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Click to advance. Roll the mouse over the underlined blue words for additional information. Earth A small history by Clóvis Ático clovis. atico@gmail. com Translation from portuguese by Ann Lowe vagalume@cableone. net

® The Earth is approximately 4. 6 billion years old and during all this time it suffered various global transformations that left many definite signs in its rock formations. ® By identifying these signs, it is possible to divide Earth’s History into distinct geological phases, thus establishing a Geological Time Scale.

® In this scale, which is not linear, we are indicating the passage of time from bottom to top, the oldest being shown at the bottom. ® Moreover, this is how rocks are normally found in nature: the most recent on top of the older.

® Since it is difficult to reason with periods of time in millions of years, we will convert our Geological Scale into a span of about 24 hours. ® Now, let us imagine we are traveling in a time machine which can move at a “velocity“ of 53, 240 years per second. ® In this manner, we will travel a million years every 18. 78 seconds.

One billion years 4, 600, 000 years ago ® So, we will start our voyage at midnight, when the Earth was formed (4. 6 billion years ago) and when the Universe was already 9. 1 billion years old. ® Now, let us move to the present, from the bottom to the top of the Scale, until the end of the Quaternary, knowing beforehand that we will take exactly 24 hours on this virtual tour. ® We will see our planet being formed from scalding rocks, dust, and chocking fumes resulting in a boiling, deformed, hideous mass. 00: 00

One billion years 4, 530, 000 years ago ® After almost 22 minutes have passed (70 million years) from the beginning of its formation, the Earth will suffer a catastrophic collision with another planet, today known as Theia, resulting in the complete destruction of the latter. ® Part of Theia’s wreckage will continue in Earth’s orbit and will eventually fuse and form our Moon, while its core will be absorbed by our surviving planet. 00: 21: 55

One billion years 4, 200, 000 years ago ® The next few hours of our trip will certainly be the most monotonous. ® We will be in the Hadean, observing the Earth persistently being bombarded by meteors and comets. ® Planet’s internal fusion will allow iron, the most dense, to sink to the center, forming a heavy core. ® The less dense material, rich in silicates, will float to the surface forming an ocean of boiling magma. 02: 05: 13

One billion years 4, 100, 000 years ago ® During the Hadean, the Earth’s atmosphere was rich in CO 2, probably as much as the atmospheres on Venus and Mars. ® Gradually, the planet will recover from the intense bombardment and will start to cool down. ® The water vapor exhaled by volcanoes and deriving from comets will form the first rains. 02: 36: 31

One billion years 4, 000, 000 years ago ® A little after 3: 00 AM, we will be in the Archean eon, and we will see the Earth, still very hot, covered by an immense ocean. ® The water of the ocean absorbed the larger portion of carbon dioxide spewed by volcanoes, but even so, the atmosphere was saturated with carbon dioxides and practically no oxygen (0. 0001%). 03: 07: 50

One billion years 3, 500, 000 years ago ® Life was not too exciting in the Archean eon, limited to simple unicellular organisms not nucleated, called prokaryotes and cyanobacteria (known as blue algae). ® Successive generations of these algae will form the stromatolites found up to this day. ® These will be the first organisms capable of photosynthesis, with the consequent release of oxygen. 05: 44: 21

One billion years 2, 500, 000 years ago ® Initially this oxygen will react with the large supply of iron found in the ocean’s waters, forming iron oxides that will be deposited in the deep waters. ® Many of the banded iron formations of this type are explored up to this day for the mining of iron ore. ® When most of the iron has been oxidized, the oxygen can escape and will contaminate the atmosphere, affecting anaerobic life predominant until now. ® We have just entered the second eon: the Proterozoic. 10: 57: 23

2, 000, 000 years ago ® Due to the increasing concentrations of oxygen in the atmosphere, the Earth will go through a mass extinction, known as the Oxygen Catastrophe. One billion years ® A new form of life dependent on oxygen will dominate the planet: the aerobic bacteria. 13: 33: 55

One billion years 542, 000 years ago ® The aerobic bacteria will rule alone, until somewhat after 9: 00 PM for almost 1. 5 billion years (08: 36 hours) ® We are now at the end of the Proterozoic eon and due to the orogenesis which will occur in the future, there will be very few fossils registered in the rocks. ® The atmosphere would have gradually changed from red to blue. ® Until now we have been visiting the Pre-Cambrian, which lasted more than 88% of our Earth’s History. 21: 10: 20

One billion years 542, 000 years ago ® At 9: 10: 20 PM we will enter the first era of the Phanerozoic eon: the Paleozoic, which will continue until 10: 41 PM. ® Because of its many events, the Paleozoic eon will be divided into 6 distinct periods. ®From this point on during our voyage, we cannot even blink an eye because everything will start happening very quickly. 21: 10: 20

One billion years 542, 000 years ago ® The volcanic activity in the Paleozoic will be more favorable around the planet, alternating between periods of calm and large explosions. ® We are in the first period of the Paleozoic era, the Cambrian, when 4 continents will emerge: Laurentia (central portion of North America), Baltic (part of Europe), Siberia (same region as west Russia) and a super continent in the southern hemisphere, which will be named Gondwana. ® There was still no vegetation and the continents were only bare rocks. 21: 06: 34

530, 000 years ago 21: 14: 05 One billion years Asaphicus wheeleri Trilobite ® The first fish, sponges, corals and mollusks will appear still in the Cambrian period and the event will be of such importance that it will be known as the Cambrian explosion. ® In a relatively short time all phyla of known marine animals will appear, including forerunners of vertebrate and the ones that have not yet been classified by science.

