The Terai:
The Terai region is composed of a 26 to 32 kilometer-wide belt of fertile alluvial plain in the southern part of the country. This belt extends all the way from the western to the eastern border, and covers about 17 percent of the total land area.
Between the Churia hills, rising abruptly to the north of the southern plains, and the Mahabharat range, are a number of low valleys called Duns. The Duns resemble the Terai in relief and climate and are called the Inner Terai. The Churia range. runs east-eset across the country and has hogback profile with a steep south face. It averages 600 to 1220 meters in altitude and 8 to 16 kilometers in breadth. The soil is immature and dry.
The Hills:
The Mahabharat range, running closely parallel to the Churia range, separates the Terai from the Hill region. This range averages 1,525 to 6,660 meters in altitude and 16 kilometers in breadth. Its structure is synclinal and the topography is steep and jagged. Forests are usually found on the higher elevations whereas the lower and gentler slopes are used for terraced cultivation. North of this range and south of the Himalaya lies the extensively cultivated broad hill complex of the Pahad of hill region which covers about 64 percent of the total land area, the major area of Nepalese settlement. Topographically rather subdued in character, the hill region has a generally salubrious climate. Broad fertile valleys including the Kathmandu Valley are the areas of densest settlement in this region.
The Himalaya:
The Himalaya or 'abode of snow' is the youngest and highest mountain system in the world. It extends over 2,400 kilometers as a vast south-facing arc between the Indus and Brahmaputra rivers with Nanga Parbat (8,125 m) in the west, in India, and Namcha Barwa (7,755 m) in the east in Tibet, as its terminal high points. Fully a third or 800 kilometers of its central section traverses Nepal and is known as the Nepal Himalaya. Here congregate more than 250 peaks that exceed 6,000 meters in height -- a unique concentration of lofty dazzling summits. Of the thirty-one Himalayan peaks over 7,600 meters, 22 lie in the Nepal Himalaya, including eight of the world's 14 highest giants. These are:-
Sagarmatha (Mt. Everest) 8,848 m Kanchenjunga 8,586 m Lhotse 8,516 m Makalu 8,463 m Cho Oyu 8,201 m Dhaulagiri 8,167 m Manaslu 8,163 m Annapurna 8,091 m
The Himalayan range within Nepal is the culmination of a series of parallel ranges. The main range lies about 90 kilometers north of the Mahabharat Lekh. The intervening space between the two parallel ranges is made up of a lower belt of low hills (Pahad) and a higher belt of elevated ridges (Lekh) that provide the first intimation of the high snow peaks (Himal). The main Himalayas do not form a continuous chain, but are a series of lofty peaks and ridges separated by deep gorges. Each of these mountain peaks or Himals in turn sends out a maze of spurs studded with numerous peaks.
In western and central Nepal, there is yet another mountain range that defines the boundary between Nepal and China. this border range has elevations ranging from 5,000 to 6,000 meters with comparatively less rugged relief but a harsh climate. Between the main Himalayan range and these border ranges lie some of the elevated Bhot valleys.
Much of the High country above 5,000 meters is under snow and ice, although the permanent snow-line varies according to aspect and gradient. Winter snowfall occurs up to an elevation of 2,000 meters and is much heavier in the west. While winter is harsh and bitter, summer is the season of alpine flowers, when the high pastures teem with grazing animals from lower valleys. For the mountain communities, it is the time for harvesting their main crops before the winter migration to warmer climates.