The concept of physiography integrates all of the main components of the natural environment, such as bedrock, surface drift deposits, landform, soils, climate, water, and plants and animals. This paper summarises the provisional physiographic zonation of Bhutan, based on soil survey fieldwork by the National Soil Services Centre, with some material incorporated from other environmental disciplines.
The main influence in shaping the landscape of Bhutan has been the uplift of the Himalayas following the collision of the Indian and Asian continental plates. This has given rise to the basic topographic structure of the country with the High
Himalaya in the north from which long ranges formed of metamorphic rocks run southwards and then descend steeply to the duars. The main valleys follow more or less northsouth course, but show considerable variation in their longitudinal profiles. They all have narrow gorge-like sections in the South but vary in the sections upstream. In western and central Bhutan the riverbeds have stepped profiles and the flatter sections form Inner Valleys with relatively gentle side slopes and wide floors at altitudes ranging from 1100 m at Wangdi to 2600 m at Jakar. The rivers in the east are cut deeper, and their valleys are narrow and steep throughout.
