Orogeny is the process of mountain-building caused by extreme volcanism or movement of tectonic plates. The first orogeny events began over three billion years ago, and the first continent formed is debated among geologists. Continents are made up of the least dense rock in the earth’s crust, and orogenies can be accurately dated using radiometric dating. The Himalayan orogeny is one of the most famous, occurring about 55 million years ago when the Indian subcontinent collided with the Eurasian plate.
Orogeny (“mountain-making” in Greek) is a mountain-building event caused by extreme volcanism (as in the Deccan Traps) or movement of tectonic plates, large slabs of rock that make up the earth’s crust. The plates float on top of a superheated plastic mantle made of partially molten rock. As the material in the mantle circulates, tectonic plates slowly move above, creating different continental arrangements over tens or hundreds of millions of years.
At first, the entire Earth was molten, with a fairly uniform height, until large segments and eventually the entire planet cooled and solidified, fragmenting into several distinct plates. Over three billion years ago, the first known orogeny events began, due to both volcanism and plate movement. The oceans already existed at that time and may have formed only 100 million years after the formation of the Earth itself.
As of 2008, there is some confusion among geologists as to which continent came first. Some claim that orogeny produced the first continent formed 3 billion years ago, which they call Ur. Ur is part of Africa, Australia, India and Madagascar and would have been slightly smaller than modern Australia. Others say the first continent formed 3.3 – 3.6 billion years ago, called Vaalbara, which today is represented by parts of Western Australia and South Africa. Whatever continent first formed, it was probably the only portion of the earth’s crust that protruded above the surface of the water. For hundreds of millions of years, the Earth may have been entirely covered by water.
Numerous orogeny events followed, creating all the continents and mountains we know today. Continents are made up of the least dense rock in the earth’s crust, which is why they “float” on top. Orogenies can be accurately dated using radiometric dating of rocks from around the world, combined with knowledge of the Earth’s tectonic plates and their divergent boundaries.
Dozens of orogenies are known. One of the most famous and recognizable is the Himalayan orogeny, which occurred about 55 million years ago, when the Indian subcontinent collided with the Eurasian plate as it moved north. These two plates pressing together caused the creation of large mountain ranges on the border, known today as the Himalayas. The Himalayas include Mt. Everest, the highest mountain on the planet.
Protect your devices with Threat Protection by NordVPN
