Rivers of Northern New Jersey. 83 
nels down to the new baselevel ; such streams may be called 
“revived.” Examples of revived streams are very common ; 
nearly all the streams of the Highlands of New Jersey are of this 
_kind ; all the streams of central and western Pennsylvania seem 
to belong in the same class. From these simple and common ex- 
amples, we shall some day, when our knowledge of rivers is 
better developed, be able to form a complete series leading to 
what is generally understood as the typical antecedent river, 
which has outlived deformation as well as elevation without 
suffering either deflection or ponding. Large rivers of strong 
slope, well enclosed in steep-sided valleys, or in other words vig- 
orous adolescent rivers have the best opportunity to persist across 
a belt of rising or writhing country,* because a great deformation 
would be required to throw them from their courses. Small 
streams or large ones of faint slope in an open low country are 
more easily deflected. From the typical antecedent river, the 
series may be continued by examples in which even the larger 
streams are less or more ponded or deflected by the deformation, 
until at the end of the series there is a complete extinction of the 
antecedent drainage and the establishment of an entirely original 
consequent drainage. The perfectly typical antecedent river, in 
the middle of this series, is certainly of rare occurrence, and is 
perhaps unknown. 
Consequent streams, whose course is taken on a relatively 
thin, unconformably overlying mass, for a time preserve their 
initial courses, even though they may be quite out of accord with 
the underlying structures on which they have descended. Such 
streams were first recognized by Marvine, and afterwards named 
“superimposed,” “inherited” or “epigenetic” by various authors. 
A full collection of examples of this class should begin with 
streams that depart from true consequent courses only locally, 
where they have discovered a small portion of the underlying 
formation, like the Merrimack at Manchester and other water- 
power towns of New Hampshire, where the stream has sunk upon 
rocky ledges beneath the surface drift and sands; or like the 
Mississippi and other rivers in Minnesota which have in places 
cut through the drift sheet to the underlying crystallines. The 
series would conclude with streams that have stripped off the 
cover on which they were consequent, and have thus become 
superimposed on the underlying formation in their whole length. 
* Stur’s expression ‘‘ Gebirgshub oder Gebirgschub” suggested to me 
the terms here employed. 
