Marylaxd Geological Survey 109 



in abundance at a higher horizon. The upper beds are but sparingly fossil- 

 iferous, shaly, and some strata are laminated. The transition to the over- 

 lying very fossiliferous member of the Helderberg is seen at a spring near 

 the south end of cut and is probably abrupt, although this fact has not been 

 sufficiently investigated. The Selinsgrove Junction section may be con- 

 sidered typical of the many exposures of the Keyser limestone of this 

 region. The features described are similar to those presented by the 

 Keyser of Maryland, permitting little doubt of the essential identity of 

 these members in both areas. 



An excellent exposure of the Helderberg is seen in the quarries at 

 Grovania 19 miles northeast of Selinsgrove Junction. The lower nodular 

 beds of the Keyser resemble those at the latter locality and contain a 

 similar massive Stromatopora reef. A short distance belovs^ this reef is a 

 bed abounding in Oladopora rectilineata and Halysites catenulatus. This 

 zone occupies a position similar to that of the Cladopora rectilineata zone 

 in the lower Keyser of Maryland with which it may be identical. A 

 notable feature of the section is a sandstone seen at the top of the quarry 

 which occurs 4G stratigraphic feet above the Stromatopora reef. This 

 stratum has been interpreted ' as indicating an unconformity by erosion 

 at the top of the Keyser, but the exposure of the overlying strata is too im- 

 perfect at the present time to fully establish this fact. 



Examination of the preceding sections renders the following conclusions 

 probable : " The Bossardville limestone of central Pennsylvania is identi- 

 cal with the Tonoloway limestone of Maryland, resembling it in lithology, 

 stratigraphic position and in containing an ostracod fauna. The sparse 

 brachiopod fauna of the Tonoloway has not been observed in central Penn- 

 sylvania, suggesting that the Maryland area was more closely connected 

 Avith the open sea. 



The Keyser member of the Helderberg is present in Pennsylvania and 

 closely resembles the corresponding Maryland beds in lithology and fauna. 

 The lower strata are nodular while the upper are in part laminated 



^Grabau, N. Y. State Mus., Bull. 92, 1906, p. 173. 



*The conclusions here advanced are only tentative. Further investigation 

 is needed before they can be established. 



