IRON ORES OF THE CLINTON FORMATION 1 3 



to overlapping of the strata, due to a slight uplift which seems to 

 have occurred at the close of the Clinton a'ge. The effect of the 

 uplift is apparent in limiting the transgression of the Xiagaran sea 

 to the east, causing the disappearance of the upper members in 

 that direction and bringing the Salina into contact with the Clinton 

 beds. 



The whole series of Upper Siluric strata of central and western 

 New York from the Medina up to and including the Niagaran group 

 was laid dow_n in the great mediterranean, known as the ^Nlississip- 

 pian sea, which came into existence probably during Cambric times. 

 The sea was shut off from the Atlantic basin by a broad barrier that 

 •extended along the Appalachian protaxis from New Brunswick 

 through New England, eastern New York and the intervening states 

 to northern Alabama and connected on the north with the conti- 

 nental old-land or Laurentia of Canada. At the opening of Upper 

 Siluric time the barrier had assumed increased proportions through 

 the Taconic revolution. The sediments which had accumulated along 

 the shore of the Appalachian and Canadian regions during Cam- 

 bric and Lower Siluric times were upraised and folded. Thus, the 

 -entire eastern section of New York State became land. Follow- 

 ing this uplift the interior sea began to extend its limits so that the 

 Upper Siluric deposits encroached more and more upon the land 

 surface to the east. 



With the Cayugan period, sedimentation took place again in 

 southeastern New York. Representatives of this group are found 

 across the State from the Niagara river to Albany county. Here 

 their line of outcrop bends to the south, passing into Ulster county, 

 and thence southwest through Sullivan and Orange counties and 

 into New Jersey in the vicinity of Port Jervis. Disconnected areas, 

 constituting outliers of the main belts, are met with in Orange 

 county, running southwest from the Skunnemunk mountain region. 

 These outliers consist of conglomerate of Salina age (the Shawan- 

 gunk conglomerate of New York State and the Crecn Pond con- 

 glomerate of New Jersey) followed by a series of sandstones, 

 shales and limestones. Formerly the series was consideretl to be- 

 long to an earlier period of deposition, the conglomerate having 

 been taken for the equivalent of the Oneida in central New York 

 and some of the overlying beds for the Clinton. 



The Upper Siluric beds follow each other in conformable ar- 

 rangement. After the Taconic upheaval sedimentation appears to 

 have been continuous durinir tlie wli. le of the tollowiuij- era. The 



