Today’s Earth is known for its peculiar climate and almost limitless biodiversity, but this planet barely resembles today’s planet billions of years ago. New research conducted by Peking University and other institutions indicates that during the Archean era, which spans 4 to 2.5 billion years ago, Earth was probably a water world, with only small patches of dry land in the form of islands.
The Ancient Contour of the Land
All the scientists agree that low land area was more pronounced at the formative stages of earth than what is apparent now. Instead of massive land masses, the earth as we know it was likely dotted with small islands surrounded by a sea unmapped by land. This notable transformation of Earth’s landscape makes one curious on how the planet changed over the years.
Factors Limiting Land Exposure
The scientists revealed two major factors that caused such a dominancy of water bodies over the land surface of Earth during the Archean period:
- Thicker Oceanic Crust
The internal Earth being at formation processes was far hotter than the core and outer and inner a hundred years ago. Due to this excess heat, a considerable amount of melting occurred consequently, a thicker oceanic crust was formed. Whereas current young oceanic crust is usually around 7 km, it has been estimated that the archaean oceanic crust was 25 to around 35 km thick.
- Minimal Altitude Alteration
As the fragmental continental crust started to develop and increased in thickness, there came a time when its further growth was no longer feasible. The base of the in the thickening basin became very compact due to phase transformation of the rocks and so no more upward growth would be experienced. This process which is known as lower crust eclogitization means wherever the boulders are deposited that will be the maximum extent of land that could be above water.
The Landscape Disparity
Because of these reasons, the land-sea separation in terms of maximum elevation of land above oceanic floors was maintained between 3 to 5 km giving the conditions of Archean. In over comparison , the last or present day elevation ocean height can come over more than 8 km. This decrease in elevation ocean height means that when the formation of the continental crust was taking place; most of this was submerged under the ocean.
The Changes of the Earth
Such phenomena have taken hundreds of years and over a considerable period of time, these factors changed the face of the earth:
- Cooling Mantle: With the cooling of the earth’s mantle, new oceanic crust has continued to grow thinner with time.
- Continental Growth: Continents were able to achieve higher elevation before reaching the level of density.
- Emerging landmasses: Vast portions of the continental crust finally emerged out of the oceans.
Such transformations impacted the weather patterns and climate in such profound ways, and even the processes of weathering and perhaps the development of life.
Implications and Importance
The atmosphere and hydrosphere of planet Earth are of critical significance for the inclusiveness in the gradual evolution of the planet. Such research offers helpful comprehension in:
- First, the evolution of Earth’s hydrosphere and atmosphere
- Second, the time of the earliest and the evolutionary development of life
- Third, processes of weathering and their effects on primordial climate
Besides, this study may shed further prospects on the existence of life in other planets with atmospheric conditions that are not necessarily like that of the earth.
Conclusion
Even if it is impossible to go back to the Archean Earth in this life, this particular research certainly serves for time travelling as it helps us to visualize the ancient oceans that once existed on our planet. So as the research proceeds, more of the fundamental patterns of the geological development of the Earth would be revealed, and increasing respect towards various mechanisms that have contributed toward the building of the planet as it is today, one with such abundant and diversity of life would be evident.
