North Bengal plains

The North Bengal plains start from the south of Terai region and continue up to the left bank of the Ganges. The southern parts of the district Jalpaiguri, North Dinajpur baring some extreme northern regions, South Dinajpur, Malda, Alipurduar and southern part of Cooch Behar districts constitute this geographical region. The narrow land mass in the North Dinajpur district is known as Mahananda Corridor. This corridor runs north to south joining Malda with the plains of Jalpaiguri, Alipurduar and Cooch Behar. The entire part of North and South Dinajpur is silt laden plain. 

The Mahananda River divides the district of Malda into two parts. The eastern part (known as Barind or Barendrabhumi) consists of undulating plains and tilas, and is made up of old alluvium and is part of the Ganges Delta. In contrast, the western part is made up of new alluvium, and here the Kalindi River joins the Mahananda River. The area north of the Kalindi River is a lowland covered with swamps and beels (small water bodies) and is known as tal. In contrast, the area south of the Kalindi is a very fertile land and is known as diara. 

The plain south of Jalpaiguri, Alipurduar, and Cooch Behar district is also made of new alluvium deposited by numerous rivers including the Teesta, Torsa, Raidak, Jaldhaka, Sankosh, Balason, Punarbhaba, and Atrai.