108 



STRUCTURAL GEOLOGY OF NORTH AMERICA 



€c 



GAYLOR 

 RIDGE 



5r 5c 



SIMS 

 MTN. 



ROME THRUST 



HORSE 

 MTN. 





SECTION 3 



SECTION 2 



Fig. 8.12. Upper cross section (No. 3 of index map, Fig. 7.1) of Rome quadrangle, Georgia and 

 Alabama. After Hayes, 1902. 



Lower cross section (No. 2 of index map) of Birmingham quadrangle, Alabama. After Butts, 

 1910. 



Cr, Rome fm.; €c, Conasauga Is.; Cbr, Beaver Is.; €Ok and £sk, Knox dolomite; Oc, Chicka- 

 mauga Is.; Sc. Clinton ss. and sh.; Sr, Rockwood fm.; Da, Armuchee chert; Cfp, Fort Payne chert; 

 Ch, Floyd ss. member; Cb, Bangor Is.; Cp, Pennington sh.; Cby and Cpv, Pottsville gr. 



and understood, and with an extensive literature that reveals a striking 

 evolution of interpretation. 



The Blue Ridge province embraces two rather distinct tectonic ele- 



ments, about coincident with the geomorphic divisions. Northeastward 

 from the vicinity of French Broad River in eastern Tennessee and western 

 North Carolina, the Blue Ridge is narrow, whereas southwestward, it is 

 broad and more complex. See Fig. 8.22. 



Stratigraphy and Structure— Potomac to the French Broad River 



The northeastern division, where most typically developed in northern 

 Virginia, is composed of a core of older Precambrian crystalline base- 

 ment rocks which are overlain and flanked by a considerable body of 

 later Precambrian metavolcanics and metasediments (Catoctin green- 

 stone and related units), and by Lower Cambrian clastic rocks 

 (Chilhowee group). This segment is known as the Blue Ridge-Catoctin 

 Mountain anticlinorium. 



The structure and stratigraphy of the north end of the Blue Ridge belt 

 of Fig. 8.22 across Catoctin Mountain and South Mountain is shown in 

 Fig. 8.23. This sction is north of Harpers Ferry. Just south of the city 

 the structure across Short Hill and the Blue Ridge is given in Fig. 8.24. 

 Farther south in the Elkton area of Virginia a section on the west side of 



GREAT 



VALLEY 



BLUE 



RIDGE 



Pu 

 Pine Mountoin foult 



MDc DSu 



Fig. 8.13. Cross section of folded and thrust faulted Appalachians in eastern Tennessee. After 

 Rodgers, 1953. (Section 4.) Pu, Pennsylvanian rocks; Mp, Pennington formation; Mn, Newman 

 limestone; Mg, Grainger formation; MDu, Lower Mississippian and Upper Devonian rocks (Fort 

 Payne, Grainger, and Chattanooga formations); MDc, Chattanooga shale; MDs, Basal Missis- 

 sippian and Devonian shale; DSu, Lower Devonian and Silurian rocks (Hancock limestone, Rock- 

 wood formation, and Clinch sandstone); Os, Sequatchie formation; Oj, Juanita formation; Ouc, 

 Upper part of Chickamauga limestone, including Reedsville shale; Omb, Martinsburg shale; 

 Olmc, Lower and Middle parts of Chickamauga limestone, undivided; Ob, Bays formation; Oo. 



Ottosee shale; Oh, Holston formation, Ol, Lenoir limestone; Oa, Athens shale; Osv, Sevier 

 shale; OCk, Knox dolomite or group, undivided; Cc, Conasauga shale or group, undivided; Ccu, 

 Upper Cambrian part of Conasauga group; €hk, Monaker dolomite; Cr, Rome formation; Ss, 

 Shady dolomite; Ce, Erwin formation and equivalent rocks (Hesse sandstone, Murray shale, and 

 Nebo sandstone); Che, Hesse sandstone; Cnb, Nebo sandstone; Ch, Hampton formation; Cni, 

 Nichols shale; €u; Unicoi formation; €ch, Cochrane conglomerate; ocu, Ocoee series, undivided; 

 ocss, Sandsuck shale; ocsb, Snowbird formation; pCc, Precambrian crystalline complex. 



; 



