48 Geology^ &fc. of the Connecticut. 



the greenstone is here disclosed by the abrasion of 

 the superincumbent sandstone — and on following the 

 line of junction a few rods on the south side of the 

 brook, he will find the sandstone in place lying directly on 

 the greenstone, also in place. To one who has been accus- 

 tomed to see this latter rock mounting above every other 

 and monopolizing so muchspace for its broken fragments, it 

 must be gratifying to see it at last pressed down by a supe- 

 rior stratum, and buried by the debris of a higher rock. In 

 two places south of the point above described, other brooks 

 have worn away the sandstone, and the greenstone forms 

 in it a like reentering angle ; but the actual contact of the 

 rocks is hidden. 



But Sunderland is not, after all, the best spot for observ- 

 ing the rocks of the coal formation lying above the green- 

 stone. I have been thus particular in describing the range 

 of greenstone in that place, rather to exhibit the difficulties 

 and trials to which the geologist is subject in examining 

 the trap ranges of the Connecticut, than because it was 

 necessary for this particular purpose. 



Let the observer follow the Sunderland greenstone ridge 

 northerly across Connecticut river into Deerfield, and he 

 will here find it widening and increasing in altitude, pre- 

 senting a mural precipice on the west, and a gradual slope 

 on the east. Where it crosses Deerfield river it has every 

 appearance of a vast dyke : although the sandstone rocks 

 do not appear immediately in contact with it. From the 

 top of the greenstone to the bottom of the river is more 

 than two hundred feet. The range continues to the falls 

 in Gill, where, as before observed, it terminates, and is suc- 

 ceeded by the red sandstone or conglomerate. And here 

 would I mention another fact in regard to the greenstone 

 and rocks of the coal formation. The latter do not mere- 

 ly lie above the former, but thty alternate with one another. 

 Let the observer pass round the northern termination of 

 the greenstone range first mentioned, and follow down a 

 gmall river called Fall river, to its mouth, and just at this 

 point he will see the fine-grained, red, fissile, argillaceous 

 sandstone of the coal formation, mounting up fifty feet upon 

 the back of the greenstone at an angle of forty-five degrees* 

 And if he follow down the west bank of the Connecticut 



