POSITION. 499 



C. H. H. Bcrnardston, near the limestone, strike N. 50 E., dip 25 E., C. H. H. Beniardston, near the limestone, 

 strike N. 60 E., dip 52 E., C. H. H. Bernardston, north of limestone, dip 60 W., C. H. H. Plymouth, north part, 

 dip about 20 E., C. H. H. Plymouth, average of range, strike N. 10 E., dip 40-50 E., A. D. H. Plymouth, north 

 part, strike N. 10 W., A. D. H. 



G-eological Position, Origin, and Equivalency of Quartz Rock. 



Quartz rock has a very large development in Vermont, as the geological map and sec- 

 tions will show. But its position relative to other rocks, its geological age, origin and 

 metamorphism, have perplexed us very much. Where it occurs in thin beds, interstrat- 

 ified with other rocks, as it often does in Vermont, its position is fixed. But in those 

 immense masses that lie along the western side of the Green Mountains the stratification 

 is often obscure, and the joints are easily mistaken for it. We think, however, that there 

 can be no doubt but that the quartz rock has a conformable stratification with the associ- 

 ated rocks, that is, along the west side of the mountain, a large easterly dip, or sometimes 

 a vertical position. 



As we pass along the west base of the Green Mountain range from the southwest corner 

 of Massachusetts, as far north as the Winooski River, nearly 170 miles, we have on our 

 right a steep wall of micaceous and gneissoid rock, from 1500 to 2000 feet high, without 

 a break in it till we reach the Winooski ; and to the east of the mountain crystalline rocks 

 extend across the State nay, to the coast. But west of us limestones, quartz rock and 

 slates prevail, being in general less crystalline, and at length disclosing fossils. The west 

 base of that mountain range seems to be a dividing line between the crystalline rocks on 

 the east and those less metamorphosed on the west. Moreover, along this valley it seems 

 as if the strata had been sharply crowded together, so as to form a synclinal axis by a force 

 from the southeast, as if the whole body of the Green Mountains had been crowded 

 against the strata to the west, causing them also to assume an easterly dip, which, how- 

 ever, becomes less and less as we go westerly, just as might be expected if thus produced. 

 That the strata of the Apalachian range have been folded by a force from the southeast, 

 seems now generally admitted. Along the line we have indicated, there seems to have 

 been one of the synclinal folds. The facts we have detailed respecting the conglomerate 

 of Wallingford and Plymouth make it probable that the crest of the Green Mountains is 

 an anticlinal fold. Yet the movement towards the northwest has caused the strata to fall 

 over, so that almost everywhere the dip is southeasterly. The strata east of the moun- 

 tain have been crowded into other folds, as our sections show, and as we have elsewhere 

 pointed out. There have been foldings, also, west of the mountain, but they seem to 

 have been less extensive. There a general movement has taken place, partly we think 

 by the lateral plication above described, and possibly by some upheaving force exerted by 

 the mountains of northern New York, and the result is a moderate and more uniform 

 elevation. 



As already intimated, along this same synclinal line at the west foot of the mountain, 

 we think there was a change of metamorphic action. To the east it was powerful and 

 all -pervading, obliterating fossils, and bringing in crystallization and other superinduced 

 structures. To the west, it did indeed convert immense masses of calcareous matter into 

 white crystalline limestone, but the associated talcose and micaceous schists have much 



