Gilbert Hill: A 65-million-year-old monolith with an explosive history
At the heart of our financial capital Mumbai lies a gigantic piece of single upright stone or monolith, that is 200 feet tall. However, size isn’t the only thing that makes it a thing of wonder. What is it then? Well, this stunning monolith, known as Gilbert Hill, has been there since the Mesozoic period (252–66 million years ago)! This hill predates the earliest trees that ever grew here and the oldest mountain ranges seen.
Formed by volcanic eruption
The last great extinction of life on earth was that of dinosaurs, which occurred 66 million years ago after the Chicxulub asteroid struck the earth. As a result, several volcanoes worldwide were set off, resulting in the formation of the land we see today. Maharashtra lies on the volcanic Deccan Plateau which is a very arid region. Deccan Plateau is a large plateau that covers most of southern India. Evidence suggests that the dark soil and barren plateau seen in this region have formed because of a volcanic explosion or something similar. Gilbert Hill, which is in Andheri West, was also formed around the same time as the dark soil and due to the same volcanic eruption.
The volcano in the Deccan Plateau erupted and the ash and lava from the volcano was accumulated, leading to what can be seen as a single vertical column of rock. This vertical column of rock is what we call Gilbert Hill today. How did the scientists find out that the volcanoes in Deccan Plateau created Gilbert Hill? The rock sample found in Gilbert Hill were found to be same as that of rocks found in the Deccan Plateau. Given its volcanic origin, it is one of India’s most astounding geological wonders and has been designated as a monument of national significance.
Why the name Gilbert Hill?
Gilbert Hill is significant in many ways. It is claimed that the hill was named after the American geologist Grove Karl Gilbert who invented the word ‘laccolith’ (lens-shaped igneous rock)! Interestingly, Gilbert Hill is famous among the locals because of the Hanuman Mandir and Gaondevi Durga Devi Mandir built on its 8,000-square-feet flat top. These are the primary contributors to the rock’s preservation!
Two other monoliths from the Mesozoic era
The Gilbert hill is just one of the three volcanic rocks on the planet. Now you know why it is so special! The other two, which have been conserved and are under protection, are in the United States. They are the Devil’s Postpile, in the Devil’s Postpile National Monument, California and the Devils Tower in Wyoming! Formed by the cooling and cracking of hot lava, Devil’s Postpile a 100-feet high waterfall known as Rainbow Falls. The Devils Tower, on the other hand, features a flat top spread across 1.5 acres (0.6 hectare). Its summit 5,112 feet above the sea level. The tower probably formed when a hard rock layer forced molten rock to take a flat shape.