What a Geologist Sees Consult the stratigraphic column for the Grand Canyon in your text or ebook. The A represents the Supai Group. The B represents the Redwall Limestone. The C represents the Mauv Limestone. The D represents the Tapeats Sandstone. The E represents the Unkar Group. BUDE Identify the places where there is an unconformable contact. Choose one or more: A. between A and B B. between B and C n C. between C and D n D. between D and E