The plains stretch from the Mahanadi delta to Kaniyakumari at the southern tip of the Indian peninsula with the Eastern Ghats forming its rough western boundary.

The plains stretch from the Mahanadi delta to Kaniyakumari at the southern tip of the Indian peninsula and traverses the states of Odisha, Andhra Pradesh, Tamil Nadu and the union territory of Puducherry.

The region consists of fertile red and black soil interspersed with gneiss and sandstone rock formations formed during the paleogene and neogene eras.

[4][3] The two river deltas form a contiguous single physiographic unit and cut across a 160 km (99 mi) wide gorge in the Eastern Ghats.

[5][7][8] The Tamil Nadu Plains (Coromandel) stretches for 675 km (419 mi) from the south of Pulicat Lake to Kanniyakumari at the southern end of the Indian peninsula.