The existence of Palaeolithic tools in Bengal was first discovered by Valentine Ball, a geologist of the Geological Survey of India, in the area of the Biharinath hill of Bankura in the 1860s. Ball did not follow up his discovery in Bengal, but he made more discoveries of this kind in the neighbouring Orissa. Palaeolithic research in Bengal had to wait for its systematic beginning till the late 1950s when V.D Krishnaswami of the Archaeological Survey of India explored the Kangsavati valley and some of its related tributary valleys in Bankura and Purulia districts. The Kangsavati valley was about to be flooded because of the construction of a dam, anc Krishnaswami's work was undertaken as an archaeological rescue work Krishnaswami published his report in Indian Archaeology a Review with a map showing the distribution of discovered sites. It was also in the 1950s that another Archaeological Survey of India archaeologist, B.B. Lal, isolated a Mesolithic horizon in West Bengal at the site of Birbhanpur which is now within the limits of modern Durgapur. Lal excavated the site and pinpointed the context of the Mesolithic occupation, apart from undertaking a detailed study of its tool typology.