A History of South India from Prehistoric Times to the Fall of Vijayanagar c7.12

c7.12

North of Goa the surface of the ghats is largely covered by an immense thickness of basaltic lava-flows—the Deccan trap of Indian geology. They reach their maximum thickness about the latitude of Bombay. ‘The weathering action of ages has shaped the trap formation into natural citadels and fortresses which dominate the crest of the hills, and were found most useful as military positions in the wild days of Maratha supremacy.’ The uplands round Poona being clothed with the volcanic cotton soil are quite as fertile as the alluvial valleys of the Narmada and Tapti rivers. South of Goa, however, the ghats become a series of gneisses and schists, much more resistant than the lava-capped belt.