380 Scientific Geology. 



Dip, Direction, fyc. of the Strata. 



I cannot but regard the hornblende slate of Massachusetts, as be- 

 longing to the same geological epochs as the gneiss, mica slate, and 

 talcose slate ; that is, it seems to me they were all produced hy essen- 

 tially the same causes, and during the same periods of time. Hence 

 we should expect, (if this opinion be correct,) that the dip and direc- 

 tion of the strata would correspond with those of the strata that have 

 been mentioned. And such is the fact : though upon the whole, this 

 rock approaches more nearly to verticality in the dip of its strata, 

 than any other rock in the State ; as the following notes will show. 



Middlefield, 

 Becket, east part, 

 do. west part, 

 Granville, .... 

 Blanford, north part, 



do. northwest part, 

 Rowe, north part, 

 Chester, west part, 

 Shelburne, 



Bernardston, east part, - 

 Monson and vicinity, 

 Westborough, 

 Marlborough, - 

 Cumberland, R. I. 

 Smithfield, R. I., lime quarries, 



Direction. Dip. 



N. and S. 70° to 80° E. 



N. and S. 90°. 



N. and S. 70° to 80° E. 



N. and S. 90°. 



N. and S. 90°. 



N. and S. 60° to 70° E. 



E. and W. South, small. 



N. and S. 90°, nearly. 



N. and S. 45° to 90° E. 



N. and S. 50° to 60° E. 



N. and S. 45° to 70° W. 



N.E.andS.W. 50° to 70° N.W. 



N.E. and S.W. 80° to 90° N.W. 



N.E. and S.W. 40° S.E. 



S.E. and N.W. 30° to 45° N.E. 



I have already alluded to the tendency of the hornblende slate to 

 divide into rhomboidal masses. I have observed this no where so 

 distinctly as at Whately. There, also, the masses sometimes affect a 

 columnar form ; (No. 938.) though perfect columns of any great ex- 

 tent are rarely the result. 



This rock is frequently remarkable for the numerous and compli- 

 cated contortions which its layers exhibit, often rivalling in this re- 

 spect, mica slate and gneiss. Not unfrequently these irregularities 

 appear to be increased by the passage of granite veins through the 

 rock, as in Granville. 



