Overview
Bitumen, the heavy tar-like hydrocarbon used in road surfacing, occurs in a belt of tar sands along the eastern edge of the Dahomey basin, most extensively in Ondo State. It has been known and surveyed for over a century and remains, unusually among Nigeria's resources, largely unexploited on any commercial scale.
Where it's found
The tar sand belt runs through Ondo State in the south-west and into adjoining parts of Ogun, Lagos and Edo states, in Yoruba country. Bitumen there is bound into shallow sands rather than pooled as liquid, which is why extracting it is a mining rather than a drilling problem.
History of exploitation
Seepages were noted in colonial geological surveys in the early twentieth century, and drilling for bitumen took place before the oil discoveries of the 1950s. Several rounds of survey, licensing and feasibility work have followed since the 1970s, but no sustained extraction industry has been established, and the deposits are still described as undeveloped.
Economic role
Because it has not been worked at scale, bitumen has played almost no part in Nigeria's export history, in contrast to crude oil from the same broader hydrocarbon story. Its interest is as an undeveloped resource rather than a producing one, and no reserve estimates or policy positions are given here.
Environmental and social impact
Extracting bitumen from tar sands elsewhere in the world is land-intensive and water-intensive, and the Ondo belt lies under farmland, forest and settlements, so any development would raise questions of land use, water and resettlement. Because there is no large-scale working, there is no comparable record of local damage to report.