Geography

Geography is a branch of study of the World, including its land, water bodies and climate.

Shape of the Earth
Till recently, we did not know what is the shape of the Earth we inhabit. Only when we were able to see the Earth from space, we exactly knew the Earth is almost an oblate spheroid - a sphere slightly flattened at the poles.

It is in fact not axactly round, as first conceived by the great Greek thinker Pythagoras in the 6th century BC. It is only nearly round or spherical. However, the flattening at the poles is too small to be perceived when this shape is of the size of a globe or football on our tables. All the mountains, rivers and other heights and depths are too little to make the surface of the earth unspherical. The heights are not more than a coat of paint and the trenches not more than scraches on this spherical shape taken as a whole.

History of the World or the Planet Earth
Many scientists believe that the Earth was formed around 4,600 million years ago.
The oldest rocks to be found on the surface of the Earth today were believed to have formed around 3,900 million years ago. The atmosphere of the Earth was still being formed.
First elementary single-cell plant life formed around 3,300 million years ago.
Rocks, popularly known as 'Lewisian rocks', in the Outer Hebrides (Scotland) formed sometime around 3,000 million years ago.
Single-cell animal life believed to have appeared in the sea around 2,500 million years ago.
Rocks in the Grand Canyon (Colorado) formed in between 1,600 and 1,800 million years ago.
Sponges, jellyfish and corals formed around 690 million years ago.
The atmosphere, just like the present atmosphere, formed around 470 million years ago.
First fish appeared perhaps around 470 million years ago.
Sharks and rays appeared around 435 million years ago.
Around 385 million years ago, there was only one mass of land. Vegetation on Earth appeared around this period, and vast swamps occurred at the places where sea met the land.
Amphibians appeared around 370 million years ago. They were marine creatures. They attracted towards the swamp water to graze on vegetation on the land.
Reptiles appeared around 335 million years ago.
Formation of coal began around 300 million years ago.
The age of the dinosaur began around 200 million years ago.
Soon after, around 195 million years ago, the first mammals and birds appeared.
The single mass of land began breaking up into continents.
The first marsupials, the animals with pouches for their young ones, appeared sometime around 100 million years ago.
The age of the dinosaurs ended around 65 million years ago.
Rabbits, rodents, seals and whales appeared around 50 million years ago.
Early primates appeared around 40 million years ago.
Kangaroos, beavers, rhinoceroses, and deer appeared around 30 million years ago.