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The Formation of Earth: Geological History and Mass Extinctions

Introduction of Formation of Earth: A Billion-Year Geological Saga #

The geological history of the Earth is a vast and intricate narrative that spans billions of years. It encompasses the formation of our planet, the evolution of continents and oceans, the emergence of life, and the shaping of the Formation of Earth through geological processes. 

This history is marked by dramatic events, including the collision that created the Moon, the development of continents, and the rise and fall of species

Formation of Earth Story: From Dust to Oceans, Extinctions, and Ice Ages #

  1. Formation of Earth:
    • Approximately 4.54 billion years ago, Earth formed from dust and gas swirling around the young Sun.
    • Early Earth was a molten mass with a formation of Earth continually bombarded by meteorites and comets.
  2. Moon’s Formation:
    • Around 4.54 billion years ago, a Mars-sized body collided with the young Earth, partially liquefying its formation of Earth and ejecting molten debris into space.
    • This ejected material coalesced to form the Moon, which remained as a ring around Earth before taking its current form.
  3. The Late Heavy Bombardment:
    • Residual gases in the early solar system created space currents, influencing the movement of massive Jupiter, causing it to migrate toward the Sun.
    • Jupiter’s gravitational influence dislodged asteroids, initiating a period of intense asteroid bombardment known as the Late Heavy Bombardment, impacting Earth and other terrestrial planets.
  4. Saturn’s Influence and Solar Wind:
    • Saturn’s gravitational pull eventually restrained Jupiter, returning it to its current position.

Formation of Earth

    • Simultaneously, the solar wind stripped away the remaining gas in the solar system, sending it into interstellar space.
  1. Water Delivery and Volcanic Activity:
    • Formation of Earth, still cooling from the Moon’s formation, endured continuous bombardment and remained volcanically active.
    • Asteroids or comets containing water ice later collided with Formation of Earth, contributing water vapour to the planet.
    • As Formation of Earth cooled, the vapour condensed and fell as rain, forming oceans.
  2. Ongoing Volcanic Activity:
    • Volcanic activity persisted, with lava flowing on the Formation of Earth for nearly 700 million years.
    • Rocks, through their layers and composition, hold a record of Formation of Earth geological history.
  3. Early Atmosphere and Supercontinents:
    • The early atmosphere was heavy, toxic, and devoid of free oxygen, with high levels of carbon dioxide, nitrogen, and sulphur due to volcanic activity.
    • Within half a million years, multiple small land masses formed and served as the foundations for future continents.
    • The oldest known rocks on Earth, found in Australia, date back to 4.4 billion years ago.
    • Two supercontinents, Vaalbara and Ur, appeared around 3.5 billion years ago.
  4. The Emergence of Life:
    • Despite the lack of oxygen in the atmosphere, life began in the early Precambrian, around 4.1 billion years ago.
    • Specific zircons from this time period suggest biological activity combined with water presence.
    • The presence of large oceans, facilitated by liquid water’s unique properties, was crucial for the emergence of life.
  5. The Oxygenation of Earth:
    • Banded iron formations, dating back to 3.7 billion years ago, indicate periodic oxygenation of water, attributed to biological processes.
    • Stromatolites, formed by microorganisms trapping sand grains, date to 3.5 billion years ago.
    • Evidence of photosynthesis emerged around 2.4 billion years ago, with cyanobacteria releasing significant oxygen into the atmosphere.
    • Formation of Earth’s atmosphere finally contained a stable supply of oxygen.
  6. Supercontinent Cycles and the Great Oxygenation Event:
    • Kenorland, a new supercontinent, formed as Vaalbara broke apart, impacting Formation of Earth geography.
    • The Great Oxygenation Event, 2.3 billion years ago, led to elevated oxygen levels, which caused the first extinction event and initiated the first ice age.
    • Mass extinctions occurred as the climate changed rapidly due to the oxygen increase.
    • The rise of oxygen reduced greenhouse gases, leading to lower temperatures and heralding an ice age.
    • Ice ages are characterised by alternating glaciation periods and inter-glaciation periods, impacting Formation of Earth climate over millions of years.
Mass Extinction:

  • A mass extinction event refers to a rapid and significant loss of species, occurring at a much higher rate than their replacement.
  • It is typically characterised by the disappearance of approximately 75% of the Formation of Earth species within a relatively short geological time frame, often less than 2.8 million years.

Historical Mass Extinctions:

  • First Mass Extinction (Ordovician):
    • Occurred around 445 million years ago.
    • Resulted in the extinction of roughly 85% of all species.
  • Second Mass Extinction (Devonian):
    • Took place approximately 375 million years ago.
    • Led to the demise of about 75% of the world’s species.
  • Third Mass Extinction (Permian):
    • Known as the Great Dying, this extinction event happened about 250 million years ago.
    • Caused the extinction of over 95% of all species, making it one of the most catastrophic mass extinctions in Formation of Earth history.
  • Fourth Mass Extinction (Triassic):
    • Occurred around 200 million years ago.
    • Resulted in the elimination of about 80% of Formation of Earth species, including some dinosaurs.
  • Fifth Mass Extinction (Cretaceous):
    • Occurred approximately 65 million years ago.
    • Renowned for the extinction of non-avian dinosaurs, altering the course of life on Earth.
  • Sixth Mass Extinction:
    • Some researchers have pointed out that we are currently experiencing a sixth mass extinction as the result of human-induced climate change (referred to as the Anthropocene extinction).
    • Currently, only an estimated 2% of all of the species that ever lived are alive but the absolute number of species is greater than ever before.

