IAS Gyan

Daily News Analysis


6th September, 2023 Geography

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  • Gilbert Hill in Andheri West is not a hidden or a secret structure, but what it stands for is something which many people are unaware of.
  • The structure is one of the world's oldest basalt rock formations which have withstood the test of time.


  • Maharashtra is situated on the Deccan Plateau, which is composed of volcanic soil and is relatively barren.
  • In this section of the country, there must have been a volcanic explosion or something similar that created the black soil and infertile plateau.
  • What Happened 66 Million Years Ago?
  • It is said that a gigantic bubble of lava froze in mid air at different place across the globe and formed three gigantic rocks which stand as a testimony to the earliest life on the planet.
  • Gilbert Hill is a monolith column of black basalt rock and actually dates back to the Mesozoic Era which dates back to 66 million years ago.

Gilbert hill


  • It is a 200-foot monolithic column of black basalt rock located in Mumbai's Andheri district.
  • The sheer vertical face of the rock was produced when molten lava was forced out of the Earth's clefts some 66 million years ago during the Mesozoic Era.
  • It was designated a National Park in 1952 and a Grade II cultural structure by the Brihan Mumbai Municipal Corporation in 2007.
  • The 'hill' is one of just three volcanic rock outcrops on the planet.
  • Gilbert Hill, arguably the country's oldest heritage property in its original form, contains a few temples and a tiny garden atop. A steep staircase chiseled into the rock leads to these.

Facts about Mesozoic era

  • This era lasted around 252 million years and ended approximately 66 million years ago.
  • This epoch is separated into three periods, which are the Triassic, Jurassic, and Cretaceous.

The Triassic period:

  • The Triassic period, which began roughly 250 million years ago and ended approximately 200 million years ago, is commonly divided into three major epochs: the Early Triassic, Middle Triassic, and Late Triassic Epochs.
  • Various species, notably nothosaurs and ichthyosaurs, began to evolve during this time period.
  • Crustaceans and corals of all kinds began to proliferate as well.
  • By the end of the Triassic Period, reptilian development had exploded, and dinosaurs had also begun to evolve.
  • However, as global temperatures began to increase, the Fourth Major Extinction, commonly known as the Triassic-Jurassic Extinction Event, occurred.
  • Except for crocodiles, this event wiped out all archosaurs and nearly all large amphibians that lived at the period.
  • It also wiped out more than 30% of all aquatic animals.

The Jurassic period:

  • The Jurassic Period, which lasted from 200 to 145 million years ago, is one of the most well-known periods on the Geologic Time Scale.
  • This time period is classified into three major epochs: the Early Jurassic, Middle Jurassic, and Late Jurassic Epochs.
  • Huge fern prairies traversed the land masses during the beginning of this epoch on the geological time scale, and dinosaurs like Diplodocus and Brachiosaurus grazed on these fern forests.
  • During this time, true crocodiles also began to evolve.
  • By the conclusion of the Jurassic Period, there was an extinction known as the Jurassic-Cretaceous Extinction Event, which killed off a large number of species.
  • This extinction event, however, is not regarded one of the significant ones on the prehistoric timeframe.

The Cretaceous Period (145 to 66 million years ago):

  • This period the dinosaurs reach their zenith of diversity.
  • The temperature cooled and dried out, and the continents continued to drift apart.
  • The period ended with the Cretaceous-Paleogene (K-Pg) extinction, which was most likely triggered by a combination of events.
  • This event resulted in the extinction of non-avian dinosaurs as well as many other species.


  1. Consider the following pairs:
  2. Cretaceous – Paleogene: Evolve of crocodile
  3. Jurrassic period : Extinction of non-avian dinosaurs
  4. Triassic period: wiped out more than 30% of all aquatic animals

How many of the above pairs is/are correct?

  1. A) Only one
  2. B) Only two
  3. C) All three
  4. D) None

Answer: A