Our planet Earth
Formed 4.54 billion years ago
Reshaped over hundreds of millions of years
Earth is estimated to have formed 4.54 billion years ago from the solar nebula, along with the Sun and other planets. Continents formed, then broke up and reformed as the surface of Earth reshaped over hundreds of millions of years, occasionally combining to make a supercontinent.
Freezing temperatures
Roughly 750 million years ago, the earliest known supercontinent Rodinia, began to break apart. The continents later recombined to form Pannotia which broke apart about 540 million years ago, then finally Pangaea, which broke apart about 180 million years ago.
During the Neoproterozoic era, freezing temperatures covered much of the Earth in glaciers and ice sheets. This hypothesis has been termed the ‘Snowball Earth’, and it is of particular interest as it precedes the Cambrian explosion in which multicellular life forms began to proliferate about 530–540 million years ago. Since the Cambrian explosion there have been five distinctly identifiable mass extinctions.
The Great Oxygenation Event
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Small, blocky shapes of towns, fields, and pastures surround the swirls of the Mississippi River
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Sahara Desert
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On the edge of the Kalahari Desert in Namibia, sand dunes are encroaching onto once-fertile lands in the north
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When landmasses collide, rock layers can break, geologists call these breaks ‘faults’
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Akpatok Island lies in Ungava Bay in northern Quebec, Canada
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The Lena River, some 2,800 miles(4,500km) long, is one of the largest rivers in the world
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The Turpan Depression, nestled at the foot of China’s Bogda Mountains
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A series of rocky outcroppings near the Terkezi Oasis in the country of Chad
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The Niger River flows north through an ancient sand sea, Mali in Western Africa
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The western region of Australia’s Great Sandy Desert is an area almost devoid of sand
Several million years ago, a species of small African ape gained the ability to stand upright. The subsequent advent of human life, and the development of agriculture and further civilization allowed humans to affect the Earth more rapidly than any previous life form, affecting both the nature and quantity of other organisms as well as global climate. By comparison, the Great Oxygenation Event, produced by the proliferation of algae during the Siderian period, required about 300 million years to culminate.
The present era is classified as part of a mass extinction event, the Holocene extinction event, the fastest ever to have occurred.
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