).Elementele grele au fost generate in interiorul stelelor prin fuziunea nucleara a hidrogenului, avand in vedere ca nu apar in mod comun in alte conditii. Astazi se pot observa procese similare ce au loc in asa numitele nebuloase difuze din galaxia noastra sau din alte galaxii (cum ar fi nebuloasa M16, foto stanga).

Soarele format in interiorul unui astfel de nor de gaze si de praf se micsoreaza prin compactizare gravitationala pana in momentul când incepe fuziunea nucleara generatoare de lumina si caldura. Particulele inconjuratoare incep sa fuzioneze datorita gravitatiei formand aglomerari mari sau planete-simale, care continua sa se acumuleze dand nastere la planete. Materialul ramas formeaza asteroizi si comete (cum ar fi asteroidul Ida, foto dreapta).

Datorita coliziunii dintre planetele-simale care a eliberat o mare cantitate de caldura, Pamantul si celelalte planete trebuie sa se fi aflat in stare topita la inceputurile lor. Datarea radiometrica da varsta rocilor eruptive din momentul solidificarii ceea ce explica de ce cele mai vechi roci lunare si meteoriti au in jur de 4500 M.a., in timp ce cele mai vechi roci de pe Pamant au 3800 M.a. In timpul primilor 800 M.a. din istoria sa, Pamantul a fost pemanent bombardat de planete telurice si trebuie sa se fi aflat in stare topita. Varste celei mai vechi roci de pe Pamant corespunde cu varsta ultimului mare episod de bombardare a Lunii. Odata cu incorporarea planetelor telurice de catre noile planete , pe Pamant s-au format roci solide si astfel a inceput propria sa istorica geologica, perioada cunoscuta sub numele de Arhaic

tHE CREATION OF THE SOLAR SYSTEM AND THE EARTH  5 500 000 000 BC 

Once again this matter came together and formed an accretion disk that would eventually give birth to our solar system. Slowly but surely the sun and the planets began to form. 

This matter created the sun and all the planets of our solar system. 

And so, the Earth came to be. After many millions of years of scooping up matter from the accretion disk the Earth formed. It was a wild and inhospitable place. The atmosphere was toxic and massive meteorites bombarded the planet on a regular basis. The Earth would have had a thick dusk filled atmosphere that blocked out the sun for the greater part and which left the

surface, a cold desolate frozen wasteland in the regions that were not flowing with lava. In its forming ages, the Earth would have been locked in an almost permanent solar winter with a toxic carbon dioxide atmosphere.   

That was 5.5 billion years ago. For the next billion years, life sought out a tenuous foothold and slowly, it crept out over the face of the planet, transforming it. Breathing in the carbon dioxide and releasing oxygen.  Earth had been born but it had some growing pains to deal with and it was still being bombarded by meteorites on a regular basis.   

THE CREATION OF THE MOON  4 500 000 000 BC 

It is told in the legends of the ancient Vedia that more than four thousand million years ago, Marduk fought Tiamet and created the new Earth. Tiamet was said to

have absorbed the cosmic waters from the universe and lay coiled coiled around a great island that traversed the heavens. In order to bring water to both the gods and

the humans, He battled this dragon and proved victorious when he used his thunderbolts to kill this monster. He brought it to the world and released the waters of

life for all.http://www.biopark.org/dragonhistory.html  

 The first trauma of the new Earth, now some 1 Billion years old came in the form of a planetary sized object that  impacted the earth and made all life extinct. Setting the process of the development of life on the Earth back 1 billion years.   

In the aftermath of this trauma, the planet once again reverted to a lifeless, cold, dust covered wasteland from which life had to start from scratch once again. The difference this time was that all of the landmasses were on one side of the planet and formed one super continent named Gondwanaland.

All life on Earth may have perished but, we had ourselves a brand new moon, and some would argue that the moon was the primary force that brought life out of the water and on to dry land through the tidal action that it imposed on the oceans.  

Four billion years ago, when the moon was formed by the ejecta when a planetary sized object impacted with the Earth, the moon was a lot closer then than it is now. It is thought to have formed up at about 50 000 kilometers from the earth. It was 5 times bigger in the sky and had an orbital period of about 14 days as opposed to the current 28 days.   It is thought by some scientists that the ejecta from meteorite impacts into the surface of Mars covered the inter-planetary gap to Earth and may in fact have re-seeded the Earth with life forms thereby giving the Earth a jump start on the ladder of life again. This theory is borne out by the discovery of rocks here on Earth that originated from Mars.  Mars of course was too small a planet to sustain life and it went on to loose most of its atmosphere because of its weak gravity and life on the small cold planet ran into a dead end. 

