148 THE CAMBRIAN AND ORDOVICIAN DEPOSITS OF MARYLAND 



bed which is so well developed east of the Martinsburg shale area is here 

 entirely wanting, the Mdulites. bed of the general section being succeeded 

 immediately by the Martinsburg shale. The easternmost belt of outcrop 

 in this western area affords the following section which is exposed south 

 of St. Thomas. This section as described by Ulrich is interesting because 

 it is in the most easternly belt of the trough in which the Caryocystites 

 bed is developed. The next outcrop of the Chambersburg limestone to 

 the east contains no representation of the 110 or more feet of tho 

 Caryocystites bed as here developed. 



Section of Chambersburg Limestone 2y 2 Miles South of St. Thomas 



Martinsburg shale. 



Typical dark shale. Feet 



Thin, calcareous shale, underlain by calcareous black shale and 



hard thin black limestone with the Corynoides fauna at top. 31 



Coarse granular fossiliferous limestone (Sinuites fauna) 7 



Chambersburg limestone. 

 Nidulites bed. 



Black cobbly thin-bedded fossiliferous limestone 53 



Tetradium cellulosum bed. 



Massive granular or finely conglomeratic gray, highly fossili- 

 ferous limestone (Beatricea numerous) 15 



Subcrystalline, very fossiliferous gray limestone (Leperditia 



numerous) 1 



Granocrystalline unfossiliferous gray limestone, in part minutely 



conglomeratic 18 



Caryocystites bed. 



Bluish subcrystalline limestone containing numerous Caryocys- 

 tites plates and Solenopora compacta 7 



Cobbly dark subcrystalline limestone, more massive in upper 



part 105 



Stones River limestone. 



Fine even-grained pure limestone, drab tb dark gray, thin bedded 



above, less pure below 



The railroad cut just north of Dickey's station, four or five miles south- 

 east from Ft. Loudon, exposes a good section of the formation, particu- 

 larly of the middle beds. The Echinospherites bed was not distinguished, 

 but it is possible that it may be included in the cobbly limestone at the 

 base of the Nidulites bed. As usual in these western bands of outcrop, 

 the Christiania bed is missing. 



