202 



Report of the State Geologist. 



of separation from the Oneida conglomerate below, succeeded by (2) beds of 

 argillaceous sandstones and shales, red or mottled red and grey ; (3) grey, 

 laminated sandstones called by Eaton the grey hand, and (4) red shales and 

 shaly sandstones banded and mottled with red and green. 



Very few of these beds are of a persistent character entirely across the 

 district, but beds of sandstone that are compact and valuable for building 

 material at one locality, are too soft and shaly for that purpose at others. 



As but a part of the group is exposed in the belt over which it is the 

 surface rock, the total thickness of its beds can only be ascertained in the few 

 deep borings that have passed through them. 



In his record of the State well at Syracuse, Dr. Englehardt makes the 

 total thickness of the Medina sandstone, 740 feet. 



If, as seems probable, the grey sandstones next below are in the horizon 

 of the Oneida conglomerate or Oswego sandstones the thickness of the 

 entire group at this locality would be increased twenty-five to fifty feet. 



In the' Rochester well, Prof. H. L. Fairchild ascribes a thickness of 

 eighty-three feet to the "Oneida or Oswego," and 1075 feet to the red 

 Medina, making a total of 1158 feet for the entire group. 



Nearly all of the numerous brine springs that are found in the counties 

 adjacent to lake Ontario issue from the sandstones, but there is nothing in 

 the character or appearance of these sediments from which the existence of 

 salt crystals at the present or any former time can be inferred. On the con- 

 trary, their condition indicates an extensive sandy flat shore, exrx>sed to the 

 influence of strong currents, tidal and otherwise, where evaporation of the 

 sea water could make but small progress. 



In the Gale well at Syracuse, brine was found in two of the Medina 

 sandstone layers, while in the State well, but little more than a mile distant, 

 no brine occurred in that formation. 



A large number of deep borings have been made into the upper sand- 

 stones in search of natural gas, in the vicinity of Seneca Falls, Seneca 

 county, West Bloomfield, Ontario county, Caledonia and Avon, Livingston 

 county, LeRoy and Batavia, Genesee county, the city of Buffalo, and other 

 localities. In some of the wells, a considerable pressure of gas is found in 

 the sandstone beds 100 to 250 feet below the top of the group. In other 

 wells a short distance away, little or no gas is present. 



In central New York the exposure of the rocks of the Medina epoch 

 begins near the southeast corner of Herkimer county, on the south side of the 

 Mohawk valley, and extends toward the northwest over a very narrow strip 



