Question

What forms when continents collide? Describe the process.

Short answer

Mountain ranges form when continents collide.

Step-by-step solution

Understanding Plate Tectonics

The Earth's crust is divided into several large and small tectonic plates. These plates float on the semi-fluid asthenosphere beneath the Earth's surface and are constantly moving due to convection currents within the Earth's mantle.

Identifying the Type of Plate Boundary

When two continental plates move towards each other, they form what is known as a convergent plate boundary. At this boundary, the plates are compelled to collide due to their mutual movement towards one another.

Observing the Collision Process

During the collision, neither of the continental plates is dense enough to subduct beneath the other. Instead, the plates crumple and fold, resulting in the upward movement of material forming mountainous regions. This process is known as orogeny.

Formation of Mountain Ranges

The collision of the continental plates results in the formation of mountain ranges. A prominent example of this is the formation of the Himalayas, which have formed as a result of the collision between the Indian Plate and the Eurasian Plate.

Key concepts

Plate Tectonics

The theory of plate tectonics describes the large-scale motion of Earth’s lithosphere, which is divided into several pieces known as tectonic plates. These plates are akin to a giant jigsaw puzzle that covers the Earth's surface. Beneath these plates lies the asthenosphere, a semi-fluid layer that allows the plates to move.
This movement is driven by the intense heat from the Earth’s core, which creates convection currents in the mantle. As plates move, they interact in various ways: they may drift apart, slide past each other, or collide. Each of these interactions can lead to different geological phenomena, such as earthquakes, volcanic activity, and the creation of mountains.

Convergent Plate Boundary

When two tectonic plates push towards each other, they form a convergent plate boundary. This is a fascinating process, as it is one of the most intense forms of interaction between plates. There are different types of convergent boundaries, but when two continental plates converge, it leads to unique geological features.
Due to their composition, continental plates are less dense compared to oceanic plates. As a result, when they collide, neither plate can easily slide under the other. Instead, these plates crumple against each other, similar to what happens when you push two sheets of paper together. This crumpling creates folds and uplifts, eventually forming high mountain ranges.

Orogeny

Orogeny is the term used to describe the forces and events leading to a large structural deformation of the Earth's lithosphere due to the interaction of tectonic plates. This process is primarily associated with mountain building.
The crumpling and thickening of the Earth's crust as a result of converging continental plates lead to the formation of mountain belts. The rocks and sediments are folded, faulted, and sometimes even thrust, creating complex structures that define mountainous landscapes.
Orogeny doesn't just happen overnight. It's a long, gradual process that can span millions of years. As these mountains rise, weathering and erosion work simultaneously, often modifying their appearance over time.

Mountain Formation

The ultimate result of orogeny at convergent plate boundaries is the formation of mountain ranges. This process begins with the collision of continental plates, where immense pressure causes the crust to buckle and rise.
One of the most well-known examples of mountain formation through continental collision is the Himalayas. These majestic mountains were formed from the collision between the Indian Plate and the Eurasian Plate, a process that began around 50 million years ago and continues today.
During mountain formation, not only are new geological layers created, but existing ones can also be uplifted to form new heights. This dynamic process dramatically reshapes the Earth's surface, creating awe-inspiring peaks and highlands that define the geography of our planet.