IRON ORES OF THE CLINTON FORMATION 9 



crosses the Niagara river at the falls and comes to an end prob- 

 ably in the Province of Ontario. The Clinton areas of Ohio and 

 Wisconsin seem to have been formed in basins separate from 

 the above. 



The width of the outcropping strata as shown on the maps 

 ranges up to a maximum of about 5 miles. It is greatest in the 

 central part, in the vicinity of Oneida lake and immediately 

 westward. It diminishes very gradually away from that sec- 

 tion, specially to the west, where the strata continue for a long 

 distance with scarcely perceptible changes. The outcrop nar- 

 rows more quickly toward the east mainly on account of the 

 increasing inclination of the beds in that direction. 



The restriction of the Clinton strata to the single belt above 

 delimited is not in accordance with the work of the early geol- 

 ogists, generally accepted until recent years, but it has the sup- 

 port of most convincing evidence. The beds in Schoharie and 

 Albany counties that were formerly supposed to represent the 

 eastern continuation of the belt are now known to be of much 

 later (Salina) age. Likewise the areas in the Skunnemunk and 

 Shawangunk mountains of Sullivan and Orange counties, some 

 60 miles long altogether, assigned to the Clinton in the early 

 reports, have since been demonstrated to be of post-Clinton 

 development. 



TOPOGRAPHIC FEATURES 



The Clinton outcrop is seldom traceable by the surface con- 

 figuration. Physically and structurally united to the beds above and 

 below, the formation has developed few topographic features, by 

 weathering or erosion, that are distinctive. 



In the extreme west the Clinton strata are involved in the Niagara 

 escarpment of which they constitute the median portion as ex- 

 posed in the Niagara gorge. Passing eastward the escarpment 

 become less prominent as a scenic feature and practically disap- 

 pears in the vicinity of Rochester. The soft shales have been 

 denuded so as to yield a gentle slope from the level of the Lock- 

 port limestone at the top down to the Ontario plain that is floored 

 by Medina sandstone. The outcrop of the formation widens out, 

 of course, with the flattening of the topography. 



At Rochester the Clinton strata are crossed by the Genesee river 

 which occupies a deep gorge at this point, causing a V-shaped up- 

 stream deflection of the outcrop. This is the only place cast of the 



