88 
PALAEONTOLOGY OF NEW-YORK. 
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N®TE C. — ( See Page 70.) 
This process of tlie subsidence of the sea-bottom when loaded by accumulating 
sediments, is clearly recognized by Hersciiel in his explanation of the rising of 
Scandinavia, which he says may be caused by the accumulation of sediments on the 
adjacent ocean bed; which, giving way beneath the pressure, will drive a portion 
of the yielding matter beneath the adjacent continent, thus causing the elevation. 
This process of depression at one point and elevation at another by the yielding 
mass beneath, doubtless offers an explanation of many phenomena both of recent 
and more ancient geological times. I have shown in the preceding pages that the 
strata composing the Lower Helderberg group, and to a great extent the Oriskany 
sandstone also, follow' a line parallel to the Appalachian chain, and do not extend 
far to the westward : at the same time it is shown that there had been a movement 
in the accumulated sediments of prior date, and these beds lie unconformably above 
the inclined beds of the Hudson-river rocks below. The depression of the accumu¬ 
lated matter along the axis of the Appalachians, displacing the yielding mass 
beneath, would cause an elevation or bulging of the ocean bed on the western side, 
which, at the distance of a hundred miles, might have risen so near to the surface 
as to prevent the accumulation of sediments; while the slope of gradually deepening 
waters towards the present mountain range would allow the formation of just such 
a set of strata as we now find, having their thickening edges towards the east, while 
they gradually thin out on the west. 
W© TE ©. 
From the study of the palmzoic formations in the Appalachian chain, and their 
distribution over the great plateau of the West, we discover why it is quite 
impossible to have uniformity in the nature of the strata, or in the conditions of 
the surface. The conditions accompanying the transportation and deposition of the 
sediments which took place along the lines which now mark the mountain chain, 
were very different from the conditions attending the accumulation on either side. 
We see that the mountainous region is mountainous, not from the folded and 
plicated condition of the beds constituting the mass, but because of former ac¬ 
cumulations of matter. The metamorphic condition is simply the result of the 
