STONE HILL. 199 



In constructing transverse sections of Stone bill several difficulties present them- 

 selves. The quartzite with detrital blue quartz and feldspar, which may naturally 

 be supposed to occur near the base of the quartzite and towards sonic underlying 

 gneissoid rock, and which Emmons places at the base <>f his "granular quartz," 

 occurs only on the cast side of the hill dipping toward the limestone outcrops of 

 Green river and Williamstown (Formation €!Ss). On the west side of the western 

 mass of quartzite the rock is massive, and seems to be conformably underlain by the 

 limestone of Formation OSs, but that quartzite we should expect to represent the 

 upper part of the quartzite (Formation €v). 



One explanation of these tacts would be that on the west the apparent superpo- 

 sition of the quartzite upon the limestone is the result of an overturn, while on the 

 east the two rocks are separated, as Emmons supposed, by a fault. 1 Such a fault 

 would be nearly, if not quite, on the line of the fault on the east side of Deer hill (Sec- 

 tion (1), and with that farther south near the west end of the Bald mountain spur 

 (Section I) and also on a line with faults in southern Vermont at East Pownal. The 

 highly contorted character of the limestone strata along Green river east of Stone 

 hill, and in the village of Williamstown 2 also lend probability to such a hypothesis. 



Upon this basis of fact and probability the folds in the Stone hill sections have 

 been constructed. On the east side of Stone hill a, fault is represented; the central 

 portion of the hill consists of a syncline followed on the west by an anticline over- 

 turned to the west ; the outlying masses of quartzite on the southeast and northwest 

 sides of the hill involve two minor anticlines. All the folds have a southerly pitch at 

 the south end of the hill and a northerly one at the north end. 



The entire thickness of the Stone hill quartzite and its associated micaceous feld- 

 spathic rocks would thus measure between SOI) and 900 feet. If a simple anticline be 

 supposed it would measure about 1,300 feet, and if a monocline, as represented by 

 E. Hitchcock iii his Massachusetts section, about 2,600 feet. 



The rocks of Stone hill are frequently jointed; one of the systems of joints may 

 possibly be connected with the pitch, as may also the occasional east to west joints 

 and some of the secondary cleavage planes on Greylock. On the east side of the 

 southern portion of the hill the massive quartzite is traversed by joints striking 

 north 65° east, and (lipping 05° to 75° northwesterly. On the east side of the central 

 part the micaceous quartzite has a set of joints striking north 80° east and dipping 

 80° southerly, and another set striking north 20 west, and dipping 45 easterly. The 

 dark pyritiferous quartzite (locality 18) near the top and center has joints striking- 

 north Tl' east, and dipping 65 c north-north west. 



See Ins Section 46 (Geology second district, New Vork, p. 145), in which he represents a fault 

 immediately cast of Stone hill, and another farther east along the western foot of the Greylock range. 

 - Dewey refers to the contortions here: Am. Jour, of .Soi., ser. i, vol. 9, 1825, p. 4!(. 

 1 Report Geol. of Vermont, vol. 2, pi. xv, tig. 5. 