Mars loses its atmosphere ; The discovery of magnetized bands in the oldest Martian crust shows that the planet in an early epoch churned with internal heat and was remarkably like the geology of Earth today. Mars was a more active world in its early history, a warmer place with liquid water on the surface and perhaps even the beginnings of simple life. Plate tectonics there ceased to be an important factor 4 billion years ago. ("Science Magazine")  The theory does have some merit and it is a romantic one for, if true, we could claim that our far distant ancestors came from another planet, and that we are using this one as but a stepping stone on our journey to other planets.   Whichever way you look at it, this was the first of eleven extinction level events that the Earth and its life forms would have to face. This one passed, and then, there were another ten to come. Fortunately, the successive ELE events, while cataclysmic in their own rights, were not as comprehensive as the very first one. Which was a good thing for us.  

THE EARLY AGES  2 700 000 000 BC - 310 000 000 BCThe ARCHEAN, PRECAMBRIAN, CAMBRIAN, ORDOVICAN, SILURIAN,

DEVONIAN PERIODS 

 2,700,000,000 B.C. Molecular-fossil evidence that life existed in the Archean era (a billion years earlier than previously thought, journal "Science") found in Australia;  2,500,000,000-2,000,000,000 B.C. Geomagnetic fields exist (from magnetic imprints in ancient rock) which also indicates the presence of an inner core;2,150,000,000 B.C. (ELE 2). The asteroid Eltanin blasted into the Bellingshausen Sea off Antarctica; Eltanin triggered waves 65-130 feet high; causing devastating mega-tsunamis that swamped the coasts of South America and Antarctica in the late Pliocene period. Sediment spread up to 2500 miles away and dust, vapor, and salts wafted around the world. The dust and vapor probably caused a major change in climate but whether that persisted or was for just a few years is unknown. There is no evidence that the climatic change caused the extinction of any species but the fallout from the blast may explain the Sirius enigma -- the puzzle of why marine fossils are found high above sea level in the Transantarctic Mountains. (British science journal NATURE)  . The late Pliocene impact of the Eltanin asteroid is the only known impact in a deep ocean (5 km) basin and was first discovered in 1981 as an Ir anomaly in sediment cores collected by the USNS Eltanin in 1965 [1]. In 1995 an expedition with RV Polarsternwe collected extensive bathymetric and seismic data sets as well as sediment cores from an area in the Bellingshausen Sea (Pacific Southern Ocean) that permitted the first comprehensive geo-scientific documentation of an asteroid impact into a deep ocean ( 5 km) basin, named the Eltanin impact [2]. Further extensive survey and sampling followed during a second RV Polarstern expedition in 2001.

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 2,000,000,000 B.C. Martian atmosphere goes from wet to dry (SCIENCE); A massive 10 cubic kilometer meteorite strikes the African continent in South Africa creating the Vredefort dome.

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850,000,000 - 800,000,000 B.C. Evolutionary explosion among complex eukaryotes; On Canada's Victoria Island, scientists un-earth a mother lode of microscopic fossils, chronicling an evolutionary explosion among complex cells more than 800 million years ago. There's a huge amount of diversity in the environment at this time, suggesting that eukaryotes were rapidly evolving in the face of some new ecological pressure, and one candidate is the appearance of the earliest animals.  

_____________________________________________  750,000,000-570,000,000 B.C. Precambrian Ice Ages (Earth went through at least four deep ice ages, each lasting millions of years);  700,000,000-600,000,000 B.C. (ELE 3) The Earth tilts as much as 50 degrees resulting in glacial equator; The Earth's equator was once a glacial winter wonderland 600-700 million years ago, possibly due to a significant increase in the Earth's tilt, at the time, by as much as 50 degrees relative to its spin axis (current tilt is 23.5 degrees). The poles, under such conditions, would have received more sunlight, and remained ice-free, while the equatorial region received little sun and was iced over. The Earth's climate also may have affected its tilt as the glaciers forming and melting there enhanced the Earth's equatorial bulge, which, in turn, changed the tilt. (James F. Kasting, professor of geosciences at Pennsylvania State University in the science journal, Nature)

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570,000,000 B.C. New life forms appear, first records of creatures with mineralized skeletons including the shelled trilobite;

_____________________________________________   540,000,000 B.C. CAMBRIAN period begins; Three-limbed tree of life diverges from a common ancestor;  Discovery of a common genetic theme that places nearly all animals -- from mollusks to humans -- on a three-limbed tree of life that first diverged from a common ancestor at least 540 million years ago. (Scientists from the University of Wisconsin-Madison, the University of Paris, Cambridge University and St. Petersburg University in Russia reporting in the journal "Nature")

_____________________________________________  530,000,000-500,000,000 B.C. (ELE 4) The Earth tilts due to a collision in outer space; Meteorite fossils discovered in Sweden add to the evidence of a collision in outer space; part of a shower of meteorites hitting the Earth after an asteroid collision, resulting in an evolutionary explosion; sudden appearance of a multitude of new life

forms around the world as well as Earth's super continents taking a 90-degree turn, shifting the polar masses to the equator and putting equatorial points at the poles.

