[Annals N.Y. Acad. Sci.,Vo1. XXIV, pp. 115-170, pll.VII-XXI. 4 August, 19243 



THE GENESIS OF CERTAIN PALEOZOIC INTERBEDDEB 



IRON ORE DEPOSITS^ librak 



By Raymond Bartlett Earle botanic. 



(Presented in abstract before the Academy, 7 April, 1913) 



CONTENTS 



Page 



lutroductiou 116 



Acknowledgments 117 



Part I. A study and criticism of previous theories 118 



The Silurian era , 118 



Iron ore deposits of the Clinton formation 120 



Types of ore 120 



Extent of deposits 121 



Other Paleozoic deposits 12.3 



Wabana deposit, Newfoundland 123 



Torbrook and Nictaux deposits, Nova Scotia 124 



Mira Valley deposit. Cape Breton, N. S 124 



Summary of theories of genesis 124 



Primary deposition , 125 



Secondary origin 129 



Residual enrichment theory 129 



Replacement theory 1,30 



Application of recent investigations 131 



Theory of original sedimentation 131 



Sedimentary aspect of ore bed 132 



Consequences of sedimentary theory 132 



Field evidence , 133 



Inadequacy of sedimentation in open sea , 134 



Sedimentation in lagoons 134 



Theories of replacement and secondary enrichment 135 



Persistence of ore seams 135 



Unreplaced limestone 135 



Secondary enrichment theories 136 



Simple replacement theory 136 



Part II. Artesian replacement theory 137 



Artesian conditions 137 



Controlling factors 137 



Circulation of artesian water 138 



Typical sections of Clinton ore 139 



Missouri 139 



Alabama 139 



Georgia I43 



Tennessee I44 



1 Manuscript received by the Editor, 15 December, 1913. (115) 



