Formation of Himalayas and Purvanchal or Eastern Himalaya

The Himalayas are the youngest and highest mountain range in the world, stretching over 2,400 km across five countries - India, Nepal, Bhutan, China, and Pakistan. The Purvanchal or Eastern Himalayas are a subrange of the Himalayas located in northeastern India and southern Bhutan. Here's how these mountain ranges were formed:

1. Plate Tectonics: The formation of the Himalayas began around 70 million years ago due to the collision of the Indian and Eurasian tectonic plates. The Indian Plate, which was previously a separate landmass, slowly moved northward and collided with the Eurasian Plate, causing the Earth's crust to fold and uplift.

2. Subduction: The Indian Plate is still moving northward and is slowly being pushed under the Eurasian Plate, a process called subduction. This process causes the Indian Plate to melt and form magma, which rises to the surface and creates volcanic activity.

3. Continental Collision: The collision between the Indian and Eurasian Plates caused the sedimentary rocks that were once at the bottom of the ocean to be uplifted and formed the Himalayan mountain range. The Himalayas continue to rise at a rate of about 5 millimeters per year due to ongoing continental collision.

4. Formation of Purvanchal or Eastern Himalaya: The Purvanchal or Eastern Himalayas were formed due to the same tectonic forces that created the Himalayas. However, the Purvanchal range is a separate geological entity that extends from the Brahmaputra River in the west to the Irrawaddy River in the east. The range was formed due to the collision of the Indian Plate with the Eurasian Plate, as well as the movement of the Indian Plate over the Burmese microplate.

5. Erosion: The Himalayas and the Purvanchal range are constantly being eroded by natural forces such as water, wind, and glaciers. This erosion has created deep valleys and gorges in the mountain ranges and has also exposed the underlying rocks that were once buried deep beneath the Earth's surface.

In conclusion, the Himalayas and Purvanchal or Eastern Himalayas were formed due to the collision of tectonic plates, subduction, and ongoing continental collision. The forces of erosion have also played a significant role in shaping these mountain ranges over millions of years.

The Himalayas bend sharply to the south beyond the Dihang gorge and move outwards to form a covering the eastern boundary of the country. They are known as ‘the Eastern or Purvanchal Hills’. It extended in the north-eastern states of India. Most of these hills are extended along the border of India and Myanmar while others are inside India namely.The Himalayas bend sharply to the south beyond the Dihang gorge and move outwards to form a covering the eastern boundary of the country. They are known as ‘the Eastern or Purvanchal Hills’. It extended in the north-eastern states of India. the Patkai Bum Hills, the Naga Hills and the Mizo Hills.• Naga Hills: It is located in India extending into Myanmar which forms a divide between India and Myanmar.
• Manipur Hills: It is located in the north of Nagaland, Mizoram in the south, upper Myanmar in the east and Assam in the west bound Manipur Hills.
• Mizo Hills: It is formerly called Lushai Hills. It is located to in south-eastern Mizoram state, north-eastern India, forming part of the north Arakan Yoma system.
• Tripura Hills: These hills are a series of parallel north-south folds, decreasing in elevation to the south until they merge into the greater Ganges-Brahmaputra lowlands (also called the Eastern Plains). Each successive ridge of hills to the east rises higher than the one before.