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500,000,000 B.C. ORDOVICIAN Period begins (Cambrian Period ends);  _____________________________________________ 

 425,000,000 B.C. SILURIAN Period begins (Ordovician Period ends);

_____________________________________________  395,000,000 B.C. DEVONIAN Period begins (Silurian Period ends);

_____________________________________________  370,000,000 to 367,000,000 B.C. (ELE 5) The Devonian extinction; A comet slamming into Nevada generates 1000-foot-high waves in what was then an ocean and was likely the first in a series of comet strikes that brought about the Devonian extinction, one of five greatest extinctions of life in Earth's history. Most organisms lived in the ocean. By itself, the impact couldn't have caused a mass extinction three million years later but craters and similar breccia rocks in other countries suggest the Devonian mass extinction was caused by numerous comet strikes within a few million years. 

HE EMERGENCE OF PLANTS,BIRDS,MAMMALS & DINOSAURS  310  000 000-65 000 000 BC

THE CARBONIFEROUS,  PERMIAN, TRIASSIC, JURASSIC, CRETACEOUS PERIODS

 345,000,000 B.C. CARBONIFEROUS Period begins (Devonian Period ends); 

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310,000,000 B.C. Divergence of birds and mammals; _____________________________________________ 

 280,000,000 B.C. PERMIAN Period begins (Carboniferous Period ends); 

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250-240,000,000 B.C. (ELE 6) The Permian extinction; massive period of volcanism in Siberia (Geophysical Research Letters); A drying trend of Pangaea that cut off the flow of nutrients to the oceans some 240 million years ago may be to blame for the greatest mass extinction the world has ever known. Massive volcanic eruptions in Siberia or a huge belch of harsh chemicals from the ocean floor could have caused the event during the last 2 million years of the Permian Period, when nearly nine-out-of-10 species vanished. Fossil marine deposits show that land sediments stopped reaching the ocean as the Permian ended. (Pennsylvania State University team at the annual meeting of the American Geophysical Union) 

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230,000,000 B.C. TRIASSIC Period begins (Permian Period ends); 

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212,000,000 B.C. (ELE 7) The Late Triassic Extinction; A series of comets slams into North America and Europe. The earliest dinosaurs may have looked up from their evening meals to witness a mountain hurtling through the sky. Blazing white-hot and moving at 61,000 kilometres per hour, the giant comet or asteroid screamed through Earth's atmosphere, close enough to snap the tops off any high peaks in its path. Then the object disappeared back into space, missing the planet by the thinnest of margins. The sky streaker would return shortly -- this time, in force. The extraterrestrial menace split into a series of large chunks that slammed sequentially into Earth, like bullets from a machine gun. This scenario is emerging from scientific studies of five ancient craters (the Rochechouart impact structure in France, the Manicouagan impact structure in Canada, the Saint Martin impact structure also in Canada, and two craters in the Ukraine and North Dakota. When located on a map of the world 214 million years ago, the first three fall almost perfectly in a line). All five are believed to have formed within a few hours of each other 214 million years ago, with planet-wrenching consequences. The late-Triassic crisis is notorious as one of the five biggest extinction events in the fossil record, wiping out the dominant reptiles of the time and spurring the rise of a hitherto minor group called dinosaurs, which went on to dominate Earth for 150 million years. 

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195,000,000 B.C. JURASSIC Period begins (Triassic Period ends); _____________________________________________ 

185,000,000 B.C. Peak of volcanic activity in eastern California; _____________________________________________ 

150-100,000,000 B.C. (ELE 8) During the breakup of the supercontinent Pangaea in the early Cretaceous period; crater Mjoelnir formed north of Norway; Dubbed Mjoelnir after the mythical hammer wielded by Thor, a 25-mile-wide, undersea meteor crater in the Arctic was the result of a stunning collision 150 million years ago. It is estimated that the roughly 1.25-mile-wide meteor was travelling about 18,600 mph when it slammed into the Earth 125 miles north of Norway. The impact caused a tidal wave that stretched from Canada to Russia and sent a plume of hot debris into the atmosphere that darkened much of the planet. (from "Gemini," a publication of the SINTEF Research Institute in Norway) 

