CBSE Class 10 Answered

In India, most of petroleum is found in structures that are associated with anticlines. An anticline trap is created by the upfolding of rocks, similar to an arch. Oil moves to the highest point in this arch's dome and then comes to rest.

Petroleum is also found in fold traps. A fault trap is a structural formation in a rock formed by the movement of rock along a fault line. Oil get trapped between porous and non-porous layers of rocks in a fold trap. In India most of the petrol is found in the rocks belonging to tertiary age. (Tertiary age refers to the geologic period from 66 million to 2.58 million years ago, a timespan that occurs between the superseded Secondary period and the Quaternary period).