GEOLOGY OF THE WHITE MOUNTAIN DISTRICT. 253 



and by a fold with similar exposures in Tamworth and Madison. The 

 presence of newer formations indicates two synclinals, though inverted, 

 along the east flank of Washington and in Jackson. We find a marked 

 anticlinal in the valley of Mt. Washington river, and between Jackson 

 and Fryeburg, Me. The Thornton section (Fig. 12, p. 135) indicates a de- 

 gree of unconformability between the Laurentian and Atlantic systems. 



StrucUire of Mt. WasJiiiigton. The section across the highest moun- 

 tain of this range may be taken to represent the structure of the range; 

 and the facts along this route have been given with much particularity. 

 (See p. 116, ct seq., and PI. VII.) The predominating dip is somewhat 

 north of west. What may perhaps be the main anticlinal axis is that 

 extending from the "cow pasture" to the upper part of Tuckerman's ra- 

 vine, while a second runs parallel to it three fourths of a mile farther east. 

 The common condition of the folds seems to us to indicate an inver- 

 sion, the easterly-dipping strata being crowded beneath those inclined in 

 the opposite direction. There will be a low, undulating easterly dip for 

 several rods ; then the strata suddenly change and stand upon their 

 edges, or else dip at a very high angle into the mountain. This sudden 

 change in the dip is supposed to be caused by the enormous pressure 

 crowding the eastern flank beneath the western. Moreover, so far as 

 investigated, there are no easterly dips on the west side. I think the 

 westerly dips in the deep Ellis and Peabody valleys may be the contin- 

 uation downwards of strata dipping easterly on the surface of the moun- 

 tain. 



The view had been proposed by Prof. Vose, that the westerly-dipping 

 schists of the Washington range represented the western part of an anti- 

 clinal, the Carter mountains being probably the commencement of the 

 eastern dip (p. 198). The measurement of Section IX across Bean's Pur- 

 chase does not confirm this suggestion. The westerly dip prevails across 

 to the line, while there are minor variations, as a limited synclinal about 

 the upper part of Mt. Carter. Passing south-easterly more nearly across 

 the strike, the north-westerly dip continues to the state line at Fryeburg, 

 and perhaps farther, save a limited area in Jackson of newer rocks, which 

 may indicate a synclinal fold. After reaching Maine, the dip changes to 

 easterly and south-easterly all the way to Sebago lake, as shown upon 

 Plate III. On the Grand Trunk Railway the easterly dips are reached 



