PLATE 12. Geologic map and section of the Edgemont NE quadrangle, Fall River and Custer Counties, S. Dak. 13. Exploded block diagram. 14. Cross section showing depositional stages of the Lakota formation. 15. Structure and distribution of ore deposits. 16. Relation of the Runge deposit to the No. 4 and No. 5 sandstones.