154 KUMMEL AND WELLER — LlMESTONKS OP KITTATINNY VALLEY 



Although these identifications are but provisional, the whole com- 

 plexion of the fauna is recognized as Calciferous, and on this evidence 

 there can be no hesitation in correlating the upper portion of the Kitta- 

 tinny limestone with the Calciferous. The evidence of the fossils there- 

 fore establishes the age of the Kittatinny limestone as including a part 

 of the Lower Cambrian, the Middle and Upper Cambrian, and extend- 

 ing into the Calciferous. A study of the stratigraphy seems to indicate 

 that there was no break in the sedimentation during this long period 

 of time. 



PREVIOUS VIEWS 



Professor Rogers* included both the Kittatinny and the overlying 

 Trenton limestone in his formation, number 2, of the Lower Secondary 

 rocks. It is the magnesian or blue limestone of Professor Cook'sf re- 

 ports, and it was by him regarded as the equivalent of the Calciferous of 

 New York. Prime J concluded that the Magnesian limestones found in 

 the extension of the Kittatinn}^ valle}^ into Pennsylvania " correspond in 

 age to the Calciferous and Chazy epochs." The discoveries by Walcott,§ 

 Dwight,|| and Dana of Lower Cambrian fossils in the lower portions of 

 the same limestone in Penns3dvania and New York finally led to correct 

 inferences as to the Cambrian and Lower Ordovician age of these rocks* 

 in New Jerse3^ Our determinations now confirm these inferences. 



Trenton Formation 



This formation consists of non-magnesian limestones and calcareous 

 shales, with a local calcareous conglomerate of var3'ing thickness at its 

 base. 



Basal Conglomerate 



Resting on the slightly eroded surface of the Kittatinny limestone 

 there is a basal conglomerate composed of pebbles of the underlying 

 magnesian limestone and chert. It is not everywhere present in equal 

 development, but it is practically coextensive with the Trenton limestone 

 in New Jersey. Where observed it varies considerably in character and 

 thickness. It is sometimes merely a thin layer of small well rounded 

 magnesian limestone pebbles in a purer limestone matrix, which occa- 



* Rogers : Loc. cit. 

 t Cook : Loc. cit., p. 90. 



X Prime : Pennsylvania Second Geol. Survey, D 3, vol. i, p. 163. 

 g Walcott : Loc. cit., p. 33. 



II Dwight : Am. Jour. Sci., 3d series, vol. xxxi, p. 125 et seq. ; vol, xxxiv, p. 27 et seq. ; vol. xxxviii, 

 p. 139. 