21: 23: 29 One billion years 500, 000 years ago ® A good portion of this biological diversity will be extinct by the end of the Cambrian period, probably due to an extensive glaciation. ® It is estimated that 85% of all life on our planet will be extinct at the end of the Cambrian period.

One billion years 488, 300, 000 years ago 21: 27: 08 Ordoviciano ® We now enter the second period of the Paleozoic era: the Ordovician. ® The continents are still deserted, lowered by epeirogenesis and invaded by extensive shallow seas. ® The north of the planet will be almost entirely covered by ocean, while the land will be confined to the south.

One billion years 466, 000 years ago 21: 34: 07 Starfish Age: 490 to 443 million years Period: Ordovician Location: Kataoua formation , Marocco ® Since the organisms now start to have some hard parts (shells, teeth, etc. ), some of them may be preserved as fossils. . . ® Some of these fossils will be discovered and studied by another species in the distant future. ® The Ordovician period will last approximately 44. 6 million years (almost 14 minutes) and the sign of its end will be another mass extinction.

443, 700, 000 years ago 21: 41: 06 Orthoceras regulare One billion years A cephalopod Eurypterus remipes A sea scorpion ® At 9: 41 PM we will enter the Silurian period, when the fauna has to recuperate from the recent mass extinction. ® The predomination of invertebrates will be maintained, principally trilobites, crinoids, eurypterids and cephalopods. ® The first terrestrial plants will appear.

416, 000 years ago Goniatites sp. fossil One billion years Middle Devonian found in Morocco ® A little more than 10 minutes before 10: 00 PM we will arrive at the Devonian period. Due to the proliferation of fish, this period is called “the fish age”. ® Climate was hot and the oceans levels high. This caused many parts of the lands to be covered by shallow oceans where large coral reefs proliferated. ® In this period the first sharks and amphibians emerged. 21: 49: 46

359, 200, 000 years ago One billion years Pecopteris arborescens Upper Carboniferous ® A little after 10: 00 PM we will arrive at the Carboniferous period, when large forests and swamps will cover most of the land. ® In the forests of this period the lycopodium and ferns will prevail (although with larger and incomparable diversity than in prior periods), deserving to be outstanding as the Pteridospermatophytas (fern with seeds) which are today extinct. ® Such forests will generate large mineral coal deposits, explored up to this date. 22: 07: 33

One billion years 299, 000 years ago ® Finally, the continents are invaded by insects… millions and millions of different insect species. ® We now enter the Permian period, when the Earth's climate will begin to heat up even more. ® Some of these insects will survive until the end of our voyage. 22: 26: 24

One billion years 270, 600, 000 years ago 22: 35: 17 Stereosternum tumidum Irati Formation - Permian ® During the Permian period we will notice a larger development and diversity of reptiles which will definitely dominate the planet. ® They will be large and will reach the top of the food chain, and at the same time we will see a decline of the giant arthropods, which will be extinguished during this period. ® In the terrestrial fauna of the period, animals that stood out were neither reptiles nor mammals but belonged to the group of Synapsids.

253, 800, 000 years ago ® Marking the end of the Permian period, a new mass extinction will devastate the planet and will be of such magnitude that it will be known as “the mother of all extinctions”. ® We will watch the extinction of 96% of marine species, about 70% of land vertebrates and 83% of insects. One billion years ® The most accepted theory is that gigantic volcanic eruptions released such a large quantity of carbon dioxide into the atmosphere that they caused a sudden increase of the planet’s temperature. 22: 40: 33

251, 000 years ago 22: 41: 26 One billion years Plateosaurus Late Triassic. ® We now arrive at the Triassic, first period of the Mesozoic era, when earth’s median temperature was almost double of today’s. ® In the forests, ferns, ginkgos and conifers will prosper. ® Reptiles will again dominate the Earth (all terrestrial fossils of the Triassic period are of reptiles). ® The first dinosaurs will appear, smaller than the ones which will follow in the Jurassic period, most being quadrupeds.

199, 600, 000 years ago 22: 57: 31 ® Close to 11: 00 PM we will arrive at the Jurassic period, when low lands will be covered by the ocean, dividing the supercontinent Pangaea into two continents: Laurasia in the north and Gondwana in the south. ® The prevailing plants will be the cycads, ginkgos and giant conifers (sequoias). One billion years ® In this period the first plants bearing flowers will also appear.

