GYPSUM DEPOSITS OF NEW YORK 23 



the period represenited by the Camillus shale. This may have been 

 due to the influx of fresh waters at frequent intervals, to which the 

 great body of silt may be attributed. 



Pittsford shale. In a few localities, the base of the Salina 

 series is marked by a bed of dark shale which rests upon the Lock- 

 port dolomite. Though of no great thickness, the bed is given an 

 independent position in the stratigraphic column on account of its 

 fauna, most interesting of wihich are the eurypterids, foiund also in 

 the Bertie waterlime. The Pittsford shale is a local phase of the 

 Salina, first recognized a few years since from exposiures at Pitts- 

 ford near Rochester. 



General structure of the Salina beds 



The Salina strata which outcrop from Albany county to the 

 Niagara river have been little disturbed since their emergence from 

 the sea. They are nowhere involved in local folds and if at all 

 faulted the displacement must be so slight as to escape general ob- 

 servation. They dip uniformly toward the south, the direction rang- 

 ing from due south to a few degrees east or west of soiith. 



Within the central and western parts their inchnation averages 

 about 40 or 50 feet to the mile, or roundly i foot in 100. This is 

 probably no more than the slope of the' sea floor on which they 

 were laid down. In the eastern section the dip is somewhat higher, 

 owing to the fact that the beds here experience in some measure 

 the influence of the Appalachian disturbance, which came at the 

 close of the Paleozoic era. 



If the whole belt be considered as a unit it becomes apparent that 

 the uplift has been accompanied by a certain amount of differential 

 movement. This is well shown by a comparison of altitudes at dif- 

 ferent places along the outcrop. The following approximate ele- 

 vations have reference to the outcrop of the gypsum beds in central 

 and western New York. The localities are given in order from west 

 to east. 



LOCALITY ALTITUDE 



Feet 



Akron, Erie co 640 



Oakfield, Genesee co 735 



Wheatland, Monroe co 570 



Garbutt, Monroe co 560 



Victor, Ontario co 500 



Seneca Falls, Seneca co 400 



Union Springs, Cayuga co 460 



Martisco, Onondaga co 600 



Jamesville, Onondaga co 580 



Lyndon, Onondaga co 640 



ClockviUe, Madison co 650 



