430 J. D. Dana—Results of the Earth's Contraction. 
ern New York southwestward to Alabama, and completed im- 
mediately after the Carboniferous age. 
e making of the Alleghany range was carried forward at 
first through a long-continued subsidence—a geosynclinal* (not 
a true synclinal, since the rocks of the bending crust may have 
had in them many true or simple synclinals as well as anti- 
clinals), and a consequent accumulation of sediments, which 
occupied the whole of Paleozoic time; and it was completed, 
finally, in great breakings, faultings and foldings or plications 
of the strata, along with other results of disturbance. The 
folds are in several parallel lines, and rise in succession along 
the chain, one and another dying out after a course each of 10 
to 150 miles; and some of them, if the position of the parts 
which remain after long denudation be taken as evidence, must 
have had, it has been stated, an altitude of many thousand 
feet; and there were also faultings of 8,000 to 10,000 feet, or, 
according to Lesley, of 20,000 feet.+ This is one example of 
a monogenetic range. 
The Green Mountains are another example in which the history 
was of the same kind: first, a slow subsidence or geosynclinal, 
and imperfect metamorphisrn over most of the western side to 
almost none in some western parts. : : 
Another example is offered by the Triassico-Jurassic region 
of the Connecticut valley. The process included the same 
stages in kind as in the preceding cases. It began in a geosy?- 
* From the Greek yi synclinal, it bei the earth’s crust. 
+ See ban ther Be Berra in these mountains by. rote W. B. and H. D. 
a ogy: 2 
} Oxide of iron produced by a wet process at a tem rature even as low as 212 
F. ge red oxide Fea Os, or at least has a red pia (Am. Jour. Sci., I, xliv, 
