!• PALAEONTOLOGY OF NEW-YORK. 



and present on a more extended scale all the phenomena which have been 

 described as occurring in localities farther south. In tracing the formations 

 still farther to the north, the highly inclined, folded and contorted stra- 

 tification of these shales, conglomerates, and limestones, gradually dis- 

 appears ; the metamorphic condition declines in the same ratio ; until the 

 strata assume nearly their normal condition and position, and exhibit 

 miequivocally the characteristics of the Trenton limestone and the Hudson- 

 river group. 



A similar change in the character of these rocks has been before shown, 

 in tracing the strata westward from the Green mountain range ; in which 

 direction the foldings and the metamorphism gradually disappear, till the 

 rocks assume their normal condition. In Canada, however, this change is 

 not to the west or the east of the trend of the metamorphic chain, but in 

 the continuation of the chain itself to the northeast, and in the trend of 

 its greatest elevation, disturbance, and metamorphism ; showing that all 

 the phenomena exhibited in the Green mountain range are superinduced 

 upon the rocks of the Trenton and Hudson river periods. Not only has 

 the general identity been thus determined, but individual beds of the 

 metamorphic belt have been traced in their line of strike till they assume 

 their normal aspect. 



Nor have the investigations rested here : for the chemical examinations 

 of Mr. T. Sterey Hunt ( of the Canada Geological Survey) have shown 

 that the unaltered beds contain the same mineral components, and in the 

 same proportions, as do the altered beds. 



The great serpentine range of rocks, which are known to belong to the 

 upper part of the Hudson-river group, have been proved to correspond in 

 chemical character to the unaltered rocks lying in the same geological 

 position, and identical with the continuation of these beds*. Geological 

 structure, therefore, and chemical and paloeontological evidence all unite 

 in proving the age of these deposits. 



• I need only refer in this place to the elaborate Reports of Progress in the Canada Geological Survey, 

 and to the varionn Essays by Sir W. E. Looan and Mr. T. S. Hc»t, for the proof in detail of what Is hare 

 dated. 