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140,000,000 B.C. CRETACEOUS Period begins (Jurassic Period ends); dinosaurs dominated; 

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100-70,000,000 B.C. Mammals were alive during the Cretaceous period; Mammals definitely were living on Earth during the Cretaceous period from 70 to 100 million years ago, before the extinction of the dinosaurs. A massive gene study suggests that

modern orders of mammals first evolved when the continents were separating during the Cretaceous era about 100 million years ago. The scientists sifted through many thousands of vertebrate gene sequences from hundreds of species to find those that develop mutations at a constant rate over time. (Penn State biology researchers Sudhir Kumar and S. Blair Hedges in "Nature") 

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92-86,000,000 B.C. Arctic as warm as present-day Florida; Immediately after volcanoes around the world spewed carbon dioxide into the atmosphere about 90 million years ago, the Arctic was as warm as present-day Florida, according to fossil evidence discovered by a University of Rochester team in the high Canadian Arctic. The find of bones from several crocodile-like beasts known as champsosaurs, along with turtles and fish -- champsosaurs' favorite foods -- is detailed in a "Science" article. Based on the numbers and sizes of the animals found, the team estimates that the annual mean temperature in the Arctic during the late Cretaceous period, from about 92 million to 86 million years ago, was about 57 degrees Fahrenheit. That means it was rarely if ever freezing during the winter, and summer temperatures consistently reached into the 80s and 90s. 

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91,000,000 B.C. (ELE 9) A smaller extinction of species perhaps caused by an extended period of volcanic activity; 

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65,000,000 B.C. (ELE 10) TERTIARY Period begins (Cretaceous Period ends); Dinosaur extinction; 6-mile-wide cometary impact in Chixilub, Yucatan; massive period of volcanism in India (Geophysical Research Letters). More clues point to impact as dinosaur killer. Two new impact crater sites in Belize and Mexico add further evidence to the hypothesis that an asteroid or comet collided with Earth about 65 million years ago, subsequently killing off the dinosaurs and many other species on the planet. Researchers Adriana Ocampo of NASA's Jet Propulsion Laboratory, Pasadena, Calif., and Kevin Pope of Geo Eco Arc Research, La Canada-Flintridge, CA, led an international team that discovered the two new sites during a recent expedition sponsored by NASA's Exobiology Program and The Planetary Society, Pasadena, CA. 

THE EMERGENCE OF BIPEDALISM  65  000 000 BCTHE TERTIARY, QUATERNARY, NEOLITHIC & PLEISTOCENE PERIODS

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55-35,000,000 B.C. Massive mountain range forms; The Himalayas, the European Alps, and the Caucasus may be the remnants of a massive mountain range -- formed around 55 million years ago when two supercontinents collided -- that may once have spanned much of the globe from Spain to New Zealand. (Geologists at the Australian Crustal Research Centre at Monash) 

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40,000,000 B.C. Glaciers began to close over Antarctica, once a mild, forested landscape; 

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35,500,000 B.C. (ELE 11) A shower of comets hit Earth (one crater is under Chesapeake Bay in Maryland and another is in Siberia; Extinction event; The 53-mile-wide crater near Virginia and the 60-mile-wide Popigai crater in Siberia created (based on analysis of rocks melted by the impacts) long-lasting changes in the global environment and caused the mass extinction that happened about the same time. ("Nature") Geochemical evidence collected from a rock quarry in northern Italy indicates that a shower of comets hit Earth and account for the huge craters at Popagai in Siberia and at Chesapeake Bay in Maryland. A large comet cloud outside the orbit of Pluto was knocked askew by a gravitational disturbance that forced a wave of comets into the centre of the solar system late in the Eocene period. ("Science") 

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28,000,000 B.C. 98% pure silica-glass formation in Western Sahara (near Libyan border) formed, from which a scarab was made for Tutenkhamen; 

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25,000,000 B.C. Huge volcanic eruptions (Antarctica); Scientists drilling into the floor of the Ross Sea near Antarctica found layers of pumice and other volcanic debris up to four-feet-thick -- evidence of huge volcanic eruptions; suggesting a past so fiery as to alter the global environment of the time. 

