Changes. This modern world can be a very disconcerting place. It just keeps on changing, without giving us an even chance to catch up.
You make an adjustment here – another there – look around. It’s all changed again. But then, the world has always been changing – ever since it began.
Once, there were no seas, just an endless expanse of barren rocks. They were studded with active volcanoes; and pitted with great craters, the constant bombardment of stray asteroids crossing the Earth’s orbit in the formation of the early Solar System.
Another time, the world was almost covered by ocean from the continual accumulation of volcanic water vapours and cometary landfall. Just a few landmasses protruded from the depths, their peaks a-swirl with activity.
We acquired the Moon by a collision with a Mars-sized neighbouring world about 50 million years after the formation of the Earth. This gave us our tidal motion but more importantly, initiated and maintained the plate tectonic system essential to the biosphere and affected our speed of rotation, thus determining our length of day.
Over the eons, this speed of rotation has slowed down as the moon has gradually moved further away, with the result that our day is currently approximately 24 hours long and will grow longer still as the Moon recedes yet further from us.
Originally our day was much shorter and the Moon was huge in our skies, hurrying across like some madman from horizon to horizon in just six hours. Although at that time life had not arisen, so there were no living creatures to observe the phenomenon.
Geological age has followed geological age upon this Earth for approximately 4600 million years so far, a stretch of time breathtakingly vast compared with that of our lifetimes,
The atmosphere was once entirely different and would have been completely unbreathable to life on Earth, as we now know it. Bacteria and other such microbial life flourished in this, and they still do in those conditions that suit them and persist in certain environments today,
Oxygen was just a poison to these earlier living forms of the world. It was produced in abundance by a sudden upsurge in the activities of flourishing photosynthesizing organisms, way back in Precambrian times somewhere between 3000 and 1500 million years ago. Those creatures that adjusted, gave rise to the dominant forms known today, of which we humans are a part.
Ice ages have come and gone with fluctuations in the Earth’s orbit, tilt and wobble, and from solar activity. Sometimes the Earth has been tropical. There has been a long procession of constantly changing flora and fauna.
The Devonian age of fishes and early land plants existed around 409 to 360 million years ago; and the Carboniferous age of swamps, ferns, insects and amphibians, lasted from approximately 360 to 290 million years ago.
And there have been many great extinctions that nearly wiped out all life on this planet. Most of those extinctions have been caused by cataclysmic events, such as an asteroid strike or large-scale volcanic activity or, as in the great Permian extinction, a juxtaposition of the continents unsuitable for life.
The Permian period lasted for about 45 million years, from approximately 290 to 245 million years ago.
One vast supercontinent existed in those times. It was called Pangaea. Surrounded by the great ocean of Panthalassa, it was the third supercontinental configuration of existing landmasses, the first being Rodinia from around 1100 mya for some 350 my and the second being Pannotia during a briefer interval of continental joining from about 600 mya till the end of the Precambrian Era around 541 mya.
Pangea’s formation created the circumstances that dried out the interior of the continent, stagnated the surrounding oceans and towards the end of the period, caused an extensive extinction of marine animals and the beginning of the proliferation of reptiles, starting with lumbering, pig-sized tanklike creatures called Lystrosaurus, a member of the dicynodont family, [therapsid mammal-like reptiles springing from the synapsid lineage and heralding the development of the mammals; as averse to the main body of the reptilian branch, sauropsida].
Sauropsida is the class that includes [Squamata] snakes and lizards,[Ryynchocephalia] tuataras, [Chelonia – now usually known as Testudines and actually belonging to the more primitive anapsid branch, which comprises turtles and tortoises and the extinct aquatic placodonts] and [Crocodylia] crocodilians, which include all the crocodiles, alligators, caimans and gharials; as well as various other extinct groups such as the dinosaurs, pterosaurs, ichthyosaurs, plesiosaurs, pliosaurs, mesosaurs and mosasaurs.
The dinosaurs were a complex clade of animals generally described as archosaurs with limbs held erect beneath the body and consisted of two main divisions: Ornithischia [bird-hipped] and Saurischia [lizard-hipped] though this nomenclature is inaccurate and misleading, for it was a subdivision of the Saurischian lineage which gave rise to the birds by rearranging the placement of their hips. The Ornithischia were originally named for a pseudo resemblance of their hip-structure to that of modern birds.
