C. L. Whittle — Main Axis of the Green Mountains. 349 



pebbles. As a rule the attitude of the beds can only be deter- 

 mined at contacts between beds of strongly unlike composition, 

 as between flinty quartzite and schist or limestone and some 

 more resistant rock. Such contacts are relatively rare and a 

 day's work in the most metamorphosed areas may not reward 

 one with half a dozen indisputable observations on strike and 

 dip. 



The eastern and western borders are belts of near-shore 

 deposits, now regarded as equivalent, of original coarse to fine 

 conglomerates, sandstones and shales, which owing to their 

 zone of deposition must have been persistent as a whole but 

 locally the character would vary greatly. Such a belt, indu- 

 rated and metamorphosed, has given rise to a series of more or 

 less crystalline rocks which, owing to their extreme diversity 

 of composition have resulted in schists and gneisses whose 

 recognizable continuance of horizon is difficult to follow. 

 Sections made east and west across their strike and one-half 

 mile apart present a great diversity of character. The minor 

 ilutings of the more schistose members of this series illustrate 

 on. a small scale the larger folds of the main range. Along 

 the western border the schists are bent into minute compressed 

 puckerings commonly overturned to the west. These pucker- 

 ings in turn compose much larger folds which in the same 

 manner are overturned to the west. In a great many localities 

 the folds and the smaller flutes are seen to accompany the 

 inversion of the entire series; but in many places induced 

 schistosity has so obliterated the stratification that the real atti- 

 tude of the strata is not apparent, and in others no inversion 

 of the strata as a whole has taken place. Throughout the core of 

 the Green Mountain axis even a greater diversity of structure and 

 rock exists. In the towns of Shrewsbury and Mt. Holly and 

 extending southward the folding and shearing and consequent 

 metamorphism are so great that final and satisfactory deci- 

 pherment seems hopeless. Days may be spent without obtain- 

 ing observations that would be of service in unravelling the 

 tangle of gneisses and schists. As suggested to me by Mr. 

 Pumpelly, platting all areas of like lithological character 

 may give us the key to the structure, but this plan is rendered 

 hazardous by the infinite variety of rock phase occurring 

 making necessary grouping of areas of rock now so unlike 

 that, in the present state of our knowledge a correlation of 

 them would be of doubtful value. In the towns of Mt. Holly, 

 Shrewsbury, Wallingford and the western part of Ludlow, 

 there are areas of amphibolite now possessing a thoroughly 

 schistose habit. At Summit station a railroad cut traverses 

 this rock for nearly half a mile. Numerous separate members 

 can still be distinguished in the pass by textual variations. 



