CENTRAL STABLE REGION OF THE UNITED STATES 



CENTRAL BASIN 



49 



CUMBERLAND 

 PLATEAU 



Fig. 5.12. Section across the Nashville dome, after C. W. Wilson, Jr., 1935. 1, Lower and Middle Devonian; 

 2, Decatur; 3, Lobelville; 4, Beach River, Bob, and Dizon; 5, Lego, Waldron, Laurel, and Osgood; 6, Brass- 

 field; 7, Richmond. 



The Cincinnati dome probably had an early Paleozoic history much like 

 the Nashville dome, but the first elevation in which appreciable erosion 

 occurred preceded slightly the one in the Nashville dome. MacFarlan 

 (1943) shows that the Middle Devonian (Boyle) limestone overlaps suc- 

 cessively older formations toward the center of the dome where it rests 

 on the Ordovician ( Richmond and Maysville ) . The Lower Mississippian 

 shale (Ohio shale, probably the Chattanooga equivalent) has been found 

 to "cut out" the Boyle limestone in a few places, and therefore locally 

 some late Devonian movement has been suggested. 



Preceding the Mid-Devonian uplift of the Cincinnati dome and about 

 100 miles east of it, arose the Waverly arch in Early Ordovician time. It 

 has a structural relief of 750 feet ( Woodward, 1961 ) . 



The Pennsylvanian-Mississippian contact is one of marked dis- 



conformity and one of considerable relief as shown in a number of 

 Pottsville-filled valleys. The post-Mississippian uplift represented by the 

 unconformity was much broader than the doming of Middle Devonian 

 time. Compare Plates 5 and 6. It is generally regarded that after the late 

 Mississippian arching, the Cincinnati dome was submerged, and that 

 Pennsylvanian beds from the Appalachian region spread westward across 

 it so that the Appalachian and central interior coal fields were connected. 

 Several of the conglomerates, fireclays, and limestones have been corre- 

 lated across the dome. See Plate 7. 



In order to produce the present distribution of the Pennsylvanian strata, 

 still another broad, gentle arching is required in post-Pennsvlvanian time. 

 This is shown on the tectonic map of Plate 8. 



Some faults cut the dome, and these will be described later as part of 



