EFFECTS OF EROSION. 
39 
ANTICLINAL HILLS. 
Iii an anticlinal structure, when a hard rock underlies a soluble or 
soft one. the effect of erosion is to denude the anticline and expose 
s hard substratum. Stone Hill, in Williamstown, a westwardly 
verturned anticline of quartzite, was once covered with the lime- 
one which now surrounds it (see fig. 1). The small transversely 
3lded quartzite and schist anticline a mile north of Stone Hill has 
like history." That anticline in places has remnants only a foot 
lick of the great limestone formation, the total original thickness of 
hich was not less than 1.000 feet. Rattlesnake Hill, in Stockbridge. 
a normal anticline of micaceous quartzite similarly denuded, 
[onument Mountain, in Great Barrington (fig. 2) which is a complex 
nticlinal block of Cambrian schist and overlying quartzite thrust 
-'. 
IG . 2. — Sketch of Monument Mountain (south side) from Mount Keith, in Great Barring- 
ton, looking north, showing the fault scarps on either side. 
ip along a transverse and two lateral fault planes, has been denuded 
its limestone covering. The quartzite area east of Xorth Ben- 
ington is probably also a denuded anticline, as are likewise two of the 
uartzite areas in Addison Count} T east of Lake Champlain. 
All of these anticlines have been denuded not only of at least 1.000 
eet of limestone but also of some 2.000 feet of schist or shale which 
>verlay them. In the case of Monument Mountain, if to the present 
iltitude of its schist summit (1.700 feet) 500 feet of quartzite, 1.000 
! eet of limestone, and 2.000 feet of schist be added to restore the orig- 
nal surface, the height of the mountain would be 5.200 feet. This 
issumes, however, that the folding and faulting occurred at the time 
)f the Ordovician emergence and took place with sufficient rapidity 
a See Sixteenth Ann. Rept. TJ. S. Geol. Survey, pt. 1, 1896, p. 553, and fig. 77. 
