BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 VOL. 16, PP. 151-182, PL. 35 APRIL 12, 1905 



ORIGIN OF THE CHANNELS SURROUNDING MANHATTAN 

 ISLAND, NEW YORK * 



BY WILLIAM HERBERT HOBBS 



(Read before the Society December 31, 1902) 



CONTENTS 



Page 



Introduction 152 



Theories of origin of the New York water front 153 



Form of the rock floor beneath the New York water front 155 



Generally accepted view 155 



Detailed study of sections 156 



Order of presentation of results 156 



Spuyten Duyvil bridge, Harlem river 157 



Kings bridge and Dyckmans cut - . . . . 158 



Washington bridge, Harlem river 158 



High bridge, Harlem river 159 



New New York aqueduct siphon under Harlem river . . . . 159 



Eighth Avenue bridge, Harlem river 160 



McCombs Dam (Central) bridge 160 



Soundings to rock east of Central bridge 161 



New York Central Railroad bridge across Cromwells creek 161 



One hundred and forty-fifth Street bridge 162 



Rapid Transit tunnel 162 



Madison Avenue bridge, Harlem river 162 



Park Avenue Railroad bridge 163 



Third Avenue bridge, Harlem river 163 



Second Avenue bridge 163 



Willis Avenue bridge.. ' 164 



One hundred and twenty-fifth and One hundred and twenty-second 



Street reefs, East river 1 64 



Projected Hell Gate railroad bridge 164 



Hell Gate reefs 165 



East River Gas Company's tunnel (Blackwells Island tunnel) 166 



Projected but abandoned Rainey bridge. 167 



East River bridge number 4 (Blackwells Island bridge) 168 



Abandoned East River tunnel 169 



Man o'- war reef. 169 



Section on center line of Forty-second street produced 169 



♦This paper was read December 31, 1902, at the Washington meeting, and is mentioned on page 

 543 of volume 14, under title " Configuration of the rock floor of the vicinity of New York." 



XXI— Bull. Geol. Soc. Am., Vol. 16, 1904 (151) 



