J. D. Dana on the Quartzite of Poughquag. 255 
Taconic series. ‘The nearly horizontal beds of quartzite lie on 
the nearly vertical Archzean, and both occur within a few hun- 
red yards of the steeply inclined Taconic beds. The rocks 
are sparingly faulted; but in some narrow vertical sections 
this faulting has been carried so far as to obliterate the stratifi- 
cation; a case of this kind is represented in the figure on page 
5, Relation of the Quartzite to the Poughquag limestone adjoin- 
ing it.—At the west end of the cut we open upon the plain of 
Poughquag, and come immediately to the Poughquag lime- 
stone (No. II). There is no section exhibiting the quartzite 
and limestone together ; yet it is obvious that the quartz is the 
inferior rock, and that the two are unconformable. Out- 
crops of the two occur within 200 yards of one another and 
on the same level; and while the quartzite is nearly horizontal 
in these outcrops as elsewhere, the limestone in the nearest 
exposure has a strike of N. 45° to 50° E., with a dip to the 
northwest of 40° to 45°; showing not only unconformability 
to the quartzite, but also a wide divergence from its ordinary 
dip in the region, which is 40° to 50° to the eastward. 
The Poughquag limestone continues westward for two miles, 
and becomes to th i 
clay-slate of the region, the rock which is the prevalent one 
ma was consolidated and jointed before the deposition of the 
atter, 
2. That the quartzite is older than the rocks of the Taconic 
beds that outcrop between Poughquag and Pawling, and uncon- 
mulated ; for (1) the beds of quartzite rest unconformably on the 
Archzean rocks, and (2) their sands were evidently sea shore or 
