GEOLOGY OF THE LAKE DISTRICT, 593 



small areas, one of which, Mt. Prospect in Holderness, is the culminating 

 point ; and the other extends from the north corner of Sandwich into 

 Waterville, occupying the north flank of Sandwich Dome. A third 

 occurs at J. H. Calder's, in the southern edge of Thornton. There 

 is but a single outcrop, dipping 20° S. 50° E. The Montalban of 

 the Dome is probably an overlying mass in the porphyritic basin. The 

 range in the north-west part of Sandwich exhibits in a section a fan- 

 shaped structure. The dip of these rocks on the south-eastern slope of 

 Squam mountain, in the north-east part of Holderness, is north-west. 

 Taking the road over this range, the hard, ferruginous schists predomi- 

 nate, dipping north-west. Section VI crosses this formation, and also 

 shows the fan-shaped structure. South of Little Squam lake in Holder- 

 ness is almost a mountain ridge of this rock. We find a north-west dip 

 at J. Weeks's in the north part of New Hampton ; a mile south, towards 

 Shaw's hill, the dips are S. 25° W. and N. 50° W, On the ridge between 

 Shaw's and Beech hills the feldspar crystals do not lie in any uniform 

 plane. Schist intervenes before reaching the stream to the south; and 

 at J. H. Harper's the porphyritic rock dips easterly. By H. Harper's, on 

 the north flank of Harper hill, are dips of N. 50° W. and S. 30° W. West- 

 erly dips prevail along the west border of the formation towards New 

 Hampton centre. From this village, for two miles towards Meredith, is 

 the most beautiful display of porphyritic gneiss I have ever seen. The 

 crystals of feldspar are of large size and very beautiful. Other ledges 

 occur in New Hampton near the railroad, but I have not preserved any 

 record of their dips. The western border of the formation assumes a 

 south-east course beyond New Hampton centre, reaching Great bay in 

 the town of Sanbornton. The rocks on the hills overlooking the bay are 

 interesting, on account of the perfection with which the twin crystals of 

 feldspar are displayed, and also for bunches of a mineral like fibrolite dis- 

 seminated through the ledges. On the west side of Randlett's pond the 

 dip is 75° N. 60° W. Between Meredith centre and the south line of 

 the town is a rich profusion of porphyritic ledges. At the road crossing 

 the outlet of Pickerel pond the rock dips westerly. West of this pond is 

 a crystalline trap dyke, ten feet wide, exposed for one hundred feet, with 

 a north and south course. The feldspar crystals in the north part of 

 Laconia have the direction N. 70^ E., and these are supposed to indicate 

 VOL. II. 75 



