76 RECORDS 



graphic development are favorable to the view that it represents 

 an orographic block left standing between down-thrown strips 

 of the crust. The rectilinear gorge of the upper Harlem 

 between Washington Heights and Fordham Heights is con- 

 tinued, so far as its western wall is concerned, some two and a 

 half miles south of the river. It is parallel to the direction of 

 the scarp of the Palisades and of the Hudson. Besides the 

 cross fractures indicated by the different parts of the Harlem 

 River which were pointed out by Stevens, several other cross 

 fractures on and about Manhattan Island were pointed out by 

 the same author. Dana also considered that the Manhattan- 

 ville cross valley was formed by a cross-fracture. A consider- 

 able number of faults has been definitely established. Their 

 directions correspond in general to the elements in the courses 

 of the river channels. The exceptions to this rule are the 

 fissures in the East River east and west of Blackwell's Island. 



The author went on to cite a number of faults which have 

 been disclosed by numerous borings and tunnels, and in closing 

 called attention to the fact that the buried rock surface in the 

 lower part of the city (south of Twenty-third street), as well as 

 that below the area of the Harlem flats (north of One Hundred 

 and Tenth Street and east of Eighth Avenue) is characterized by 

 the most abrupt changes of level. In his opinion the area of 

 these portions of the island represent orographic blocks de- 

 pressed by faults, reefs of gneiss and limestone rising along the 

 Harlem area, while reefs of gneiss alone characterize the southern 

 district. 



Professor Hobbs' paper was discussed briefly by Professors 

 Kemp, Dodge and Stevenson, and it was evident that the 

 author's theory would not be accepted without considerable 

 further investigation. 



At the outset of his paper on Bingham Canon, Professor 

 Kemp stated that the article was not a formal one for publica- 

 tion, and that he did not wish to forestall in any degree the 

 forthcoming Bingham folio by Mr. Boutwell of the United States 

 Geological Survey. He then described the geological forma- 

 tions in the vicinity of the large mines. These formations em- 



