200 



Repokt of the State Geologist. 



posed but they are also individually uneven in thickness and variable in 

 character. 



Two or three formations that have strongly marked characteristics, and 

 are important and easily recognized bench marks in the eastern part of the 

 salt district, thin out and entirely disappear before reaching the western 

 counties. Others have their highest development in the central or western 

 part of the state. 



The strike or line of surface exposure of any given formation is in its 

 general course on an east and west line and approximately parallel with the 

 southern shore of Lake Ontario, but the uneven elevations of the numerous 

 hills and valleys make it extremely tortuous in detail. 



The dip of the strata toward the east or west is hardly appreciable 

 except in the vicinity of an undulation, though the beds are rarely or never, 

 exactly horizontal. 



Cross sections of the strata show a general dip toward the south. 

 Over a large part of the district forty feet per mile is considered a fair average 

 of the amount of the dip, but it is very irregular, and varies from 100 feet or 

 more toward the south to almost as much toward the north, revealing the 

 existence of many undulations in the strata, some of which are extensive and 

 important. 



Besides the undulations, which are low in proportion to their width, and 

 over which the strata rise and fall in easy, graceful curves, there are many 

 small but sharp anticlinal folds where the layers of rock are fractured at the 

 apex and at the base on both sides. 



The sides sometimes have an inclination of 45°, but usually much less. 



There are also many dislocations of the strata in overthrust and vertical 

 faults, and fissures and joints that must penetrate to great depths are more or 

 less common in all of the formations. 



Hudson river group. The Hudson river group, as developed in the Third 

 District, includes the Frankfort slate, Lorraine shales, and the Pulaski shales 

 of Vanuxem's report. They constitute the upper or third division of the 

 rocks of the Trenton period of lower Silurian time. 



No distinct line of separation has as yet been clearly laid down between 

 the base of the Hudson river slate and the Utica slate. 



The dark blue and black bituminous and fissile slates of the latter 

 formation pass by almost imperceptible gradations into much lighter colored 

 and more arenaceous beds with w hich thin layers of grey sandstone frequently 

 are interstratified. No thin limestone, as in the case of the Utica slate, 



