How old is our Earth? how is the prehistoric environment of Earth?
How old is our Earth? How is the prehistoric environment of Earth?
Scientist has briefly studied about the earth and reach to the conclusion as
per the scientific findings and proof. Some details about our Earth are given
below :
|
Age
of Earth |
4.5
billion years |
|
Total
surface area of Earth |
509,700,000
sq.km |
|
Total
area of lithosphere |
148,400,000
sq.km |
|
Total
area of hydrosphere |
361,300,000
sq.km |
|
Average
surface temperature |
15
degree Celsius |
|
Average
relative density |
5.5 |
|
Mass |
6x10^24
Kg |
|
Satellite |
Moon
(1) |
|
Diameter |
12756.3
km |
Scientist tried to estimate the age of the earth by different
methods like studying the age of fossils, age of the rocks, examining the
earth's crust, carbon dating etc. They also tried to understand about the
incidents that occurred at different time's scales in the history.
During the dramatic 4.5 billion years history of the earth, it has
gone through a series of major geological and biological changes along with the
chemical changes. Geological time scale describes the order and duration of
major events and the evolution on the earth that have occurred since its origin.
Thus, geological time scale is the representation of a series of major
geological and biological changes throughout 4.5 billion year history of the
earth.
Geological time scale covers a vast expanse of time. It is divided
into various time intervals. According to chronology, they are arranging in the
order of eon, era, period and epoch.
An eon is the largest time unit ever
calculated and epoch is the smallest time unit in the geological time scale
ever calculated.
Eon
It is the largest unit of the geological time scale consisting of millions
of years long. It is divided into four major eons. They are Hadean, Achaean,
Proterozoic and Phanerozoic eons.
Era
Era is the smaller units of eons. The geological time scale of Era
is divided into four major eras.They
are Precambrian era, Paleozoic era, Mesozoic era and Cenozoic era viz.
1) Pre - Cambrian Era:
- It refers to the time scale from origin to 57 crore years ago
duration.
- There is no sign of life.
- Organic and Inorganic compounds are formed in large scale.
- First sign of life bacteria is found at about 3.8 billion years
ago.
- Algae were also evolving in about 3.2 billion years.
2) Paleozoic Era:
- It refers to the time scale of 57 crore years ago to 25 crore
years duration.
- Many terrestrial and marine invertebrates evolved and died in
this era.
- Many winged insects, fishes, amphibians and reptiles were
evolved.
- Many bryophytes and pteridophytes were evolved.
- This Era is called Ages of fishes because of many fishes evolve
in this time and they developed to different form.
3) Mesozoic Era:
- This age extend from 25 crore to 6.5 crore years ago and is
third generation.
- All aquatic, terrestrial and aerial animals evolve in this era.
- Dinosaurs evolved, developed and flourished over a large area
and finally became extinct forever.
- This Era is divided into three division as Triassic, Jurassic
and Cretaceous.
- This Era is called age of reptiles because reptiles evolved in
this era.
4) Cenozoic Era:
- This Era extends from 6.5 crore years ago long to the present
time.
- In this Era fragmentation and displacement of rocks occurred
with the formation of new geography.
- Mountain peaks are covered with ice.
- Earth is covered by ice wholly and is called Ice Age.
- Mammals like horse, rats, Elephants, humans, cats, dogs etc
evolved.
- Human, gorilla, chimpanzee etc are dominant in this Era so is
called Ages of Apes and human beings.
Short Biography of the world famous scientist Charles Darwin
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