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The geologically time calendar - Referat



Perhabs you know, that our earth isn't very young.
Almost she's about 4,6 billion years old.
At this time the earth-crust was still liquid.
This time is called Precambria. It persists till about 570 million years before our time, so it's the longest era of the earth's history

The next era is the Paleozoic era it persists about 320 million years. and it's partitionated in 6 periods:

-Cambria:(60 million years) The oxygenconten of the atmosphere incresed--> First oxigen dependet organisms.
in the end there were already simple organisms like worms

-Ordovician: (75million years) invertebrate marine animals and primitive kinds of fish

-Silurian: (30 million years)dry land: scorpions; millipedes
water: fish with jaws

-Devonian: (50million years) In the end the shores were settled by amphibians

-Carbonifereus: (65 million years) apundant swamp forest vegetation on the land
and in the sea there were the first bones-and-gristle-fish like sharks.

-permian: (60million years) The first and only time in the history all land masses were united in one giant continent called pangaea because the two continents Euramerica and Gondwanaland collided
Cryptogams like fers withdrew in favour of seed plants and the reptilles made some great evolutionary developments


In the end of the permian there was the most devasting catastrophe in history:
The sciencist robert Berner found out that there was much carbonamassed in thein the sea. After som examinations he found out that much scenarios happend at the same time:
-Great settlings of the instable chemical "methanhydrid" became gaseous and distrebuted in the athmosphere because of earthquakes.

-Also in sibiria there were much active volcanos wich also blew carbon in the air.
-Perhabs there was also an astronomic actuator like an asteroid wich killed many animals. their rooting animals also would have produced carbon
After this 90% of al sea-creatures were killed. completly died out were for example the Trilobites, a kind of cancer.Also 70% of all land creatures died.

All in all the carboneotation had to organize completly new

Althought many animals died the flora and the fauna regenerated quickly.
/> After this all a new era began:

The mesocoic era. It persists about 180 million years and is partionated in 3 periods:

-Triassic: (45 million years)Sea: Ichtyosaur
Dry land: Dinosaurs

The giant continent Pangaea broke up into the two giant continents Laurasia (North): All continents of the northern hemisphere and
Gondwana(South): all continents of the southern hemisphere


-I thing the next periods name you've already heard because it's part of the name of a film:
Jurassic:(65million years) The Jurassic was the evolutionary top of the reptilles. Also there were first mammals: they were predators and had the size of rats.

-Cretacious(70million years) In this era a gratasteroid collieded with the earth so the athmosphere were cooling down
But this explication is not really disproven or proven

The next era is the kenozoic era(From 65million years before us till today)
It's partionated in2 periods:
-Tertiary: (63 million years): A great variety of mammals appeared:Predators, hoofed mammals and our ancestor the primancies.

-Quartenary:(since about 2 million years)
in this period the evolution of the humans happend.
While the Ice ages the humans aetted on all continents instead the antarctica.
They made some great evolutionary stepstill there were the most developed "animal" the homo sapiens



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