STR UCTURE OF THE MO UNT WA SIZING TON MA SS. 7 3 I 



east of Mt. Thorpe, whence it continues northward as a transi- 

 tional zone between the valley limestone and the Everett Schist. 

 The rock of Mt. Thorpe is filled with garnets, and the area of 

 schist east of the easterly branch of the stream" has also abund- 

 ant garnets, though they have only been found at some distance 

 from the graphitic rock. Between the two forks of this stream, 

 the upper schist rests as in a saddle, its southern termination 

 being a small triangular hill. The southeastern portion of the map, 

 which exhibits areal and structural features of much interest, 

 will receive fuller treatment in another paper, which will deal 

 with the structure of the area to the southeast of Mt. Washington. 



Method of Constructing Sectiojis. — The lines of sections have 

 been made as nearly as possible perpendicular to the strike of 

 the strata. The strike has been obtained either by actual 

 measurement with the compass at the locality, or from the direc- 

 tions of the boundaries of horizons. The curvings of the sec- 

 tion lines must therefore indicate, either that the crest or trough 

 lines are inclined (pitch) or that the flexures are of variable 

 width. To the southward of section E the average pitch is 

 found to be northward, as shown by the areal relations, and as 

 indicated in the steep southern and gradual northern slopes of 

 the "Lion's Head." 1 To the north of section E the convexity 

 of the section lines towards the south is explained both by 

 southerly pitch and by a greater compression of the flexures in 

 the northern portion. Southerly pitch is suggested by the topo- 

 graphy of Mts. Everett and Undine, as well as by the pitching 

 trough and crest lines of coarse corrugations on the slope that 

 rises at the south end of Guilder Hollow (cf. reference to Dale 

 below). These facts when taken in connection with the sections 

 (Plate IV), show the mountain to have a general basin structure. 



The determination of the dip is made with great difficulty 

 within the area studied, since the lamination indicative of the 

 plane of bedding is often obscured or even obliterated by subse- 



1 For the detection of pitch by the contour of an elevation I am indebted to Pro- 

 fessor Pumpelly for suggestions. He was, I think, the first to discover that these con- 

 tours betray in an important manner the inclination of the trough and crest lines of 

 folds. 



