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 by 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. and S. 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. 



