In 1843, he started to prepare a geological map of British India. In 1852 he produced a series of maps of Hindustan, mainly hydrographical, defining all the important elements of the ten water basins of the Indian Peninsula (for the Asiatic Society), and in 1854 a large-scale geological map of the whole of British India, published as a 'General Sketch of the Physical and Geological Features of British India. Greenough never visited India but much as he had done for his earlier maps of England and Wales, he compiled his map from scraps of information gathered from many observations of officers in the East India Company who were provided forms to submit. He was assisted in this effort by Colonel William Henry Sykes of the East India Company and sixty copies of the map were purchased by the company for distribution. One of Greenough's key strengths was his assiduous ability to collect and collate information for his empirical cause. However, this 'remote' method of map construction resulted in 53 errors on his India map, some topographical as well as geological and palaeontological, that were listed by a committee led by Thomas Oldham, Director of the Geological Survey of India, in 1856. Nevertheless, Greenough's geological map of India was a pioneering effort.