Anomalies in geomagnetic Sq(H), Sq(Z) and Sq(D), as recorded at an array of 21 magnetometers and 5 permanent observatories in peninsular India during 1979--1980, and analyzed and discussed in relation to geology. Signatures of Kodaikanal batholith, the Dharwar series of rocks and a graben structure in the Palk Strait on the geomagnetic records of nearby stations are unmistakably identified and associated with internal induction effects. The extent and influence of the ionospheric equatorial electrojet and oceanic induced currents observed on the ground in this complex region are also mapped.