CHAPTER X. 



CLASSIFICATION OF THE NEW HAMPSHIRE FORMATIONS. 



E have at last reached that epoch in the development of New 

 Hampshire geology when it is proper to state our conclusions in 

 regard to the establishment of the stratigraphical column. The rocks of 

 each topographical district have been taken up in turn, and the most 

 important details of their position and mineral composition presented. 

 As this work has been progressing, many of the formations have quietly 

 found a place for themselves, and there has insensibly arisen a scheme of 

 classification, in some respects peculiar, but mostly similar to the general 

 order of the older American systems. The reference of most of our rocks 

 to systems older than the Silurian early commended itself in preference 

 to the more modern doctrine of alteration from Paleozoic sediments. It 

 has been our business to grapple with one of the most difficult strati- 

 graphical problems ever presented to an American geologist for solution, 

 and it would be presumption in us to claim that entire satisfaction has 

 been obtained. I will first attempt to show how the formations may be 

 classified without reference to their supposed age, — using local names 

 derived from the localities where each one is best exposed for investiga- 

 tion. This course will enable those who may not accept our views of 

 correspondence to establish for themselves any relation to Paleozoic 

 groups which will commend itself. It has been our constant aim so to 

 divorce the facts and theories from each other in the descriptions, that 

 those who hold different general views from our own will not find the 

 observations unwarrantably obscured by individual speculations. 



