334 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



discussion of these last in the Eeport of 1833, suppressed in that of 1841, 

 which, as he develops it, has some resemblance to the theory of "sehlie- 

 rengiing-e," as developed by E. Reyer. 



The greater part of the veins in our syenite consists of material foreign to the 

 nature of the rock and introduced subsequently to its original production. I do not 

 say subsequently to its consolidation, for it has appeared to me possible that while a 

 molten mass of rock— say syenite — was iu an incipient state of refrigeration matter of 

 a similar kind still more intensely heated might have been injected into it, so as to 

 form veins. 



Other veins associated with faulting he refers to the filling of fissures 

 formed in the solid rot-k. 



Under the head "Mineral contents" he refers a mineral crystallizing in 

 four-sided ])risnis to rutile. It is allanite. He mentions quartz crystals 

 and "gashed quartz," quartz "full of thin fissures, as if made by random 

 cuts of a knife," and explains it as due to the growth of quartz about some 

 mineral no\v removed. This mineral was doubtless barite. The minerals 

 of the Hatfield baryta mine are also enumerated. Under the head "Theo- 

 retical conclusions" the hypothesis is advanced that "the syenite was formed 

 ])v tlie melting down of the hornblende-schist," and in proof of this he pre- 

 sents a rude diagram of the state of things at the north end of the syenite in 

 Whately. In this diagram the syenite is represented as being succeeded to 

 the north by hornblende-schist, the two being in contact and the bedding of 

 the schist being continued in a rude stratification of the syenite. He adduces 

 also the fact that the hornblende-schist on its western border, a mile north 

 of the syenite, is massive, columnar, and feldspathic, and theorizes that there 

 was here heat "sufficieut for the production of feldspar, but not for its crys- 

 tallization;" tliat with a greater degree of heat syenite would have been 

 produced; with a still greater, the production of hornblende would have 

 been imjiossible and grainte would have resulted. 



The diagram and description of the relations of the syenite and the 

 hornblende-schist in Whately are based upon a serious error of obsei'vation. 



The hornblende-schist which outcrops in great force north and soutli 

 of the south line of Whately is toward the north separated by argillite from 

 tlu^ broad band of hornl)lende-granite wdth which the diagram connects it. 

 C. H. Hitchcock, in 1871,' classed the rock as a Laurentian gneiss. 



' Explanation of geological map of United States, in Walling's Atlas of Massaohnsetts. 



