GEOGRAPHIC HISTOR Y OF PIEDMONT PLA TEA U 2G3 
and the cutting of streams, while the rocks underlying the fertile 
fields of the plain are softer schists easily weathered and worn 
away. Now, the development of topographic forms is an evolu- 
tion whose key-note is the survival of the hardest”; hence the 
Piedmont ranges may be (and indeed must be, since no other 
rational exi>lanation has ever been framed) regarded as remnants 
of an ancient plateau whose softer portions have been swe})t away 
b}’’ the storms and streams of the ages. These ranges rise 500 to 
2,000 feet above the undulant plain by which they are flanked ; 
it follows that not onl}'- the vertical furlongs required to raise the 
present plateau to the higher crests has been borne seaward, but 
so much more as the crests themselves may have lost ; it follows, 
too, that the time required for the waste of these thousands of 
vertical feet of rock matter at the known rate of a third of an 
inch in a century must have been vast, too vast for ready reali- 
zation. So the Piedmont ranges declare the antiquit}'’ of the 
province, and testify that the modern plateau is but the founda- 
tion of a greater one in ages gone. 
Turn now to the structure of the rocks exposed in gorge and 
mountain side: Collectively these are known as the Piedmont 
schists ; they are harder or softer, traversed by dikes, or cut by 
quartz veins, but everywhere they are highly tilted in a trend 
conforming to the extension of the province; yet the composi- 
tion of the schists indicates that they were originally marine 
sediments such as are accumulated in nearly horizontal sheets 
on the sea bottom. Now, sedimentary rocks are tilted and 
altered only by profound movements in the earth-crust which 
at the same tiine produce great mountain ranges, and the struc- 
ture of the Piedmont rocks indicates that they are the roots of a 
broad mountain range ; such is the conclusion of modern geol- 
ogy. Under this interpretation, the undulant and mountain- 
embossed plateau of the Piedmont must be regarded as the basal 
portion of a vast mass of inclined rocks of winch an unmeasured 
upper j)ortion has been planed away ; no trace of tbe original 
surface api)ears; tbe softer strata end in tbe soil and tbe harder 
strata crop out in the ranges, and both point mutely to an ancient 
surface far al)Ove ; there is nothing to indicate that originally the 
mass may not have extended ten miles upward, and tbe struc- 
ture cannot be interpreted by geology save by assuming that its 
summit was at least half a mile or a mile above the highest 
crests of today. W'liile tbe height of tbe ancient mountain 
of which the present I'iedinont is the foundation may not be 
