518 PROCEEDINGS OF COLUMBUS MEETING. 



Mill brook, at the northern foot of the Dorset mountain mass, the quartzite and 

 blue quartz conglomerate reappear, although not shown on the Vermont report, with 

 the lower Silurian schists in contact on the west. This fault thus trends at righl 

 angles to the east-west fault described in that report. 



The obscurity of the fault on the ridge at many points is due to its bringing 

 together certain dark mica (sericite) schists, consisting of alternating more quartzose 

 with more micaceous laminae, which belong to the Cambrian quartzite series, on 

 the cast, with the dark but not banded and generally more or less graphitic sericite 

 schists of the lower Silurian on the west. The fault is also further obscured by a 

 cleavage-foliation in both schists, dipping at a high angle eastward and parallel to 

 the fault plane, whereas the stratification of both Cambrian and Silurian schists, 

 except in rare instances, dips westward in low undulations, as can be made out here 

 and there and as the vertical and horizontal relations of the limestone and the 

 Silurian schist at Clarendon necessitate in the case of the latter. 



Resume. 



Tlie Rutland-Dauby ridge is a complex anticlinal of gneiss and Cambrian 

 quartzite, conglomerate and schist flanked by Cambrian limestone and lower 

 Silurian limestone ami schist. The upper part of the Cambrian quartzite on its 

 western side dips under the base of the limestone of the Tinmouth, Center Rutland 

 valley, and on it- eastern side, as shown by Mr. Wolff at Pine hill, under the base 

 of the limestone of the Vermont valley. , 



Mr. Wolff has shown the Cambrian age of the base of the limestone on the eastern 

 side, ami this paper shows the corresponding fact on the western side. Admitting 

 that the schist overlies the Stockbridge limestone in these valleys at about the same 

 horizon, the entire thickness of that limestone in this part of Vermont maybe 

 reckoned at 1,200 feet, and the Hyolithesbed at West Clarendon shows that about 

 470 feet of the lower part of this belong to the ( 'ambrian ; but the upper part of the 

 Stockbridge limestone has been shown by Reverend Augustus Wing's fossil locali- 

 ties at West Rutland* and Mr. Foerste's collections at (enter Rutland, Clarendon 

 Springs and South WaUingford to be of Lower Silurian age, and to this age belongs 

 also a part, if not all, of the overlying mass of schist. 



Owing to a fault extending from Pine hill in Rutland to WaUingford, about 16 

 miles, causing a displacement measured at Clarendon as l.oiio feet, the Cambrian 

 quartzite and conglomerate and schist have been brought up to the level of the 

 bower Silurian schists, which latter they in one place overlie. It is owing to the 

 anticlinal structure, complicated by faults, of the Rutland-Danby ridge that at some 

 points the base of the Stockbridge limestone with its Cambrian fauna, while at 

 others, not far oil', the top with its Lower Silurian fauna, is alone exposed. 



besides these general results, many minor facts were established and the explora- 

 tions were continued southward on the Dorset mountain mass, but they are not 

 yet sufficiently elaborated for publication. 



Professor B. K. Emerson spoke as follows: 



It is a pleasure to express my high appreciation of the importance of the results 

 reached in tins investigation and of the care and fullness with which it was con- 



* "An Account of the Discoveries in Vermont Geology of the Reverend Augustus Wing," by J. D. 

 Dana: Am. Journ. 9ci., :i'l ser., vol. xiii, 1 s 7 7 . p. 332. 



