India's Gondwana coalfields lie mainly in the valleys of

1. India's coal is of two geological ages: Gondwana (about 200 million yrs) and Tertiary (about 55 million yrs). 2. Gondwana coal (metallurgical quality, bituminous) is found in Damodar valley (Jharia, Raniganj, Bokaro), Godavari, Mahanadi and Son river valleys. 3. Tertiary coal (younger, more moisture, lignite type) is found in the North-East (Assam, Meghalaya) and J&K. 4. India's largest coalfield is Jharia in the Damodar valley. _Source: syllabus Social Science (Geography), Ch 5 "Minerals and Energy Resources", §5.3 Coal_