On the Geological Age of the White Mountains. 419 
the more ancient Apalachian rocks, from the earliest to perhaps 
the Levant sandstones, suffered a contortion and general uplift in 
the region which is now the northern part of the Hudson valley, 
the same disturbance and elevation of the earth’s crust extended to 
the district which is now the White Mountain chain. If we con- 
ceive indeed the whole of the wide tract of undulating and in 
some places mountainous surface, from the upper Hudson and 
Lake Ontario, eastward’ to Maine inclusive, and possibly a large 
territory north of the St. Lawrence, to have emerged from the 
waters into-_permanent land, during the close of the Matinal period 
and the first ages of the Levant, while the still wider spaces to 
the S. W. and N. E. remained undisturbed, for the reception of 
later strata, we shall be able to interpret many important facts in 
the geological structure not only of this ancient district but in 
that of the neighboring regions. ; 
- The hypothesis which supposes that the bed of the Apalachian 
ocean was violently and extensively agitated by a succession of 
earthquake movements, at the end of the Matinal and early in the 
Levant periods, resulting in the ion of allnorthern New York 
and New England, and probably the whole southeastern border of 
that seainto permanent dry land, supplies us in the first place with 
an explanation of the unconformable superposition of the Levant 
upon the Matinal rocks, discovered by one of us in 1837 near the 
city of Hudson, and visible at a number of other points E. and 
N. E. of the Catskills. It furnishes moreover a cause for the ex- 
tremely wide diffusion, and the coarse conglomeritic composition of 
the early Levant sandstones, amid the pebbles and sand-grains of 
which, are many fragments obviously derived from the uplifted 
and broken Matinal and Primal strata. It provides furthermore 
a physical reason for the marked transition observable in the spe- 
cies, when we ascend from the organic remains of the Matinal to 
those of the Levant formations. An era of paroxysmal action 
would be naturally the period of a modification in the conditions 
and forms of life, for extensive and permanent changes would arise 
in the bed of the sea, the waters would grow shallow in many 
places, would deepen in others, their temperature and their cur- 
rents would alter, and even the proportions of the elements held 
in chemical solution, which are the very pabulum of the aquatic 
ald sustain change. But perhaps the most interesting 
races, 
application of the hypothesis here referred to, is the explanation 
