266 



except at Lofton. Rntlierford Comity, where the upper ten feet of the Mur- 

 freesboro is absent. 



Ridley limestone. This limestone was named by Safford^ in 1869 from 

 the exposure at Ridley's Mills (now Davis' mill) near Jefferson, Tennessee. 

 Only the lower thirty feet of the formation are exposed at this locality. 

 The Ridley limestone has a much wider svirface distribution than the older 

 formations of the Stones River group. It accurs in Rutherford. Wilson. 

 Bedford, Marshall, Williamson, and Davidson counties. Its thickness 

 varies from 05 to 120 feet. 



The formation consists of massive, dense, light blue, bituminous lime- 

 stone with considerable chert, appearing upon the weathered surfaces. 

 These characters are much like those of the Murfreesboro limestone, and 

 it is not surprising that Safford confused the formations lithologically. 

 The faunas, however, are decidedly different, but in many outcrops 

 fossils do not occur and correlation is uncertain except where the contacts 

 with either the Pierce or the Lebanon are seen. 



The Ridley limestone is in most places apparently conformable upon 

 the Pierce, except near Jefferson, Rutherford County, where the contact is 

 slightly undulating. The small variation in thickness of the Pierce lime- 

 stone does not indicate a prolonged period of erosion. The following are 

 among the most characteristic and abundant fossils : Camerella varians, 

 Hcbertella bellarugosa, Gonioceras anceps, Orhignyella sublamellosa, Lio- 

 spira convexa, Protorhyncha riilleyana and Strom at ocerium rugosum. 



Lebanon formation. This formation was "called the "glade limestone'' 

 by Safford in 1869^, since it is the surface rock beneath the extensive "cedar 

 glades" of central Tennessee. In 1900 Safford and Killebrew- changed the 

 name to "Lebanon limestone" presumably from the splendid outcrops of 

 the formation in the town of Lebanon, Wilson County. The thickness meas- 

 ured by Safford^ near Readyville, Rutherford County, is 118 feet. Other 

 measurements in other localities show a variation from 80 to 120 feet. 



The outcrops of this limestone extend over a considerable area in Ruth- 

 erford, Wilson, Cannon, Bedford, Marshall, Maury, Williamson, and David- 

 son counties, and almost everywhere valuable cedars grow in the shallow 

 Lebanon soil. The formation consists of thin layers of dense, light blue, 

 fossiliferous limestone separated by seams of shale. In some sections a 

 massive coarsely crystalline unfossiliferous bed of limestone occurs near the 

 base. Ripple-, rill- and wave-marks are common in different parts of the 

 formation, indicating that shallow water conditions prevailed at different 

 times during the deposition of the beds. 



Some layers of the formation are made up almost wholly of a single 

 species of Plectambomtes as seen two miles south of Murfreesboro. Other 

 abundant and characteristic fossils are : Scenidium anthonense, Batostom^i 

 libana, Escharopora briarcAts, Pht-agmoUtes grandu^, and Zygospira saffordi. 



The Lebanon lies with apparent conformity upon the Ridley. 



iGeol. Tenn. (1869), p. 261. 

 iGeol. Tpnn. (1869). p. 258. 

 2Elem. Geol. Tenn. (1900), p. 125. 

 3G'eol. Tenn. (1869), p. 263. 



