THE SILURIAN PERIOD. 



373 



owes its existence to the obduracy of this rock, which successfully 

 withstood erosion while the less resistant formations to the east and 



Fig. 171. — A section across the Kittatinny Mountain in northwestern New Jersey. 

 Length of the section, about five miles; vertical scale, nearly twice the horizontal; 

 angle of dip, approximately doubled. 3 = Poxino Island shale; 4 = Bossardville 

 limestone; 5 = Decker Ferry beds; 6 = Manlius limestone and Rondout limestone; 

 7 = Coeyman limestone; 8~=Becraft limestone, New Scotland beds, and Storm- 

 ville sandstone. 



west were carried away. The same formation (the Green Pond Moun- 

 tain conglomerate) appears also in the Green Pond mountain of New 



Fig. 172. — The Delaware Water Gap. The crest of the mountain range seen in the 

 background is the crest of the Kittatinny range made by the resistant Oneida 

 conglomerate. 



Jersey, and in its northward continuation in New York. The outcrop 

 of the Oneida is also conspicuous farther south, and for the same reason. 

 The Medina formation. — The Medina formation, consisting of 

 sandstone and shale (including the Longwood shale of the Green Pond 

 Mountain region), overlies the Oneida. Its materials, like those of 



