350 STRATIGRAPHICAL GEOLOGY. 



explore it, but it may be followed north-easterly a considerable distance. 

 It has been quarried largely here (at Mason's) for burning. It should 

 also extend westerly. South of the quartz towards East Haverhill the 

 gneiss dips 40° N. 20° E. The limestone crops out near the quartzite, 

 but is connected unmistakably with the gneiss. On Knight's hill the 

 gneiss dips 70° N. 30° W., holding a large trap dyke. The high land to 

 the south-west of Knight's is probably composed of a later formation, 

 overlying the gneiss unconformably. The village of East Haverhill lies 

 upon a drift plain. Many large blocks are of gneiss, so as to give one 

 the impression at first that this rock underlies the village, especially as 

 it constitutes Iron Ore hill to the south. An outcrop of the Bethlehem 

 gneiss by J. Blake's, a mile and a half north of the railroad station, has 

 the dip of 40° N. 32° W. Between this and the limestone quarry is the 

 westerly extension of the Sugar Loaf Mountain quartzite. The latter 

 may form a synclinal resting upon the gneiss. Sugar Loaf showing strata 

 dipping south, and Hogsback mountain having the north dip of the quart- 

 zite. The gneiss crops out upon Blueberry and Owl's Head mountains 

 in Benton; but I have no data to show whether the synclinal structure 

 pertains to the lower as well as the upper series in that town. There is 

 evidence of its existence in the east part of Haverhill, as shown in Fig. 

 47. Gneiss exists near Haverhill town-house and in the valley of Cold 

 Spring brook, but I have no facts to present in reference to its position. 



As the conclusion to be drawn from these statements, we have, first, 

 the anticlinal ridge from North Haverhill village to Swift Water, flanked 

 westerly by obscure Huronian rocks at one time thought to represent the 

 Montalban scries ; second, an anticlinal line from near Knight's hill north- 

 easterly ; third, there is the synclinal between these anticlinals; and, 

 fourth, the more important basin underlying the Sugar Loaf quartzite. 

 These axial lines all have a general north-easterly course. I have not 

 described the whole of this area, as a portion of it passes out of the Con- 

 necticut into the Merrimack district, and it will be alluded to again in a 

 subsequent chapter. 



The Orford-Lyme Area. This extends from near Indian pond in the 

 north part of Orford, to include l^ear hill in the south part of Lyme, a 

 distance of ten miles. It may possibly represent the continuation of the 

 Haverhill area, the intervening space of about ten miles being covered 



