REPORT OP THE DIRECTOR AND STATE GEOLOGIST 1903 97 



fied with sedimentary rocks which show little evidence of meta- 

 morphism. (2) In no case, so far as has come to the knowledge 

 of the author, has a fossil been found in gypsum deposits. In 

 case the gypsum beds were the result of metamorphism or 

 chemical change from beds of limestone, some trace would un- 

 doubtedly be found of the fossils occurring in the original beds 

 of limestone. Even in cases of the most violent metamorphism 

 of limestone, occasional fossils are found, so that the absence of 

 these fossils in the beds of gypsum and the crystalline nature of 

 all deposits, make it almost certain that these deposits were 

 formed by crystallization from solution. 



Geography and topography. The gypsum mines of the State are 

 found near the southern border of the area of Salina rocks which 

 may be called the Salina depression. It extends from Lake Erie 

 and the Niagara river into Oneida county. The limits of this de- 

 pression are marked on the north by the outcrop of the Niagara 

 limestone, which forms a low ridge, known as the Niagara 

 " escarpment." 



The southern boundary is marked by the outcrops of the Onon- 

 daga limestone, though much of the drainage of the region covered 

 by Devonian rocks passes through the depression. The extreme 

 width of the depression is not more than 20 miles but the length 

 is about 200. 



Proof of the existence of this depression is to be found in an 

 inspection of the map, where it will be noticed that there is an 

 almost continuous line of creeks and rivers flowing in an east or 

 west direction between the Niagara river and Utica. At only four 

 points do these streams break through the Niagara escarpment, 

 these four exceptions being the Oak Orchard creek, the Genesee 

 river, Irondequoit river and the Oswego river. Taking the streams 

 which drain this depression in their order from the east to the 

 west, we find the Oswego river, which takes the drainage from 

 Oneida lake and also from the Finger lakes; tributary to the 

 Oswego river, the Clyde and Seneca rivers and Oanandaigua out- 

 let; west of the Finger Lake region, Honeoye creek, flowing-west 



