LITHOLOGY. 24I 



this work, it will be noticed that a large number a'nd a large variety of 

 rocks have been classified under a small number of heads. The effort 

 has been made to show that by the introduction of the microscopic 

 method, many of the difficulties which have complicated the study of 

 our crystalline rocks disappear, while its interest and beauty are 

 increased; for not only are the compositions and present conditions 

 of the rocks easily determined, but the thin sections contain a chapter 

 of their histories and a record of the changes through which they 

 have passed. I wish to recall again the scope of the work. It has 

 not aimed to be a description of the rocks of the state, but has rather 

 aimed to be a study of specimens which have been carefully selected, 

 v/ith the hope that all our important rocks would be represented 

 among them. As, now, each new section that has been prepared has 

 almost always presented some new features, I am certain that those 

 people in the state who may be encouraged to pursue these studies 

 will find in the specimens they examine, even from the very ground 

 that I have traversed, as many other things of interest as have been 

 here developed. New Hampshire is grand in her rocks, and it has 

 been an object of this treatise to show that the beauty of them is 

 not confined to those modes of arrangement which cause our state to 

 be filled with the most picturesque scenery that this part of the coun- 

 try has to offer, but that our rocks, in their minutest structures, are 

 beautiful, and possess features which, though small, are of remarkable 

 interest and of geological significance. 



VOL. IV. 31 



