Blog

You will need

What to do

Make your pancakes

Create pancake tectonics

What’s happening?

The surface of the Earth (the crust) is broken into large pieces called tectonic plates, represented here as pancakes. The gradual process of plate shifting is called plate tectonics.

Mountains like the Himalayas and Karakorum resulted from the collision of plates. Millions of years ago moving tectonic plates brought the continents of Asia and India into contact with one another. Such continental collisions build spectacular mountain ranges.

The crust of the Earth is not always the same. Crust under the oceans, called oceanic crust, is much thinner than continental crust. It is only about five kilometres thick while continental crust can be up to 65 kilometres thick. These plates are constantly moving, but very slowly. Also, the two types of crust are not made of the same materials. Oceanic crust is made of a denser collection of minerals than continental crust.

Tectonic plates are made up of the Earth’s crust and the upper part of the mantle layer underneath. Together the crust and upper mantle are called the lithosphere and they extend about 80 kilometres deep. The lithosphere is broken into giant plates that fit around the globe like puzzle pieces. These puzzle pieces move a little bit each year as they slide on top of a somewhat fluid part of the mantle called the asthenosphere.

The asthenosphere is solid even though it is at very hot temperatures of about 1600 degrees Celsius due to the high pressure from above. However, at this temperature, minerals are almost ready to melt and they become ductile and can be pushed and deformed like silly putty in response to the warmth of the Earth. These rocks actually flow, moving in response to stresses placed upon them by the churning motions of the Earth’s deep interior. The flowing asthenosphere carries the lithosphere of the Earth, including the continents, on its back.

Applications

The geology of the Himalayas is a record of the most dramatic and visible creations of plate tectonic forces. The Himalayas, which stretch over 2400 kilometres, are the result of a collision between two continental tectonic plates.

The Karakoram and the Himalayas are important to Earth scientists for several reasons. They are one of the world’s most geologically active areas, at the boundary between two colliding continents, so are important in the study of plate tectonics. Mountain glaciers may also serve as an indicator of climate change, growing and shrinking with changes in temperature and rainfall.

The Himalayas are among the youngest mountain ranges on the planet. According to the modern theory of plate tectonics, their formation is a result of a continental collision between the Indo-Australian Plate (India) and the Eurasian Plate. The collision began in the Upper Cretaceous period about 70 million years ago, when the north-moving Indo-Australian Plate, moving at about 15 centimetres a year, collided with the Eurasian Plate.

The Indo-Australian plate is still moving at 67 millimetres a year, and over the next 10 million years it will travel about 1500 kilometres into Asia. About 20 millimetres a year of the India-Asia convergence is absorbed by thrusting along the Himalayan southern front. This leads to the Himalayas rising by about five millimetres a year, making them geologically active. The movement of the Indo-Australian plate into the Asian plate also makes this region seismically active, leading to earthquakes and tsunamis.