172, 550, 000 years ago ® The fauna of the Jurassic period will be marked by the hegemony of the reptiles in all environments: dinosaurs on the land, pterosaurs in the air and plesiosaurs in the ocean. ® This period is also marked by the appearance of the first birds and the first true mammals. One billion years ® More intelligent and developed dinosaurs will appear, superior to the primitive reptiles of the Triassic. 23: 05: 59

One billion years 145, 500, 000 years ago ® During the Cretaceous period the dinosaurs will reach their apex (more than half of the known species lived during this period). ® At the same time, placental primitive mammals and flowering plants will proliferate. ® In this period the continents will start to migrate to the position they are today. 23: 14: 27

65, 500, 000 years ago ® A new mass extinction will occur at the end of the Cretaceous. ® The stratigraphic registry shows that the sudden disappearance of species at the end of the Cretaceous coincides with a rich level of iridium, a chemical element not very abundant on the Earth, and is generally associated with extraterrestrial bodies, or volcanic phenomena. One billion years ® The most accepted theory is the fall of a meteorite in the Yucatan peninsula in Mexico, creating a cloud of dust which covered the Earth, causing the planet to cool down by obstructing the passage of the Sun’s light. 23: 39: 30

One billion years 60, 000 years ago ® After the extinction of the dinosaurs (11: 39: 30 PM) we will enter the first period of the Cenozoic era: the Paleogene, which will last until 11: 52: 47 PM. ® The Paleogene period is divided into 3 epochs: Paleocene, Eocene and Oligocene. 23: 40: 48

58, 700, 000 years ago 23: 41: 37 ® In the Paleocene epoch, we will see the proliferation of small mammals but giant birds will assume the top of the food chain. One billion years ® The climate will continue very warm and the planet, in a general form, will be similar to the final of the Cretaceous period. Fossil of Diatryma Paleocene

One billion years 55, 800, 000 years ago ® In the beginning of the Eocene epoch, birds will be the dominating predators, but in time, carnivore mammals will develop and replace them. ® Around 11: 48 PM the climate starts cooling down and vegetation near the poles starts getting similar to the tundra and taiga, starting the process of freezing the poles. ® These changes will cause a considerable extinction of the animals of that time. 23: 42: 32

One billion years 33, 900, 000 years ago ® Around 11: 49 PM we will enter the Oligocene epoch, which will last until 11: 52: 47 PM. ® Australia will separate from the Antarctic, India will unite with Asia, and North and South America will start coming closer together. ® Orogenic events which started in the Cretaceous period will expand, resulting in the formation of the Alps and the Carpathians in Europe, and the Atlas in North Africa. 23: 49: 23

23, 030, 000 years ago One billion years Fossilized insects in amber ® At about 11: 43 PM we will enter the penultimate geological period, the Neogene, whose first epoch, the Miocene, will extend until 11: 58: 20 PM. ® During this epoch the mountain ranges of the Pyrenees, Alps and the Himalayas will continue to rise in elevation. ® The temperature will be lower than today’s and masses of ice will start forming in the Antarctic. ® Various species of mammals will proliferate, among them the rhinoceros, the cat, the camel, the horse and the great simians. 23: 52: 47

One billion years 5, 332, 000 years ago ® Right after 11: 58 PM we will enter the Pliocene epoch, which will continue until 11: 59: 11 PM. ® The two Americas will be united through the Panama Isthmus and the temperature will become colder and drier. ® The first recognized hominid will appear: the Australopithecus. 23: 58: 19, 85

One billion years 2, 588, 000 years ago ® With less than 49 seconds remaining to finish our voyage, we will enter the first epoch of the Quaternary period: the Pleistocene, which will last until one fifth of a second before midnight. ® The Homo sapiens, which will show up 12 seconds before the end of our voyage, will for a time live together with an older species: the Homo neanderthalensis. ® Homo sapiens will survive the last glaciation and will start its fabulous journey as a dominant species on the planet. 23: 59: 11, 39

11, 700 years ago ® In less than one fifth of a second (Holocene) the Homo sapiens will control fire, will domesticate animals and plants, will work with metals, will manufacture arms and will make wars… Many wars. ® They will build architectural wonders and develop technologies with the potential to provoke another mass extinction. One billion years ® They will occupy practically all environments, molding them according to their necessities and influencing the ecosystems which took a long time to balance. 23: 59, 78

24: 00 One billion years 40 years ago ® Man will dominate the lands, the oceans and the air… ® Will fly as no bird ever dared. ® But this is another History… End of the trip

Artistic conceptions: various authors, collected over the internet Chronological data : International Stratigraphic Chart (IUGS – 2009) Music: Also sprach Zarathrusta (Richard Strauss ) Jurassic Park gate (John Williams) Journey to the center of the Earth (Rick Wakeman) Formatting: Clóvis Ático (clovis. atico@gmail. com) Translation: Ann Lowe (vagalume@cableone. net)