Formation of Earth Timeline: Stratigraphy, Fossils, and the Geological Time Scale #

  • The field of geology known as Stratigraphy studies and dates rock layers, offering insights into Formation of Earth history.
  • Hierarchical Structure:
    • The geological time scale is hierarchical, with units of time organised in descending order of duration. 
    • These units include eons, eras, periods, epochs, and ages.

Formation of Earth

  • Stratigraphy and Fossils:
    • The primary basis for the geological time scale is stratigraphy, which involves the study of rock layers and their sequences.
    • Fossils found in rocks play a crucial role in establishing the time scale. 
    • The appearance and disappearance of specific fossil species help define and refine the boundaries between different time units.
  • Key Time Units:
    • Eon: The largest division of time, encompassing billions of years. 
      • The Phanerozoic, Proterozoic, Archean, and Hadean are the four eons that make up Formation of Earth geological history.
    • Era: Eons are subdivided into eras, each characterised by distinct geological and biological events. 
      • The Phanerozoic Eon, for example, includes the Paleozoic, Mesozoic, and Cenozoic eras.
    • Period: Eras are further divided into periods, marked by notable changes in Formation of Earth history. 
      • For example, the Cenozoic Era is divided into the Paleogene, Neogene, and Quaternary periods.
    • Epoch: Periods are divided into epochs, representing shorter intervals of time. 
      • The Pleistocene epoch, for instance, is known for the last ice age.
    • Age: The smallest time unit within the geological time scale.
      • Ages are characterised by specific events and often correspond to the duration of a particular species’ existence.
The Meghalayan Age: A Geological Epoch Shaped by Climate and Cultural Shifts

It is  a relatively recent addition to the geological time scale, marking a distinct period in Formation of Earth history. 

Definition:

  • The Meghalayan Age is one of the stages within the broader Holocene Epoch.
  • Geologists officially designated it as a separate age, marking the last 4,200 years of Formation of Earth history, extending from 4,200 years ago to the present day.

Holocene Epoch:

  • The Holocene Epoch covers the past 11,700 years and is characterised by a period of warming that followed the last ice age.
  • The International Commission on Stratigraphy (ICS) proposed subdividing the Holocene into upper, middle, and lower phases to better represent significant climatic and environmental changes.

Major Climatic Event:

  • The Meghalayan Age is unique among geological time intervals because it coincides with a global cultural event driven by a significant climatic event.
  • The age began with a destructive drought that lasted for two centuries. 
  • This drought had severe consequences for human civilizations in various regions, including Egypt, Greece, Syria, Palestine, Mesopotamia, the Indus Valley, and the Yangtze River Valley.
  • The drought is believed to have been triggered by shifts in ocean and atmospheric circulation patterns, impacting precipitation and climate.

Cultural and Environmental Impact:

  • The Meghalayan Age represents a period of great environmental stress and human adaptation.
  • The drought had a profound impact on agriculture, water resources, and societies, leading to migration, collapse of civilizations, and cultural changes.

Note:

  • The International Commission on Stratigraphy (ICS) holds a prominent position within the International Union of Geological Sciences (IUGS) and serves as the principal authority responsible for defining precise geological time units, including periods, epochs, and ages within the Geologic Time Scale.
  • Mawmluh Cave(Meghalaya), situated at an elevation of 1,290 metres, stands as one of India’s most extensive and profound cave systems. 
  • These caves serve as vital repositories of Holocene paleoclimatic and paleomonsoon data, as they remain unaltered by diagenesis, erosion, or terrestrial deposits. 
  • The unique conditions within the caves have facilitated the preservation of chemical markers indicative of oxygen transitions across various ages.

 

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 Final Result – CIVIL SERVICES EXAMINATION, 2023.   Udaan-Prelims Wallah ( Static ) booklets 2024 released both in english and hindi : Download from Here!     Download UPSC Mains 2023 Question Papers PDF  Free Initiative links -1) Download Prahaar 3.0 for Mains Current Affairs PDF both in English and Hindi 2) Daily Main Answer Writing  , 3) Daily Current Affairs , Editorial Analysis and quiz ,  4) PDF Downloads  UPSC Prelims 2023 Trend Analysis cut-off and answer key

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 Final Result – CIVIL SERVICES EXAMINATION, 2023.   Udaan-Prelims Wallah ( Static ) booklets 2024 released both in english and hindi : Download from Here!     Download UPSC Mains 2023 Question Papers PDF  Free Initiative links -1) Download Prahaar 3.0 for Mains Current Affairs PDF both in English and Hindi 2) Daily Main Answer Writing  , 3) Daily Current Affairs , Editorial Analysis and quiz ,  4) PDF Downloads  UPSC Prelims 2023 Trend Analysis cut-off and answer key

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UDAAN PRELIMS WALLAH
Comprehensive coverage with a concise format
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Designed as per recent trends of Prelims questions
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