Figure 1.
Gravity map showing Midcontinent Rift (MCR), Fort Wayne Rift (FWR), and East Continent Gravity High (ECGH). Grenville-age Appalachian inliers with Laurentia and Amazonia affinities are shown as light and dark gray regions. Grenville Front shown by solid line where observed and dashed line where inferred. OH 1/2 indicates location of COCORP seismic profile (Stein et al., 2014).