OUTLINES. 
195 
ciated, — by the action of trost and flood, so that the preexisting soils and 
earths and the more disintegrate rocks were removed and rapidly accu- 
mulated in the ravines and valleys, which were often in part, or entirely 
obliterated by the floods of sand and gravel constantly thrown into them 
from the steeper slopes, more rapidly than they could be removed by the 
same volume of water with its diminished velocity, after reaching the 
gentler inclinations of the ordinary flood-plains of the rivers; so that for 
the most part, their channels have, in the course of post-glacial ages, been 
re-excavated by the slow erosion and transport of these vast accumulations 
of debris, to successively lower levels and to the sea, leaving only occa- 
sional and accidental patches and benches at different elevations, to bear 
witness of so great changes. 
Recent . — This brings us to the subject of terraces , which represent the 
latest period of the Quaternary. These are nearly level-topped accumu- 
lations of drift, such as have been described, along the sides of the river 
valleys, against the shoulders of the enclosing hills, or the foothills of the 
mountains. Two or three such terraces, besides the flood-plain, are fre- 
quently found, one above another, the highest sometimes more than 100 
feet above the river. Examples of these are to be seen on all the large 
rivers of the State, but more conspicuously in the mountain and piedmont 
regions, as on the Yadkin, below Patterson, and on the French Broad,, 
below Warm Springs. 
These terraces or benches are the remnant patches of former flood- 
plains, as the torrents of the closing glacial epoch subsided and shrunk 
gradually towards their present dimensions, cutting for themselves suc- 
cessively deeper channels through the loose drift which had filled up the 
old valleys, and thus lowering their flood-plains bench by bench. The 
gradual elevation of the land also, which, as has been seen, was depressed 
several hundred feet, no doubt aided in the formation of these terraces, 
by successive accelerations of the currents. 
Sand dunes, or wind-drifis of sand, as incidentally intimated above, 
overlie the drift in places towards the coast. Instances may be seen on 
the hills about Wilmington, and very conspicuously in the peninsula be- 
tween the Neuse and Pamlico rivers, which is traversed from river to 
river in a north-west and south-west direction by a line of sand hills some- 
times fifty and sixty feet high, marking an ancient dune, and a stage also 
in the retreat of the shore in later Glacial times. 
Modern . — The sand dunes of the present coast line, in constant forma- 
tion and movement and transformation, have already been described ; as, 
have also the marshes which are formed by the silting up of the narrow 
