16 



ILLUSTRATIONS 



PLATE FACING PAGE 



IX. Fig. 1. Cryptozoon reef at base of Conococheague formation, ex- 

 posed along Norfolk and Western Railroad about one mile 

 southwest of Antietam Station, Maryland. Photograph about 

 one-fifteenth natural size 76 



Fig. 2. Cryptozoon structure in upper part of Conococheague 

 limestone exposed along Western Maryland Railway, one- 

 quarter mile west of Charlton, Maryland. Photograph one- 

 sixth natural size 76 



X. Fig. 1. Exposure of Conococheague limestone on edge, along road 

 near Bakersville, Maryland. The characteristic strongly 

 crinkled, sandy laminae are well developed 80 



Fig. 2. Lower Conococheague scoriaceous chert exposed in fence 

 along Hagerstown turnpike just north of Sharpsburg, Mary- 

 land 80 



XI. " Edgewise beds " characteristic of Beekmantown and Conoco- 

 cheague formations, Hagerstown Valley, Washington County. 82 

 XII. Fig. 1. Quarry in upper part of Conococheague limestone with 



Security Cement Works, Security, Maryland, in distance. ... 84 



Fig. 2. Typical exposure of the lower pure finely conglomeratic 

 beds of the Stonehenge limestone along National Highway, 

 just south of Funkstown, Maryland 84 



XIII. Fig. 1. Exposure of steeply inclined Stonehenge limestone 



(upper division) at Charlton, Maryland, showing the dis- 

 integration into siliceous shale, upon prolonged weathering. . . 96 

 Fig. 2. Typical exposure of edgewise conglomerate from the 

 upper part of the Stonehenge limestone, Baltimore and Ohio 

 Railroad, one mile north of Balls, Maryland 96 



XIV. Fig. 1. View of a weathered outcrop of the upper Stonehenge 



limestone, eastern edge of Hagerstown, Maryland 100 



Fig. 2. View taken from hill of upper Stonehenge limestone, 

 eastern edge of Hagerstown, Maryland, looking east, showing 

 effect of weathering of the various formations upon topog- 

 raphy 100 



XV. Fig. 1. Exposure of lower Beekmantown limestone just above 

 the Stonehenge member in brickyard, eastern edge of Hagers- 

 town, Maryland. Clay for brick manufacture results from the 



weathering of the purer beds 104 



Fig. 2. Beekmantown limestone at LeGore quarry, LeGore, Mary- 

 land. The weathered outcrops of these strata have yielded 



numerous cephalopods 104 



XVI. Fig. 1. Near view of Beekmantown limestone at LeGore quarry, 

 LeGore, Maryland. Strata penetrated by a six-inch diabase 



dyke (marked by hammer) 108 



Fig. 2. View of contact between the Beekmantown (B) and 

 Stones River (S) limestone along the south side of the 

 National Highway at Wilson, Maryland. The zone of cauli- 

 flower chert (C) is well displayed at this place 108 



