mm the vicinity of Great Barrington, Mass. 87 
the north end of the mountain with that on the west. It 
remains, therefore, only to trace out the changes in the synclinal 
fold to the southward through the rest of the mountain. 
long the section in fig. 6.—The low quartzite ridges W and 
L (see map) are overlapping parts of an interrupted series, in 
which L is situated half a mile to the west of the line of W. 
The high inclination of the strata in L is evidently connected 
with this more western shove of the ridge. In consequence of 
it the limestone is bent up into a close fold and the Tom Ball 
ndge west of it into another equally close, the strata having a 
dip of from 50° to 75°; and as the slates of Tom Ball form a 
synclinal, the limestone corresponds to an anticlinal. This is 
indicated in the curved lines in fig. 6. 
I may add that in the limestone of eastern and western 
Alford there are probably other anticlinals. With regard to 
these more western ranges of limestone, especially that west of 
Alford ridge, the evidence is not yet complete. 
Along the section in fig. 3.—To understand the fold abreast 
of Williamsville we must note that in this section the lime- 
stone of the Housatonic fold, A’, dips westward, and continues 
apparently at no great distance beneath the surface to the Tom 
all ridge, where the foot rocks on the east are nearly horizon- 
tal; and then, after passing under the mountain, emerges on 
the west at a high angle like that of the Tom Ball slates adjoin- 
ing. Now, following the strata from Monument Mountain 
westward, it is plain that they do not dip beneath the surface in 
the Williamsville valley, and thence bend up into Tom Ball; | 
but their course, as just stated, is nearly horizontal till reaching 
the present position of Tom Ball. ‘The downward bend in 
the synclinal, therefore, took place along what is now the 
eastern slope of the mountain. In fic. 3 the part of the section 
along the junction of the horizontal and pe tee Loa | slates 
~ left blank; fig. 3A shows the same with this bend in the 
ayers. 
In section 6, the quartzite of the ridge on the east (L) is unrep- 
resented on the opposite or western side of Long Pond valley. 
ted, non- 
