NO. lO 



SMITHSONIAN EXTLORATIONS, I923 



Fu.. 12. — \'iew of Middle Urdovician-Alississippian unconformity near 

 Hollow Springs, Tennessee, showing the undulating line of contact between 

 the Cannon limestone (C) and the Chattanooga black shale (B). (Photo- 

 graph by Bassler. ) 



Fig. 13. — View of Highland Rim in er.st central Tennessee, dissected by 

 Central Basin stream. (Photograph by Bassler.) 



