146 
GEOLOGY CF NORTH CAROLINA. 
but a small part of the original series. It is probable that these beds at 
one time covered the larger part of the middle section of the State, al- 
most to the flanks of the Blue Ridge. 
The present area of Triassic in the State is about 1,000 square miles, 
about one-third of it estimated to be underlaid with coal ; but since there 
are outcrops of black shales and of lignites in other parts of the Deep 
River belt at great distances from the area commonly set down as coal- 
bearing, there is a strong probability that coal will be found over a much 
larger territory. 
Another point worthy of note has been mentioned incidentally, viz : 
that the materials of the coarse conglomerates which characterize the 
the eastern belt (and its eastern margin), as compared with the western, 
w T ere evidently derived from the Archaean rocks to the eastward ; the 
the large pebbles and bowlders (sometimes 10 to 15 inches thick), may 
often be traced to the very ledges a few miles east, from which they were 
torn. And the rudely stratified condition of these beds, and the coarse- 
ness and miscellaneous character of their materials, being made up of slight- 
ly worn fragments of rocks of various degrees of hardness, indicate a 
derivation from neighboring and steep highland or mountain slopes; and 
indeed they are of such likeness to some Quaternary, semi-stratified accu- 
mulations, as even to strongly suggest a sub-Triassic glaciation. If it be true 
that the materials of this formation came, even in large part, from the east, 
and it seems impossible to resist the conclusion, and if their extent, hori- 
zontal and vertical, was at all such as has been shown to be probable, it 
follows that there existed in Triassic times a large coastward tract of ele- 
vated and probably mountainous territory. The changes, therefore, in 
the topography of this portion of the continent, in comparatively late 
geological ages, have been much greater than is generally supposed, in- 
volving such a depression of this Atlantic tract, that the whole of it was 
swept over and planed down still further by the great gravel floods of 
Glacial times ; and a tranverse upthrust of more than a thousand feet, 
along a nearly east and west axis, sufficient to throw oft' the margins into 
high opposite dips across a anticlinal bulge of nearly 100 miles breadth. 
A very marked peculiarity of the Triossic formation in this State, in 
all its outcrops is the frequency of dolerytic dikes. These beds are every 
where intersected, in various directions, by these ledges of dark grey, 
generally fine grained traps ; the thickness being usually not more than 
a few yards to 2 or 3 rods, and the length not generally exceeding a few 
hundred yards, but occasionally extending to several miles. These traps 
are sometimes brecciated, and occasionally contain serpentine and chlorite; 
and magnetite and pyrite in disseminated grains are quite common. The 
