MARYLAND GEOLOGICAL SURVEY 143 



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Incomplete Faunal List of the Christiania Bed, Chambersburg Limestone 



Echinospherites aurantium americanum Bassler 



Crinoid plates 



Hemiphragma cf. H. irrasum 



Trematopora cf. primigenia 



Arthropora bifurcata Ulrich 



Rhinidictya cf. R. neglecta 



Orbiculoidea lamellosa Hall 



Orthis tricenaria Conrad 



Scenidium cf. 8. anthonense 



Dinorthis sp. cf. D. subquadrata 



Strophomena sp. 



Leptaena cf. L. charlottae 



Plectambonites sp. 



Plectambonites pisum Ruedemann 



Christiania trentonensis Ruedemann 



Triplesia (Cliftonia) simulatrix Bassler 



Triplecia cf. T. nucleus 



Parastrophia hemiplicata Hall 



Zygospira exigua (Hall) 



Ctenodonta sp. 



Lepidocoleus, 2 undet. sp. (near L. jamesi) 



Illaenus sp. 



Isotelus gigas Dekay 



Fragments of Cryptolithus or Tretaspis 



Greencastle Bed. The thickest sections of Chambersburg limestone 

 are in southern Pennsylvania in the vicinity of Greencastle, where 200 

 feet of heavy bedded, impure limestone follow the usual Christiania bed 

 and underlie the base of the Martinsburg shales. Reference to the sec- 

 tions on another page shows that this member can be recognized as far 

 north as Chambersburg, but that it does not appear in any of the sections 

 west of the Martinsburg shale belt. It appears that after the deposition 

 of the rather widely distributed Christiania bed, a local depression in the 

 sea, extending from about the Maryland state line northward to and 

 beyond Chambersburg, allowed the accumulation of this considerable 

 thickness of calcareous sediments before the inauguration of the basal 

 Martinsburg shale. This division, for which the local name Greencastle 

 bed is employed for convenience of reference, is interesting from a 

 paleontological standpoint, first because it contains fossils found also 



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