GEOLOGICAL RELATIONS, 3 I 



It is evidently a part of the Montalban series, as may be possibly the coarser but still 

 rather fine-grained granite of Mt. Deception. The succeeding formation in Jefferson 

 is more nearly allied to the Lake than the Montalban division of the Atlantic system, 

 though not so labelled upon Plate III. On Jefferson hill and at the mills the rock is a 

 common gneiss, with a plenty of feldspar, and usually but slightly inclined to the hori- 

 zon at the surface exposures. The deeper portions are represented as very highly 

 inclined, in order to make the dips conform to the supposed position of the Huronian 

 rocks which succeed. 



Our information respecting this Huronian band in Lancaster and Guildhall is meagre. 

 The first met with is mostly a quartzite, with slight signs of stratification. The portion 

 in Vermont can be readily referred to both the Lyman and Lisbon divisions of the for- 

 mation, and there are certainly two folds. In this area the usual copper belt of these 

 green hydro-mica rocks has been discovered. This group is followed by a synclinal of 

 Coos staurolite schists in Granby, which is supposed to be the continuation of the Con- 

 necticut River range of this formation, though on the west flank of the underlying Hu- 

 ronian. It is connected with the main Coos group in the north part of the Cocis and 

 Essex district, which is entirely on the same side of the lower group. In the west part 

 of Granby the Montalban series reappear, with an easterly dip. This is supposed to 

 be the repetition of the White Mountain rocks beneath the Huronian and Cocis series, 

 and it may underlie the granites of East Haven and Willoughby mountain. 



The space betv/een the two granite masses just referred to is occupied by the Calcif- 

 erous mica schist, v.'ith a monoclinal easterly dip, most likely a synclinal fold. A well- 

 defined synclinal structure can be made out in the same rock in Brownington and 

 Barton, which corresponds to the behavior of the same formation for the first thirty 

 miles of its occurrence in Quebec. (See Plate VI.) The clay slate and Helderberg 

 limestone farther west hold the same position with the corresponding groups on Lake 

 Memphremagog, at Owl's Head. Logan thinks they occupy a long, narrow, inverted 

 synclinal trough at OwPs Plead, which is apparently the correct theory of their position. 



We come next to the beginning of the great development of Huronian, or the meta- 

 morphic Quebec group, as designated by Logan. There seem to be first an anticlinal 

 and then a synclinal axis, before reaching the Green Mountain older ridge. Beds of 

 serpentine and steatite appear in Troy, and they dip towards each other, according to 

 the Vermont report. The anticlinal altitude of the Green Mountain range is agreed 

 upon by all observers, though Logan thinks it subordinate to a basin, and that the 

 whole mass of the mountain is newer than the serpentines. Inasmuch as ten out of 

 fourteen sections across this range, according to the Vermont report, have the ridge 

 structure, while the others may be interpreted easily as folded axes, it seems more likely 

 that the Green Mountain gneiss is of the same age with the Montalban series, which it 

 resembles, and that both underlie the adjacent serpentinous rocks, or the Huronian. 



The remainder of the section is copied from Logan's representations in the Canada 

 reports. After the first basin there succeed the Stanbridge anticlinal and the Farnham 

 synclinal, before we come to the great fault between the older metamorphic schists and 



