About 98 per cent of coal resources of the country are confined to the Damuda Series of the Lower Gondwana rocks and the remainder comes from the Lower Tertiary and Eocene rocks of the extra-Peninsula.

The Damuda Series contribute over se.80 per cent the total coal production of the country. Far the largest part of production (46.1 %) comes Bafom the coalfields of Jharkhand-Bihar, Orissa and west Bengal; 37.49% from the fields of Chhattisgarh-Madhya Pradesh and Maharashtra; 10% from the fields of Andhra Pradesh; 5.37% from Uttar Pradesh and remaining 1.05 per cent from north­eastern states (Assam and Meghalaya). presents the relative importance of some important coalfields of the country and their average annual output in recent years (1976):