Himalayan Mountain Range Formation
To kick off international rock day (July 13th) I will be posting a series of articles about rocks, minerals, and fossils of the Himalayan mountains. I will also be discussing how the Himalayan mountain range formed. If you enjoy geology and the Himalayas, these articles are a must read! If you are planning a trek in Nepal, these articles will make great conversation starters… “did you know Everest used to be at the bottom of the Tethys Sea?
Plate tectonics and Earth
To describe how the Himalayan mountain range formed, I need to first describe the structure of the earth and plate tectonics. The earth has 4 layers, which are the inner core, outer core, mantle, and crust. This may not seem like a lot, but when consider that these layers are 3,958.75 miles thick, it gets heavy.
Scientists used seismic waves to discover the outer core is a fluid while the mantle behaves like a fluid but is a solid. the inner core and crust are solid. This is important because the way the layers interact with each other determines what happens on the crust. All the volcanoes, earthquakes, and mountains are the results of these interactions.
In short, the earth’s crust “floats” on the mantle, which is also divided into layers. These layers are composed of solid and semisolid (partially molten) rocks. The composition of the earth is like trying to stack confetti on Jell-O on a piece of tile on a hamster ball, with the hamster inside, on the top of a needle. Good thing gravity is holding it all together!
You can see how unstable the top layer might be. When you couple this with molten magma seeping up through the crust along weak/ thin points, it only magnifies the instability. This instability is known as plate tectonics.
The destruction of Pangea
All the continents on earth were once connected creating a super continent. Over the course of 4.5 billion years the super continent has broken up and reformed 7 times. I’m including Gondwana and Laurasia as one super continent.
Due to plate tectonics and the instability of earthly processes, these continents drifted apart, collided into each other, then drifted apart again.
The last super continent was Pangea. During the breakup of Pangea, the landmass known as India broke apart from Antarctica, Africa, and Australia, and moved north. This move pushed the Tethys Sea’ floor up, on top of the Eurasian subcontinent. Eventually overtime, Tethys Sea’ floor became the highest peak in the world, Everest.
India initially moved at a rate of 7.9 inches per year. It is still moving north, but at a much slower rate (almost 1 inch per year).
Rocks in the Himalayan mountain range
You can expect a collection of different types of rocks, minerals, and fossils in the Himalayas. What you may not expect is that most of the rocks are much older than the Himalayas. The mountains are about 50 million years old, while the rocks that are on the mountains are over 570 million years old! Pretty cool huh.
You can find all three rock types/ classes, igneous, metamorphic, and sedimentary, in the Himalayas. Within these classes there are multiple different kinds ranging from biotite to trachyte.
You can also find some low quality precious and semi-precious stones in the Himalayas. These include garnet, tourmaline, ruby, and others.
Some of the coolest things you can find while hiking on the Himalayan mountains are fossils. It is against the law to take them with you though. The most common type of fossils are ammonites. They are extinct mollusks, related to squids, octopi, and nautiluses. You can also find brachiopod, belemnites, and plant fossils.