T. D. DALE — THE STOCKBRIDGE LIMESTONE. 515 



|u I >;i 11 1 >\ hill in Danby.* Its altitude above Otter creek ranges from about 400 to 

 l.ioo feet. 



This ridge was described by the geologists of the Vermonl survey t as an anticlinal 

 of quartzite flanked both on the cast and west in places by Talcoid schists, in others 

 by the Eolian limestone, and the schists forming its southern end were represented 

 as cut off from those of the Dorset mountain mass by an east -west fault. 



Professor ('. 11. Hitchcock in his sections! omits the anticlinal structure from the 

 quartzite, calls the schists on the eastern side Cambrian slates, and the limestone 

 on both sides ( 'amhro-Silurian. 



Mr. J. E. Wolff, in his paper read before this Society last December, shows the 

 composition of the northern end of the ridge to be as follows, beginning at the 

 eastern side: (1) Cambrian Limestone overlying (2) Cambrian quartzite and its 

 associated conglomerates and gneisses; then (.'!) schist overlying (4) the lower 

 Silurian limestone of the Center Rutland valley, lie also shows the continuity at 

 the surface id' the quartzite of the ridge with that of the western flank of the Green 

 mountain range. He would explain the abnormal relations between the quartzite 

 of the ridee and the Stockbridare limestone on the west by "A great thrust nlane by 

 w Inch the Cambrian is made to overlie the lower Silurian limestone." \ 



During the past summer, after examining Mr. Wolffs localities and finding, as he 

 says, that they do not yield a decisive proof of such a thrust plane. ! I crossed the 

 ridge at several points between Rutland and Danby to find a more favorable 

 locality. Such an one was found in Clarendon, where a deep and wide saddle in 

 the ridge afforded many excellent outcrops. 



A contour map on a scale large enough to show the details in the wooded area- 

 was hereof prime importance. Such a map was therefore made, and a reduced 

 copy of it is here given (plate 16). In addition to the usual symbols for the strike 

 and dip and pitch of the stratification-foliation, those used by Dr. II. Reusch, of 

 Christ iania.' : to indicate the strike and dip of the cleavage-foliation have been em- 

 ployed. 



A REAL < rEOLOGY. 



The areal geology is simple. The eastern half of the ridge consists of the 

 quartzite, conglomerates and schists of the Cambrian i including, perhaps, some 

 older gneisses and eruptives), coming in contact in the valley on the east at one or 

 two points with the Stockbridge limestone. This quartzite is in contact on the 

 west, along the axis of the ridge, with limestone in the lower pari of the saddle, 

 and with a schist overlying that limestone in the higher parts both north and 

 south. In the southern half of the map t he limestone area is only 650 feet wide, 

 and the schist tapers to about 250 feet. Both schist and limestone are here fol- 

 lowed westwardiy by another mass of quartzite, which dips normally under the 

 limestone of t he Ti mi ion t h valley, which is continuous with thai of center b'ut land. 



♦ Danby hill lie-- two miles north of the northern purl of ! > . » t- — . • r i ntain, which in the Vermonl 



report is called I (nnby mountain. 



f Report on the Geology of Vermonl by B. and B. and. C. H. Hitchcock and \ D. Hager. 1801 : 

 vol. 1. p. 350, 863; vol. ii. p. 703, pi. \ iii. fig. - : pi. x\ i. sec. iv . \ . 



Geol. sections across N. II. and Vt. : Bull. \in. Mus. Nat. Hist., nil. I, no. ii, 1884, pi. Ii 

 i \ . \ . \ i. 



ji" On the Lower Cambrian \ge of the Stockbridge Limestone." Bull. Geol - • V in., vol. 

 pp. :;:;l ; 



I '". cit., p. 337. 



• Neues .1 dull. I'm- Min . Geol , etc, V Beilageband, Stuttgart, 1887 



