THE HOUSATONIC VALLEY. 



787 



erly, the local pitch J varies greatly both in degree 

 and direction, and is as frequently southerly as 

 northerly, as indicated by the arrows on the map. 

 At the south base of Tom's Hill the southerly 

 pitch varies from 30 to 50 , and on the road 

 cutting across the north foot of Barack M'Teth, 

 beautiful corrugations in the Everett Schist pitch 

 southward at as steep an angle as 50 . These 

 corrugations are unsymmetrical, the west limbs 

 being the shorter and steeper. The local varia- 

 tions in pitch are strikingly indicated on the map 

 by those ridges of schist which are arranged line- 

 arly in the direction of the prevailing strike, being 

 cut off from one another by limestone. The 

 minor changes in pitch are further shown by 

 variations in width of the ridges. Thus we find 

 along the western margin. of the area three marked 

 undulations in the crest-line of an anticlinal of 

 Riga Schist trending north-northeast. The north- 

 ernmost is essentially the double undulation of 

 Horse Hill and area No. 29, then follows the area 

 northeast of Chapinville (14), and the area south 

 of Chapinville Station (10). Fig. 1, which is a 

 longitudinal section along this line, shows besides 

 the three main undulations just mentioned, a num- 

 ber of secondary waves of more or less importance. 

 In Fig. 2 (A) these curves of the crest-line may 

 be better observed. The manner in which this 

 anticlinal ridge disappears near the southern limit 

 of the map is shown in Fig. 1 of Plate VII. The 



I The pitch at any given locality is determined, either (1) by 

 the direction in which the strike of the two limbs of a fold diverge 

 in a synclinal fold or converge in an anticlinal fold ; or (2), by the 

 pitch of the plications in the schist. The harmony in direction and 

 degree of inclination between the pitch of plications and that of 

 the folds of which they are a part, was first suggested by Pro- 

 fessor Pumpelly, and proven in the Greylock area. (Cf. T. Nelson 

 Dale, Amer. Geologist, July, 1891). 



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