<P> The Teesta River originates from the Pahunri (or Teesta Kangse) glacier above 7,068 metres (23,189 ft), and flows southward through gorges and rapids in the Sikkim Himalaya . </P> <P> It is fed by rivulets arising in the Thangu, Yumthang and Donkha mountain ranges . The river then flows past the town of Rangpo where the Rangpo River joins, and where it forms the border between Sikkim and West Bengal up to Teesta Bazaar . Just before the Teesta Bridge, where the roads from Kalimpong and Darjeeling join, the river is met by its main tributary, the Rangeet River . </P> <P> At this point, it changes course southwards flowing into West Bengal . The river hits the plains at Sevoke, 22 kilometres (14 mi) northeast of Siliguri, where it is spanned by the Coronation Bridge linking the northeast states to the rest of India . The river then goes merging up with the Brahmaputra River after it bifurcates the city of Jalpaiguri and flows just touching Cooch Behar district at Mekhliganj and moves to Fulchori in Bangladesh . </P> <P> Through its course, the Teesta river has carved out ravines and gorges in Sikkim meandering through the hills with the hill station of Kalimpong lying just off the river . Variegated vegetation can be seen along this route . At lower elevations, tropical deciduous trees and shrubs cover the surrounding hills; alpine vegetation is seen at the upper altitudes . The river is flanked by white sand which is used by the construction industry in the region . Large boulders in and around the waters make it ideal for rafting enthusiasts . </P>

Which plains lie between ghaggar and teesta rivers
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