1 8 NEW YORK STATE MUSEUM 



highly improbable that any valuable deposits occur in the northern 

 sections, where conglomerates and sandstomes are the prevailing 

 strata. If present at all, they will be found in the extreme south- 

 ern part near the New Jersey border, in association with the 

 shales which, as before stated, are here much thicker and even be- 

 come the predominant member of the series. 



In so far as the climatic factor may be concerned in the forma- 

 tion of the salt and gypsum, conditions must have been very simi- 

 lar in the two regions. The long continued concentratiion of the 

 Salina seas by evaporation was widespread throughout the nicirth- 

 eastern section of the interior basin as shown by the occurrence of 

 one or both minerals in the Salina of Ontario, Ohio and Michigan, 

 and there is no reason for believing that tlie climate was essentially 

 less arid or otherwise different in the nearby part of the Atlantic 

 basin, especially as the intervening barrier had undergone steady 

 submergence during the epoch and was to disappear wholly before 

 the close of Siluric time. 



The colors of the strata in both regions are very similar. Deep 

 red shales which some geologists regard as indicative of arid cli- 

 matic conditions are a prominent feature of the sections in south- 

 ern Orange county as well as of the Lower Salina of central New 

 York. 



Salina stratigraphy 



The Salina stage as developed in central New York is divisible 

 into five parts. The different members are seldom sharply de- 

 limited by physical features and owing to the scarcity of fossils 

 throughout the beds their demarcation on the map is only possible 

 in a general way. They are usually connected by zones of grada- 

 tion ; or sometimes the transition from one member to another is 

 marked by a sequence of alternating layers. The latter is the con- 

 dition, for example, of the passage from the waterlime that caps 

 the formation, to the underlying shale. 



The full series is found only in the part of the belt that lies west 

 of Madison county. To the east they overlap upon the lower 

 formations and gradually thin out to disappearance. The general 

 relations of the members are shown in the accompanying diagram 

 [%. 2]. 



Bertie waterlime. This is an argillaceous, more or less magne- 

 sian limestone which forms the top member of the Salina stage. It 

 is a persistent formation of quite uniform character. It extends 

 from the Province of Ontario, where the type locality is found, 