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4,000,000 B.C. Emergence of bipedalism; Tests on volcanic material confirm that fossils discovered in Kenya in 1995 are from the earliest known ancestor of man to walk erect, more than four million years ago, pushing the emergence of walking on two legs back more than 500,000 years. The origins of bipedalism go back well over 4 million years. (Craig Feibel, Rutgers University geologist, "Nature") 

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3,500,000 B.C. Date for oldest human ancestor found in S. Africa; A complete fossil skeleton more than 3.5 million years old was found in South Africa. It predates any remains found anywhere south of Tanzania by half a million years but scientists will want to examine the skeleton closely to establish whether its upper jaw has the tell-tale, ape-like "arrow-head" formation or whether it more closely resembles modern humans. A complete skeleton will provide details about how upright these species stood, what kind of gait he had, and how well developed his hands were for making and using tools. (University of the Witwatersrand) 

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3,300,000 B.C. Cometary or asteroid impact in Argentina; air and ocean temperatures cooled quickly, and large scale extinctions (geology); An 18-mile-long layer of greenish

glass in a seaside cliff between Mar del Plata and Miramar on the central Atlantic coast of Argentina, may have been deposited by the fiery impact of a comet or asteroid hitting the Earth 3.3 million years ago, according to researchers, at least 36 different types of animals became extinct around the time of the impact. (Science article be Peter H. Schultz of Brown University) 

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2,500,000 B.C. Current glacial-interglacial cycle set in motion; rise of Himalayas; closing of Isthmus of Panama; The current glacial-interglacial cycle is set in motion more than 2.5 million years ago by gradual closing of isthmus of Panama, which re-routed oceanic currents that carry water and heat around the globe. Others say the cause was the rise of the Himalayas, resulting in a realignment of atmospheric circulation. 

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1,800,000 B.C. QUATERNARY Period begins (Tertiary Period ends); _____________________________________________ 

480,000-430,000 B.C. GLACIAL PERIOD; _____________________________________________ 

200,000-100,000 B.C. GLACIAL PERIOD; 75,000-13,000 B.C. (ELE12) GLACIAL PERIOD followed by genetic divergence; A horrific "volcanic winter" 71,000 years ago (caused by the super-eruption of Mount Toba in Sumatra) followed by the coldest 1000 years of the last Ice Age, brought widespread famine and death to modern human populations around the world. The relentless volcanic winter led to substantial lowering of global temperatures, drought and famine, and to a global human population crash during which, if geneticists are correct, no more than 15,000 to 40,000 people survived. The abrupt decrease, in population brought about the rapid genetic divergence of the surviving populations. (Stanley Ambrose, University of Illinois, in the June issue of the Journal of Human Evolution; linking geneticists' research to that of volcanologists) Changes in the Earth's orbit affect the amount of sun that falls on the Earth which in turn can affect the long-term climate. In a SCIENCE article, researchers report that as the Earth moves up and down in the plane of the solar system, differing quantities of extraterrestrial debris, dust, and meteoroids come into the Earth's atmosphere which, in turn, results in cyclical variations in our climate. There have been ten periods of glaciation in the past million years. A NATURE article reports that the Earth's orbit can itself be influenced by the way geophysical processes deep within its crust interact with the solar system's movement. Features of the Earth's orbit, such as the rotation of the poles and changes in the tilt of its axis, may be influenced by factors such as the way the Earth's crust is affected by the melting of continental ice sheets. Also in NATURE, ocean currents and differences in water pressure are what makes the Earth wobble a few yards as it spins on its axis. The evidence emerged from a computer simulation of the oceans. 

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48,000 B.C. Space boulder smashes into Earth, creating Arizona's Meteor Crater; _____________________________________________ 

38,000 B.C. Harsh climate; Neanderthal man disappears; _____________________________________________ 

 13,000 B.C. Neolithic period begins

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13,000-9000 B.C. The Atlantean period. Neolithic period begins; rain in Egypt near Sphinx (West); Sumerian Enuna Elish tradition (Sitchin and Biblical deluge); Final sinking of Atlantis (Cayce); Sudden warming with CO2 Methane "spike" in ice-core; (Science); Atlantis sinks (Plato) – Japanese city off Okinawa becomes submerged, dating its construction back to +- 11,500 B.C. linking back to the first traces of South American colonization. 

_____________________________________________  11,630 B.C. End of the Pleistocene Period; 

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10,500 B.C. Polar shift occurs, freezing temperate zones, and Woolly mammoth. There are two main theories as to why this polar shift ocurred. The first is that an asteroid impacted the oceans off the Florida Coast at an oblique angle (which it did - but whether or not it shifted the crust of the earth is argued.) and the second (more likely)  is that massive ice build up on the poles caused an imbalance which cased the crust to shift on its molten code. 

10,500 B.C. The top and bottom of the Earth warmed sharply, suggesting that some climate-change events once thought to be regional may have, instead, affected the entire planet; 

The Vredefort Structure.

Dr. Joe Mayer