GEOLOGY OF SARATOGA SPRINGS AND VICINITY 93 



D. contortus Ruedemann 



Climacograptus bicornis Hall 



C. parvus Hall 



C. putillus var. eximius Ruedemann 



Glossograptus ciliatus Emmons 



Lasiograptus bimucronatus (Hall) 



Leptobolus sp. 



Correlation. The writer, finding the Normanskill shale below 

 beds with Diplograptus amplexicaulis, had inferred 

 (1901) that it was at least as old or older than middle Trenton and 

 correlated it with the middle and lower Trenton. It appears now 

 from evidence obtained by Ulrich (op. cit. page 512) in the Athens 

 trough, that the formation is still older and corresponds in age to 

 the upper Chazy. But the Rysedorph Hill conglomerate of Black 

 River age is intercalated in the Normanskill shale in a number of 

 localities, some of which have been cited above (page 82) and to 

 which may be added the fossiliferous exposure of the conglomerate 

 in the big cut of the Boston & Albany Railroad south of Rensselaer. 



These militating observations of the Chazy age of the Normans- 

 kill shale and of the intercalation of the Rysedorph Hill con- 

 glomerate of Black River age, appear to find their solution from 

 observations made lately by the writer, leading to the inference 

 that the Normanskill shale comprises two divisions or formations, 

 the lower of which is of Chazy age and the upper of Black River 

 age and possibly somewhat younger. This upper formation con- 

 tains the Rysedorph Hill conglomerate. The inference of the sub- 

 division of the Normanskill shale is based partly upon an unmis- 

 takable distinction in the graptolite faunules, indicating an older 

 and a later horizon — to be worked out more fully when favorable 

 sections present themselves — and partly upon the observation of 

 traces of other fossils than graptolites and younger than Chazyan 

 in age in the upper Normanskill shale. 



SNAKE HILL BEDS 



The Snake Hill formation occupies the southeast corner of the 

 Saratoga quadrangle, from Ballston Spa and the Kayaderosseras 

 creek to Saratoga lake. It crosses the Schuylerville quadrangle 

 diagonally as a belt 4 to 5 miles wide, and a second eastern belt 

 follows the Hudson river and unites with the western belt north 

 of the Batten kill. These belts are segments of a greater belt that 

 extends from Pennsylvania through southern New York along the 



