The northern part of West Bengal is covered by fans of sediment washed down from the Himalayas. The Baikanthapur formation is the youngest fan in the area. It consists of very fine white sand inter-layered with ochre yellow sticky silty clay and overlain by dark grey to thick silty loam. The Shangaon formation represents the deposits of the flood plain faces of the Baikunthapur formation. Measurements have shown a maximum arsenic content well beyond the permissible limit (0.05 mg/L, Indian standard) within a depth range of 10-30m, in the Shaugaon surface. This raises concerns about the possibility of arsenic poisoning in the region and in downstream locations.