766 NEW YOKIv STATE MUSEUM 



Goniatite 

 This is a local layer of limestone found near tlie base of the 

 Hamilton group in Onondaga county. Westward in Genesee 

 county at the village of Stafford it is called the Stafford lime- 

 Btone^ and extends from there to Lake Erie. 



TulJy 



This is the most southern limestone formation found in any part 

 of ]^ew York except Orange and Westchester counties, and the 

 limestone of those counties is largely dolomitic. It forms a layer 

 about 10 feet thick at the top of the Hamilton group, and derives 

 its name from its type occurrence at the village of TuUy in Onon- 

 daga county. It is rather local in its extent, and does not occur 

 in the eastern or western part of the state, extending only from 

 Ontario to Madison. Few quarries have been opened in it, and it 

 has only been extracted at times for purely local wants. 



Excellent exposures of it occur however on the shores of both 

 Cayuga and Seneca lakes, and the material could be easily quar- 

 ried at these places. 



Quaternary marls 



These represent the only unconsolidated types of limestones 

 found in JSTew York. The deposits are usually found underlying 

 swampy areas, specially in the central portion of the state between 

 Syracuse and Rochester, being commonly underlain by clay, and 

 overlain by muck. 



The origin of these marls is a matter of much interest. While 

 the marl is sometimes spoken of as " shell marl ", at the same 

 time the shells found in it form but a very small part of the 

 whole, the greater portion being made up of granular carbonate 

 of lime, and the probable cause of accumulation is by precipita- 

 tion from calcareous waters, the snails being found in the marl 

 because they frequent water carrying lime. 



Central i^ew York contains an abundance of calcareous rocks, 

 and fragments from them are also found in the drift, so that 

 there is abundant opportunity for the carbonated spring waters 



