Figure 6. Precambrian unconformity structure contour map with the addition of southeast oriented faults. GRTZ—Grand River tectonic zone; CMTZ—Central Missouri tectonic zone; OFZ—Osceola fault zone; BMTZ—Bolivar-Mansfield tectonic zone; WRFZ—White River fault zone. EM—Eastern Rift Margin faults, AF—Axial fault, WM—Western Rift Margin fault, RF—Reelfoot fault, NM—New Madrid. Elevation datum is sea level.