J. D. Dana on the origin of the Earth's Features. 209 
The effects would, hence, be widely distributed, and be but 
feebly peepee in any region, as will be seen on plotting to the 
scale of nature. A small part only of the action would tend to 
cause aispla acements over the region of the thickened (and thereby 
ab aderme ag sinking crust. Flexures on the scale of magnitude 
mber presented in the Appalachian region, grouped, as 
en are, most thickly over its middle and to the eastward, and 
fading out westward where the crust has not one. fourth as s great a 
thickness of sediments, are a to the fundamental principle 
appealed to in the hypot 
We observe, further, that the ines part, at least, of the bold 
flexing of the A alachian rocks ace toward, or at, the 
close of the ave waar age, aie the Paleozoic deposits of 
Pennsylvania had been laid down; while, on the contrary, it 
should have very ipo attended its progress, if sinking were 
the cause, since seven-eighths of this sinking had taken place 
before the era of the Coal-measures. ptm the metamorph- 
ism and the making of the mountains fon mainly involved in 
the pas final result, and were a part o 
We well question whether the ‘ded as long as its crust 
was so mcanive to the weight of a layer of gravel, would any- 
where be able to hold up mountains; for mountains have grav- 
ity as well as gravel beds or other sediments. We should ba 
have expected, after a sinking had been going on in the A 
lachian region for ages through simple gravity, a foot for a foot 
of deposits, that there, on that same yielding crust, the Appa- 
lachian mountains should have found a firm sta tanding place, and 
especially before the vast Rocky mountain region, half the con- 
tinent in breadth, was ae a with its sinking process; or that 
in Triassic and Jur: es, the Green mountains should have 
kept their place on ie Hag and the high table Jands on the 
east, when the crust was so weak below that the sands washed 
into the Connecticut valley by the hillside streamlets caused it 
to bend downward an inch for every inch of cing till 
some thousands of feet of sandstone and of subsidence been 
egaadd or that the more ancient ridges of the Alga. should 
ave been able to stand with uplifted heads while great Tertiary 
basins in Stipes and over the regions of the present Ap- 
ennines and Pyrenees, and in other parts of Kurope, were so 
P 
thinly Coieomet ‘abatis a sinking, through the weight of gravel of 
no aig specific gravity than the rocks of “the Alps, was 
going on by the thousands of feet; and that these same ‘sink- 
ing basins should have next become the site of mountain pea 
t has been remarked above that the hypothesis of Mr. 
* These Triassico-Jurassic beds of the Connecticut valley have a width o 
miles or so, and extend from Long Island Sound at New Haven 120 miles to stl oe 
ern Massachusetts. Prof. Hall includes the > region among the exam 
dence from (See Paleonto 1. N. tel - 
ed Sar 
