STRATIGRAPHY AND STRUCTURE. 27 
From evidence furnished by the structure which is described in the next section, a 
succession has been determined which is probably fairly correct. Beginning with the 
lowest member the rocks arc biotite schist, limestone, biotite schist, sericite schist, con- 
glomerate, quartzite, graphite, or graphic schist, sericite schist containing a bed of manga- 
nese ore, beds of iron ore, sericite schist. The thickness of the beds was not determined. 
These strata are penetrated or separated by layers of amphibolite lying in parallel 
position. It seems probable that part of the amphibolite represents intercalated intrusions 
into the sediments, while part represents interstratified deposits of basaltic tuff or flows 
of basalt lava. Ancient bodies of granite, now converted into a more or less foliated 
gneiss, are likewise intercalated with the other rocks. More recent intrusions of granite, 
pegmatite, and diabase have also penetrated these strata. 
STRUCTURE. 
The strike and dip which are most prominent in these rocks are dependent on the 
direction of schistosity or foliation induced by movement. But it is found that the foliation 
is parallel to the bedding of the rocks. There may be in some cases a slight divergence of the 
plane of schistosity from that of sedimentation, but such was not observed. A determi- 
nation of the strike and dip of the foliation will therefore throw light on the structure and 
position of the sedimentary strata and hence will indicate what changes have taken place 
since the beds were deposited in their originally horizontal position. 
A traverse across the Kings Mountain Range in the vicinity of Blacksburg shows that 
the ridges are composed of the hard, resistant quartzites and that the valleys between 
mark the position of the softer schists and the limestone. Starting near the North Carolina 
boundary and passing along a southeasterly line through the town of Blacksburg, the 
observer encounters the upturned edges of the beds enumerated above, beginning at the 
top. These rocks dip steeply to the northwest; in places they are nearly vertical. To 
the southeast from Blacksburg the same rocks are observed but in the reverse order 
and generally dipping very steeply to the southeast, although in some cases — for instance, 
the quartzite of Kings Mountain — the dip is steep to the northwest. 
It is evident that the rocks are, in general, symmetrically arranged with respect to an 
axis which lies between the two layers of limestone .« While the evidence is not so con- 
clusive as would be desirable, it seems probable that the dips on the opposite sides of this 
axis are, in general, away from each other. In other words, this strip of country is probably 
an anticlinal fold, with its axis running northeast and southwest. Blacksburg is situated 
just northwest of this axis. Because of their comparatively small extent, the beds of iron 
and manganese ore and the conglomerate do not always form continuous outcrops and are 
not always present on both sides of the fold. With these exceptions the repeated suc- 
cession in reversed order is very distinct. Local variations in the dip between the exposures 
of limestone and quartzite on the southeast limb of the fold indicate that minor folding 
has taken place and has formed a part of the main anticline. Another deviation from 
exact symmetry on the two sides of the axis is the fact that the dips on the southeast are 
rather steeper than those on the northwest limb of the fold,. with an actual reversal to 
northwesterly dip in some places on the southeast side. This indicates an approach toward 
isoclinal structure with dip to the northwest. 
If the results of this folding had not been modified by erosion, a steep-sided ridge much 
higher than Kings Mountain or Whitaker Mountain would be present to-day. But after 
the folding had taken place, erosion wore away the highest parts, so that the crest of this 
fold has now been completely cut down. The rate of erosion has been slowest on the 
resistant quartzite, which therefore remains higher than the surrounding rocks. Viewed 
in this way it is probable that the two beds of limestone were once parts of a single, con- 
tinuous, flat stratum and that the quartzite of Whitaker Mountain and of the ridge extend- 
aCf. Tuomey, M., Geology of South Carolina, 1848, p. 76. Only one of these limestone outcrops 
was seen by the writer. Old pits are said to have been made on the other limb and now to be caved 
in and filled. 
