Magnetometer array data, collected by H. Porath and co-workers from the University of Texas at Dallas in the midwest United States during the fall of 1969, have been reanalyzed to further define the nature of the reporte geomagnetic variation anomaly in the region of the midcontinent gravity high. Variation events with a wide range of horizontal source field polarization and frequency haved been digitized from the original film records. These data have been used in a vertical-field response arrow (induction vector) analysis. The results indicate that there is no significant overall conductivity anomaly associated with the geologic structure causing the gravity feature. Rather, the pattern of anomalous variation fields is one of isolatedd anomalies at high frequency. These anomalies are coincident with postulated fault structures perpendicular to the gravity high lineament and with localized regions of high heat flow.