Different Stages of the Earth
1. Formation (4.6 billion years ago):
– The Earth was formed from the accretion of dust and gas in the solar nebula.
– It was a hot, molten ball of rock and metal.
2. Differentiation (4.5 billion years ago):
– The Earth differentiated into layers based on density – the core, mantle, and crust.
– The magnetic field and atmosphere began to form.
3. Heavy Bombardment (4.1 to 3.8 billion years ago):
– The Earth was subjected to intense meteor bombardment, leaving numerous impact craters.
– The Moon was likely formed during this period due to a massive impact.
4. Cooling and Solidification (4 billion years ago):
– The Earth’s surface cooled enough for the crust to solidify
– The earliest oceans and continents began to form.
5. Archean Eon (4 to 2.5 billion years ago):
– The Earth’s crust and continents were continuously reshaped by volcanic activity and plate tectonics.
– The earliest life forms (single-celled microorganisms) appeared.
6. Proterozoic Eon (2.5 billion to 541 million years ago):
– Oxygen levels in the atmosphere increased due to photosynthetic organisms.
– Complex life forms like algae and fungi emerged.
7. Phanerozoic Eon (541 million years ago to present):
– This is the period of visible life, with the appearance of invertebrates, vertebrates, plants, and eventually humans.
– Continents and oceans took their present-day forms.
Evolution of Earth Class 11 Geography Notes
The Earth is a remarkable planet that has undergone a fascinating journey of formation and evolution over billions of years. From its humble beginnings as a hot, molten sphere to the diverse and life-sustaining world we know today, the Earth has witnessed countless transformations shaped by cosmic events and geological processes.
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