The Saurischian Class was composed of the Theropods: [bipedal carnivores], which included the Megalosaurs, Carnosaurs, Allosaurs, Coelurosaurs, Tyrannosaurs, Maniroptera, Oviraptors, Deinonychosaurs, and Avians [birds] – and the Sauropods; [herbivorous quadrupeds], comprising the long-necked Brontosaurs [renamed Apatosaurs], Diplodocids, Brachiosaurs and Titanosaurs.
The Ornithischians included the horned dinosaurs [Ceratopsians such as Triceratops and Styracosaurus], armoured dinosaurs [Stegosaurs and Ankylosaurs], Iguanodonts, and their genetic successors, the duck-billed dinosaurs [Hadrosaurids].
The Permian period gave rise to the age of dinosaurs [Mesozoic] and was the biggest extinction event this world has ever known, larger even, than that which caused the eventual demise of the dinosaurs 65 million years ago.
The Mesozoic era spanned approximately 180 million years from about 245 million years ago, comprising the Triassic, Jurassic and Cretaceous periods, in which the dinosaurs flourished.
In the Early-Middle Jurassic about 175 Mya, the supercontinent Pangea began to breakup into the southern section known as Gondwanaland, consisting of Africa, India, Australasia, Antarctica and South America; and Laurasia, the northern part, comprising the present day crustal constituents of Europe, North America and Asia.
Tectonic activity has ensured the continual shifting, sinking and rising of continents and oceans and will continue to do so for about another four thousand million years.
Then, the radioactive heat source inside the Earth will begin to run down. The Earth’s mantle will stop circulating, cool down and become solid. The plates on the surface will stop moving and fuse together.
Without the replenishment of volcanic action, all surface water will gradually disperse into space. Cooling of the core will stop the generation of the Earth’s magnetic field. The protective ionosphere will then also disperse and the Earth will be flooded with harmful radiation.
The Earth will be geologically dead. By this time the Moon will have moved so far away that the Earth’s rotation will have slowed to a crawl and a day will last for about a month and a half.
As if this is not enough, some millions of years later, the Sun’s hydrogen supply will run down. It will then start burning the helium at its core and flare up into a huge red giant, pushing out a shell of oxygen and carbon, engulfing Mercury and Venus and scorching the Earth, before finally also engulfing the Earth as it continues to expand.
Then, after the Sun has expended all its gases it will shrink [arriving At the incredibly dense white dwarf phase of its life]. In this state it may be seemingly arrested for the remainder of the age of the universe. After this it may continue growing dimmer and dimmer; turning gradually to a cold dark cinder and what is left of the Solar System will be in darkness.
Eventually the whole universe will run down. Actually, the current consensus holds that the universe is supposed to be continually expanding at an exponential rate. If it carries on like that everything will attenuate so much that nothing will be left.
Sounds like a barrel of fun, doesn’t it? But nothing for us to worry about, we won’t be here to observe it, we’ll all be long gone, for you and I are but a wink in eternity’s eye.
CHANGES DAVE DRAPER © JULY 2010
Information on the Featured Image and Slideshow
is contained in the notes beneath:
The featured illustration of the Earth as seen from space was painted in acrylic watercolours in 1982. It is an artistic representation, and only loosely based on any actual photographic image, rather than an absolutely perfect likeness of the real thing. However I think it is a little more accurate than Ptolemy’s view of the World in 150 AD [and a host of other depictions running from those of Herodotus 450 BC, Eratosthenes 194 BC and Strabo’s of around 18 AD, right up to the 20th Century]. The main body of text I’ve set to accompany it was written in 2010, except for a few touches of recent editing and the addition of the final three short paragraphs created in 2014.
I have set a slideshow beneath the Featured Image consisting of the following items:
Space View of Africa
Europe seen from Space
Earth in Space
Dave Draper August 2014
SEE ALSO –
Jurassic Swamp: located in ART under Landscape
Moonrise: In ART under Landscape