700 GEORGE W. STOSE 



about the same interval but apparently including beds which in the 

 Chambersburg area are calcareous sandstones and are mapped with 

 the overlying Waynesboro formation, has been named Sherwood 

 limestone by H. D. Campbell. The new name Tomstown is from 

 a village in the Chambersburg quadrangle. The formation has been 

 recognized also in the Carlisle quadrangle to the north, where it forms 

 a deeply weathered belt about the foot of the mountain, largely covered 

 by wash. 



V^AYNESBORO FORMATION 



The Waynesboro formation is a series of sandstones, purple shales, 

 and limestones overlying the Tomstown formation. Because of 

 its resistant siliceous character it forms hills and knobs, parallel to 

 the mountain front. At the base are very siliceous gray limestones 

 that weather to slabby porous sandstone, large round masses of 

 rugose chert, and white vein quartz. 



In the middle of the formation are dark-blue to white subcrystalline 

 limestones and dolomites, which become siliceous upward and merge 

 into mottled slabby sandstone anji dark-purple siliceous shale at the 

 top. The thickness of the formation, computed from the width of 

 outcrop and dips, and allowing for minor folding, is 1,250 feet. 



The formation occupies a belt about one-half mile wide along the 

 east side of the Cumberland Valley in the Chambersburg quadrangle. 

 Its most complete development is in the hills northeast of Waynesboro, 

 from which its name is taken. It has been traced northward beyond 

 Mt. Holly Springs in the Carlisle quadrangle, but is there seldom 

 exposed. 



The only fossils found in this formation are a few poorly preserved 

 shells, two of which are identified as Oholus {Lingulella) sp. undet. 

 They were obtained from sandy shale at the very top of the formation, 

 just east of Waynesboro. They suggest Acadian (Middle Cambrian) 

 age but are not conclusive. 



In central Virginia the Buena Vista shale, described by H. D. 

 Campbell, is at this general horizon, but, as previously stated, appar- 

 ently has a different lower limit. It is described as bright variegated 

 shale, 600 to 900 feet thick, with mottled limestone and shale in the 

 lower part. Mr. Walcott found in it a species of Ptychoparia related 

 to Acadian (Middle Cambrian) species of Tennessee. 



