Eastern Himalayas

The ancient folds, running mainly along an east-west axis, were worn down during a long period of denudation lasting into cretaceous times, possibly over a hundred million years.

The core of the mountain is exposed across the centre, where Paleozoic rocks, mainly Cambrian and Silurian slates and Takhstasang gneiss outcrops are visible in the northwest and northeast, the latter extending to western Arunachal Pradesh in India.

This was the time of Alpine mountain and large number of "active volcanoes" formation which act as backbone of the Himalayas and much of the movement in the palaeozoic region was probably connected with it.

The Chomolhari tourmaline granites of Bhutan, stretching westwards from the Paro Chu and adds much depth below the present surface, were formed during this period of uplift, fracture and subsidence.

The hot season commences around the middle of April reaching its maximum temperature in June, and finishing by the end of August.

The northeast monsoon is the predominant feature of the Eastern Himalayan region's weather, while on the southern slopes cold season precipitation is more important.

In the highlands the soil is morainic, and the hill slopes are cut by the locals into successive steps or terraces only a few meters broad, thus preventing water run-off and allowing spring crops to thrive.

The region's economy remained stagnant and at subsistence levels for centuries due to the lack of capital, investor access, or entrepreneurial knowledge.

[3] Wildlife in Nepal includes snow leopard in its Himalayan region, and Indian rhinoceros, Asian elephant and water buffalo in the foothills of the Himalayas, making the country one of the world's greatest biodiversity hotspots.

It was theorised this misclassification may have arisen due to the finding that some Himalayan flora readily hybridize with each other and produce viable seeds, causing wider morphological diversity.