Physiographic zones of Uttarakhand :

Uttarakhand can be divided into several physiographic zones, all running parallel to each other from northwest to southeast. The northern zone, popularly known as the Himadri, contains segments of the Zaskar and the Great Himalaya ranges, Adjacent to and south of the Great Himalayas is a zone containing the Lesser Himalayas, known popularly as the Himachal.To the south of the Himachal is a stretch of the Siwalik Range. The southern edge of the Siwalik Range merges with a narrow bed of gravel and alluvium known as the Bhabar, which interfaces to the southeast with the marshy terrain known as the Tarai. The combined Siwalik-Bhabar-Tarai area ranges in elevation from 1,000 to 10,000 feet (300 to 3,000 metres). South of the Siwaliks are found flat-floored depressions, known locally as duns, such as the Dehra Dun. These are :

• The Greater Himalaya
• The Lesser Himalaya
• Siwaliks and Doon
•  Bhabhar and Tarai zones

The Greater Himalaya  :

The extreme northern belt of the region is above the snowline and the mountains are always snow covered. Therefore this zone is also known as Himadri. The width of this zone is about 50 km. This zone is made up of rich fossiliferous sedimentary structures and is quite prominent. This zone is also known as the Bhot region because it is the summer base camp of the Bhotia tribe which is an industrious tribe. “This zone consists of a magnificent series of glacier-garlanded peaks: Bandar Punch (6,315 m), Gangotri (6,614m), Kedarnath (6940 m), Chaukhamba (7,138 m), Kamet (7,756 m), Nanda Devi (7,817m), Dunagiri (7,066 m), Trisul (7,120 m), Nandakot (6,861 m). The topography of the Greater Himalaya (Himadri) is highly rugged and difficult with precipitous slopes. Horned peaks, serrated crests of high ridges, cirques and glaciers, snow-clad slopes, hanging valleys, cascades of sparkling water coming from the melting ice, torrential rapids, and gigantic escarpments comprise a gorgeous topography. Deep canyons, roaring streamlets, huge boulders and glistening lakes create a breath-taking scenery. The zone of perpetual snow is characterized by many high peaks with numerous mountains and valley glaciers. It is South and South west of the Trans-Himalayan zone. Here also the habitation is sparse” .

The Lesser Himalaya :

 The Lesser Himalayan belt expands between the Greater Himalaya on the north and sub-Himalaya or Siwaliks region on the south. This region covers about 50 per cent area of Uttarakhand. It is composed of crystallines, granites, gneisses and schist rocks. “In this zone of separation the Precambrian and Paleozoic, sedimentaries with granites injected metamorphics, are divisible into the succession of the three thrust sheets or Nappes: a) the Krol belt; b) Almora Dudatoli crystalline mass; c) Deoban–Tejam group . This region is full of mineral resources like limestone, talc, dolomite etc. Besides, this region is also rich in metals, as many copper ore, iron ore, sulfur, lead mines have been found. Many ancient mining  and smelting sites have been discovered by D.P. Agrawal and his team through his research project in metallurgy, it clearly indicates that metallurgy was practiced here on a large scale in ancient times. The region is characterized by a varied relief - consisting of deep river valleys, the ridge and mid-slope areas and the high upland zones. The average rainfall in the region varies from 1000 to 1500 mm. The climate is cold to temperate.

The ecology and environment of these hills are marked by certain specificities such as fragility, inaccessibility, marginality and diversity. The area is prone to natural hazards and disasters aggravated by anthropogenic activities. These difficult and unique conditions have resulted in a symbiotic relationship between the people and their environment, which is based on the continuous observations, experiments, experiences and intimate understanding of the immediate surroundings. It is realized that the life of local people is very much tied to local environment. Environment is not something out there for these hill people but a part of their being. They depend upon the local flora and fauna to eke out their living, but it?s a symbiotic relationship. They realize that preserving the environment is a matter for their survival also. They depend upon the environment and plants not only for their livelihood, but also for their healthcare. Massive deforestation, unchecked mining and quarrying activities due mainly to the pursuit of mindless material development has caused soil erosion problems in this region of Uttarakhand, damaging watersheds and the livelihood base

Siwaliks and Doon  :

This region is located south of the Lesser Himalaya. Narrow valleys are found in between the Lesser Himalaya and the Siwaliks. There is a local belief behind the name of Siwaliks, that in ancient time 125 lakh mountains were found in this region due to which the region is known as Siwaliks but according to another belief, the word Siwaliks is formed by the combination of two words Shiva and Alak which literally mean God Shiva and eyebrows of Shiva. These ranges are separated from the main Himalayan ranges by the main boundary thrust. Lithologically, these ranges are quite different from those of the Lower Himalaya. This is the outermost and the youngest zone on the south of Lesser Himalaya. These are also the lowest ranges of the Himalaya and the altitude varies between 500 m along the deep river valleys to about 1200 m at the ridge tops.

 Bhabhar and Tarai Zones  :

The Bhabhar and Tarai region is the southernmost stretch of Uttrakhand. This spreads from east to west, on the south of Siwaliks range. This belt is about 35 km wide on the west but it becomes narrow continuously towards east. Haldwani, Ramnagar etc of district Nainital and Jaunsar Bhabar in district Dehradun fall in Bhabar whereas Udham Singh Nagar comes under Tarai.