SIUIDIOSS OW Wells; SO2CAEILIEID WOMEN GINIEISS 
OF NEW HAMPSHIRE. 
CONTENTS. 
Introduction. 
Historical summary of opinion on the “ porphyritic gneiss.”’. 
Geographical distribution of the formation. 
Brief description of the rock-nomenclature. 
Field relations. 
The Winnipiseogee area. 
The Ashuelot area. 
The Main area. 
Contact Metamorphism. 
The origin of the foliation. Criteria of flow structure. 
Significance of the uniformity of the porphyritic granite. 
Pegmatite veins cutting the porphyritic granite. 
The age of the intrusions. 
Summary. 
Introduction.—The following paper embodies the results of 
some weeks of field work on the New Hampshire terrane, 
heretofore considered by some writers to be a metamorphosed 
Archean sediment, but suspected by others to be eruptive. The 
conclusions of the author corroborate this suspicion and he has 
attempted to express them here with the special point in mind. 
The author desires to express his best thanks to Professor J. E. 
Wolff, of Harvard University, for valued suggestions and very 
material aid during the progress of the work. 
fiistorical summary of opinion on the ‘‘porphyritic gneiss.’’—From 
the conspicuous nature of its outcrops the ‘‘ porphyritic gneiss” of 
New Hampshire early attracted the attention of geologists. In 
the first annual report of the Jackson survey, in 1841, Whitney 
and Williams, in describing its occurrence remark that “large 
bowlders of porphyritic granite are very numerous over the sur- 
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